Added Value of CZT SPECT Myocardial Blood Flow Quantification for Detecting Obstructive Coronary Artery Disease in Patients with Normal Perfusion Imaging

Abstract Purpose The goal of this study was to investigate the added value of absolute MBF quantitation measured with cardiac-dedicated CZT SPECT to enhance the detection of hidden myocardial hypoperfusion for patients with obstructive coronary artery disease and normal perfusion. Methods A total of 501 patients with normal myocardial perfusion imaging (MPI) results who underwent dynamic cardiac-dedicated CZT SPECT for MBF quantitation, routine MPI, and invasive coronary angiography (CAG) were retrospectively identified from the clinical database. Stenosis of > 50% in the left main artery or > 70% in major coronary arteries was defined as obstructive coronary artery disease (OCAD). Results Among patients with normal MPI results, 44.7% had angiographically confirmed OCAD. Male patients exhibited a higher proportion of false-negative MPI results than female patients (54.2% vs. 39.9%, p < 0.05). Quantitative parameters, including stress myocardial blood flow (MBF) and myocardial flow reserve (MFR), were significantly reduced in the OCAD group, while myocardial flow capacity (MFC) was notably impaired. When flow parameters with cutoffs derived from comparison with CAG were added, the detection rate of myocardial hypoperfusion increased to 45.2% in male patients and 27.9% in female patients. The diagnostic sensitivity of SPECT MBF quantitation for detecting hypoperfusion of OCAD in patients with normal MPI was 45.1%-50.9%, and the diagnostic specificity was 81.6%-99.6%. Conclusions Absolute quantitative MBF measurements with cardiac-dedicated CZT SPECT add clinical benefits in uncovering hidden myocardial hypoperfusion for patients who had OCAD and normal MPI.