Myocardial blood flow analysis of stress dynamic myocardial CT perfusion for hemodynamically significant coronary artery disease diagnosis: The clinical value of relative parameter optimization.

Background: The methods for calculating the optimal myocardial blood flow (MBF) relative parameters in stress dynamic myocardial CT perfusion (CTP) in the detection of hemodynamically significant coronary artery disease (CAD) are non-uniform and lack standards.

Methods: A total of 86 patients who were prospectively recruited underwent APT stress dynamic myocardial CTP. The relative MBF perfusion parameters were calculated as av_Ratio, Q3av_Ratio and hi_Ratio according to the three types of reference MBF values, respectively: (1) average segmental MBF value, (2) the third quartile of the average segmental MBF value, and (3) highest segmental MBF value. All the data were derived from both the endocardial and transmural layers of the myocardium. Invasive coronary angiography and fractional flow reserve (ICA/FFR) were used as the reference standards for myocardial ischemia evaluation.

Results: A total of 151 vessels of 60 patients (43 men and 17 women; 61.38 ± 8.01 years) were enrolled in the analysis. The performance of the endocardial layer was superior to that of the transmural layer (all P < 0.05). The hi_Ratio of the endocardial myocardium (AUC = 0.906, 95% CI: 0.857-0.954), for which the highest segmental value was selected as the reference MBF, was superior to both av_Ratio and Q3av_Ratio for ischemia detection (AUC, 0.906 vs.0.879, P < 0.05; 0.906 vs.0.891, P = 0.18), and the sensitivity, specificity, PPV, NPV and diagnostic accuracy were 74.1%, 93.6%, 87.8%, 85.3% and 86.1%, respectively. The cutoff value of hi_Ratio was 0.675.

Conclusions: The relative MBF parameter of the endocardial myocardium using the highest segmental MBF value as a reference provided optimal diagnostic accuracy for the detection of hemodynamically significant CAD.