Clinical impact of myocardial blood flow and myocardial flow reserve with ^99mTc-sestamibi CZT SPECT as improving diagnostic accuracy in CAD patients

Objectives: Myocardial blood flow (MBF) and myocardial flow reserve (MFR) quantified noninvasively by positron emission tomography (PET) has been a golden index of clinical diagnosis and a powerful predictor of cardiac events and mortality in patients with suspected coronary artery disease (CAD). Not surprising, the expense and complicated procedures of PET scans have limited widespread clinical use. Recently, advances of CZT SPECT technologies have been applied to develop MBF quantitation as a clinical tool to assess CAD. However, whether the SPECT MBF and MFR can improve the diagnostic accuracy over conventional nuclear myocardial perfusion imaging (MPI) needs clinical investigations. In this study, we retrospective reviewed the diagnostic value of conventional MPI and MFR with ^99mTc-sestamibi CZT SPECT using invasive coronary angiography (CAG) as the standard.

Methods: This study included 40 patients with suspected or known CAD who had received dynamic CZT SPECT and CAG (CAG+ group: 25 with ≥50 % stenosis in any vessel; CAG- group: 15 with patent arteries or <50 % stenosis). All patients underwent 1-d dipyridamole stress-rest dynamic ^99mTc-sestamibi CZT SPECT. All dynamic data were rebinned into 18 frames (ten 10-s, five 20-s, two 60-s, and one 280-s frames). Global and regional stress and rest MBF, and MFR values were obtained with MyoFlowQ. Myocardial perfusion defect scores were automated analysis using Emory Cardiac Toolbox (ECT) to obtain summed stress score (SSS) and summed difference score (SDS). Receiver-operating characteristic (ROC) was conducted to evaluate the diagnostic performance.

Results: Using the criteria of ≥50 % stenosis as positive CAG, areas under the ROC curve (AUCs) of flow assessment were overall greater than those of perfusion. For patient-based analysis, AUCs for stress MBF, MFR, SSS and SDS were 0.78±0.07, 0.80±0.07, 0.74±0.07 and 0.67±0.08. For vessel-based analysis, AUCs for stress MBF, MFR, SSS and SDS were 0.83±0.03, 0.83±0.03, 0.78±0.03 and 0.73±0.04.

Conclusions: The preliminary data suggest that MBF quantitation with CZT SPCT and the flow quantitation method is a clinically reliable approach to assist CAD diagnosis.