Stress dynamic myocardial CT perfusion for symptomatic patients with intermediate- or high-risk of coronary artery disease: Optimization and incremental improvement between the absolute and relative myocardial blood flow analysis

Background: The optimization of myocardial CT perfusion (CTP) assessment remains inconsistent and uncertain. Our aim was to explore the superior analysis selection and incremental improvement of myocardial blood flow (MBF) assessment on CTP in diagnosing hemodynamically significant coronary artery disease (CAD). Methods: Sixty patients (43 men and 17 women; 61.38 +/- 8.01 years) were prospectively recruited and underwent stress dynamic myocardial CTP examinations. Absolute and relative MBF was used for ischemia evaluation with the invasive coronary angiography and fractional flow reserve were used as the reference standard. Areas under the receiver operating characteristic curves (AUCs) and cutoff values were calculated and compared. Results: There were 151 vessels in 60 patients finally enrolled for analysis. The sensitivity, specificity, PPV, NPV and diagnostic accuracy for the absolute MBF value and relative MBF ratio were 82.76%, 98.92%, 97.96%, 90.20%, and 92.72% and 74.14%, 93.56%, 87.76%, 85.29%, and 86.09%, respectively. The absolute MBF value was superior than the relative MBF ratio in detecting ischemia (AUC, 0.955 [95%CI: 0.919-0.990] vs.0.906 [95%CI:0.857-0.954])(P = 0.02). For territories with both sensitivity and specificity <90%, the diagnostic accuracy increased from 79.1% to 88.4% when the specific data were assessed using the absolute MBF value instead of the relative MBF ratio. Conclusions: The absolute MBF value from the endocardial myocardium on stress dynamic myocardial CTP showed superior diagnostic performance compared to the relative MBF ratio for the detection of myocardial ischemia in intermediate-to-high risk patients. The absolute MBF value provides an incremental benefit toward diagnostic performance for the relative MBF ratio evaluation.