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Abstracts of Original Contributions ASNC2021 The 26th Annual Scientific Session of the American Society of Nuclear Cardiology

A Correction to this article was published on 19 October 2021

This article has been updated

Program Committee

Piotr J. Slomka, PhD, FASNC, Chair

Karthikeyan Ananthasubramaniam, MD, FASNC, Vice-chair

Niti Aggarwal, MD, FASNC

Mouaz Al-Mallah, MD, MSc, FASNC

Renee Bullock-Palmer, MD, FASNC

Dennis Calnon, MD, MASNC

Panithaya Chareonthaitawee, MD

Benjamin Chow, MD, FASNC

Sarah Cuddy, MB ChB

Robert deKemp, PhD, FASNC

Sharmila Dorbala, MD, MPH, MASNC

W. Lane Duvall, MD, FASNC

Cesia Gallegos, MD

Fadi Hage, MD, MASNC

Gary Heller, MD, PhD, MASNC

Robert Hendel, MD, MASNC

Chi Liu, PhD

Maria Mackin, CNMT, RT, RT(N)

Samia Massalha, MD

Robert Miller, MD

Venkatesh Murthy, MD, PhD, FASNC

Rene Packard, MD, PhD

Shivda Pandey, MD, FASNC

Krishna Patel, MD

Amalia Peix Gonzales, MD, PhD

Lawrence Phillips, MD, FASNC

Mehran Sadeghi, MD

Ibrahim Saeed, MD

Rupa Sanghani, MD, FASNC

Nishant Shah, MD, MPH, FASNC

Mrinali Shetty, MD

Albert Sinusas, MD, FASNC

Prem Soman, MD, PhD, MASNC

Brett Sperry, MD

Sina Tavakoli, MD, PhD

Javier Valencia Gomez, MD

Jaime Warren, CNMT, MBA

Kim Williams, MD, MASNC

ePoster Session 015: Beyond Perfusion

015-01

Clinical Use of 68Ga-DOTATATE PET/CT for Diagnosis and Response Assessment in Cardiac Sarcoidosis

H. Lee*,1 E. G. Peyster,2 K. C. Patterson,2 F. E. Marchlinski,2 L. R. Goldberg,2 M. D. Rossman,2 P. E. Bravo3; 1Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, PA, 2Department of Medicine, Hospital of the University of Pennsylvania, Philadelphia, PA, 3Department of Radiology & Department of Medicine, Hospital of the University of Pennsylvania, Philadelphia, PA

Introduction: Somatostatin receptor (SSTR) subtype 2 is expressed in sarcoid granulomas, and preliminary clinical studies have shown that myocardial sarcoidosis can be identified on SSTR-targeted imaging such as 68Ga-DOTATATE PET/CT. We examined the clinical use of 68Ga-DOTATATE PET/CT for diagnosis and response assessment in cardiac sarcoidosis compared to 18F-FDG PET/CT as the reference standard.

Methods: Ten patients with cardiac sarcoidosis and available cardiac 18F-FDG PET/CT with multifocal uptake were subsequently imaged with cardiac 68Ga-DOTATATE PET/CT. Background myocardial DOTATATE uptake was assessed using a four-point scale from moderate to absent. For each patient, the 68Ga-DOTATATE PET/CT was interpreted independently and was compared with 18F-FDG PET/CT for both overall interpretation and left ventricular segment-level positivity. In patients with focal areas of DOTATATE uptake, the maximum standardized uptake value in the left ventricular myocardium (SUVmax) was normalized to the mean blood-pool uptake and was compared between 68Ga-DOTATATE and 18F-FDG PET/CT using the paired t-test. Follow-up 68Ga-DOTATATE PET/CT was assessed for treatment response in 7 patients.

Results: 68Ga-DOTATATE PET/CT was obtained 46 ± 19 days after 18F-FDG PET/CT. Background myocardial DOTATATE uptake was moderate in 1 patient, mild in 6 patients, faint in 2 patients, and absent in 1 patient.

Overall patient-level interpretation was 90% concordant between 68Ga-DOTATATE and 18F-FDG PET/CT: 9 patients had focal or multifocal DOTATATE uptake suggestive of active cardiac sarcoidosis and 1 patient showed non-diagnostic diffuse DOTATATE uptake.

On segment-level analysis, 68Ga-DOTATATE PET/CT showed 77.7% agreement with 18F-FDG PET/CT (Kappa 0.53 ± 0.07). 75% (18 out of 24) of the false-negative lesions were located in the anterior, anteroseptal, septal, and inferoseptal segments. 71% (10 out of 14) of the false-positive lesions were located in the inferior and inferolateral segments.

The SUVmax to blood-pool uptake ratio was significantly lower on 68Ga-DOTATATE PET/CT compared to 18F-FDG PET/CT (mean of 2.3 vs 3.7, P = 0.006).

Follow-up 68Ga-DOTATATE PET/CT was obtained 8.0 ± 3.8 months after the initial PET/CT, and 1 out of 7 patients showed partial response to treatment. Among the 6 patients with follow-up 18F-FDG PET/CT, 3 patients showed treatment response, including two with complete response.

Conclusions: 68Ga-DOTATATE PET/CT can identify active cardiac sarcoidosis with high patient-level concordance when compared to 18F-FDG PET/CT. However, on segment-level analysis, it has considerable false-negative and false-negative rates with low signal-to-background ratio. Compared to 18F-FDG PET/CT, 68Ga-DOTATATE PET/CT tends to underestimate treatment response.

015-02

Evaluation of Disease Relapse After Cessation of Therapy in Patients with Cardiac Sarcoidosis Using PET/CT

C. Wiefels*, R. A. deKemp, R. S. Beanlands, P. B. Nery, D. Birnie; University of Ottawa Heart Institute, Ottawa, ON, Canada

Introduction: Cardiac involvement can be the first manifestation of sarcoidosis even in patients with systemic disease. Positron emission tomography (PET) imaging is an important diagnostic tool as it is able to detect active disease but is also useful in guiding therapy by detecting non-responsiveness or relapse. With the absence of randomized trials, first-line treatment with corticosteroids has been recommended by most experts during the past 50 years, but it is unknown if all patients should be treated nor for how long. We aimed to evaluate the incidence of relapse and patient characteristics associated with relapse after stopping initial therapy with steroids in patients with cardiac sarcoidosis (CS).

Methods: Consecutive newly diagnosed, treatment naive patients with clinically manifest cardiac sarcoidosis were prospectively recruited. All patients were treated with 0.5 mg·kg prednisone up to a maximum dose of 40mg OD. All patients had a follow-up PET scan after 3-6 months of therapy (FU PET1). Patients were then classified as responders or non-responders. In the responders, the prednisone was then weaned over 6 months and stopped. Three months after stopping, the PET was repeated to look for disease relapse (FU PET2). Evaluation with PET/CT included whole-body and dedicated cardiac imaging for the presence of extra-cardiac sarcoidosis using 18F-FDG, and myocardial perfusion at rest using 82Rb or 13N-ammonia to evaluate perfusion and LV function. Parameters evaluated included 18F-FDG distribution pattern in the myocardium (focal or focal on diffuse), LV SUVmax, LV SUVmean, RV uptake and summed rest score (SRS).

Results: Twenty patients were included and 19/20 were responders. Of these 14/19 relapsed after prednisone was stopped. There was no significant difference between age at presentation and patient’s sex among the two groups. Non-relapser patients had steroids for a longer time compared to the relapsers (529 ± 184 days vs 393 ± 110 days, P = 0.03, respectively). Focal myocardial uptake was the predominant pattern of 18F-FDG distribution both at baseline and after disease relapse. Twenty percent of the non-relapsers had RV uptake at presentation compared to 42% of the patients who had a relapse. Comparing the non-relapse and the relapse groups, SUV max was (mean ± SD): 11.1 ± 7.7 and 8.9 ± 0.2 (P = 0.2); 3.0 ± 1.1 and 3.7 ± 1.3 (P = 0.15) and 2.9 ± 1.0 and 7.8 ± 3.7 (P = 0.004) at baseline, FU PET 1 and FU PET2, respectively.

Conclusion: Therapy guided by serial PET scanning can identify a subset of patients with clinically manifest cardiac sarcoidosis who do not require chronic therapy.

015-03

Deep Learning for the Detection of ATTR Cardiac Amyloidosis on Cardiac Scintigraphy Imaging

R. M. Wehbe*,1 S. Dutta,1 S. Barutcu,1 F. S. Ahmad,1 J. D. Thomas,1 P. M. McCarthy,1 P. Kansal,1 T. A. Holly,2 A. K. Katsaggelos,1 S. J. Shah1; 1Northwestern University, Chicago, IL, 2University of California - Davis, Sacramento, CA

Introduction: Early and accurate diagnosis of transthyretin cardiac amyloidosis (ATTR-CA) is critical since targeted therapy has demonstrated benefits in improved survival and quality of life. Cardiac scintigraphy has emerged as a key diagnostic modality for ATTR-CA; however, “real-world” performance outside expert centers is likely worse than that reported in the literature given challenges in interpretation and lower pre-test probability of disease. We hypothesize that a deep-learning (DL) system could augment the discriminative performance of cardiac scintigraphy for detection of ATTR-CA.

Methods: We analyzed frontal planar images (at one hour only) from 161 consecutive patients (2018-2020) imaged with 99mTechnetium-pyrophosphate. Ground truth labels for ATTR-CA were derived from conclusive diagnostic evidence (biopsy or genetic testing), if available, followed by clinical interpretation of cardiac scintigraphy. Studies interpreted as “equivocal” with no follow-up confirmation were excluded due to labeling uncertainty. We reserved the most recent 69 studies for testing, simulating a prospective test set, with the remainder split 80%-20% into training and validation sets. To avoid overfitting, we used domain–domain transfer learning by first pre-training the DenseNet-121 convolutional neural network on chest X-ray classification (using the NIH CXR-14 dataset) and then fine tuning it on our training dataset.

Results: Our DL model exhibited excellent accuracy (96%) and discriminative performance (AUC 0.988) for detecting ATTR-CA in the test set (Figure 1A-B). Gradient class activation heatmaps demonstrated that the model appropriately assigned high importance to features in the cardiac silhouette (myocardial tracer uptake) for predicting ATTR-CA positivity (Figure 1C-D).

Conclusions: DL augmented interpretation has the potential to improve the discriminative performance of cardiac scintigraphy imaging for ATTR-CA diagnosis.

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015-04

The Use of SPECT/CT Quantification of 99m-Tc-PYP Uptake in the Evaluation of ATTR Cardiac Amyloidosis

M. Elsadany,1 C. Godoy Rivas,2 M. Hobocan,3 W. Duvall*2; 1Cardiology department, Hartford Hospital, Hartford, CT, 2Hartford Hospital, Hartford, CT, 3University of Connecticut School of Medicine, Farmington, CT

Background: 99m-Tc-PYP with planar and SPECT imaging is commonly used for the diagnosis of ATTR cardiac amyloidosis. However, the quantification of 99m-Tc-PYP uptake is based on a poorly reproducible semi-quantitative visual score and heart to contralateral lung ratio. A more robust method of quantifying uptake and reporting results would be beneficial and may be possible using volumetric assessment with fused SPECT/CT acquisition. The aim of this study was to evaluate novel quantitative software used to diagnose ATTR cardiac amyloidosis in patients who underwent 99m-Tc-PYP SPECT/CT imaging.

Methods: This was a retrospective, single-center study of consecutive patients who underwent 99m-Tc-PYP SPECT/CT imaging from September 2020 until June 2021. Quantification software was used to obtain standardized uptake values (SUVs) of 99m-Tc-PYP activity in the heart. The total SUVs, mean SUVs, and percentage of injected dose in the heart were obtained. Mean SUVs in the lung and bone were used to calculate heart to bone and heart to right lung ratios. SUV quantification was compared to final results from combined planar and SPECT/CT imaging.

Results: A total of 180 patients were imaged during this time with an average age of 73 ± 11, and 111 (61.7%) were male. 40 patients were positive for amyloid, 135 were negative, and 5 equivocal. The mean percentage of injected dose in positive patients was 3.6% vs 2.3% in negative patients (P < 0.0001). Similarly, the mean SUV was 2.5 vs 2.1 (P <0.0001). The mean total SUV in positive patients was 2803 compared to 1,973 in negative patients (P <0.0001). The average heart to bone ratio (1.5 vs 1.1, P < 0.0001) and heart to right lung ratio (3.2 vs 2.4, P <0.0001) also discriminated between abnormal and normal studies.

Conclusion: Volumetric software quantification may provide additional useful methods of evaluating 99m-Tc-PYP cardiac amyloidosis studies. This methodology may allow for a quantitative definition of a normal or abnormal 99m-Tc-PYP cardiac amyloid study and provide for the potential of following response to therapy.

figure b

015-05

Correlation of Quantitative Technetium Pyrophosphate with Transthyretin Cardiac Amyloidosis Disease Burden Assessed Using Cardiovascular Magnetic Resonance Imaging

R. Choo*,1 A. Szava-Kovats,1 D. Mah, 1 G. C. White,2 S. Cadet,3 N. M. Fine,2 A. Satriano,2 J. A. White,1 P. J. Slomka,3 D. Chan,1 R. J. Miller2; 1Department of Nuclear Medicine, University of Calgary, Calgary, AB, Canada, 2Department of Cardiac Sciences, University of Calgary, Calgary, AB, Canada, 3Department of Imaging, Medicine, and Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA

Introduction: 99m Tc-pyrophosphate (PYP) scintigraphy is a highly sensitive and specific non-invasive method to diagnose transthyretin cardiac amyloidosis (ATTR-CM). However, the correlation between abnormal myocardial PYP activities with disease burden has not been well described. Cardiovascular magnetic resonance (CMR) provides robust quantitative evaluation of disease burden and its impact on myocardial deformation. We performed a retrospective study to examine the relationship between PYP and CMR quantitative parameters in ATTR-CM patients.

Methods: Consecutive patients (N = 36) who underwent clinical PYP (imaged with GE NM Discovery 670) and CMR imaging diagnosed with ATTR-CM were included. PYP activity was quantified in myocardial segments according to the 17-segment model from SPECT images using dedicated research software, normalized to background activity. Native myocardial T1 (N = 20), extracellular volume (ECV, N = 8) were assessed in patients imaged with a 3T CMR scanner (Prisma or Skyra, Siemens Healthineers, Erlangen, Germany). 3D CMR strain analysis was also available in a subset (N = 25). We assessed the correlations between PYP uptake and CMR quantitative parameters.

Results: The mean age was 70.4 ± 1.4 years. There were no significant correlations between segmental or overall normalized radiotracer counts and left ventricular ejection fraction (LVEF) or left ventricular mass (P > 0.1 for all). There was significant correlation between normalized radiotracer counts with native myocardial T1 (Figure) and ECV (P < 0.05 for all). Mean radiotracer counts from the mid-segments correlated with longitudinal, circumferential, and radial strain (P < 0.05 for all).

Conclusions: Quantitative PYP measures correlate with CMR markers of disease burden. While there was no correlation with LVEF, there was correlation with measures of myocardial deformation. Quantitative PYP imaging may potentially be a useful marker of disease burden in ATTR-CM.

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015-06

High Prevalence of Microvascular Dysfunction in cardiac ATTR Amyloidosis: a CZT SPECT Study

R. A. Nieves*,1 J. Dietz,2 K. Hynal,2 J. Ibrahim,1 P. Soman1; 1University of Pittsburgh Medical Center, Pittsburgh, PA, 2UPMC Cardiovascular Institute, Pittsburgh, PA

Introduction: Cardiac ATTR amyloidosis (CA) is a disorder characterized by amyloid fibril infiltration of the myocardial extracellular space. A positron emission tomography study has suggested that microvascular dysfunction maybe prevalent in CA. Solid state SPECT myocardial perfusion imaging (MPI) can measure myocardial blood flow (MBF). We evaluated MBF in CA patients using a CZT SPECT system.

Methods: Patients with ATTR CA who underwent stress MPI were included. Regadenoson stress, and Tc-99m sestamibi (MIBI) injection were performed with the patient under the camera. The protocol consists of 9mCi and 30mCi of MIBI in 2 ml saline for the rest and stress studies, respectively, with the tracer injection performed 50 s after regadenoson stress using an automated injector, followed by a 40 mL saline flush. Data acquired in list mode were processed on the Cedars platform. Rate pressure product (RRP) and residual subtraction corrections were applied.

Results: Fourteen patients with available SPECT flow were included with average age of 75.8 years, 81.2% male, LVEF 48% ± 14.6 and LV septal thickness 1.68 cm ± 0.41. MPI did not show reversible perfusion defects in any patient. RRP corrected rest flow ranged from 0.27 to 1.04 ml·gm·min (0.58 ±0.26, median: 0.58). Peak stress flow (PSR) ranged from 0.63 to 2.6 ml·gm·min (1.38 ± 0.54, median: 1.45) with 13 (92%) patients having abnormal PSR (< 2 ml·gm·min) indicative of microvascular disease. All patients showed a vasodilator response, with MFR ranging from 1.89 to 4.32 (2.76 ± 0.86, median: 2.47).

Conclusions: Microvascular disease as determined by SPECT MBF quantification is prevalent in cardiac ATTR amyloidosis. Its mechanistic and therapeutic implications should be explored.

015-07

Treatment Response and Adverse Cardiovascular Events in Patients with Biopsy-proven versus Non-biopsy Proven Sarcoidosis

C. Rojulpote*,1 A. Bhattaru,1 P. Karambelkar,1 H. Lee,2 V. Patel,1 J. Rodriguez,1 P. E. Bravo1; 1University of Pennsylvania, Philadelphia, PA, 2Department of Radiology, University of Pennsylvania, Philadelphia, PA

Introduction: Patients with suspected cardiac sarcoidosis (CS) undergo FDG-PET imaging to assess disease activity. However, there are a paucity of data in the understanding of treatment response and major adverse cardiovascular events (MACE) amongst individuals with and without biopsy-proven disease.

Methods: We identified 83 patients with suspected CS (53 ± 1.8 years, 71% males, 69% white) who had evidence of myocardial inflammation at baseline, were treatment naïve, and underwent repeat PET imaging after treatment initiation. Our cohort was divided into three groups as follows: Group (1) biopsy-proven sarcoidosis (N = 51); Group (2) non-biopsy-proven sarcoidosis with extra-cardiac inflammation at baseline (N = 18); Group (3) non-biopsy-proven sarcoidosis without extra-cardiac inflammation (N = 14). Follow-up PET scans were reported as complete myocardial suppression (CMS), partial myocardial suppression (PMS), or no suppression (NS). Treatment response was defined as CMS/PMS. Patients were also followed for the occurrence of MACE defined as sustained ventricular tachycardia/ventricular fibrillation (VT/VF), heart failure (HF) admission, and death with Cox regressions compared to Group 1 as the reference.

Results: Biopsy-proven patients with suspected CS were most likely to achieve suppression after treatment when compared to both non-biopsy-proven suspected CS with extracardiac features and isolated CS (80.4% vs 61.1% vs 50%, P = 0.048). Risk for MACE was not significantly different between the three groups (Hazardgroup 2 1.9; Hazardgroup 3 1.7; P = 0.11, Figure 1). However, there was a trend for better outcomes amongst biopsy-confirmed patients.

Conclusion: A difference in myocardial FDG suppression rates was noted in biopsy-proven suspected CS patients in comparison to non-biopsy-proven patients, irrespective of prednisone dose. Moreover, isolated CS patients had inferior suppression rates in comparison to the remaining cohort.

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015-08

SPECT/CT Quantification of 99mTc-PYP Uptake to Assess Tafamidis Treatment Response in ATTR Cardiac Amyloidosis

C. Godoy Rivas,1 M. Elsadany,2 S. Arora,1 A. Jaiswal,1 A. Weissler-Snir,1 W. Duvall*1; 1Hartford Hospital, Hartford, CT, 2Cardiology department, Hartford Hospital, Hartford, CT

Background: Tc-99m-PYP is commonly used to diagnose transthyretin (ATTR) cardiac amyloidosis employing only limited quantification with a visual score and a heart to contralateral lung ratio. SPECT/CT acquisition and analysis with dedicated software can provide volumetric assessment and quantification of cardiac tracer uptake. While therapy for ATTR cardiac amyloid is available with tafamidis, there are no data regarding the longitudinal assessment of 99mTc-PYP imaging findings to determine if treatment with tafamidis results in any change in quantitative measures of tracer uptake.

Methods: A prospective, single-center, study of patients with ATTR cardiac amyloid being treated with tafamidis who had baseline and follow-up 99mTc-PYP studies. SPECT/CT quantification software was used to quantify heart, lung, and bone tracer uptake and generate standardized uptake values (SUVs). Comparison of baseline (before treatment) total SUVs, mean SUV value, percentage of the injected dose, mean SUV of heart to mean SUV of bone ratio, and to mean SUV of right lung ratio was made to the values obtained at follow-up. Measurements were obtained from the whole heart and the isolated left ventricle by 2 physicians and the results averaged.

Results: Seventeen patients were analyzed with a mean age 75.6 ± 8.7, 82% were males, and a mean length of tafamidis therapy at repeat imaging of 9.8 ± 3.7 months. At follow-up, there was an average change in left ventricular total SUV counts of − 7.9 ± 18.9%, in the mean SUV value of − 0.7 ± 19.9% and in the percentage of injected dose of − 8.4 ± 18.2%. Less pronounced changes were seen in the whole heart measurements. Heart to bone and heart to lung ratios showed a mixed response to therapy. Detailed results are provided in the table.

Conclusion: The quantitative SUV measurements showed mild, although mixed improvement with tafamidis treatment. The length of time on treatment was relatively short, and continued assessment is warranted. This new technique offers a potential method for following tafamidis therapy and assessing the cardiac amyloid burden.

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015-09

Serial Quantitative 99mTc Pyrophosphate Imaging in Transthyretin Amyloid Cardiomyopathy Patients Treated with Tafamidis

S. Gill*,1 P. Chandrashekar,2 S. Warner,1 L. Al-Rashdan,1 Y. Burton,1 A. Masri1; 1Oregon Health & Science University, Portland, OR, 2Knight Cardiovascular Institute, Oregon Health & Science University, Portland, OR

Introduction: Our group recently evaluated 2D LV myocardium to descending aorta mean counts ratio (2D TBR) as a quantitative method for myocardial 99mTc-PYP tracer uptake on SPECT imaging. It is unknown if tafamidis use affects PYP uptake. In this report, we describe the longitudinal change of 2D TBR in patients with transthyretin amyloid cardiomyopathy (ATTR-CM) on tafamidis as compared to controls.

Methods: Six patients with known ATTR-CM on tafamidis therapy and 4 controls who each underwent two serial PYP SPECT scans were included. PYP uptake was quantified using 2D TBR and change in uptake was compared using Mann-Whitney U test.

Results: Six ATTR-CM patients (100% male, 100% wtATTR; mean age 72 ± 3.4 years) received tafamidis therapy for a median of 1.2 (range 0.6-2.2) years before the second PYP scan. Five were ESC Stage 1 (other ESC Stage 3), and 50% were on diuretic therapy. Controls were 75% female (all were ATTR variant carriers undergoing screening for ATTR-CM), mean age of 53 ± 9.6 years at first PYP scan with mean septum thickness of 9.2 ± 2.7 mm. Their 2nd PYP scan was performed a median of 2.1 years later. PYP quantification was not significantly different between two consecutive scans among ATTR-CM patients on tafamidis (Fig 1). All PYPs among ATTR-CM demonstrated Perugini Grade 3 uptake, with only a single scan changing from Grade 3 to 2.

Conclusions: Use of tafamidis in ATTR-CM was associated with stable 99mTc PYP uptake on SPECT imaging without evidence of regression. Larger studies are needed to confirm these findings and investigate if transthyretin silencers affect quantitative 99mTc PYP myocardial uptake.

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015-10

Correlation of a Practical 99mTc Pyrophosphate Quantification Method with Severity of Disease and Echocardiographic Features of Transthyretin Amyloid Cardiomyopathy

P. Chandrashekar*, S. Gill, S. Warner, L. Al-Rashdan, Y. Burton, A. Masri; Oregon Health & Science University, Portland, OR

Introduction: There are no current accepted methods for PYP quantification of SPECT imaging. It is unclear if the degree of 99mTc-PYP uptake on SPECT imaging correlates with the severity of disease or echo characteristics. We investigated the correlation of two methods of SPECT imaging quantification with clinical and echocardiographic markers of severity disease.

Methods: Approach to quantifying PYP uptake in 30 patients with ATTR-CM is summarized in Figure 1. We calculated the correlation with clinical and echocardiographic variables using Pearson’s or Spearman’s correlation coefficient as appropriate.

Results: Clinical markers of severity of ATTR-CM (NYHA class, NAC ATTR Stage, and NT-proBNP) were not found to significantly correlate with quantified PYP uptake using the 2 different TBR methods (Table 1). There was a weak negative correlation between 2DTBR-LV-DAo with left atrial volume index (r = − 42; P = 0.02) as well as stroke volume index (r = − 0.37; P = 0.05).

Conclusions: In this pilot study, quantification of PYP uptake on SPECT was not found to strongly correlate with most clinical or echo variables in ATTR-CM. Larger studies are warranted to further investigate this as well as estimate correlation with clinical outcomes.

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015-11

[99mTc]Tc-DPD Imaging for Transthyretin Cardiac Amyloidosis. Single Center Experience

A. Teresinska*, K. Jozwik-Plebanek, J. Wnuk, M. Cacko, M. Gawor, J. Grzybowski; National Institute of Cardiology, Warsaw, Poland

Introduction: Most common types of cardiac amyloidosis (CA) are light chain amyloidosis (AL) and transthyretin amyloidosis (ATTR). Differentiation between AL CA and ATTR CA is of high therapeutic and prognostic importance. An algorithm of noninvasive diagnosis of ATTR CA, based on bone scintigraphy (SCINT), has been proposed (Gillmore’s algorithm) (Gillmore et al, Circulation 2016). <b>Aim:</b> To describe the exploitation and evaluate the utility of [99mTc]Tc-DPD (DPD) SCINT in the differential diagnosis of cardiomyopaties in patients (pts) with a suspicion of CA in a single cardiac center.

Methods: During 2.5 years since the introduction of DPD SCINT for routine diagnostics (Aug 2018) in our cardiac center, the test was performed in 100 pts (69M,31F) with a cardiomyopathy and with a suspicion of CA based on the clinics and ECHO and/or CMR. Whole-body, chest planar, and chest SPECT (if planar was positive) imaging was performed 3 hours after DPD injection. Semi-quantitative visual grading of myocardial DPD uptake by comparison to bone (rib) uptake was performed according to four-grade Perugini scale (grade 0—no uptake, grade 3—uptake grater than rib uptake with mild/absent rib uptake). Images were assessed by 2 independent observers experienced in nuclear medicine and in case of discrepancy the result was established by consensus. In all the points, the assay of a monoclonal protein in blood and urine (MPb/u) was performed. Extended diagnostics (DIAG-EXT) included histology and hematological examination.

Results: Cardiac uptake of DPD was observed in 26 pts (26%): grade 3 – in 22 pts, grade 2 – in 2 pts, and grade 1 – in 2 pts. The inter-observer variability was 0% in cases of grade 0 and grade 3 (agreement of 100%). In cases of grade 1 or 2, the result was established by consensus. In 14 of 24 pts with grade 2 or 3 (‘high’) DPD cardiac uptake and no evidence of MPb/u, ATTR was diagnosed according to Gillmore’s algorithm. On the basis of DIAG-EXT, (a) in all the remaining 10 pts with grade 2 or 3, ATTR was recognized, (b) in both pts with grade 1, AL was recognized, (c) among 73 pts without DPD cardiac uptake, no ATTR was recognized. Altogether, ATTR was diagnosed in all the 24 pts with grade 2 or 3 and ATTR was not diagnosed in any of the 76 pts with grade 0 or 1.

Conclusions: DPD SCINT is a method easy in terms of acquisition and highly reproducible in terms of image interpretation for CA. In 58% of pts with ATTR CA, the result of SCINT (high DPD cardiac uptake) in conjunction with lack of MPb/u allowed to make a diagnosis of ATTR CA without additional diagnostics, on the basis of Gillmore’s algorithm. However, as our population of pts referred for an examination for CA consisted of 24% of pts with ATTR CA, it concerned only 14% of the whole population studied.

015-12

Post-test Management and Clinical Outcomes of Patients with Suspected Cardiac Amyloidosis and Equivocal Tc-99m Pyrophosphate Scans

S. Jamal*,1 A. ElZouhbi,1 Z. Altaha,2 Y. Manla,1 F. Al Badarin1; 1Cleveland Clinic Abu Dhabi, Abu Dhabi, United Arab Emirates, 2Sh Shakhbout Medical Center, Abu Dhabi, United Arab Emirates

Introduction: While significant cardiac uptake of Tc-99m pyrophosphate (PYP) is consistent with transthyretin cardiomyopathy (ATTR-CM) in patients with suspected cardiac amyloidosis, there is paucity of data on the importance of milder degrees of PYP uptake. Accordingly, we sought to describe post-test management and clinical outcomes in patients with equivocal PYP studies.

Methods: Consecutive patients referred for PYP cardiac scintigraphy at a single center (10/2018–10/2020) were identified. Data on patient demographics, baseline characteristics, PYP scan interpretation, subsequent utilization of cardiac imaging studies, heart failure hospitalizations, and death were retrospectively collected through review of electronic medical records. Scans were interpreted as “strongly suggestive,” “equivocal,” or “non-suggestive” based on combined input from semi-quantitative (Perugini Grade) and quantitative—expressed as heart to contralateral lung ratio (H/L)—myocardial uptake, according to published guidelines.

Results: A total of 149 unique patients underwent PYP imaging (mean age 68.4 ± 12.3 years; 52.3% women). SPECT was used in 35.6% of the studies and SPECT/CT in 63.1%. Overall, 40 (26.8%) patients were deemed to have “strongly suggestive” scans, 77 (51.7%) had “equivocal scans, while the rest were deemed to have “non-suggestive” studies.

Conclusion: In this single-center experience, half of the patients referred for cardiac amyloidosis screening were found to have equivocal PYP studies. This finding was associated high rates of downstream testing but no increase in subsequent cardiac amyloidosis diagnosis, heart failure hospitalization, or death.

015-13

Use of 99mTc-PYP Scintigraphy in Patients with Suspected Cardiac Amyloidosis – Experience of a Nuclear Medicine Department in a Cardiology Hospital

I. Palazzo*,1 N. Correa,1 W. Ker,1 F. Costa,1 A. Cotrado,1 C. T. Mesquita2; 1Hospital Procardiaco, rio de janeiro, Brazil, 2Radiology Department, Universidade Federal Fluminense, Niteroi, Brazil

Introduction: Display the use of pyrophosphate (99mTc-PYP) scintigraphy in patients with suspected cardiac amyloidosis. Cardiac amyloidosis can be divided into two main groups, the first being the light chain (AL) and the second transthyretin (ATTR), with completely different prognoses and treatments.

Methods: Retrospective analysis of consecutive exams between October 2017 and March 2021 with 99mTc-PYP scintigraphy. The diagnostic criteria included visual analysis (grade 0 – without myocardial uptake / grade 1 – myocardium uptake less than the rib uptake/ grade 2 – myocardium uptake equal to the rib uptake / grade 3 – myocardium uptake greater than the rib with reduced or absent rib uptake), analysis of the heart to contralateral lung ratio at 1 hour (H/CL) and SPECT-CT images. Suggestive studies for ATTR amyloidosis were those that had grade 2 or 3, H/CL ratio> 1.5 and that in SPECT-CT with myocardium uptake.

Results: A total of 43 scintigraphies were performed the studied period. There were 11 studies performed from January to March 2021 versus 10 in 2020 and 13 in 2019. There were 15 women and 28 men (62.74% male) with an average age of 77.8 ± 12 years. Scintigraphic criteria for ATTR amyloidosis were met in 19 patients (44.18%) with a predominance of males, with only 2 women (17 vs 2, P = 0.002). The comparison of visual analysis and H/CL ratio showed good correlation between the methods, grades 0 and 1 showed H/CL ratio values of 1.13 and 1.10 respectively, and grades 2/3 showed average H/CL ratio CL of 1.68 (P < 0.001). Of the total of 43, in 2 cases, the SPECT-CT changed the interpretation of the final report. In one patient with grade 2 uptake, the SPECT-CT showed blood-pool uptake and in the second patient with costochondritis SPECT-CT images confirmed myocardial uptake.

Conclusions: The use of 99mTc-PYP scintigraphy for cardiac amyloidosis is crucial, it allows to differentiate AL and ATTR amyloidosis and can be a substitute for endomyocardial biopsy in those patients who have suspected echocardiogram and/or Magnetic resonance imaging and also have the AL amyloidosis excluded. The assess of monoclonal protein is of great importance for the correct interpretation of the 99mTc-PYP scintigraphy and to avoid imaging pitfalls. Scintigraphy is a simple, inexpensive, reproducible exam that can reduce costs and morbidity for patients compared to endomyocardial biopsy.

ePoster Session 112: Myocardial Perfusion and Function Imaging

112-01

Identifying Coronary Collateral Flow Capacity in Patients with Chronic Total Occlusion Treated with External Counterpulsation Using PET Myocardial Perfusion Imaging

M. E. Merhige*,1 C. Davis,2 J. Keppler,2 K. Wilson,2 C. Knapp3; 1SUNY@Buffalo, Buffalo, NY, 2Michael E. Merhige M.D., L.L.C., Tonawanda, NY, 3ECP of Western New York, Amherst, NY

Introduction: Noninvasive augmentation of diastolic blood pressure with external counterpulsation (ECP) has been shown to improve collateral flow index in man. We sought to measure coronary collateral flow capacity (CCFC) noninvasively, in patients with chronic total coronary occlusion (CTO), treated with ECP using PET myocardial perfusion imaging (MPI). We hypothesized that flow into the ischemic bed measured with vasodilator stress (DIP), which reduces supply side pressure causing coronary steal, would improve with dobutamine stress (DBT) which maintains supply-side pressure, identifying the presence and adequacy of collateral circulation.

Methods: Seven patients with CTO, treated with 35 one-hour sessions of ECP, were studied with both DIP and DOB stress PET MPI. Absolute flows and coronary flow capacity (CFC), which integrates absolute rest and stress flow with coronary flow reserve on a per pixel basis, were measured objectively with FDA approved HeartSee software.

Results: The figure shows CFC in the same patient with CTO of both the right and LAD coronary arteries after ECP therapy, imaged with DIP (top row) and DBT (second row). Both global and regional CFC into the ischemic bed, improved significantly during demand ischemic stress compared to vasodilator stress (KS = 0.93; P < 0.001), identifying successful collaterogenesis. All 7 patients demonstrated a decrease in the size of the ischemic zone at risk, defined as moderate or severely reduced CFC, when CFC with DIP was compared with DOB: 28% LV mass vs 5%; P < 0.02. Absolute stress flow into the ischemic zone (lowest myocardial quadrant) improved significantly in ECP-treated patients during demand ischemia compared with vasodilator stress (1.9 vs 1 ml·min·g; P < 0.02). One of two patients who did not improve global CFC significantly, despite ECP treatment, underwent coronary arteriography demonstrating a new flow limiting stenosis in the supply-side vessel, which was successfully stented.

Conclusion: Quantitative PETMPI identifies coronary collateral flow capacity in patients with CTO, treated with ECP.

figure h

112-02

Relative Contribution of Perfusion and Non-Perfusion High-Risk Markers on Rb-82 PET Myocardial Perfusion Imaging for Diagnosis of High-risk Coronary Artery Disease

F. Patel*,1 A. Singh,1 K. Lehenbauer,2 A. McGhie,2 T. M. Bateman,2 K. K. Patel3; 1St. Luke's Mid America Heart Institute, Kansas City, MO, 2St. Luke's Mid America Heart Institute, Kansas City, MO, 3Cardiology, St. Luke’s' Mid America Heart Institute, Kansas City, MO

Introduction: Relative perfusion assessment with MPI often underestimates the extent of ischemia in patients with balanced ischemia from high-risk CAD. Non-perfusion high-risk markers on PET such as reduced myocardial blood flow reserve (MBFR), LVEF, LVEF reserve (LVEF-R), and transient ischemic dilation (TID) contribute to increased sensitivity and diagnostic accuracy of PET. We aimed to study the relative contribution of perfusion and non-perfusion high-risk markers on PET in diagnosis of high-risk CAD.

Methods: Out of 1282 patients who underwent coronary angiogram within 6 months of Rb-82 PET MPI between 2010 and 2016, we included patients with significant left main (≥ 50% stenosis, LM) and multi-vessel CAD (≥ 2 epicardial stenosis ≥ 70%, MVD). Rates of LM and MVD were estimated among patients with normal (0%), mild (1–10%) and moderate-severely abnormal (> 10%) perfusion. For patients with high-risk CAD and normal perfusion, prevalence of non-perfusion high-risk markers on PET were estimated.

Results: Significant LM stenosis was present in 91 (7%) and MVD in 478 (37%). Overall, 82% had >10% perfusion defect, 28% had transient ischemic dilation, 32% had LVEF < 50%, 48% had LVEF-R< 0%, 69% had MBFR < 2 and 87% had stress MBF < 1.6 ml·min·g. Of patients with LM, 2% (N = 2) had normal perfusion, 20% (N = 18) mild and 78% (N = 71) had moderate-severely abnormal perfusion. Both patients with LM and normal perfusion had at least 2 non-perfusion high-risk markers. Of patients with MVD, normal, mild, and moderate-severely abnormal perfusion was present in 3% (N = 15), 15% (N = 70), and 82% (N = 393), respectively (Figure). Of the 15 patients with normal perfusion and MVD, 2 (13%) had no high-risk markers, and 8 (53%) had at least two.

Conclusion: The rate of high-risk CAD resulting in normal perfusion on PET is 3%. Non-perfusion high-risk markers on PET helped identify high-risk CAD in 99.6% of these patients. High-risk CAD is unlikely to be missed if PET MPI is used as a gatekeeper for catheterization

figure i

112-03

Going Beyond Summed Stress Scores: Correlating Global and Territorial Coronary Flow Reserve by Single-Photon Emission Tomography with Routine Myocardial Perfusion Imaging

A. S. Koh*,1 B. M. Keng,2 X. Teng,2 R. Tan,1 L. Baskaran,2 T. Chua,3 F. Keng1; 1National Heart Centre Singapore; Duke-NUS Medical School, Singapore, Singapore, 2National Heart Centre Singapore, Singapore, Singapore, 3Cardiology, National Heart Centre Singapore; Duke-NUS Medical School, Singapore, Singapore

Introduction: The ability to use single-photon emission tomography (SPECT) to measure myocardial blood flow (MBF) through dynamic acquisition represents a major advance for SPECT laboratories in this decade, providing greater sensitivity towards coronary health assessment, beyond semi-quantitative myocardial perfusion imaging (MPI). We determined global and territorial MBF in absolute quantitation by dynamic SPECT, in relation to grades of abnormality on routine MPI.

Methods: We studied SPECT MPI images of consecutive clinical subjects who underwent vasodilator gated MPI stress and rest studies. Measurements of routine static myocardial perfusion were compared with dynamic measurements of MBF for each subject using standard software package. For MBF, we computed global and territorial [i.e., left anterior descending (LAD), left circumflex (LCX), right coronary artery (RCA)] coronary flow reserve (CFR). CFR was calculated by dividing stress MBF with rest MBF. Coronary flow reserve cut-off value of < 2.5 for each coronary territory is used to define abnormality.

Results: Of 90 subjects (mean age 67 ± 8 years; 68 (76%) males), 44 (49%) had normal MPI (summed stress score (SSS) < 3; LV ejection fraction > 50%). There was a graded reduction in global and territorial CFR in all coronary arteries across SSS categories from normal, mildly to moderately, to severely abnormal MPI (Figure 1). Table 1 shows mean MBF values for each SSS category. Among normal MPI scans, patients who had abnormal global CFR had lower LAD CFR (1.94 ± 0.27 vs 2.96 ± 0.59, P < 0.0001), LCX CFR (1.92 ± 0.46 vs 3.19 ± 0.47, P < 0.0001), RCA CFR (2.14 ± 0.37 vs 3.52 ± 0.51, P < 0.0001), and were older in age (69 ± 7 vs 62 ± 9 years, P = 0.034). Correlation of CFR with age was significant with LAD, LCX, and RCA CFR (Figure 2).

Conclusions: We present global and territorial MBF values corresponding to SSS categories determined by dynamic SPECT. Abnormal CFR values in otherwise normal MPI scans may suggest a particular role for dynamic SPECT in certain higher risk populations such as older adults, enabling finer risk stratification.

figure j

112-04

Mechanical Myocardial Dysynchrony evaluated with Gated SPECT Phase Analysis for Cardiovascular Risk Prediction

L. Gutierrez*,1 F. A. Peñafort2; 1Instituto de Diagnostico y Resonancia de Mendoza, Mendoza, Argentina, 2Penta Medicina Cardiovascular, Mendoza, Argentina

Introduction: Through functional images, we found several variables for the appropriate stratification of cardiovascular risk in patients (p) with ischemic heart disease. Through Phase Analysis (PA) from MPI, we can assesses Mechanical Myocardial Dysynchrony (MMD) and given incremental prognostic value simultaneously with perfusion and function

We analyze the predictive value of MMD in MPI by Phase Analysis, (PA) identifying groups of risk

Methods: We retrospectively evaluated an outpatient population of 1041(p) with a prospectively telephone follow-up. We analyze MPI MMD parameters and clinical events in their evolution. MMD analysis groups by PA were created; G1: Absence of MMD; G2: MMD only Rest; G3: MMD only Stress; G4: MMD in Stress and Rest. Combined Outcome (O.CV) of Cardiac Death (CM) + Heart Failure Hospitalization was analyzed. Statistical analysis was performed using frequency analysis, multivariate Cox regression to identify predictors, and Kaplan-Meier survival curves in follow-up. A P value of < 0.05 was considered statistically significant.

Results: The follow-up period was a median of 27 months with ranges of (1 month–114 months). G1: 946p (90.8%); G2: 32p (3.2%); G3: 18p (1.7%); and G4: 45p (4.3%). Incidence of O.CV was for G1: 26p (2.7%); G2: 4p (12.5%); G3: 2p (11.1%); G4: 12 p (26.7%) P: < 0.001. During our follow-up, we observed an event-free survival time mean for O.CV G1: 108 ± 1.2 months; G2: 69 ± 5.7 months; G3: 78 ± 8.6 months; G4: 68 ± 6.5 months P: < 0.001. Independent variables for O.CV were quantification of Moderate Scar OR: 8.2 (95% CI 3.78-18.07) P < 0.001 and Severe Scar OR: 3.4 (95% CI 1.24-9.8) P: < 0.018. Regarding the groups analyzed, we observed that G2 presented an OR: 4.4 (95% CI 1.5-12.9) P: 0.007 and G4 presented an OR: 4.4 (95% CI 1.76-11, 4) P: 0.002

Conclusions: The evaluation of the Mechanical Myocardial Dysynchrony by Phase Analysis from Gated SPECT allowed to incorporate a robust parameter of risk stratification of the combined event for Cardiac Outcome.CV in our registry.

figure k

112-05

Impact of Glycosylated Hemoglobin HBA1C on Myocardial Perfusion and Function by Gated Myocardial Perfusion SPECT imaging

H. Nasr*,1 H. Alsomali2; 1Nuclear Medicine Unit, Faculty of Medicine, Cairo University, Cairo, Egypt, 2Radiology Department, Security Forces Hospital Program (SFHP), Riyadh, Saudi Arabia

Introduction: Glycosylated hemoglobin (HbA1c) allows for long-term blood glucose level monitoring and may be helpful for early detection of cardiovascular complications related to diabetes mellitus or abnormal glucose homeostasis. Our aim is to assess the relation of HBA1C to perfusion and function parameters on GMPS imaging.

Methods: We retrospectively reviewed 200 patients who had GMPS studies. Data collected included patients’ demographics, clinical data, and lab findings (HTN, smoking, dyspnea, chest pain, DM, HA1C, total cholesterol, HDL and LDL), perfusion parameters (SSS, SRS, SDS, and TPD), function, and gated parameters (EF, EDV, ESV and wall motion abnormalities (WMA)). We used unpaired student T-test to compare mean values of continuous variables. ROC analysis was used to define the cutoff values for HA1C that best identifies patients with abnormal GMPS parameters. Chi-square test was used to compare difference in frequency between categorical variables. Pearson correlation was used to assess the correlation between continuous variables.

Results: The study included 200 patients (mean age of 58.21±11.53 years; 102 (51%) males). Study included 132 (66%) diabetic patients. The mean HBA1C in diabetic patients was significantly higher compared to non-diabetic group (7.92±1.99 vs 6.05±0.99; P < 0.001). HBA1C% was negatively correlated to EF% and HDL (r = − 0.262; P < 0.001 and r = − 0.316; P < 0.001, respectively) while it was positively correlated to EDV and ESV (r = 0.291; P < 0.001 and r = 0.221; P = 0.002, respectively). The mean EF% and HDL were significantly lower in patients with HGA1C% > 6.5 (53.17 ± 14.55 vs 57.8 ± 12.61; P = 0.017) and (1.046 ± 0.262 vs 1.196 ± 0.295; P < 0.001). Patients with HGA1C% > 6.5 had more frequency of EF < 50% (30.0% vs 15.6%; P = 0.017), more incidence of WMA (24.5% vs 12.2%; P = 0.027) and more ESV > 44 ml (38.2% vs 20.0%; P = 0.005). Patients with HGA1C% > 6.5 had more prevalence of hypertension (77.3% vs 54.4%; P = 0.001) and more frequency of dyspnea (27.3% vs 15.6%; P = 0.047); however, with less prevalence of chest pain (70.9% vs 83.3%; P = 0.039). In diabetic patients subgroup again, there was lower mean EF% and HDL in patients with HGA1C% > 7.5 (52.0 ± 14.59 vs 57.6 ± 11.55; P = 0.018 and 1.005 ± 0.239 vs 1.148 ± 0.273; P < 0.002, respectively). Also HGA1C% > 7.5 revealed more frequent EF < 50% (33.3% vs 14.5%; P = 0.011), WMA (30.2% vs 11.6%; P = 0.008), more ESV > 44 ml (41.3% vs 20.3%; P = 0.009) and in addition more EDV > 100 ml (34.9% vs 18.8%; P = 0.037). No statistically significant relation could be found between HBA1C% and GMPS perfusion parameters including SSS, SRS, SDS, and TPD%.

Conclusions: A higher HBA1C% was associated with multiple function parameters abnormalities including lower EF, more WMA and larger ESV in addition to larger EDV in diabetic patient population. Unfortunately no significant association was found between HBA1C% and perfusion parameters.

112-06

Assessment of Stress-induced Left Ventricular Diastolic Dysfunction using GSPECT among Obese Filipinos with Normal Myocardial Perfusion Imaging

A. L. Ramos-Manalaysay*; St. Luke's Medical Center, Quezon City, Philippines

Introduction: LV diastolic dysfunction is prevalent among obese but remained undiagnosed with echocardiography alone. Evaluation of LVDD using GSPECT is rarely done. Studies reported that diastolic dysfunction evaluated by echocardiography correlated with LVDD by GSPECT. Addition of cardiac stress may unmask diastolic abnormalities that are not evident at rest. Early diagnosis and management of LVDD may prevent the development of overt heart failure.

Methods: 160 Filipino patients who underwent one-day rest/stress (treadmill or dipyridamole) 99mTc-sestamibi myocardial perfusion imaging with GSPECT between January 2016 and January 2020 in our institution were included in the study given that they have a normal MPI, resting systolic, and diastolic parameters. Patients with known CAD, hypertension, diabetes, heart failure, pericardial disease, and moderate to severe valvular heart disease were excluded. Included patients were grouped into 3 BMI class: Normal weight, overweight, and obese. The % rest-to-stress difference of the G-SPECT diastolic parameters (PFR, MFR/3, TTPF) was determined and compared among groups and among different stressors (Treadmill exercise vs Dipyridamole). Data were analyzed using ANOVA and Kruskal–Wallis test. Tukey test and Dunn’s test were used for post-hoc analysis.

Results: Findings showed no significant differences in PFR and TTPF among the BMI classes at baseline and after stress test. The resting MFR/3 was significantly lower among obese patients compared to the other two groups (P = .027). The % rest-to-stress decrease of MFR/3 was lower in normal BMI patients than in overweight or obese patients (P = .009).

Conclusions: No significant differences in PFR and TTPF among the BMI classes at baseline and after stress test. The resting MFR/3 was significantly lower among obese patients compared to the other two groups (P = .027). The % rest-to-stress decrease of MFR/3 was lower in normal BMI patients than in overweight or obese patients (P = .009).

112-07

Randomized Clinical Trial of Positron Emission Tomography-Derived Pixel-Level Coronary Flow Capacity to Guide Immediate Revascularization in Patients with Stable Coronary Artery Disease (PETREVASC): Study Rationale and Design

F. M. Lang*,1 M. Argenziano,1 K. L. Gould,2 K. P. Rentrop3; 1Division of Cardiothoracic Surgery, Department of Surgery, Columbia University Vagelos College of Physicians & Surgeons, New York, NY, 2Weatherhead PET Center for Preventing and Reversing Atherosclerosis, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, 3Division of Cardiology, Department of Medicine, Columbia University Vagelos College of Physicians & Surgeons; Gramercy Cardiac Diagnostic Services, New York, NY

Background: Positron emission tomography (PET) myocardial perfusion imaging (MPI) is the only modality capable of non-invasively measuring absolute myocardial blood flow (MBF) in patients with coronary artery disease (CAD). Recent guidelines for PET MPI advocate for a 17-segment evaluation of coronary flow reserve (CFR), which is the ratio of stress MBF (sMBF) to rest MBF (rMBF). However, this methodology does not track artery-specific perfusion, and CFR can be misleading under certain physiological conditions. Developed to overcome these limitations, coronary flow capacity (CFC) is a categorical measure utilizing a two-dimensional scatterplot of CFR and sMBF to classify different levels of ischemia burden at the pixel level. Prospective observational studies in stable CAD patients have suggested that CFC is a superior metric for predicting major adverse cardiovascular events (MACE) and improved post-revascularization survival compared with CFR, sMBF, and relative flow. This hypothesis could profoundly affect clinical practice if verified in randomized studies.

Methods: We are conducting the first randomized clinical trial using PET CFC to guide enrollment prior to revascularization (PETREVASC). The study’s primary objective is to assess whether optimal medical therapy (OMT) can reduce the extent of myocardial perfusion abnormalities as effectively as immediate revascularization in stable CAD patients who have reduced CFC. Patients will be randomized 1:1 to receive OMT with immediate revascularization (active) or OMT without immediate revascularization (control). Patients will undergo PET MPI at Screening, Day 105, and Day 365. Patients in the control group will have the option to receive revascularization any time after Day 105. The study population includes patients who have ≥ 10% of left ventricle (LV) with CFCgreen (sMBF 0.83 to 1.09 ml·min·g and CFR 1.27 to 1.60) and at least one pixel with CFCblue (sMBF ≤ 0.83 ml min g and CFR ≤ 1.27) OR ≥ 2% of LV with CFCblue. Observational data suggest that these patients are at substantial risk of MACE. Patients with a large myocardial scar (rest relative defect in > 5% of LV) are excluded. The primary endpoint of the study is change from baseline to Day 105 in the % of LV with CFCblue plus CFCgreen. This endpoint was chosen as a surrogate for MACE and death. Secondary endpoints include changes from baseline to Day 105 and Day 365 in other PET perfusion metrics (e.g. CFR), MACE rate, and adverse event rate. We will also assess whether PET processing differs significantly between a secondary care practice and a tertiary academic core laboratory. We plan to randomize 104 patients (Δ = 15, SD = 20, α = 0.05, power = 90%). The study has been reviewed and approved by WCG IRB. Recruitment is currently ongoing at Gramercy Cardiac Diagnostic Services, a secondary care practice in New York. University of Texas Health Science Center at Houston is the study sponsor.

112-08

The Safety of Cardiac Stress Testing in Patients with Carotid Stenosis

W. Perucki*,1 R. Shaikh,2 A. F. Becerra,3 A. Shaik,2 W. Duvall4; 1Hartford Hospital, Hartford, CT, 2University of Connecticut, Farmington, CT, 3Internal Medicine, University of Connecticut, Farmington, CT, 4Nuclear Cardiology, Hartford Hospital, Hartford, CT

Introduction: Thousands of patients undergo stress testing for risk stratification and evaluation of coronary artery disease annually. The risk of exercise and pharmacologic stress testing of patients with carotid artery disease has never been defined, but it is thought to increase the risk of ischemic stroke and transient ischemic attack. We sought to understand the risk of stress testing in patients with different degrees of carotid artery stenosis (CAS).

Methods: We retrospectively reviewed records of all patients with either ultrasound or CT evaluation of their carotid arteries from 2015 to 2020 who also underwent stress testing within 180 days without carotid intervention in the interim. We performed a manual chart review of all patients looking for any adverse events that occurred within 24 hours of the stress test. We defined the primary end point as any cerebrovascular event or syncope. Secondary endpoints included death, myocardial infarction, urgent angiography, urgent revascularization, or exaggerated hemodynamic response (SBP drop > 20 mmHg). Patients were stratified based on the level of CAS into either severe (greater than 80%), moderate (50%–79%), or mild/no (less than 49%) stenosis. Patients with severe CAS were compared to those with mild/no stenosis. Propensity matching was performed, using the following patient risk factors: history of diabetes, hypertension, hyperlipidemia, smoking status, coronary artery disease, gender, and age.

Results: A total of 4457 patients underwent carotid ultrasound, 10,644 CT, and 16,011 stress testing during this time period, with 514 having both a carotid evaluation and a stress test within 6 months of one another. After propensity matching, 62 patients with severe CAS were matched to 170 patients with mild/no CAS. In the non-propensity matched cohort, patients with severe CAS were older, more likely to smoke, have diabetes, hyperlipidemia, or known coronary artery disease. All patients with severe CAS underwent pharmacologic stress compared to those with mild/no CAS. There were no primary endpoints and only three adverse events occurring in two patients – both patients requiring urgent angiography, one of whom required urgent revascularization with coronary artery bypass grafting. Both of these patients were in the group with mild/no CAS. The proportion of exaggerated hemodynamic response to stress was similar in both groups, 21.0% in the CAS group and 31.2% in the group without CAS (P = 0.17).

Conclusions: In our study, there were no primary and few secondary outcome events with no events occurring in patients with severe CAS. This small cohort study suggests that stress testing bares no increased risk in patients with severe CAS but continued care should be taken in this cohort.

112-09

Association of Regadenoson and Splenic Switch-off in Rubdium-82 PET Myocardial Perfusion Imaging

J. Saad*, A. Ahmed, Y. Han, F. Nabi, T. Alnabelsi, M. H. Al-Mallah; Houston Methodist DeBakey Heart and Vascular Center, Houston, TX

Background: Splenic switch-off (SSO) is a phenomenon describing a decrease in splenic radiotracer activity from rest to stress. Previous studies have shown that adenosine- and dipyridamole-induced splenic switch-off can be used to assess vasodilator response. The prior study using cardiac magnetic resonance perfusion stated that regadenoson does not show evidence of splenic switch-off, which was suggested to be specific to adenosine. The aim of this study is to assess whether regadenoson vasodilator stress is associated with splenic switch-off in Rubdium-82 Positron emission tomography (PET) myocardial perfusion imaging (MPI).

Methods: Patients were selected from an institutional registry of Regadenoson Rb-82 PET MPI between August 2020 and April 2021. A total of 100 consecutive patients with normal regadenoson PET MPI studies having no perfusion defects (SDS = 0), normal myocardial blood flow, no wall motion abnormalities, and calcium score of zero were selected. Radiotracer activity concentrations (Bq·ml) were measured in region of interests (ROIs) from the spleen, liver, and myocardium both at rest and stress. Each study was evaluated by two investigators blinded to the others results.

Results: A significant decrease was observed between spleen activity from rest to stress (79.9 kBq·ml vs 69.1 kBq·ml, respectively, P < 0.001). Inversely, there was a significant increase in blood flow to the liver (P < 0.001) along with an expected increase in blood flow to the myocardium (P < 0.001). This was consistent among young vs elderly patients, men versus women or among patients with or without hypertension or dyslipidemia. There was a strong inter-rater reliability of radiotracer activity concentrations across the spleen, liver, and myocardium (ICC > 0.95)

Conclusion: Patients with normal regadenoson vasodilator stress in PET MPI studies exhibit significant decrease in splenic radiotracer activity from rest to stress.

112-11

Added Prognostic Role of Computed Tomography-Derived Fractional Flow Reserve

A. Ahmed*,1 Y. Han,1 T. Alnabelsi,1 M. Al Rifai,2 F. Nabi,1 S. Chang,1 J. J. Mahmarian,1 M. A. Chamsi-Pasha,1 W. Zoghbi,1 M. H. Al-Mallah1; 1Houston Methodist DeBakey Heart and Vascular Center, Houston, TX, 2Baylor College of Medicine, Houston, TX

Introduction: Cardiac-computed tomography angiography (CCTA)-derived fractional flow reserve (FFRCT) adds incremental diagnostic value by providing functional severity of coronary lesion in patients with coronary artery disease (CAD). We aimed to assess the incremental prognostic value of FFRCT on a CCTA-based anatomic assessment.

Methods: Consecutive patients who had clinically indicated CCTA and FFRCT determination were included. FFRCT was determined off-site using a Food and Drug Administration (FDA) approved commercially available tool. Segment involvement score (SIS), the total number of coronary artery segments with plaque on CCTA irrespective of stenosis, was used to quantify the burden of CAD. Patients were followed for major adverse cardiovascular events (MACE, inclusive of all-cause death, non-fatal myocardial infarction, hospitalization for chest pain/unstable angina and percutaneous coronary intervention (PCI)/coronary artery bypass grafting (CABG) 90-days after imaging test.) Results: A total of 667 patients with at least coronary artery disease reporting and data system (CAD-RADS) 2 were included (mean age 68 ± 10 years, 37% women, 73% hypertension, 12% diabetes, and 61% dyslipidemia). More than half (57%) of the patients had moderate (CAD-RADS 3) stenosis. FFRCT < 0.8 was found in 59% of patients, with an increasing percent across categories of CAD-RADS. After a median follow-up of 9 months, 52 patients (7.2%, 6.7 events per 1000 person-year) experienced MACE. In multivariable Cox regression models adjusted for age, sex, CCTA obstructive stenosis, and SIS, FFRCT < 0.8 was not significantly associated with outcomes (HR 1.63, P = 0.185).

Results were the same on sensitivity analysis using lower thresholds of FFRCT.

Conclusion: We have shown that in this real-world cohort of patients with suspected CAD and at least 30% stenosis on CCTA, FFRCT provides no significant incremental prognostic value over an assessment of stenosis and plaque burden.

Table 1 Nested cox regression on primary outcome

112-12

Tolerance Profiles of Coronary Vasodilators in Myocardial Perfusion Imaging – Comparing Adenosine and Dipyridamole

J. Momodu*, A. Ayeni, K. Purbhoo, W. Vangu; University of the Witwatersrand, Johannesburg, South Africa

Introduction: In myocardial perfusion imaging (MPI), a widely used non-invasive nuclear imaging technique for the evaluation of coronary artery disease, maximal myocardial hyperemia is typically achieved with physical stress. However, in patients who are unable to tolerate exercise, pharmacological stress with intravenous coronary vasodilators is employed as an alternative. This study compares the tolerance profiles of intravenous adenosine and dipyridamole; the two routinely used coronary vasodilators in our department.

Methods: Between August 2018 and November 2019, patients with known or suspected coronary artery disease referred for pharmacological stress MPI (N = 264) were closely monitored for adverse effects during or immediately after termination of the intravenous vasodilator infusion. One hundred and forty-seven patients (55.7%) received adenosine while 117 patients (44.3%) received dipyridamole. Adverse effects were graded using a four-point scale as follows: 0 = no adverse effects; 1 = less than 3 adverse effects (mild); 2 = 3–6 adverse effects (moderate); 3 = more than 6 adverse effects (severe) or side effects requiring reversal with intravenous aminophylline.

Results: The overall prevalence of adverse effects was 62.1%, the majority of which were (Grade 1) adverse effects. Only 3 patients (1%) developed Grade 3 adverse effects. The most common adverse effects reported by patients who received adenosine were chest pain and dyspnea while headache was more common in the dipyridamole group. Adenosine was three times more likely to cause adverse effects compared to dipyridamole (OR 3.23; 95% CI 1.93-5.43; P < 0.001). However, dipyridamole showed a greater propensity to cause higher grade adverse effects as all participants with Grade 3 adverse effects received dipyridamole (P < 0.001). Compared to dipyridamole, adenosine was also associated with a more significant drop in systolic blood pressure from baseline to end of infusion (P < 0.009).

Conclusions: Although both vasodilators show an overall satisfactory safety profile, adenosine has demonstrated a marginally better tolerance profile than dipyridamole which was associated with more severe adverse effects.

112-13

Maximizing Value of SPECT CT in Prognostic Prediction of Diabetic Patients by Using a Simple Visual Calcium Burden Score in Overall Interpretation

T. Makki*,1 W. Al-Darzi,1 R. Saco,1 M. Van Harn,1 K. Ananthasubramaniam2; 1Henry Ford Hospital, Detroit, MI, 2Division of Cardiology, Henry Ford Hospital, Detroit, MI

Introduction: SPECT CT attenuation correction (AC) coronary calcium detection is an important non-perfusion finding that has been shown to help identify atherosclerosis despite normal perfusion as well as aid in SPECT interpretation. The value of a visual calcium score burden (VCS) derived from AC-CT to refine risk and added prognostic value in high-risk subsets like diabetes mellitus (DM) has not been well established. We aimed to evaluate the role of VCS in patients with DM calculated from SPECT CT.

Methods: A retrospective data review of patients who underwent cardiac SPECT CT at our center from January 2009–August 2012 with a mean follow-up of 4.5 years. Baseline characteristics and outcomes were collected. VCS scoring was completed on all scans by 3 senior cardiology fellows. When not congruent, adjudication by an attending reader was performed. The presence of visual calcium in any of the following arteries was recorded as a score of 1 with VCS range 0-6: left main, left anterior descending, left circumflex, right coronary, ascending aorta, and descending thoracic aorta. Composite outcomes included congestive heart failure, myocardial infarction, unstable angina hospitalization, cardiac death, and all-cause mortality were studied.

Results: 538 consecutive patients with SPECT CT were evaluated. There were 232 (43%) patients with DM. Mean age was 63.4 years (± SD 12.3) with females comprising 52%. There were 84 DM patients with composite outcomes. VCS was higher in DM patients with events compared to DM patients with no events (VCS 2.57 vs 1.74 P = 0.002). Controlling for summed stress and rest scores, systolic blood pressure, history of smoking, stroke, and COPD, there were higher odds of composite outcomes with each 1-point increase in VCS using a multivariable logistic regression model (OR 1.23, 95% CI 1.06, 1.43; P value = 0.006). Similarly, there was a correlation with higher mean VCS and all-cause mortality. All cause mortality endpoint occurred in 50 diabetic patients. Mean VCS was higher in DM patients who died than those who did not (VCS of 3 as compared to 1.78; P value <0.001). When controlling for history of smoking, COPD, and stroke, multivariate regression analysis revealed a higher adjusted odds ratio in these patients with each 1-point increment in VCS (adjusted OR 1.38, 95% CI 1.17, 1.63; P value <0.001).

Conclusion: This study shows the importance of VCS in risk-stratifying patients with DM undergoing SPECT CT. A simple VCS can help with risk assessment, particularly as it pertains to the composite outcomes of heart failure, myocardial infarction, unstable angina, cardiac death, and all-cause mortality. Clinicians interpreting SPECT can easily adopt this VCS scoring tool to help management and prognostication decisions. Visual Coronary Calcium assessment should be integrated in SPECT CT reports to enhance risk assessment.

112-14

Comparison of Dobutamine and Regadenoson MPI for Pre-liver Transplant Evaluation

H. J. Fichardt*, C. Buch, D. I. Rosu, B. Y. Choi, R. Fernandez, I. Agoston; UTHSCSA, San Antonio, TX

Introduction: Liver transplantation (OLT) has experienced tremendous growth and success in the past 3 decades in the US. The main cause of death after OLT is coronary artery disease (CAD). Despite the well-described importance of identifying CAD prior to OLT, there is no clear consensus on the best diagnostic imaging modalities to use.

Methods: We used a database from a single institution (UTHSCSA) and evaluated patients from 2013 to 2020 who underwent pre-OLT cardiac evaluation. The criteria for inclusion were a nuclear perfusion stress test (MPI) (done on a Siemens C-cam) and a left heart catheterization (LHC) within a 12-month period. 226 patients met criteria and were divided into two groups based on the type of stressor: Dobutamine vs Regadenoson. There were 157 patients in the Dobutamine and 69 patients in the Regadenoson groups.

Nonparametric maximum likelihood estimators of the survival curves of the respective patients were estimated. A log-rank test was performed to test if the survival curves were different.

Results: We found that the positive predictive values of Regadenoson and Dobutamine were comparable but slightly higher in the Dobutamine group (90.7% vs 92.6%). Survival analysis showed a statistically significant increase in survival in the Dobutamine group (− 2.3; P value 0.0199). The baseline characteristics of the groups showed no statistically significant difference. See Image 1.

Conclusions: In patients undergoing evaluation for OLT, Dobutamine and Regadenoson MPI demonstrate comparable effectiveness at detecting CAD and correlates highly with LHC. The survival benefit in the Dobutamine group post-LHC shows a significant increase in survival. Given the correlation with LHC but difference in long-term mortality and the absence of population differences, this is an interesting finding that requires further research.

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Young Investigator Session 125-Part 1: Clinical Abstracts

125-01

Explainable Deep Learning Improves Physician Interpretation of Myocardial Perfusion Imaging

R. Miller*,1 K. Kuronuma,2 A. Singh,2 Y. Otaki,3 S. W. Hayes,2 P. Chareonthaitawee,4 P. Kavanagh,2 T. Parekh,2 B. K. Tamarappoo,5 T. Sharir,6 A. J. Einstein,7 M. Fish,8 T. D. Ruddy,9 P. A. Kaufmann,10 A. J. Sinusas,11 E. J. Miller,12 T. M. Bateman,13 S. Dorbala,14 M. DiCarli,15 S. Cadet,2 J. X. Liang,16 D. Dey,17 D. S. Berman,3 P. Slomka18; 1University of Calgary, Calgary, AB, Canada, 2Cedars Sinai Medical Center, Los Angeles, CA, 3Cedars-Sinai Medical Center, Los Angeles, CA, 4Mayo Clinic, Rochester, MN, 5Imaging, Cedars Sinai Medical Center, Los Angeles, CA, 6Assuta Medical Center, Ramat Gan, Israel, 7Columbia University Medical Center, New York, NY, 8Oregon Heart and Vascular Institute, Springfield, OR, 9University of Ottawa Heart Institute, Ottawa, ON, Canada, 10University Hospital Zurich, Zurich, Switzerland, 11Yale University School of Medicine, New Haven, CT, 12Yale University, New Haven, CT, 13St. Luke's Mid America Heart Institute, Kansas City, MO, 14Brigham and Women's Hospital, Boston, MA, 15Division of Nuclear Medicine and Molecular Imaging, Boston, MA, 16Cedars Sinai Medical Center, Los Angeles, CA, 17Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, 18Cedars-Sinai Medical Center, Los Angeles, CA

Introduction: Artificial intelligence may improve the diagnostic accuracy of myocardial perfusion imaging (MPI); however, it will likely be implemented as an aid to physician interpretation. Explainable deep-learning (DL) model has high diagnostic accuracy for obstructive coronary artery disease (CAD), but its influence on physician interpretation is unknown. We assessed whether access to explainable DL predictions improves physician interpretation of SPECT MPI.

Methods: We selected a representative cohort of patients imaged with conventional or solid-state camera systems with reference invasive coronary angiography. Obstructive CAD was defined as stenosis ≥ 50% in the left main artery or ≥ 70% in other coronary segments. We utilized an existing explainable DL model (CAD-DL), developed in a separate patient population. CAD-DL estimates the probability of CAD and highlights regions of the polar map contributing to predictions. Three physicians interpreted studies with clinical history, stress results, and perfusion but without the explainable DL results, then with all the data plus the explainable DL results. Diagnostic accuracy was assessed using area under the receiver-operating characteristic curve (AUC).

Results: In total, 240 patients were included with median age 65 (IQR 58-73) and 120 (50.0%) having obstructive CAD. The diagnostic accuracy of physician interpretation with access to CAD-DL results (AUC 0.779) was significantly higher compared to physician interpretation without CAD-DL (AUC 0.747, P = 0.003) and stress TPD (AUC 0.718, P < 0.001). All readers had numerically higher accuracy with the use of CAD-DL, with improvement in AUC ranging from 0.018 to 0.049. Interpretation with explainable DL resulted in net reclassification improvement of 17.5% (95% CI 9.8–24.7%, P<0.001).

Conclusion: Access to explainable DL results leads to meaningful improvements in the accuracy of physician interpretation. This technique could be implemented clinically as an aid to physician diagnosis in order to improve the diagnostic accuracy of SPECT MPI.

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125-02

Potential Use of Stress Myocardial Blood Flow Measurement to Reduce Need for Rest Imaging with Stress First/Only Single-Photon Emission-Computerized Tomography Myocardial Perfusion Imaging

M. AlShaheen*, A. Tavoosi, C. Carey, B. Marvin, P. Irvine, G. R. Small, R. Wells, T. D. Ruddy; University of Ottawa Heart Institute, Ottawa, ON, Canada

Introduction: Rest/stress myocardial perfusion imaging (MPI) with single-photon emission-computerized tomography (SPECT) is used to diagnose significant obstructive coronary artery disease (CAD). Rest MPI assists interpretation of stress MPI and helps differentiate artefacts from ischemia or scar. Stress first MPI may help avoid rest MPI if the stress MPI is interpreted as normal. Cancelling rest MPI reduces radiation dose to the patient and staff and camera time. We have developed and validated the SPECT technique of myocardial blood flow (MBF) measurement which has high diagnostic accuracy for obstructive CAD. Our objective was to explore the potential value of stress MBF to increase certainty of the clinical diagnosis of a normal stress MPI and facilitate cancelling of rest MPI. The purpose was to determine the change in the number of stress MPI studies interpreted as normal when stress MBF data are added to the conventional approach.

Methods: The study was approved by the University of Ottawa Research Ethics Board. All patients provided informed consent. Patients were referred for evaluation of suspected or known CAD. Patients underwent dipyridamole stress MPI with dynamic imaging during stress injection and delayed gated imaging using a cardiac SPECT camera (Discovery NM530c, GE HealthCare). Stress global and regional MBF were calculated using inter-frame motion correction and a previously validated 1-tissue-compartment model. Stress MPI images were interpreted by 1 reviewer with and without stress MBF data. Clinical data including referral information, stress testing results and gated images were available at time of stress MPI review. Results were compared using McNemar’s test for paired nominal data.

Results: The study population included 31 patients with a mean age of 57 years, 22 males and 3 with known CAD. Stress MPI studies were identified as normal on the first interpretation without stress MBF in 8/31 patients (26%) and on the second interpretation with stress MBF in 23/31 patients (74 %, P < 0.001). The additional 15 patients identified as normal using stress MBF data on the second interpretation underwent rest MPI since the first interpretation did not identify them as normal and were reported as normal after including the rest MPI.

Conclusion: This pilot study demonstrated incremental value of stress MBF data for classifying stress MPI studies as normal and reducing need for rest MPI. A larger study is necessary to confirm the initial results, compare the predictive value of stress MBF to other available clinical ECG and imaging data and provide follow-up for cardiac outcomes in patients not undergoing rest MPI.

125-03

Convolutional Multi-Task Deep Neural Network Precisely Predicts Time-Dependent Survival of Major Adverse Cardiac Events After Myocardial Perfusion Imaging

K. Pieszko*,1 A. Singh,1 Y. Otaki,1 T. Sharir,2 A. J. Einstein,3 M. B. Fish,4 T. D. Ruddy,5 P. A. Kaufmann,6 A. J. Sinusas,7 E. J. Miller,8 T. M. Bateman,9 S. Dorbala,10 M. Di Carli,11 D. Dey,12 J. X. Liang,1 D. S. Berman,1 P. J. Slomka1; 1Cedars-Sinai Medical Center, Los Angeles, CA, 2Assuta Medical Center, Ramat Gan, Israel, 3Columbia University Medical Center, New York, NY, 4Oregon Heart and Vascular Institute, Sacred Heart Medical Center, Springfield, OR, 5University of Ottawa Heart Institute, Ottawa, ON, Canada, 6University Hospital Zurich, Zurich, Switzerland, 7Yale University School of Medicine, New Haven, CT, 8Yale University, New Haven, CT, 9St. Luke's Mid America Heart Institute, Kansas City, MO, 10Brigham and Women's Hospital, Boston, MA, 11Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Brigham and Women's Hospital, Boston, MA, 12Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA

Introduction: Myocardial perfusion imaging (MPI) provides valuable functional information, which together with clinical data can help predict occurrence of major adverse cardiac events (MACE); however, the time-to-event information is often neglected both in training and in evaluation of the models.

Methods: We analyzed data from the multi-center REgistry of Fast Myocardial Perfusion Imaging with NExt generation SPECT (REFINE SPECT) and evaluated the prediction MACE and its individual components (all-cause death, acute coronary syndrome [ACS], and late revascularization) by the DeepHit model, consisting of one shared neural network followed by event-specific sub-networks. Latent features from a convolutional network pre-trained to predict MACE form polar maps were used as input to the DeepHit network along with 39 clinical features. The model was evaluated in 10-fold cross-validation at 1 and 3 years from scan using concordance index and Brier score.

Results: We included 20,414 patients (64 ± 8 years, 56% male) undergoing stress Tc-99m SPECT-MPI were followed for 4.5 ± 1.7 years. Early revascularization (< 90 days from scan; N = 698) as well as patients with missing imaging data (N = 13) were excluded. DeepHit model allowed for time-dependent estimation of event risk (Figure). The concordance index for the prediction of MACE was 0.71 and 0.72 at 1 and 3 years from scan. The Brier scores for the prediction of MACE at 1 and 3 years were 0.04 and 0.06. For the prediction of all-cause death, ACS, and revascularization, the concordance indices at 1 and 3 years from scan were 0.8 and 0.8, 0.71 and 0.72, and 0.77 and 0.77, respectively

Conclusions: The use of multi-task survival model allows for accurate prediction of time-dependent probability of adverse events

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Young Investigator Session 125 – Part 2: Basic, Technical, Other

125-04

A Practical 99mTc Pyrophosphate Quantification Method for the Diagnosis of Transthyretin Amyloid Cardiomyopathy

P. Chandrashekar*, S. Gill, Y. Burton, L. Al-Rashdan, S. Warner, E. Mittra, J. Lindner, A. Masri; Oregon Health & Science University, Portland, OR

Introduction: 99mTc-PYP SPECT imaging is superior to planar imaging in the diagnosis of ATTR-CM. We aimed to investigate a practical method of PYP quantification on SPECT imaging.

Methods: PYP uptake was quantified in 44 SPECT and planar scans (29 ATTR-CM; 15 controls) using 3 methods: 2DTBR (Target-Background Ratio)-LV-DAo, 3DLV-TBR, and free form H/CL. (Fig 1) Their diagnostic performance was compared to conventional planar H/CL ratio. TBR (paraspinal muscle to spine) was used as control.

Results: 2DTBR-LV-DAo was associated with the highest AUC of 0.995 (Fig 2A). Control TBR was similar between groups (Fig 2B). The difference between 2DTBR-LV-DAo between groups appeared to persist across NYHA classes (Fig 2C). Five scans considered equivocal were correctly reclassified as negative using the 2DTBR-LV-DAo method.

Conclusions: 2DTBR-LV-DAo is a practical and simple method of PYP quantification on SPECT imaging. Further studies are needed to understand the relationship between PYP SPECT uptake and natural history of ATTR-CM as well as response to therapy.

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125-05

18F Sodium Fluoride PET Imaging for in vivo Evaluation of Calcification Dynamics in a Novel Murine Model of Calcific Aortic Valve Disease

A. A. Ahmad*, J. Toczek, K. Gona, J. J. Jung, J. Zhang, L. Wei, M. Salarian, M. Ghim, D. Ojha, M. M. Sadeghi; Yale University, School of Medicine, New Haven, CT

Objectives: Calcific aortic valve disease (CAVD) is the main cause of aortic stenosis (AS), which is more severe in patients with bicuspid aortic valve (BAV), as opposed to tricuspid aortic valve (TAV). The treatment of CAVD remains limited to valve replacement for advanced disease, in part because of a lack of representative animal models for human disease. Fluorine-18 sodium fluoride ([18F]-NaF) PET can detect the calcification process in vivo. Pursuing the observation that Discoidin, CUB, and LCCL domain-containing protein 2 (DCBLD2) are reduced in patients with AS, we observed that DCBLD2-deficient mice develop BAV. The purpose of this work was to address the feasibility of [18F]-NaF PET/CT and evaluate valvular stenosis and calcification in Dcbld2-/- mice in comparison with wild-type (WT) animals.

Methods: Aortic valve leaflet separation and transvalvular jet velocities were determined by echocardiography in cDcbld2−/− (N = 49) and age-matched WT mice (N = 6) at the age of > 9 months. Valvular calcification was detected in vivo by [18F]-NaF PET/CT in Dcbld2−/− mice at 3–4 months (young, N = 4) and > 9 months (old, N = 4). The animals were injected with 28.3 ± 5.4 MBq of [18F]-NaF and underwent a 30 minutes long PET acquisition starting at 1 hour post-injection. Contrast-enhanced CT images were also obtained. The mean SUV values were determined in regions of interest drawn over the aortic valve region and the left ventricle, as identified by CT, and normalized to the blood SUV values measured in the left ventricle to determine target to blood ratios (TBR). Valvular calcification was confirmed by quantitative autoradiography ex vivo. Dcbld2−/− mice at > 9 months (old, N = 9), and age-matched WT (N = 4) animals were injected with 16.3 ± 4.9 MBq of [18F]-NaF, and the aorta and aortic valve were dissected after 1 hour, and aortic valve tracer uptake was quantified.

Results: Fifty three percent (26/49) of Dcbld2−/− mice had a BAV. Mice with BAV had a significantly higher aortic valve velocity compared to those with TAV (Dcbld2−/− BAV: 2838 ± 1383; TAV: 1781 ± 759 mm⋅s, P < 0.05) and WT animals (1060 ± 173 mm·s, P < 0.001), and lower leaflet separation versus TAV (P < 0.01) and WT (P < 0.0001) mice. The aortic valve [18F]-NaF signal was clearly visible in a subset of PET/CT images. Aortic valve TBR was significantly higher in older Dcbld2−/− mice compared to younger animals (1.32 ± 0.05 vs 1.18 ± 0.08, P < 0.05). Ex vivo autoradiography showed higher uptake of [18F]-NaF in old Dcbld2−/− mice relative to age-matched WT controls (P < 0.05).

Conclusion: [18F]-NaF PET/CT is feasible in murine CAVD. Older Dcbld2−/− mice develop AS and valvular calcification. In addition, AS is more severe in older Dcbld2−/− mice with BAV. This combination of a new animal model of CAVD and small animal [18F]-NaF PET/CT to track the aortic valve calcification process can accelerate pathophysiology research and facilitate the development of novel therapeutics for CAVD.

125-06

Right Ventricular Amyloid Deposition is Inversely Correlated to RV Ejection Fraction in Patients with Cardiac AL Amyloidosis: A F-18 florbetapir PET/CT and CMR Study

Y. Datar*,1 M. F. Kijewski,1 S. R. Rao,1 A. Taylor,1 S. Cuddy,1 G. Bianchi,1 A. Yee,2 V. Sanchorawala,3 F. L. Ruberg,3 H. Landau,4 R. Liao,5 M. DiCarli,1 M. Jerosch-Herold,1 R. Kwong,1 R. Falk,1 S. Dorbala1; 1Brigham and Women's Hospital, Boston, MA, 2Massachusetts General Hospital, Boston, MA, 3Boston Medical Center, Boston, MA, 4Memorial Sloan Kettering Cancer Center, New York, NY, 5Stanford University, Stanford, CA

Objective: To evaluate right ventricular (RV) amyloid burden and RV function in patients with systemic light chain (AL) amyloidosis.

Methods: We prospectively enrolled 73 subjects (mean age 62 ± 8 years, 45.5% women) with biopsy-proven AL amyloidosis into 3 study groups: Active AL-CMP (abnormal cardiac biomarkers, N = 41), Active AL-non-CMP (normal cardiac biomarkers and normal left ventricular wall thickness, N = 14), and Remission-AL-CMP (hematalogical remission for ≥ 1 year, N = 18). All subjects underwent 18F-florbetapir PET/CT (8-10 mCi) and gadolinium enhanced cardiac magnetic resonance imaging (CMR). RV amyloid burden was estimated on a voxel level by 18F-florbetapir activity concentration (kBq/cc) in RV from static images (4-30 minutes) using PMOD software; voxels with activity concentration more than two times mean left atrial activity concentration were considered abnormal. RV function was quantified by RVEF on CMR. RV amyloid in the study groups was compared using one-way ANOVA with post-hoc Bonferroni testing and correlated to RVEF using a Pearson’s R.

Results: RV amyloid was present in 11/14 patients without CMP (Fig A). Mean RV 18F-florbetapir activity was highest and RVEF was lowest in the active AL-CMP cohort (Fig. A and B). RV amyloid activity was significantly lower in the remission-AL-CMP cohort (Fig. A) compared to active-AL-CMP, yet RVEF was similarly reduced (Fig. B). RV amyloid was moderately and inversely correlated to RVEF in both AL-CMP cohorts (Fig. C). Estimated RV systolic pressure was 33 ± 13, 28 ± 12, and 10 ± 12 mm⋅Hg, respectively, in the three groups.

Conclusions: This is the first study, to our knowledge, to evaluate RV amyloid using a molecularly targeted amyloid tracer. Notably, we found (1) RV amyloid deposits in most patients without known cardiac involvement and (2) persistent AL amyloid deposits in the right ventricle after successful AL therapy with remission; these may contribute to persistent RV dysfunction and functional limitation.

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Best Clinical Abstract Session 207

207-01

Bypass Grafting and Native Coronary Artery Disease Activity: an 18F-NaF PET study

J. Kwiecinski*,1 E. Tzolos,2 A. Fletcher,3 M. N. Meah,3 S. Cadet,4 P. D. Adamson,3 K. Grodecki,4 N. Joshi,5 M. Williams,3 E. J. van Beek,3 A. A. Tavares,3 M. G. MacAskill,3 D. Dey,6 A. H. Baker,3 J. Leipsic,7 D. S. Berman,8 S. Sellers,9 D. Newby,3 M. R. Dweck,3 P. J. Slomka8; 1Institute of Cardiology, Warszawa, Poland, 2Cedars Sinai Medical Center, Los Angeles, CA, 3University of Edinburgh, Edinburgh, United Kingdom, 4Cedars Sinai, Los Angeles, CA, 5University of Edinburgh, Edinburgh, Scotland, United Kingdom, 6Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, 7University of British Columbia, Vancouver, BC, Canada, 8Cedars-Sinai Medical Center, Los Angeles, CA, 9St. Paul’s Hospital, University of British Columbia, Vancouver, BC, Canada

Introduction: As well as developing graft vasculopathy, coronary artery bypass grafts (CABG) have been proposed to accelerate native coronary atherosclerosis. We aimed to describe the potential of 18F-sodium fluoride positron emission tomography (18F-NaF PET) to identify graft vasculopathy and to investigate the influence of CABG surgery on native coronary artery disease activity and progression.

Methods: Patients with established coronary artery disease underwent baseline 18F-NaF PET, coronary artery calcium scoring, coronary CT angiography, and one-year repeat coronary artery calcium scoring. We quantified the whole-vessel 18F-NaF PET coronary microcalcification activity (CMA) and change in calcium scores in those with and without CABG surgery.

Results: Among 293 participants (65 ± 9 years; 84% male), 48 (16%) had CABG surgery 2.7 [1.4-10.4] years previously. Although all arterial and the majority (120/128, 94%) of vein grafts showed no 18F-NaF uptake, 8 saphenous vein grafts in 7 subjects had detectable CMA. Bypassed native coronary arteries had 3 times higher CMA values (2.1 (0.4-7.5) versus 0.6 (0-2.7), P<0.001) and greater progression of one-year calcium scores (118 [48-194] versus 69 [21-142] AU, P = 0.01) compared to those who that had not undergone CABG: an effect largely confined to native coronary plaques proximal to the graft anastomosis. In sensitivity analysis, bypassed native coronary arteries had higher CMA (2.0 [0.4-7.5] vs 0.8 [0.3-3.2], P < 0.001) and faster disease progression (24 [16-43] versus 8 [0-24] %, P = 0.002) than matched patients (N = 48) with comparable burdens of coronary artery disease and cardiovascular comorbidities in the absence of bypass grafting.

Conclusions: Native coronary arteries that have been bypassed, demonstrate increased disease activity and more rapid disease progression than non-bypassed arteries, an observation that appears independent of the baseline atherosclerotic plaque burden. Microcalcification activity is not a dominant feature of graft vasculopathy.

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207-02

Relationship between Coronary Artery Calcium, Ischemia, and Major Adverse Cardiovascular Events

R. Miller*,1 D. Han,2 Y. Otaki,3 H. Gransar,2 P. J. Slomka,3 J. D. Friedman,2 K. Pieszko,4 S. W. Hayes,2 L. Thomson,4 B. K. Tamarappoo,5 A. Rozanski,6 D. S. Berman3; 1University of Calgary, Calgary, AB, Canada, 2Cedars Sinai Medical Center, Los Angeles, CA, 3Cedars-Sinai Medical Center, Los Angeles, CA, 4Cedars Sinai Medical Center, Los Angeles, CA, 5Imaging, Cedars Sinai Medical Center, Los Angeles, CA, 6St. Luke's Roosevelt Hospital, New York, NY

Background: Positron emission tomography (PET) is frequently obtained with gated computed tomography (CT) for coronary artery calcium (CAC). This allows for a combined anatomic (CAC) and functional (ischemia) assessment of coronary artery disease (CAD) burden. We evaluated the independent prognostic value of ischemia and CAC in patients undergoing PET MPI.

Materials and Methods: Consecutive patients who underwent PET with CAC scoring between 2008 and 2018 were identified. Patients with known CAD and those who underwent revascularization within 90 days of PET were excluded. Ischemia and CAC were quantified during clinical reporting. Our primary outcome was major adverse cardiovascular events (MACE) including all-cause mortality, myocardial infarction (MI), admission for unstable angina (UA), and late revascularization. Associations with MACE were assessed using multivariable Cox proportional hazards models adjusted for age, sex, medical history, symptoms, and fixed perfusion defects.

Results: In total, 3055 patients were included with median age 70 (interquartile range [IQR] 62-78) and 50.3% female. During median follow-up of 4.1 (IQR 2.2-6.5) years, 755 patients experienced at least one MACE (death 613, MI 52, UA 22, and late revascularization 68). Increasing ischemia and CAC were associated with an increased risk of MACE. In multivariable analysis, both increasing log CAC (adjusted hazard ratio [aHR] 1.09, 95% confidence interval [CI] 1.06-1.13, P < 0.001) and increasing ischemia (aHR 1.13 per 5%, 95% CI 1.03-1.24, P = 0.013) continued to be associated with an increased risk of MACE. The addition of log CAC and ischemia to the multivariable model improved fit compared to the addition of log CAC or ischemia alone (log-rank P < 0.01 for both).

Conclusions: Ischemia and CAC were independently associated with MACE. Anatomic and functional measures of CAD should be incorporated when predicting MACE risk after PET MPI.

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207-03

Direct Explainable Mortality Risk Assessment from Myocardial PET Flow and Perfusion Using Artificial Intelligence with Prospective Validation

A. Singh*,1 Y. Otaki,1 J. Kwiecinski,2 P. B. Kavanagh,1 R. Miller,3 S. D. Van Kriekinge,1 C. Wei,1 T. Parekh,1 H. Gransar,1 N. Chen,1 D. S. Berman,1 P. J. Slomka1; 1Cedars-Sinai Medical Center, Los Angeles, CA, 2Institute of Cardiology, Warsaw, Poland, 3University of Calgary, Calgary, AB, Canada

Introduction: We aimed to develop and evaluate a novel explainable deep-learning (DL) network for the prediction of all-cause mortality (ACM) directly from perfusion and myocardial blood flow (MBF) polar maps and evaluate it in simulated prospective regimen.

Methods: A total of 4784 consecutive patients undergoing rest/pharmacologic stress 82Rb PET from 2010 to 2018 were followed for all-cause mortality (ACM) for mean 4.4 ± 2.6 years. DL network utilized stress and rest polar maps of raw perfusion, MBF, myocardial flow reserve (MFR) and spillover fraction, cardiac volumes, singular indexes, age, and sex. 3,568 patients scanned from 2010 to 2016 were used as a training set, and internal validation was performed with the training set. The network was validated in the remaining 1137 patients scanned from 2017 to 2018 (age 70 ± 11 years, 38% female), after excluding early revascularization, to simulate prospective implementation. The output of DL was ACM probability along with an attention map highlighting the polar map regions contributing DL prediction. Summed stress and difference scores (SSS, SDS) were obtained during clinical reading. Quantitative parameters including stress and ischemic total perfusion deficit (TPD), stress MBF, and MFR were obtained with standard software. ACM prediction of DL was compared to visual and quantitative assessment in a prospective temporal validation set.

Results: During follow-up, 85 patients died (7.5%) in the prospective temporal validation set. The area under the operating curve (AUC) for ACM prediction by DL (0.8 [0.75-0.84]) was higher than SSS (0.67 [0.61-0.73]), SDS (0.60 [0.54-0.66]), stress TPD (0.69 [0.62-0.75]), ischemic TPD (0.65 [0.59-0.72]), stress MBF (0.70 [0.64-0.76]), and MFR (0.7 [0.64-0.76]), (P for all <0.0001).

Conclusions: The DL model trained with perfusion and MBF polar map from 82Rb PET MPI allows improved risk stratification in comparison to visual perfusion assessment and quantitative PET assessment.

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207-04

Diagnostic Utility of Regadenoson-Induced Splenic Switch-off in Rubdium-82 PET Myocardial Perfusion Imaging

J. Saad*,1 A. Ahmed,1 Y. Han,1 L. I. El Nihum,2 F. Nabi,1 T. Alnabelsi,1 M. H. Al-Mallah1; 1Houston Methodist DeBakey Heart and Vascular Center, Houston, TX, 2Texas A&M College of Medicine, Bryan, TX

Background: Splenic switch-off (SSO) is a phenomenon describing a decrease in splenic radiotracer activity from rest to stress. Adequate stress response is imperative for the detection of ischemia in positron emission tomography (PET) myocardial perfusion imaging studies (MPI); therefore, inadequate vasodilatory response may result in false-negative studies. The aim of this study is to explore the diagnostic utility of visual splenic switch-off and splenic response ratio (SRR) in Regadenoson Rubdium-82 PET MPI studies.

Methods: The splenic response ratio was calculated with spleen and liver radiotracer concentrations obtained from a derivation cohort defined as Regadenoson Rb-82 PET MPI patients with normal MPI studies and no perfusion defects: SRR = (Spleen stress/Liver stress)/(Spleen rest/Liver rest). SRR was used to classify splenic responses from a validation group formed from patients who had undergone both PET-MPI studies and invasive coronary angiography (ICA). Based on the results of the coronary angiographies, false-negative and true-positive PET-MPI studies were used to assess clinical utility of visual SSO (fig.1) and SRR.

Results: Using the derivation cohort (N = 100), a splenic response ratio cut-off of 0.88 was established. Patients with an SRR ≤ 0.88 were classified as splenic responders while patients above that were non-responders. When applied to the validation cohort (N = 323), 72% were classified as splenic responders and 28% were splenic non-responders compared to visual assessment (85% and 15%, respectively). MFR was significantly lower in splenic non-responders defined by SRR (1.5 vs 1.7 P = 0.01) or visual assessment (1.4 vs 1.7 < 0.001). Moreover, patients with undetected ischemia on PET (as confirmed by ICA) were more likely to be splenic non-responders especially with corrected MFR < 1.5 based on SRR (62% vs 27% P = 0.02) or visual assessment (80% vs 30% P = 0.006).

Conclusion: Patients with inadequate vasodilatory response in Regadenoson Rb-82 PET MPI studies can be identified using visual splenic switch-off or splenic response ratio.

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207-05

Comparable Performance of Technetium-99m Pyrophosphate SPECT and SPECT/CT for Diagnosis of Transthyretin Cardiac Amyloidosis

C. Akincioglu*,1 J. Romsa,1 J. Warrington,2 M. Swiha,3 R. M. Abazid,4 D. Sutherland,1 A. Khatami,1 N. Rideout,1 C. McCorry,1 S. Malhotra5; 1Western University - LHSC, LONDON, ON, Canada, 2Western University-LHSC, London, ON, Canada, 3Western University - LHSC, London, ON, Canada, 4Western University -LHSC, London, ON, Canada, 5Cardiology, Cook County Health, Chicago, IL

Introduction: SPECT improves diagnostic specificity of Technetium-99m pyrophosphate (PYP) scintigraphy and is recommended to be performed whenever there is evidence of tracer uptake on planar imaging. Given the ability to co-localize tracer activity, hybrid SPECT/CT could provide superior diagnostic accuracy when compared to SPECT-only.

Methods: This retrospective, quality assurance study was performed on imaging data from patients who underwent PYP SPECT/CT between 2017 and 2021 at Western University. All images were reviewed by two experienced independent readers. Reader 1 reviewed planar and PYP SPECT with CT, while reader 2 was blinded to CT, and reviewed planar and SPECT-only PYP data. Imaging was performed at 1 hour after tracer injection and data were processed by a nuclear medicine technologist and not reprocessed by the two readers. Demographic, clinical, and other testing data were obtained from the electronic medical records.

Results: PYP scintigraphy was performed in 120 Caucasian patients (mean age 76 + 11 years), of whom 63% were men. Of these, 37 (29%) were considered to be positive based on myocardial uptake on SPECT/CT, with 86% of the patient with grade 3 uptake on planar imaging. There was excellent correlation between the two readers on the visual score (94%, P < 0.0001) and tomographic uptake (98%, P < 0.0001) by SPECT-only and SPECT/CT. Only one study was categorized as being falsely negative by SPECT only and was noted to have focal myocardial uptake on SPECT/CT (Figure). Both readers reported high confidence in their reads in 97% of the studies, with reader 2 reporting a low level of confidence in only 2 studies.

Conclusions: When read by experienced readers, SPECT-only reconstruction of PYP scintigraphy has near perfect concordance with PYP SPECT/CT. In cases with only focal myocardial uptake that may be seen in early cardiac amyloidosis, SPECT/CT is likely to provide greater diagnostic certainty.

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ePoster Session 212: New Technologies and Multimodality Imaging

212-01

Inter-Scan and Inter-Rater Agreement for CAC Scoring in ECG-Gated CAC Scans and Ungated Low-Dose CT Attenuation Correction Scans for Positron Emission Tomography

K. Pieszko*,1 A. Shanbhag,1 S. D. Van Kriekinge,1 M. Lemley,1 M. C. Hyun,1 Y. Otaki,1 D. Dey,2 D. S. Berman,1 P. J. Slomka1; 1Cedars-Sinai Medical Center, Los Angeles, CA, 2Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA

Introduction: We aimed to evaluate inter-scan and inter-rater agreement of Coronary Calcium (CAC) scores obtained from ECG-gated CAC scans and low-dose, ungated computer tomography attenuation correction (CTAC) scans obtained routinely during myocardial perfusion PET imaging.

Methods: From the patients who underwent Rb-82 cardiac positron emission tomography (PET/CT and gated CAC scans without prior revascularization, we have studied 200 cases selected randomly after stratification for the calcium scores categories. Both dedicated gated CAC and ungated CTAC scans were scored for coronary calcium with the quantitative clinical software by two experienced readers. The score agreement was assessed using 5 CAC categories (no CAC: 0, very low: 1-10, low: 11-100; moderate 101-400; and high > 400). The absolute inter-reader differences in scores (bias) between CAC scans and ungated CTAC maps were compared with the Wilcoxon signed-rank test.

Results: Median age of included patients was 70 (inter-quartile range 61-77), 51% were male. The inter-reader concordance index and Cohen’s Kappa were 0.9 and 0.87, respectively, for CAC scans and 0.86 and 0.8 for CTAC scans respectively. Class agreement is shown in figure. Inter-reader bias was larger for CTAC than for gated CAC scans: 16.74 (95% confidence interval [CI] − 1.13, 34.61) vs − 5.06 (95% CI − 14.93,4.82), P < 0.0001. Inter-reader levels of agreement (LOA) were wider for CTAC compared to CAC scans: (− 233.81 to 267.29) vs (− 143.47 to 133.36). The inter-scan concordance index and Cohen’s Kappa for reader 1 and 2 were 0.7; 0.62 and 0.74; 0.67, respectively.

Conclusion: The overall concordance in 5 classes of CAC scores was good for both gated CAC and CTAC scans. Overall, inter-scan (CTAC vs gated CAC) agreement was comparable to inter-reader agreement in terms of bias and LOA. However, inter-reader agreement was worse on the ungated CTAC maps with significantly larger bias.

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212-02

Repeatability of 18F-Sodium Fluoride Coronary Quantification Exported from Non-contrast PET/CT Scans

E. Tzolos*,1 J. Kwiecinski,2 T. Pawade,1 T. R. G. Cartlidge,1 M. Doris,1 W. Jenkins,1 D. S. Berman,2 D. Newby,1 P. J. Slomka,2 M. R. Dweck1; 1University of Edinburgh, Edinburgh, United Kingdom, 2Cedars-Sinai Medical Center, Los Angeles, CA

Introduction: Coronary 18F-sodium fluoride (18F-NaF) on uptake positron emission tomography/computed tomography (PET/CT), determined by coronary microcalcification activity (CMA), displays excellent observer reproducibility and interscan repeatability. We wanted to test whether we could quantify CMA using non-contrast PET/CT with similar precision.

Methods: Patients underwent 18F-NaF PET/CT scanning on 2 occasions in close succession. Subjects were administered 125 MBq 18F-NaF and underwent PET/CT (Biograph mCT; Siemens) 60 minutes later. We used 3 methods to evaluate coronary 18F-NaF activity: the maximum standard unit value (SUVmax); the maximum target-to-background (TBR) approach; and the CMA which represents the integrated coronary activity in SUV units exceeding blood-pool activity in the right atrium (mean blood-pool SUV plus 2 standard deviations. We calculated intraobserver, interobserver, and interscan reproducibility using Bland-Altman analysis repeatability coefficients and coefficients of variation.

Results: Fifteen patients (73 ± 7 years, 67% men) had 2 scans, 3.9 ± 3.3 weeks apart. 40 (89%) coronary arteries were analysed in total; vessels with no visible uptake were not assessed. Median [interquartile interval] SUVmax for LAD, RCA, and LCx arteries was 1.39 [1.08-1.73], 1.21 [0.95-1.49], and 1.50 [1.06-1.87], respectively; TBRmax was 1.32 [1.10-1.58], 1.15 [0.99-1.38], and 1.36 [1.18-1.54]; and CMA was 0.07 [0.00-0.79], 0.00 [0.00-1.21], and 1.15 [0.00-1.93]. SUVmax, TBRmax and CMA analysis across all vessels showed wide limits of agreement; Table 1 with interscan coefficients of reproducibility showing of 0.45, 0.40, and 2.72, respectively, and coefficients of variation of 34%, 35%, and 135%: Similar results were observed for interobserver and intraobserver reproducibility.

Conclusion: The precision of coronary 18F-NaF PET quantification (SUV, TBRmax and CMA) is sub-optimal when using non-contrast, ECG-gated CT scans.

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212-03

Multidisciplinary Cardiovascular Integrated Report – a Novel Method to Communicate Cardiovascular Imaging Results

C. T. Mesquita*,1 J. Serafim,2 A. C. Oliveira-Junior,2 C. E. Rochitte,2 A. Rabyschoffsky,2 A. C. Rocha,2 P. R. D. Silva,2 D. Machado,3 F. Salomao,2 A. Chambi,2 N. Correa,2 W. Ker,2 I. Palazzo,4 M. Montera,2 A. C. Siciliano2; 1Universidade Federal Fluminense, Niteroi, Brazil, 2Hospital Procardiaco, Rio de Janeiro, Brazil, 3Hospital Vitoria e Samaritano Barra, Rio de Janeiro, Brazil, 4Nuclear Medicine, Hospital Procardiaco, rio de janeiro, Brazil

Introduction: Integrating multiple specialties in a single meaningful report requires coordinated multispecialty collaboration. To meet this need, we developed a new strategy: a multidisciplinary cardiovascular integrated report (MCIR). In this report, we provide the first analysis of this experience in a tertiary cardiology hospital.

Methods: Our Multidisciplinary Cardiovascular Imaging Reporting Team (MCIRT) includes specialists in cardiovascular medicine and surgery, echocardiography, nuclear medicine, and radiology. MCIRT is organized as a team discussion that meets weekly in-person or online (as social distancing is needed) and generates a single integrated report of cardiovascular imaging studies (MCIR) as demanded by requesting physicians or by the imaging team. The online tool used was TEAMS by Microsoft. We prospectively obtained clinical, diagnostic aspects, and decision-making data during the first 10 months of experience.

Results: In 10 months, there were 56 clinical cases that were reported as MCIR. Coronary artery disease (CAD) was the most common etiology demanding integrated reports (23 cases – 41%), most frequently including coronary CT angiography and myocardial perfusion scintigraphy. The second commonest disease was cardiac infectious endocarditis (IE) in 8 cases (14%). The other diagnosis reported was cardiac amyloidosis (CA - 5), dilated cardiomyopathies (5), myocarditis (4), valvar diseases (3), hypertrophic cardiomyopathy (2), pulmonary hypertension (2), coronary fistula (1), COVID-19 complication (1), cardiac tumor (1), and pacemaker complication (1). The online discussion was limited because of internet instability in less than 5% of cases. The impact in decision making and clinician satisfaction was significant with some physicians bringing cases from other institutions for discussion.

Conclusions: We report a novel method to communicate cardiovascular imaging results as a single integrated report. This report was produced by a multidisciplinary team that engages multiple clinical/surgical and imaging specialists contributing to delivering efficient, organized, and evidence and value-based care. MCIR was technically successful in almost all cases, and it was mostly used in diseases that demand difficult decision making like CAD, IE, and CA.

212-04

Incremental Prognostic Role of SPECT to Computed Tomography Angiography Anatomic Assessment in Patients with Suspected Coronary Artery Disease

A. Javaid*,1 A. Ahmed,2 Y. Han,2 J. Saad,2 M. H. Al-Mallah2; 1Internal Medicine, University of Nevada Las Vegas, Las Vegas, NV, 2Houston Methodist DeBakey Heart and Vascular Center, Houston, TX

Introduction: Single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) has an established role in both the accurate detection of ischemia and identification of patients at high risk of future cardiovascular events. We aimed to assess the incremental prognostic role of SPECT to a coronary computed tomography angiography (CCTA) anatomic assessment in patients with suspected coronary artery disease (CAD).

Methods: Consecutive patients with suspected CAD who underwent CCTA and SPECT MPI within 180 days of each other were reviewed. Anatomically obstructive CAD by CCTA was defined as ≥ 50% in the left main artery and ≥ 70% stenosis severity in proximal, mid, and distal branches of the left anterior descending, left circumflex, and right coronary artery without including side branches. Ischemia and scar on SPECT were defined as summed difference score and rest score > 0, respectively. Patients were followed from the date of first imaging to incident major adverse cardiovascular events (MACE – composite of all-cause death, myocardial infarction (MI), and unplanned revascularization – percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) occurring more than 90 days after index imaging).

Results: Our study population consisted of 956 patients (mean (SD) age 61.1 ± 14.2 years, 54.1% men, 89% hypertension, 81% diabetes, and 84% dyslipidemia). After a median follow-up of 31 months (IQR 12-65 months), 102 patients (10.7%, 29.2 events per 1000 person-year) experienced the primary outcome. In multivariable Cox regression models adjusted for several CAD risk factors, the addition of SPECT variables to CCTA obstructive stenosis significantly improved model C-statistic (P = 0.037) and net reclassification (P < 0.001).

Conclusion: In this high-risk cohort of patients with suspected CAD, SPECT added incremental prognostic value to CCTA anatomic assessment.

Table 1 Nested multivariable Cox models on the primary outcome (MACE)

212-05

Feasibility of Early Post-Injection Myocardial Perfusion Imaging using Tetrofosmin and Attenuation-Corrected CZT SPECT

J. A. Case*,1 B. W. Sperry,2 K. K. Patel,3 A. McGhie,4 E. Moloney,2 S. A. Courter,1 E. V. Burgett,5 T. M. Bateman4; 1Cardiovascular Imaging Technologies, Kansas City, MO, 2Saint Luke's Health System, Kansas City, MO, 3Cardiology, Saint Lukes' Mid America Heart Institute, Kansas City, MO, 4St. Luke's Mid America Heart Institute, Kansas City, MO, 5St. Luke's Hospital, Kansas City, MO

Introduction: Recent societal guidelines recommend stress-first and stress-only if normal myocardial perfusion imaging (MPI) as a means of improving laboratory efficiency, reducing radiation and minimizing patient and staff interaction times to lower the risk of COVID-19 transmission. This protocol could be further enhanced if the post-injection delay could also be reduced. This study tested a rapid and early post-injection stress-only Tc-99m tetrofosmin (TETRO) protocol using attenuation-corrected CZT SPECT to establish comparability of images acquired early (Early) versus the standard (Late) 45-60 minute delay post-injection.

Methods: A total of 95 patients (61 male, BMI = 29 ± 5 km⋅m2) referred for MPI were examined as part of a quality improvement project. Patients were imaged upright and then supine on a Spectrum Dynamics, D-SPECT CZT system following injection of 16.7 ± 0.7 mCi of TETRO at peak stress. All had both early and late post-injection images acquired for 106 myocardial counts (approx. 2-5 minutes). Supine images were reconstructed using CT-based attenuation correction. Early and late images were interpreted in random sequence by a blinded panel of three expert readers for image quality (excellent, good, fair, poor), reader confidence (Low, Moderate, High), overall diagnosis (Normal, Abnormal) and need for follow-up rest imaging.

Results: The average time delay between tracer injection and start of imaging was 17 ± 4 minutes (Early) and 67 ± 15 minutes (Late). Image quality was good or excellent in 86% Early vs 94% Late (P = 0.001), with 63% of Early and Late images judged equal in quality. Reader confidence was high for Early (78%) and Late (76%) images (P = ns). Diagnosis was identical for 86% of Early vs Late images, and perceived need for a rest image was the same (12% for both).

Conclusions: Acquiring images much earlier after injection of Tc-99m tetrofosmin than is standard in practice appears feasible using CZT instrumentation and attenuation correction. Despite small differences in image quality, the rates for needing follow-up rest imaging were identical and there was a very high degree of agreement in overall diagnosis.

212-06

Techniques to Reduce Extracardiac Activity in Myocardial Perfusion Imaging After Pharmacological Stress in Obese Patients

M. Štalc*, M. Dolenc Novak, B. Gužič Salobir; University Medical Centre Ljubljana, Ljubljana, Slovenia

Introduction: Extracardiac activity can produce artefacts which can degrade the quality of myocardial perfusion imaging (MPI), especially after vasodilator pharmacological stress. Various techniques have been used to reduce intestinal activity in MPI with inconsistent results. There are limited data for their application in obese patients. The purpose of this study was to investigate the effect of delayed imaging time and carbonated water on extracardiac activity in obese patients.

Methods: Consecutive patients referred for MPI with pharmacological stress using 99mTc tetrofosmin (Myoview, GE Healthcare) were assigned to three different groups: A – imaging 60 min after radiopharmaceutical injection, B – delayed imaging (75-90 min post-injection), C – delayed imaging and drinking of 200 ml of carbonated water. Patients with BMI ≥ 30 kg/m2 were considered obese. Patients were imaged in the sitting position using a Cardius® X-ACT camera (Digirad, California, USA). The extracardiac activity adjacent to the inferior myocardial wall was determined visually by two experienced readers who accepted MPI for interpretation or decided for repeated acquisition. The proportion of accepted scans was collected prospectively.

Results: We studied 490 patients (60% women, age 69.5 ± 10.5 years) and 213 obese (BMI 34.3 ± 3.5). Figure 1 shows the proportion of accepted MPI scans. Obese patients in group A had significantly lower acceptance rate than non-obese patients while there were no differences between them in groups B and C (Figure 1). In obese patients, delayed scanning time was shown to increase the acceptance rate by 86% versus a regular scanning time (HR 1.86, 95% CI 1.3-2.6; P = 0.0006). The addition of carbonated water to delayed scanning time further improved the success rate by 20% (HR 1.20, 95% CI 1.0-1.4; P = 0.04).

Conclusions: A combination of delayed image acquisition and drinking of carbonated water led to a significant and clinically important decrease of interfering extracardiac activity in obese patients referred to MPI with pharmacological stress.

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212-07

The Feasibility of Formal Coronary Artery Calcium Score CT to Accurately Replace SPECT /CT Attenuation Correction Scans When Used for Processing Perfusion Images

M. Elsadany,1 C. Godoy Rivas,2 P. Jayapal,2 B. Stringer,3 D. Pelletier,2 S. Lee,2 S. McMahon,2 V. Nadig,2 W. Duvall*2; 1Cardiology department, Hartford Hospital, Hartford, CT, 2Hartford Hospital, Hartford, CT, 3University of Connecticut School of Medicine, Farmington, CT

Background: Modern SPECT MPI includes attenuation correction (AC) using a low-dose CT scan to improve image reconstruction. This AC CT can grossly identify coronary artery calcification (CAC), but a formal CAC score more accurately provides this information adding valuable diagnostic and prognostic information. However, performing both CT scans during a MPI study may unnecessarily increase radiation exposure and duplicate data needed for AC. If a formal CAC score could replace the standard AC CT scan, one would save time and radiation exposure while gaining important clinical information.

Methods: Patients presenting for a SPECT MPI study who consented to have a formal CAC score performed were included. Patients under 45, with previous PCI or CABG, were excluded. AC images were processed by the same nuclear technologist with the routine 5 mm low-dose attenuation scan and with a 5 mm CT reformatted from the CAC score acquisition. These perfusion images were reviewed by two board certified nuclear cardiologists for image quality (1-4, with 4 = excellent), sub-diaphragmatic tracer uptake (1-4, with 4 = severe), summed stress (SSS), summed rest (SRS), and summed difference scores (SDS). Any datasets with large discrepancies were reprocessed and re-reviewed to exclude processing errors.

Results: A total of 20 patients (mean age 62.6 ± 8.3, and 65% male) were included. The average coronary artery calcium score was 636 ± 1251 with four patients having a calcium score of 0. The average image quality of the AC CT scan images was 3.2 ± 0.5 compared to 2.9 ± 0.5 (P = 0.02) and the average GI tracer uptake was 2.3 ± 0.9 vs 2.4 ± 1.0 (P = 0.19). The average difference in the SSS between groups was 0.7 ± 4.3, in the SRS was -0.6 ± 4.8, and in the SDS was 1.4 ± 3.6 (Figure). Three patients had a summed score difference greater than 5 when using the CAC score for AC versus the standard AC CT.

Conclusion: In this small patient cohort, use of the CAC score CT for attenuation correction was feasible, but further study to confirm the consistency of perfusion findings and interpretation is necessary.

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212-08

Diagnostic Accuracy of Single-Photon Emission-Computed Tomography with Deep-Learning-Based Attenuation Correction

A. Shanbhag*,1 K. Pieszko,2 R. Miller,3 E. J. Miller,4 M. Lemley,2 D. Dey,5 D. S. Berman,2 P. J. Slomka2; 1Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, 2Cedars-Sinai Medical Center, Los Angeles, CA, 3University of Calgary, Calgary, AB, Canada, 4Yale University, New Haven, CT, 5Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA

Introduction: Cardiac single-photon emission-computed tomography (SPECT) studies commonly use computed tomography (CT)-based attenuation correction (AC) to improve diagnostic accuracy. However, this is unavailable for SPECT-only scanners and increases radiation exposure to the patient. We developed a method to simulate CTAC images from non-corrected (NC) myocardial perfusion imaging (MPI).

Methods: SPECT-MPI was performed using Tc-99m sestamibi or Tc-99m tetrofosmin on scanners with solid-state multi-pinhole detectors. We developed Conditional Generative Adversarial Neural Network (cGAN) which generates simulated attenuation-corrected images (PseudoAC). The model was trained using 798 (train 700: validation 98) pairs of non-corrected and CT-AC MPI studies performed at a single site. We tested the model using studies from an external dataset (N = 178). We assessed the agreement of measures obtained automatically with using quantitative clinical software: stress total perfusion deficit (S-TPD) and stress volume (S-VOL) as well as perfusion change for AC vs PseudoAC and NC scans. Wilcoxon rank-sum test was used to compare median values of S-TPD and perfusion change.

Results: The median (IQR) of S-TPD was 4.54 (1.39, 11.29) for AC and 5 5.50 (2.02, 11.69) for Pseudo-AC scans (P = 0.4). The mean difference in S-TPD was 0.32 (95% Confidence Interval [CI] − 0.06,0.71) between AC and Pseudo-AC and −1.15 (95% CI −1.66,-0.64) between AC and NC. The median S-VOL was 76.45 (54.35, 103.04) for AC and 76.43 (53.31, 105.44) Pseudo-AC (P > 0.9). The median change (IQR) was 11.33% (7.31, 17.75) and 2.25 (1.07, 4.10) for AC vs NC and AC vs Pseudo-AC, respectively (P < 0.001).

Conclusion: Automatic clinical measurements of stress TPD myocardial volume do not differ significantly between Pseudo-AC and AC MPI scans. Perfusion change values as measured by the clinical software are significantly smaller between AC vs Pseudo-AC than AC vs NC scans.

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212-09

Myocardial Blood Flow Estimation with Automated Motion Correction in 82Rb PET Myocardial Perfusion Imaging

Y. Otaki*, C. Wei, S. D. Van Kriekinge, T. Parekh, M. H. Lemley, P. B. Kavanagh, D. S. Berman, P. J. Slomka; Cedars-Sinai Medical Center, Los Angeles, CA

Introduction Patient motion correction (MC) is critical for the accurate quantification of myocardial blood flow (MBF) and flow reserve (MFR) from dynamic PET myocardial perfusion imaging (MPI). However, frame-by-frame manual correction is time consuming and is not reproducible. Therefore, we aimed to develop and validate an automated algorithm to perform motion correction in dynamic PET MPI.

Methods The algorithm uses simplex iterative optimization of a count-based cost function customized to different dynamic phases for performing frame-by-frame MC. Two experienced operators performed MC in 224 consecutive patients undergoing dynamic rest/stress 82Rb PET MPI across 16 frames for stress and rest images in three directions (inferior–superior, septal–lateral, apex–base). The third operator reconciled the MC results by a consensus with each operator. 224 patients were split into a tuning group (N = 112) and a validation group (N = 112). Automated and manual MC were compared in the early (first 2 minutes) and late phases for the validation group. Additionally, operators performed MC on a population undergoing 82Rb PET and invasive angiogram within 18 days (N = 112) which is separate from the tuning and validation groups. MFR was obtained by fitting the corresponding time–activity curves for each polar map region using QPET software (Cedars-Sinai). The per-patient diagnostic performance for the detection of obstructive coronary artery disease (CAD) by minimal 17-segment MFR was compared for automated MC in the angiographic group. Obstructive CAD was defined as ≥50% stenosis in the left main trunk or ≥ 70% stenosis in any of the main coronary arteries.

Results The automated algorithm generates the corrections in < 12 seconds per case (stress and rest). The mean/max manual shifts in any direction were 0.8/16 mm at stress and 0.5/14 mm at rest in early phase, and 0.3/8 mm at stress and 0.2/13 mm at rest in late phase. Manual shifts ≥ 5 mm at stress and rest, respectively, were made in 10% and 7% in septal–lateral, 51% and 17% in anterior–inferior, and 27% and 15% in apex–base directions. The frequency of motion differences ≥ 5mm between manual and automated MC in septal–lateral and anterior–inferior directions were < 5% across all frames at stress and rest. In base–apex direction, motion differences ≥ 5mm were observed still in 14% in frame 3 at stress and < 5% in remaining frames at stress and rest. There was no significant difference in area under the curve for obstructive CAD detection by MFR between operator MC and the automatic MC (0.77 [0.68-0.86] vs 0.79[0.71-0.88], P = 0.38).

Conclusion Patient MC on dynamic rest/stress 82Rb PET MPI can be performed automatically and rapidly with good agreement with experienced operators. Automatic and manual MC demonstrate similar diagnostic performance for the detection of CAD.

212-10

Prognostic Concordance of Computed Tomography Angiography Anatomic Assessment and Myocardial Perfusion Imaging in Patients with Suspected Coronary Artery Disease

A. Ahmed*,1 Y. Han,1 J. Saad,1 M. Al Rifai,2 F. Nabi,1 M. H. Al-Mallah1; 1Houston Methodist DeBakey Heart and Vascular Center, Houston, TX, 2Baylor College of Medicine, Houston, TX

Introduction: In patients with suspected coronary artery disease (CAD), evaluation using coronary computed tomography angiography (CCTA) and Single-Photon Emission-Computed Tomography (SPECT) Myocardial Perfusion Imaging (MPI) provide complimentary information on the anatomical extent and functional significance of disease. We aimed to assess the prognostic significance of concordant vs discordant test findings in patients who were investigated with both tests.

Methods: Consecutive patients with suspected CAD who underwent CCTA and SPECT MPI within 180 days of each other were reviewed. Anatomically obstructive CAD by CCTA was defined as ≥ 50% in the left main artery and ≥ 70% stenosis severity in proximal, mid, and distal branches of the left anterior descending, left circumflex, and right coronary artery without including side branches. Ischemia on SPECT was defined as summed difference score > 0. Patients were followed from the date of first imaging to incident major adverse cardiovascular events (MACE – composite of all-cause death, myocardial infarction (MI), and unplanned revascularization – Percutaneous Coronary Intervention (PCI) or Coronary Artery Bypass Graft (CABG) occurring more than 90 days after index imaging.)

Results: Our study population consisted of 956 patients (mean (SD) age 61.1 ±14.2 years, 54.1% men, 89% hypertension, 81% diabetes, and 84% dyslipidemia). Obstructive stenosis on CCTA and any ischemic defect on SPECT were present in 14% of patients. After a median follow-up of 31 months (IQR 12-65 months), 102 patients (10.7%, 29.2 events per 1000 person-year) experienced the primary outcome. The highest event rates were in patients with both stenosis on CCTA and ischemia on SPECT (Figure 1). Patients with abnormal test on either CCTA or SPECT had higher event rates compared to those with normal tests.

Conclusion: In this analysis, we have shown that in our high-risk cohort of patients with suspected coronary artery disease, stenosis on CCTA and ischemia on SPECT can be used to identify patients at higher risk of incident cardiovascular outcomes.

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212-11

Change in Positron Emission Tomography Perfusion Imaging Quality with a Novel Data-Driven Motion Correction Algorithm

Y. Han*,1 A. Ahmed,1 C. Hayden,2 A. K. Jung,3 F. Nabi,1 A. Khan,1 J. Saad,1 B. Spottiswoode,2 M. AI-mallah1; 1Houston Methodist DeBakey Heart and Vascular Center, Houston, TX, 2Siemens Medical Solutions USA, Knoxville, TN, 3Siemens Medical Solutions USA, Houston, TX

Introduction: Respiratory and bulk motion frequently reduce the interpretability of cardiac PET images. This study utilized a prototype data-driven motion correction (DDMC) algorithm to generate corrected images, and evaluated image quality and change of perfusion defect size and severity by comparing DDMC images with non-corrected images (NMC).

Methods: Rest and stress images with NMC and DDMC from 40 consecutive patients with motion were rated by 2 blinded investigators on a 4-point visual ordinal scale (VOS) (0: no motion; 1: mild motion; 2: moderate motion; 3: severe motion/uninterpretable). DDMC tracks heart motion at a high spatiotemporal resolution from list mode PET data. Resulting motion vectors can be used to quantify the severity of motion, which is represented here as the fraction of time the heart is within 6mm craniocaudal of the average position (Dwell Z).

Results: A total of 40 patients had mild, moderate, and severe motion, respectively. Fig.1 shows example NMC (1A, VOS = 3) and DDMC (1B, VOS = 0) images from the same patient. All corrected images showed an improvement in quality and were interpretable after processing (Fig 1C). This was confirmed by a significant correlation between data-driven measurements of motion quantification and physician interpretation (Fig 1D-F).

Conclusions: The novel DDMC algorithm improved quality of cardiac PET images with motion. Correlation between data-driven motion quantification and physician interpretation was significant.

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212-12

Prior SARS-CoV-2 Infection is Associated Coronary Vasomotor Dysfunction as Assessed by Coronary Flow Reserve from Cardiac Positron Emission Tomography

B. Weber*,1 S. Parks,1 A. Kim,1 C. Bay,1 J. Brown,1 S. Divakaran,2 J. Hainer,1 C. Bibbo,1 V. R. Taqueti,1 S. Dorbala,1 R. Blankstein,3 A. Woolley,1 M. DiCarli1; 1Brigham and Women's Hospital, Boston, MA, 2Brigham & Women’s Hospital, Boston, MA, 3Brigham & Women's Hospital, Boston, MA

Background: Cardiovascular complications from COVID19 contribute to its high morbidity and mortality. The vasculature is affected in COVID-19, both directly by the SARS-CoV-2 virus and indirectly due to systemic inflammation. The effect of COVID-19 infection on the coronary vasculature is not known. Coronary flow reserve (CFR), an integrated measure of focal, diffuse, and small-vessel coronary artery disease, identifies patients at risk for cardiac death. We hypothesized that COVID-19 infection is associated with coronary vasomotor dysfunction.

Methods: We identified subjects with prior PCR-confirmed SARS-CoV-2 infection who underwent clinically indicated myocardial stress perfusion PET imaging. We obtained a matched control group without SARS-CoV-2 infection (PCR negative). Baseline and stress hemodynamics were obtained, and the CFR was calculated as the ratio of myocardial blood flow (ml⋅min⋅g) at peak stress over rest.

Results: We studied 15 COVID-19 patients and 43 matched controls (median 3 per case) (Table). The median time from SARS-CoV-2 PCR to cardiac PET was 4 (IQR 1.2-5.6) months. 9/15 (60%) of patients were previously hospitalized for COVID-19 infection. Baseline cardiac risk factors were common, and 8 (53%) patients in the COVID-19 group had abnormal perfusion (defined as summed stress score >3). CFR was abnormal (< 2) in 46% (7/15) of the COVID-19 patients compared to 16.2% (7/43) of matched controls (P = 0.041). The mean CFR was 16.4% lower in COVID-19 patients compared with control patients (2.05 ± 0.5 vs 2.45 ± 0.53, P = 0.029).

Conclusion: CFR was impaired in patients with prior COVID-19 infection compared with matched controls, suggesting a relationship between SARS-CoV-2 infection and coronary vascular health. These data provide potential insight into long-term vascular health and highlight the need to assess long-term consequences of COVID-19 in future prospective studies.

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212-13

Visual Patterns of Breast Attenuation Artifacts in Women and Men with an Upright and Supine Cadmium-Zinc-Telluride Camera

F. Waqar*,1 M. Athar,1 A. Dwivedi,2 S. Ahmad,1 S. Sanghvi,3 E. Scott,4 N. Khan,1 M. Gerson1; 1University of Cincinnati College of Medicine, Cincinnati, OH, 2Texas Tech University Health Sciences Center El Paso, El Paso, TX, 3University of Illinois College of Medicine at Chicago, Chicago, IL, 4University of Cincinnati Medical Center, Cincinnati, OH

Introduction: Breast attenuation is a common source of artifacts in single-photon emission-computerized tomography-based myocardial perfusion imaging. Breast attenuation artifacts occurring with upright Cadmium-Zinc-Telluride (CZT) cardiac imaging systems have not been well characterized.

Methods: 216 consecutive patients with Single-Photon Emission-Computerized Tomography myocardial perfusion imaging and no angiographically significant obstructive coronary artery disease were identified. All upright and supine SPECT images as well as coronary angiograms were reviewed and analyzed in blinded fashion. Patients were sub-grouped as obese or non-obese. Comparisons of visual defects between anterior and inferior myocardial territories were evaluated for rest and stress conditions and separately for each gender. All stress and rest images were acquired in upright as well as supine position.

Results: In women imaged upright, more visual false-positive defects were noted in the inferior wall compared to the anterior wall (26 vs 10 at rest, P = 0.006, and 33 vs 13 at stress, P < 0.001). Visual inferior wall defects were more common in the upright than supine position at stress (33 vs 23, P = 0.018) and rest (26 vs 14, P = 0.011), and most apparent in non-obese women (13 vs 8, at stress, P = 0.059 and 11 vs 5, at rest, P = 0.014).

Conclusions: With upright CZT myocardial perfusion imaging, women often have visible inferior wall attenuation artifact defects, likely from pendant breast tissue. These inferior wall attenuation artifacts may be seen in non-obese female patients.

figure ae

212-14

99mTc-Doxycycline Encapsulated in a Radiopaque Hydrogel for Dual-Modality Theranostic Imaging for Modulation of Post-Infarction Remodeling

S. Lee*,1 S. Uman,2 S. Thorn,3 B. Marquez-Nostra,1 F. G. Spinale,4 J. A. Burdick,2 A. J. Sinusas3; 1Yale School of Medicine, New Haven, CT, 2University of Pennsylvania, Philadelphia, PA, 3Yale University School of Medicine, New Haven, CT, 4University of South Carolina, Columbia, SC

Introduction: Myocardial infarction (MI) is complicated by post-MI remodeling, which is mediated in part by matrix metalloproteinase (MMP) activation. Intramyocardial injections of hydrogels post-MI can mitigate remodeling, particularly when incorporating MMP inhibitors. Doxycycline (DOX) is a weak MMP inhibitor with limited clinical benefit when administered i.v. post-MI. We radiolabel DOX with 99mTc (Tc-DOX) and encapsulate tracer into a two-component hydrogel (HG) made with: cyclodextrin-modified hyaluronic acid (CD-HA) which forms an inclusion complex with DOX, and adamantane-modified hyaluronic acid (Ad-HA) to form a supramolecular hydrogel with encapsulated CT contrast agent (iohexol), creating a dual modality theranostic hydrogel for tracking local DOX delivery.

Methods: A one-pot reaction was developed to radiolabel 10 mg doxycycline hyclate with [99mTcO4], ascorbic acid, and SnCl2. A range of conditions were tested to optimize specific activity (SA) and radiochemical purity (RP) of Tc-DOX. Quality-control testing was performed via radio-TLC and radio-HPLC. Ad-HA was dissolved in iohexol solution, while CD-HA was dissolved in equal volume of Tc-DOX and combined into HG in Eppendorf tubes. Saline was added to mixture to define Tc-DOX effusion from hydrogel over 24 hours. Supernatant was assayed for radioactivity and exchanged with saline at 1, 2, and 4 hours after gel formation, and HG serially imaged via SPECT/CT.

Results: The optimal SA of Tc-DOX was 100 MBq⋅µmol, with RP > 95%. Tc-DOX is stable at room temperature 6 hours after labeling, while precursor was stable for labeling for 2 mon at − 80 °C. Once in HG, Tc-DOX is slowly released with ~ 50% HG retention over 24 hours.

Conclusion: DOX can be labeled with [99mTcO4]- with high radiochemical purity and encapsulated in a HG that is imageable via hybrid SPECT/CT. Our novel Tc-DOX theranostic HG demonstrated favorable release kinetics for tracking local DOX release following intramyocardial delivery post-MI.

figure af

ASNC2021 Abstract Author Index

A

Abazid, R. M.; 207-05

Adamson, P. D.; 207-01

Agoston, I.; 112-14

Ahmad, A. A.; 125-05

Ahmad, F. S.; 015-03

Ahmad, S.; 212-13

Ahmed, A.; 112-09, 112-11, 207-04, 212-04, 212-10, 212-11

Akincioglu, C.; 207-05

Al Badarin, F.; 015-12

Al-Darzi, W.; 112-13

Al-Mallah, M. H.; 112-09, 112-11, 207-04, 212-04, 212-10, 212-11

Alnabelsi, T.; 112-09, 112-11, 207-04

Al-Rashdan, L.; 015-09, 015-10, 125-04

Al Rifai, M.; 112-11, 212-10

AlShaheen, M.; 125-02

Alsomali, H.; 112-05

Altaha, Z.; 015-12

Ananthasubramaniam, K.; 112-13

Argenziano, M.; 112-07

Arora, S.; 015-08

Athar, M.; 212-13

Ayeni, A.; 112-12

B

Baker, A. H.; 207-01

Barutcu, S.; 015-03

Baskaran, L.; 112-03

Bateman, T. M.; 112-02, 125-01, 125-03, 212-05

Bay, C.; 212-12

Beanlands, R. S.; 015-02

Becerra, A. F.; 112-08

Berman, D. S.; 125-01, 125-03, 207-01, 207-02, 207-03, 212-01, 212-02, 212-08, 212-09

Bhattaru, A.; 015-07

Bianchi, G.; 125-06

Bibbo, C.; 212-12

Birnie, D.; 015-02

Blankstein, R.; 212-12

Bravo, P. E.; 015-01, 015-07

Brown, J.; 212-12

Buch, C.; 112-14

Burdick, J. A.; 212-14

Burgett, E. V.; 212-05

Burton, Y.; 015-09, 015-10, 125-04

C

Cacko, M.; 015-11

Cadet, S.; 015-05, 125-01, 207-01

Carey, C.; 125-02

Cartlidge, T. R. G.; 212-02

Case, J. A.; 212-05

Chambi, A.; 212-03

Chamsi-Pasha, M. A.; 112-11

Chan, D.; 015-05

Chandrashekar, P.; 015-09, 015-10, 125-04

Chang, S.; 112-11

Chareonthaitawee, P.; 125-01

Chen, N.; 207-03

Choi, B. Y.; 112-14

Choo, R.; 015-05

Chua, T.; 112-03

Correa, N.; 015-13, 212-03

Costa, F.; 015-13

Cotrado, A.; 015-13

Courter, S. A.; 212-05

Cuddy, S.; 125-06

D

Datar, Y.; 125-06

Davis, C.; 112-01

deKemp, R. A.; 015-02

Dey, D.; 125-01, 125-03, 207-01, 212-01, 212-08

Di Carli, M.; 125-01, 125-03, 125-06, 212-12

Dietz, J.; 015-06

Divakaran, S.; 212-12

Dolenc Novak, M.; 212-06

Dorbala, S.; 125-01, 125-03, 125-06, 212-12

Doris, M.; 212-02

Dutta, S.; 015-03

Duvall, W.; 015-04, 015-08, 112-08, 212-07

Dweck, M. R.; 207-01, 212-02

Dwivedi, A.; 212-13

E

Einstein, A. J.; 125-01, 125-03

El Nihum, L. I.; 207-04

Elsadany, M.; 015-04, 015-08, 212-07

ElZouhbi, A.; 015-12

F

Falk, R.; 125-06

Fernandez, R.; 112-14

Fichardt, H. J.; 112-14

Fine, N. M.; 015-05

Fish, M. B.; 125-01, 125-03

Fletcher, A.; 207-01

Friedman, J. D.; 207-02

G

Gawor, M.; 015-11

Gerson, M.; 212-13

Ghim, M.; 125-05

Gill, S.; 015-09, 015-10, 125-04

Godoy Rivas, C.; 015-04, 015-08, 212-07

Goldberg, L. R.; 015-01

Gona, K.; 125-05

Gould, K. L.; 112-07

Gransar, H.; 207-02, 207-03

Grodecki, K.; 207-01

Grzybowski, J.; 015-11

Gužič Salobir, B.; 212-06

Gutierrez, L.; 112-04

H

Hainer, J.; 212-12

Han, D.; 207-02

Han, Y.; 112-09, 112-11, 207-04, 212-04, 212-10, 212-11

Hayden, C.; 212-11

Hayes, S. W.; 125-01, 207-02

Hobocan, M.; 015-04

Holly, T. A.; 015-03

Hynal, K.; 015-06

Hyun, M. C.; 212-01

I

Ibrahim, J.; 015-06

Irvine, P.; 125-02

J

Jaiswal, A.; 015-08

Jamal, S.; 015-12

Javaid, A.; 212-04

Jayapal, P.; 212-07

Jenkins, W.; 212-02

Jerosch-Herold, M.; 125-06

Joshi, N.; 207-01

Jozwik-Plebanek, K.; 015-11

Jung, A. K.; 212-11

Jung, J. J.; 125-05

K

Kansal, P.; 015-03

Karambelkar, P.; 015-07

Katsaggelos, A. K.; 015-03

Kaufmann, P. A.; 125-01, 125-03

Kavanagh, P.; 125-01

Kavanagh, P. B.; 207-03, 212-09

Keng, B. M.; 112-03

Keng, F.; 112-03

Keppler, J.; 112-01

Ker, W.; 015-13, 212-03

Khan, A.; 212-11

Khan, N.; 212-13

Khatami, A.; 207-05

Kijewski, M. F.; 125-06

Kim, A.; 212-12

Knapp, C.; 112-01

Koh, A. S.; 112-03

Kuronuma, K.; 125-01

Kwiecinski, J.; 207-01, 207-03, 212-02

Kwong, R.; 125-06

L

Landau, H.; 125-06

Lang, F. M.; 112-07

Lee, H.; 015-01, 015-07

Lee, S.; 212-07

Lee, S.; 212-14

Lehenbauer, K.; 112-02

Leipsic, J.; 207-01

Lemley, M. H.; 212-01, 212-08, 212-09

Liang, J. X.; 125-01, 125-03

Liao, R.; 125-06

Lindner, J.; 125-04

M

MacAskill, M. G.; 207-01

Machado, D.; 212-03

Mah, D.; 015-05

Mahmarian, J. J.; 112-11

Makki, T.; 112-13

Malhotra, S.; 207-05

Manla, Y.; 015-12

Marchlinski, F. E.; 015-01

Marquez-Nostra, B.; 212-14

Marvin, B.; 125-02

Masri, A.; 015-09, 015-10, 125-04

McCarthy, P. M.; 015-03

McCorry, C.; 207-05

McGhie, A.; 112-02, 212-05

McMahon, S.; 212-07

Meah, M. N.; 207-01

Merhige, M. E.; 112-01

Mesquita, C. T.; 015-13, 212-03

Miller, E. J.; 125-01, 125-03, 212-08

Miller, R.; 015-05, 125-01, 207-02, 207-03, 212-08

Mittra, E.; 125-04

Moloney, E.; 212-05

Momodu, J.; 112-12

Montera, M.; 212-03

N

Nabi, F.; 112-09, 112-11, 207-04, 212-10, 212-11

Nadig, V.; 212-07

Nasr, H.; 112-05

Nery, P. B.; 015-02

Newby, D.; 207-01, 212-02

Nieves, R. A.; 015-06

O

Ojha, D.; 125-05

Oliveira-Junior, A. C.; 212-03

Otaki, Y.; 125-01, 125-03, 207-02, 207-03, 212-01, 212-09

P

Palazzo, I.; 015-13, 212-03

Parekh, T.; 125-01, 207-03, 212-09

Parks, S.; 212-12

Patel, F.; 112-02

Patel, K. K.; 112-02, 212-05

Patel, V.; 015-07

Patterson, K. C.; 015-01

Pawade, T.; 212-02

Pelletier, D.; 212-07

Peñafort, F. A.; 112-04

Perucki, W.; 112-08

Peyster, E. G.; 015-01

Pieszko, K.; 125-03, 207-02, 212-01, 212-08

Purbhoo, K.; 112-12

R

Rabyschoffsky, A.; 212-03

Ramos-Manalaysay, A. L.; 112-06

Rao, S. R.; 125-06

Rentrop, K. P.; 112-07

Rideout, N.; 207-05

Rocha, A. C.; 212-03

Rochitte, C. E.; 212-03

Rodriguez, J.; 015-07

Rojulpote, C.; 015-07

Romsa, J.; 207-05

Rossman, M. D.; 015-01

Rosu, D. I.; 112-14

Rozanski, A.; 207-02

Ruberg, F. L.; 125-06

Ruddy, T. D.; 125-01, 125-02, 125-03

S

Saad, J.; 112-09, 207-04, 212-04, 212-10, 212-11

Saco, R.; 112-13

Sadeghi, M. M.; 125-05

Salarian, M.; 125-05

Salomao, F.; 212-03

Sanchorawala, V.; 125-06

Sanghvi, S.; 212-13

Satriano, A.; 015-05

Scott, E.; 212-13

Sellers, S.; 207-01

Serafim, J.; 212-03

Shah, S. J.; 015-03

Shaik, A.; 112-08

Shaikh, R.; 112-08

Shanbhag, A.; 212-01, 212-08

Sharir, T.; 125-01, 125-03

Siciliano, A. C.; 212-03

Silva, P. R. D.; 212-03

Singh, A.; 112-02, 125-01, 125-03, 207-03

Sinusas, A. J.; 125-01, 125-03, 212-14

Slomka, P. J.; 015-05, 125-01, 125-03, 207-01, 207-02, 207-03, 212-01, 212-02, 212-08, 212-09

Small, G. R.; 125-02

Soman, P.; 015-06

Sperry, B. W.; 212-05

Spinale, F. G.; 212-14

Spottiswoode, B.; 212-11

Stringer, B.; 212-07

Sutherland, D.; 207-05

Swiha, M.; 207-05

Szava-Kovats, A.; 015-05

Štalc, M.; 212-06

T

Tamarappoo, B. K.; 125-01, 207-02

Tan, R.; 112-03

Taqueti, V. R.; 212-12

Tavares, A. A.; 207-01

Tavoosi, A.; 125-02

Taylor, A.; 125-06

Teng, X.; 112-03

Teresinska, A.; 015-11

Thomas, J. D.; 015-03

Thomson, L.; 207-02

Thorn, S.; 212-14

Toczek, J.; 125-05

Tzolos, E.; 207-01, 212-02

U

Uman, S.; 212-14

V

van Beek, E. J.; 207-01

Vangu, W.; 112-12

Van Harn, M.; 112-13

Van Kriekinge, S. D.; 207-03, 212-01, 212-09

W

Waqar, F.; 212-13

Warner, S.; 015-09, 015-10, 125-04

Warrington, J.; 207-05

Weber, B.; 212-12

Wehbe, R. M.; 015-03

Wei, C.-C.;207-03, 212-09

Wei, L.; 125-05

Weissler-Snir, A.; 015-08

Wells, R.; 125-02

White, G. C.; 015-05

White, J. A.; 015-05

Wiefels, C.; 015-02

Williams, M.; 207-01

Wilson, K.; 112-01

Wnuk, J.; 015-11

Woolley, A.; 212-12

Y

Yee, A.; 125-06

Z

Zhang, J.; 125-05

Zoghbi, W.; 112-11

ASNC2021 Keyword Index

Acute Coronary Syndrome: 212-10

Atherosclerosis: 125-05, 207-01, 212-02

Attenuation: 212-01, 212-08

Calcium Scoring: 112-13, 207-02, 212-01, 212-07

Cardiac MRI: 015-05

Cardiomyopathy: 015-03, 015-07, 015-09, 015-10, 015-11, 015-12, 015-13, 125-04, 207-05

Clinical Trials: 112-07

Computer Processing: 015-03, 015-04, 212-08

Coronary Flow Reserve: 015-06, 112-03, 212-09, 212-12

CT Angiography: 112-11, 212-04

Diabetes: 112-05, 112-13

Diastolic Function: 112-06

Fluorodeoxyglucose: 015-02, 015-07

Gender: 212-13

Guidelines: 112-14

Hybrid Imaging: 207-05

Image Processing: 207-03, 212-11

Ischemia: 112-02

Molecular Probes: 125-06

Myocardial Perfusion: 112-01, 112-07, 112-12, 112-14, 125-01, 125-02, 212-04, 212-05

Other: 015-04, 015-08, 015-11, 015-13, 112-11, 125-03

Outcomes: 015-08, 015-12, 212-10

PET: 015-01, 015-02, 112-01, 112-02, 112-09, 125-05, 207-01, 207-02, 207-03, 207-04, 212-02, 212-09, 212-11, 212-12

Quality: 212-03

Quantification: 015-10, 125-04

Radiopharmaceutical: 015-05, 212-14

Receptor Imaging: 015-01

Right Ventricle: 125-06

Risk Assessment: 112-04, 112-08, 212-03

Solid State Detectors: 015-06

SPECT Techniques: 015-09, 112-03, 112-04, 112-05, 112-06, 125-01, 125-02, 125-03, 212-06, 212-07, 212-13, 212-14

Tetrofosmin: 212-05

Vasodilators: 112-08, 112-09, 112-12, 207-04, 212-06

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Abstracts of Original Contributions ASNC2021 The 26th Annual Scientific Session of the American Society of Nuclear Cardiology. J. Nucl. Cardiol. 28, 2425–2455 (2021). https://doi.org/10.1007/s12350-021-02760-1

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