First Validation of Myocardial Flow Reserve Derived from Dynamic Tc-Sestamibi CZT-SPECT Camera Compared with N-Ammonia PET.

N-ammonia positron emission tomography (NH-PET) can evaluate myocardial blood flow (MBF) at rest, stress, and myocardial flow reserve (MFR) as well as the ratio of MBF at stress to that at rest. MFR is useful in predicting the prognoses of patients with various heart diseases. Cadmium-zinc-telluride single photon emission computed tomography (CZT-SPECT) enables us to acquire dynamic images of radiotracer kinetics and measure original MBF and MFR using Tc-sestamibi. This study aimed to investigate the utility of CZT-SPECT for quantitative assessment of MBF compared to NH-PET. We validated the correlation of MBF and MFR between CZT-SPECT and NH-PET. Fourteen patients using one-day rest/stress CZT-SPECT, D-SPECT followed by NH-PET within 1 month were enrolled and analyzed prospectively. The reproducibility of the MBF and MFR obtained with these two methods was examined using Spearman's correlation coefficient and Bland-Altman plot analysis. The diagnostic value of D-SPECT for abnormal MFR defined using NH-PET results as MFR < 2.0 was assessed using receiver-operating characteristic (ROC) analysis. The median duration between D-SPECT and NH-PET was 20 days. Although MBF was overestimated by D-SPECT compared to NH-PET at high value (mean difference, 0.43 [0.34-0.53]), MBF and MFR were correlated with the two modalities (MBF: r = 0.71, P < 0.0001, MFR: r = 0.60, P < 0.0001). The ROC curve analysis demonstrated a cutoff of 1.6 for detecting abnormal MFR with D-SPECT (sensitivity, 68%; specificity, 91%; AUC, 0.75). MBF and MFR obtained using D-SPECT and NH-PET had a good correlation, suggesting that the quantitative MFR evaluation by CZT-SPECT may help understand the trend of NH-PET MFR.