Fractional Flow Reserve Measurement Using Dynamic CT Perfusion Imaging in Patients with Heavy Coronary Calcification...

Background/Objectives: A novel CT dynamic angiographic imaging (CT-DAI) analytic algorithm was evaluated against the clinical gold standard for fractional flow reserve (FFR) measurement in patients with coronary artery disease (CAD) characterized by diffuse dense calcification and previous stent implantation. Methods: This retrospective feasibility study included 24 coronary arteries in 16 patients (age 69.9 ± 8.9 years, 11 males) with CAD who underwent dynamic CT myocardial perfusion scanning using a dual-source CT scanner after intravenous infusion of adenosine triphosphate. The included patients had analyzable proximal and distal coronary artery segments adjacent to the stenosis in the myocardial perfusion images and had corresponding invasive catheter-based FFR measurements for that stenosis. An in-house software based on the CT-DAI algorithm was used to compute FFR using the coronary time-enhancement curves sampled across the stenosis from stress myocardial CT perfusion images. The CT-DAI derived FFR values were then compared to the corresponding catheter-based FFR values. A coronary stenosis was considered functionally significant for FFR values below 0.8. Results: The mean axial length and calcium score of the coronary stenoses were 47.9 mm and 1911.63 Agatston Units, respectively. Eight coronary arteries received stents from previous treatments. The CT-DAI derived FFR values (0.822 ± 0.143) showed an excellent linear correlation (R = 0.974) with and were indifferent from the invasive FFR values (0.826 ± 0.147, p = 0.537), resulting in 100% per-vessel and per-patient sensitivity and specificity for the detection of functionally significant coronary stenosis. Bland-Altman analysis revealed a minimal mean difference in FFR measurements (0.004) between the two modalities with the lower and upper limits of agreement at -0.061 and 0.069, respectively. Conclusions: The findings suggest that CT-DAI can derive FFR for the coronary arteries with heavy calcification and stents from dynamic myocardial CT perfusion images.