A method to measure the extent of myocardial ischemia and steal with SPECT myocardial blood flow quantitation

Objective We introduced a method to measure the extent of myocardial ischemia and steal with SPECT MBF quantitation. Methods Eighty-seven patients who received rest/Dipyridamole-stress 99m Tc-Sestamibi (MIBI) dynamic SPECT scans and coronary angiography were included. Dynamic SPECT images were reconstructed with full physical corrections. The one-tissue kinetic model was utilized to quantify K1 and further converted to MBF with required corrections. Rest MBF, stress MBF and myocardial flow reserve (MFR) were converted to a flow status polar map by a flow diagram. Extents of 7 flow statuses were verified their cutoff points for detecting stenoses. The diagnostic performance (DP) was compared to that of MFR. Results Cutoff point of the extent to detect ≥ 50% stenosis was 3.01% for ischemia–steal status and 20.3% for the combined status of ischemia–steal and moderate. Using these criteria, sensitivity, specificity and accuracy to detect ≥ 50% stenosis were (80%, 75%, 79%) and (86%, 68%, 80%) for ≥ 70% stenosis. The DP was superior to that of MFR < 2.0 criterion (≥ 50%: 70%, 63%, 69%; ≥ 70%: 73%, 61%, 69%) (all p < 0.015). Conclusion SPECT MBF quantitation integrated with the flow diagram can measure the extent of myocardial ischemia and steal which appeared more accurate to detect angiographic stenoses than the single MFR parameter.