Background

Cardiovascular magnetic resonance (CMR) myocardial perfusion is a well established method for detection of significant obstructive coronary artery disease (CAD). In patients with arrhythmias, standard methods using ECG-gating can result in poor image quality. Additionally, with typical stress/rest protocols, a true rest state may not be achieved after administration of regadenoson. However, rest-first may present issues with peri-infarct ischemia and so here we give little time for late enhancement by keeping rest and stress perfusion scans close in time. Given these issues, the two-fold aim of this study is to evaluate the accuracy of a rapid rest-first protocol using an ungated myocardial image pulse sequence.

Methods

This prospective, single-blinded study included seven atrial fibrillation patients who underwent ungated rest/stress perfusion imaging and coronary x-ray angiography. Images were acquired using an ungated radial myocardial perfusion sequence (TR/TE = 2.2/1.2 msec, 3T, 20 rays/slice, 5 slices after each saturation pulse, ~2 × 2 × 8 mm), as described in a previous adenosine stress-first study. Rest/stress protocol was performed in the following fashion: rest image acquisition (0.05 mmol/kg gadoteridol, 1.5 minutes), administration of regadenoson 0.4 mg intravenously (0.4 mg/5 mL) to induce hyperemia, 70 second wait, then stress image acquisition (0.075 mmol/kg gadoteridol, 1.5 minutes). CMR images were interpreted (0 = normal, 1 = equivocal, but probably normal, 2 = probable ischemia, 3 = definitely abnormal) and evaluated for quality (1 to 5, lowest to highest quality) by two blinded readers. Perfusion results were condensed to normal (0-1) or disease (2-3). 14 readings for 7 patients were derived from separate reader results. CMR perfusion diagnostic accuracy for the detection of ischemic heart disease was determined by comparison to x-ray angiography with significant lesions defined as ≥70% stenosis or FFR≤0.8 (Figure 1).

Figure 1
figure 1

Rest and stress perfusion images showing inferior wall defect with corresponding coronary x-ray angiography. a. Rest perfusion image demonstrating mid inferior wall defect (white arrow). b. Stress perfusion image demonstrating mid inferior wall defect with septal wall extension (green arrow). c. Coronary X-ray angiography demonstrating chronic total occlusion of the mid right coronary artery (red arrow). d. Coronary X-ray angiography demonstrating distal right coronary artery filling via collaterals (blue arrow).

Full size image

Results

Sensitivity and specificity of this CMR perfusion in the detection of significant coronary lesions were 1 and 0.88, respectively. Average quality of the readings was 3.8 ± 0.8 for both rest and stress perfusion images. Average scan-time for rest/stress perfusion imaging acquisition including time of pharmaceutical injection was 6.5 ± 4.0 minutes.

Conclusions

Initial results for this ongoing rest/regadenoson stress protocol using an ungated myocardial perfusion sequence yielded high sensitivity and specificity for the detection of significant CAD with good image quality. This combination of a novel protocol and an ungated radial sequence addresses the concerns of lingering hyperemia with regadenoson along with problematic gating in arrhythmias.

Funding

Astellas Pharma Inc.