Diagnostic Performance of Fractional Flow Reserve From CT Coronary Angiography With Analytical Method

Figure 1. Study inclusion flowchart. CTCA, CT coronary angiography; FFR, fractional flow reserve.

Figure 2. The sequential steps involved in the calculation of non-invasive fractional flow reserve (FFR) include (A) computed tomography coronary angiography (CTCA) image acquisition, (B) CTCA image segmentation via extracting centerlines and delineating lumen contours in the transversal and cross-sectional images, (C) 3D reconstruction of subject-specific coronary artery tree, and (D) using either analytical method to calculate FFRAM (green box) or computational fluid dynamics simulation to compute FFRB (blue box). In this case, FFRAM and FFRB were 0.79 and 0.75, respectively, at the site of invasive FFR 0.72 measured with a pressure catheter (right, inset) during invasive coronary angiography (yellow box).

Figure 3. (A) Representative computed tomography coronary angiography (CTCA) cross-sectional slice, (B) curved multiplanar reconstructed images of a left anterior descending (LAD) coronary artery, (C) straightened LAD with segmented lumen lines (yellow color) in transversal and (D) cross-sectional views, (E) reconstructed 3D left coronary tree, and (F) enlarged view to illustrate how to measure Ap, As , Ad, Lps, Lsd, and L from the model. (G) Left ventricular (LV) endocardial and epicardial contours were delineated from CTCA images to calculate the LV mass. (Note: Ap, As, and Ad represented the lumen area at proximal, maximally stenosed, and distal segments, respectively; Lps, Lsd, and L were the length measured from the proximal end of the coronary lesion to the proximal end of the maximally stenosed segment, the distal end of the maximally stenosed segment to the distal end of the coronary lesion, and the proximal to the distal ends of the whole coronary lesion, respectively. Flow entrance and exit angles (α and β) were then calculated using Eqs. (A-1) and (A-6) in the Supplementary Material, respectively.

Figure 4. Correlation and Bland–Altman plots (A) between flow rates calculated from computational fluid dynamics simulation (QCFD) and estimated from the analytical model (QAM) and between invasively measured fractional flow reserve (FFR) with (B) FFRAM and (C) FFRB on a per-vessel basis.

Figure 5. Comparison of the receiver operating characteristic curves for the discrimination of myocardial ischemia (fractional flow reserve, FFR ≤0.8) using diameter stenosis (DS; DSCTCA and DSICA, with a threshold of 50%) and non-invasive FFR (FFRAM and FFRB) on (A) per-vessel and (B) per-patient levels.

Figure 6. Comparison of the receiver operating characteristic curves for the discrimination of myocardial ischemia (fractional flow reserve, FFR ≤0.8) using diameter stenosis (DS; DSCTCA and DSICA, with a threshold of 70%) and non-invasive FFR (FFRAM and FFRB) on (A) per-vessel and (B) per-patient levels.