Coronary artery stenosis-related perfusion ratio using dynamic computed tomography myocardial perfusion imaging: a pilot for identification of hemodynamically significant coronary artery disease

Abstract

The purpose of this study was to evaluate the feasibility of the stenosis-related quantitative perfusion ratio (QPR) for detecting hemodynamically significant coronary artery disease (CAD). Twenty-seven patients were retrospectively enrolled. All patients underwent dynamic myocardial computed tomography perfusion (CTP) and coronary computed tomography angiography (CTA) before invasive coronary angiography (ICA) measuring the fractional flow reserve (FFR). Coronary lesions with FFR ≤ 0.8 were defined as hemodynamically significant CAD. The myocardial blood flow (MBF) was calculated using dynamic CTP data, and CT-QPR was calculated as the CT-MBF relative to the reference CT-MBF. The stenosis-related CT-MBF and QPR were calculated using Voronoi diagram-based myocardial segmentation from coronary CTA data. The relationships between FFR and stenosis-related CT-MBF or QPR and the diagnostic performance of the stenosis-related CT-MBF and QPR were evaluated. Of 81 vessels, FFR was measured in 39 vessels, and 20 vessels (51%) in 15 patients were diagnosed as hemodynamically significant CAD. The stenosis-related CT-QPR showed better correlation (r = 0.70, p < 0.05) than CT-MBF (r = 0.56, p < 0.05). Sensitivity and specificity for detecting hemodynamically significant CAD were 95% and 58% for CT-MBF, and 95% and 90% for CT-QPR, respectively. The area under the receiver operating characteristic curve for the CT-QPR was significantly higher than that for the CT-MBF (0.94 vs. 0.79; p < 0.05). The stenosis-related CT-QPR derived from dynamic myocardial CTP and coronary CTA showed a better correlation with FFR and a higher diagnostic performance for detecting hemodynamically significant CAD than the stenosis-related CT-MBF.

Keywords: Computed tomography; Coronary artery disease; Fractional flow reserve; Myocardial blood flow; Myocardial ischemia.

Fig. 1

Flow chart for the calculation of the stenosis-related CT-QPR. CTA computed tomography angiography, CT-MBF computed tomography-derived myocardial blood flow, CTP computed tomography perfusion, CT-QPR computed tomography-derived quantitative perfusion ratio

Fig. 2

Relationships between the FFR and stenosis-related CT-MBF (a) and the QPR (b). CT-MBF computed tomography-derived myocardial blood flow, QPR quantitative perfusion ratio, FFR fractional flow reserve

Fig. 3

Graphs demonstrating significant differences in the stenosis-related CT-MBF (a) and QPR (b) between hemodynamically significant and non-significant CAD. Both stenosis-related CT-MBF and QPR in hemodynamically CAD (FFR ≤ 0.8) were significantly lower than those in non-significant CAD (FFR > 0.8) (both p < 0.05). CT-MBF, computed tomography-derived myocardial blood flow, QPR quantitative perfusion ratio, FFR fractional flow reserve

Fig. 4

Receiver operating characteristic curves for stenosis-related CT-MBF and QPR to identify hemodynamically significant CAD. CT-MBF computed tomography-derived myocardial blood flow, QPR quantitative perfusion ratio, CAD coronary artery disease, FFR fractional flow reserve, AUC area under the curve, CI confidence interval

Fig. 5

An 80-year-old female with stable angina. The ICA shows significant stenosis in the LAD (a). The FFR of this lesion was 0.70. The stenosis-related area was derived using a Voronoi diagram (b). The stenosis-related CT-QPR for the lesion was 0.74 (c), and the stenosis-related CT-QPR was comparable to the FFR. ICA invasive coronary angiography, LAD left anterior descending, FFR fractional flow reserve, CT-QPR computed tomography-derived quantitative perfusion ratio