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The effect of time-of-flight and point spread function modeling on 82Rb myocardial perfusion imaging of obese patients

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Journal of Nuclear Cardiology Aims and scope

Abstract

Background

The effect of time-of-flight (TOF) and point spread function (PSF) modeling in image reconstruction has not been well studied for cardiac PET. This study assesses their separate and combined influence on 82Rb myocardial perfusion imaging in obese patients.

Methods

Thirty-six obese patients underwent rest-stress 82Rb cardiac PET. Images were reconstructed with and without TOF and PSF modeling. Perfusion was quantitatively compared using the AHA 17-segment model for patients grouped by BMI, cross-sectional body area in the scanner field of view, gender, and left ventricular myocardial volume. Summed rest scores (SRS), summed stress scores (SSS), and summed difference scores (SDS) were compared.

Results

TOF improved polar map visual uniformity and increased septal wall perfusion by up to 10%. This increase was greater for larger patients, more evident for patients grouped by cross-sectional area than by BMI, and more prominent for females. PSF modeling increased perfusion by about 1.5% in all cardiac segments. TOF modeling generally decreased SRS and SSS with significant decreases between 2.4 and 3.0 (P < .05), which could affect risk stratification; SDS remained about the same. With PSF modeling, SRS, SSS, and SDS were largely unchanged.

Conclusion

TOF and PSF modeling affect regional and global perfusion, SRS, and SSS. Clinicians should consider these effects and gender-dependent differences when interpreting 82Rb perfusion studies.

Spanish Abstract

Antecedentes

El efecto de los algoritmos de reconstrucción “time of flight” (TOF) y “point spread function” (PSF) en la reconstrucción de imágenes no ha sido bien estudiado para el PET cardiaco. Este estudio evalúa su influencia en por separado y combinado en los estudios de imagen de perfusión miocárdica con 82Rb en pacientes obesos.

Métodos

Treinta y seis pacientes obesos fueron sometidos a un PET cardiaco 82Rb en estrés y en reposo. Las imágenes fueron reconstruidas con y sin TOF y PSF. La perfusión fue comparada cuantitativamente utilizando el modelo segmentario AHA17 para pacientes agrupados por IMC, área corporal transversal in el campo de vista del escáner, sexo y volumen ventricular izquierdo miocárdico. Los puntajes sumados de reposo (SRS), los puntajes sumados de estrés (SSS) y el puntaje diferencial sumado (SDS) fueron comparados.

Resultados

El TOF mejoró la uniformidad visual del mapa polar e incrementó la perfusión de la pared septal hasta un 10%. Este incremento fue mayor para pacientes más grandes, más evidentemente en pacientes agrupados por área transversal que por IMC, y siendo más prominente en mujeres. El PSF aumentó la perfusión por cerca de 1.5% en todos los segmentos cardiacos. El TOF generalmente disminuyó el SRS y el SSS con disminuciones significativas entre 2.4 y 3 (P < .05), lo cual podría afectar la estratificación por riesgo; el SDS permanece igual. Con el modelamiento PSF, el SRS, el SSS y el SDS no presentaron cambios.

Conclusión

El TOF y el PSF afecta a la perfusión regional y global, el SRS y el SSS. Los clínicos deberían considerar estos efectos y las diferencias dependientes de sexo cuando se interpretan los estudios de perfusión con 82Rb.

Chinese Abstract

背景

飞行时间(TOF)和点扩散函数(PSF)建模对于心脏 PET 成像重建的影响尚未完善建立。本研究评估其单独以及联合使用对肥胖病人行铷 82 心肌灌注成像的影响。

方法

36 个肥胖病人接受静息-负荷的铷 82 心脏 PET 成像扫描。图像分别在有无 TOF 和 PSF 建模的情况下被重建。病人按照 BMI、扫描仪视野下横断面的体表面积、性别和左室容积进行分组,采用 AHA 17节段模型量化对比灌注情况,比较静息灌注总积分(SRS),负荷灌注总积分(SSS)和灌注总积分差值(SDS)。

结果

TOF 改进了靶心图的视觉一致性, 间隔壁的灌注增加了10%。这种增加表现为: 体型越大的病人增加越大, 以横断面体表面积分组的病人比用 BMI 分组的病人增加更明显,女性比男性增加更突出。在所有的心脏节段中, PSF 建模增加了约 1.5% 的灌注。TOF 建模总体上显著降低了SRS和 SSS(在 2.4 和 3.0 之间, P < .05), 这会影响风险分层; SDS 保持不变。利用 PSF 建模, SRS, SSS 和 SDS 在很大程度上保持不变。

结论

TOF 和 PSF 建模影响局部和整体灌注、SRS 以及 SSS。当阅读铷 82 灌注图像时, 临床医生应该考虑这些因素的影响以及性别导致的不同。

French Abstract

Contexte

L’effet de la modélisation du temps de vol (TOF) et de la fonction d’étalement ponctuel (PSF) pour la reconstruction d’images n’a pas été bien étudiée pour la TEP en cardiologie. Cette étude évalue l’influence séparée et combinée des ces deux facteurs sur la perfusion myocardique par imagerie au 82Rb chez les patients obèses.

Méthodes

Trente-six patients obèses ont été soumis à une étude TEP repos-effort au 82Rb au repos. Les images ont été reconstruites avec et sans modélisation TOF et PSF. Les résultats de la perfusion myocardique a été comparée quantitativement en utilisant le modèle de 17 segments de l’American Heart Association (AHA). Les patients ont été groupés selon l’index de leur masse corporelle (IMC), et selon leur dimension corporelle transversale dans le champ de vision du scanner, sexe et volume myocardique ventriculaire gauche. Les score de perfusion myocardique au repos (SRS), après effort (SSS) et les scores différentiels (SDS) ont été comparés.

Résultats

TOF améliore l’uniformité visuelle de la carte polaire et augmente la perfusion de la paroi septale de 10%. Cette augmentation est plus importante chez les patients de grande taille et plus apparente chez les patients groupés selon leur dimension corporelle transversale zone plutôt que par l’IMC, et plus élevée chez les femmes. La modélisation PSF augmente la perfusion d’environ 1,5% dans tous les segments cardiaques. La modélisation TOF diminue significativement les scores SRS et le SSS de 2,4 et 3,0 points (P < 0,05), ce qui peut changer la stratification; le score SDS est dans l’ensemble inchangé. Avec la modélisation PSF, SRS, SSS et SDS sont largement inchangés.

Conclusion

La modélisation TOF et PSF affectent la perfusion régionale et globale, SRS et SSS. Les cliniciens devraient tenir compte de ces effets et des différences entre les sexes lors de l’interprétation 82Rb études de perfusion.

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Abbreviations

BMI:

Body mass index

CAD:

Coronary artery disease

FWHM:

Full-width at half-maximum

FOV:

Field of view

LMM:

Linear mixed effects model

LV:

Left ventricular/left ventricle

MPI:

Myocardial perfusion imaging

OSEM:

Ordered subsets expectation maximization

OSEMTOF:

OSEM reconstruction with TOF modeling

PET:

Positron emission tomography

PSF:

Point spread function/OSEM reconstruction with PSF modeling

PSFTOF:

OSEM reconstruction with TOF and PSF modeling

SDS:

Summed difference score

SNR:

Signal-to-noise ratio

SPECT:

Single-photon emission computed tomography

SRS:

Summed rest score

SSS:

Summed stress score

TOF:

Time-of-flight

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Disclosure

This work was supported in part by Siemens Medical Solutions. P.K.R. Dasari, V. Dilsizian, M.F. Smith, and Y. Liang were employees of the University of Maryland, Baltimore when this research was conducted. J.P. Jones and M.E. Casey were employees of Siemens Healthineers.

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Authors and Affiliations

  1. Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, 22 South Greene St., Baltimore, MD, 21201, USA

    Paul K. R. Dasari PhD, Vasken Dilsizian MD & Mark F. Smith PhD

  2. Siemens Healthineers, Knoxville, TN, USA

    Judson P. Jones PhD & Michael E. Casey PhD

  3. Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, MD, USA

    Yuanyuan Liang PhD

Authors
  1. Paul K. R. Dasari PhD
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  2. Judson P. Jones PhD
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  3. Michael E. Casey PhD
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  4. Yuanyuan Liang PhD
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  5. Vasken Dilsizian MD
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Corresponding author

Correspondence to Mark F. Smith PhD.

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The authors of this article have provided a PowerPoint file, available for download at SpringerLink, which summarises the contents of the paper and is free for re-use at meetings and presentations. Search for the article DOI on SpringerLink.com.

JNC thanks Erick Alexanderson MD, Carlos Guitar MD, and Diego Vences MD, UNAM, Mexico, for providing the Spanish abstract; Haipeng Tang MS, Zhixin Jiang MD, and Weihua Zhou PhD, for providing the Chinese abstract; and Jean-Luc Urbain, MD, PhD, CPE, Past President CANM, Chief Nuclear Medicine, Lebanon VAMC, PA, for providing the French abstract.

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Dasari, P.K.R., Jones, J.P., Casey, M.E. et al. The effect of time-of-flight and point spread function modeling on 82Rb myocardial perfusion imaging of obese patients. J. Nucl. Cardiol. 25, 1521–1545 (2018). https://doi.org/10.1007/s12350-018-1311-y

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