Computation of Non-Invasive Fractional Flow Reserve Based on CT Images
Junmei Zhang,
Senior Research Fellow, National Heart Centre Singapore (NHCS) Assistant Professor (Adj),
Duke-NUS Medical School
Fractional flow reserve (FFR) is the gold standard to assess the functional significance of coronary stenosis. However FFR can only be measured invasively through coronary angiography. In contrast to FFR, non-invasive assessment of diameter stenosis (DS) using coronary computed tomography angiography (CTA) has high false positive rate. Recently, FFRCT has been computed by combining CTA with computational fluid dynamics (CFD) technologies. Although FFRCT has shown superior diagnostic performance over CTA alone in assessing the severity of stenosis, the CFD models tended to be computationally expensive and require several hours for completing analysis. In order to predict noninvasive FFR with substantially less computational cost, we introduce a simplified model and test on a retrospective pilot study, which recruited 21 patients. All patients received coronary CTA and subsequent invasive FFR measurement for a total of 32 vessels. Based on CTA and steady-state simulation, FFRSS was calculated non-invasively and compared with FFR. On a per-vessel basis, the accuracy, sensitivity, specificity, positive predictive value and negative predictive value were 90.6%, 80.0%, 95.5%, 88.9% and 91.3% respectively for FFRSS, and were 75.0%, 50.0%, 86.4%, 62.5% and 79.2% respectively for DS. On a per-patient basis, the area under the receiver operating characteristic curve (AUC) was 0.963 and 0.741 for FFRSS and DS respectively. The CTA-derived FFRSS performed well in contrast to invasive FFR and had better diagnostic performance than DS from CTA in identifying functionally significant lesions. In contrast to FFRCT, FFRSS requires much less computational time.
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