CT Fractional Flow Reserve: A Practical Guide to Application, Interpretation, and Problem Solving

CT fractional flow reserve (FFRCT) is a physiologic simulation technique that models coronary flow from routine coronary CT angiography (CTA). To evaluate lesion-specific ischemia, FFRCT is measured 2 cm distal to a stenotic lesion. FFRCT greater than 0.8 is normal, 0.76-0.8 is borderline, and 0.75 or less is abnormal. FFRCT should always be interpreted in correlation with clinical and anatomic coronary CTA findings. FFRCT increases the specificity of coronary CTA in the evaluation of coronary artery disease, decreases the prevalence of nonobstructive disease in invasive coronary angiography (ICA), and helps with revascularization decisions and planning. Patients with intermediate-risk coronary anatomy at CTA and abnormal FFRCT can undergo ICA and revascularization, whereas those with normal FFRCT can be safely deferred from ICA. In borderline FFRCT values, management is decided in the context of the clinical scenario, but many cases could be safely managed with medical treatment. There are some limitations and pitfalls of FFRCT. Abnormal FFRCT values can be seen in mild stenosis, and normal FFRCTvalues can be seen in severe stenosis. Gradually decreasing or abnormal low FFRCT values at the distal vessel without a proximal focal lesion could be due to diffuse atherosclerosis. Coronary stents, bypass grafts, coronary anomalies, coronary dissection, transcatheter aortic valve replacement, unstable angina, and acute or recent myocardial infarction are situations in which FFRCT has not been validated and should not be used at this time. The authors provide a practical guide to the applications and interpretation of FFRCT, focusing on common pitfalls and challenges. Online supplemental material is available for this article.©RSNA, 2022.