Comparison of myocardial stress perfusion defect assessment using 99mTc sestamibi SPECT vs BMS747158 PET

Objectives Myocardial uptake of BMS747158 exhibits a stronger relationship with myocardial blood flow across the range of achievable flow than 99mTc sestamibi. We sought to compare the assessment of myocardial perfusion defects by BMS747158 PET and 99mTc sestamibi SPECT in a phase II trial at a single center.

Methods Twenty six patients (20 men) underwent SPECT and PET within 6-months without change in clinical state. PET was performed with BMS747158 at rest (2.3-3.9 mCi) followed 60 min (n=18) or 24h (n=8) later with exercise (n=16) or adenosine (n=10) stress (7.3-8.6 mCi). Image quality of SPECT and PET was consensually assessed by 2 independent blinded readers and graded as excellent, good or fair. Stress and rest perfusion defects on SPECT and PET were assessed by the same readers by computer-assisted visual interpretation, using the standard 17 segment, 5 point-scoring model (0=normal; 4=absent uptake). The extent and severity of ischemia (summed difference score(SDS)) was derived from the difference between summed stress (SSS) and summed rest scores (SRS).

Results Image quality with PET was excellent in 24 and good in 2 patients. In contrast, there were 7 excellent, 18 good, and 1 fair quality study, p<0.001 by SPECT. In 14 patients with abnormal SPECT (SSS≥4), mean SDS was greater with PET than with SPECT (9.6 ± 1.8 vs 5.4 ± 0.7, p=0.02). In all 12 patients with normal SPECT (SSS<4), SDS was zero by PET and SPECT.

Conclusions Compared to 99mTc sestamibi SPECT, BMS747158 PET provides better image quality and results in a significant increase in the SDS in patients with abnormal SPECT. Our results suggest that PET imaging with BMS747158 may provide better assessment of the magnitude of myocardial ischemia than SPECT