Fractional flow reserve and myocardial perfusion by computed tomography: a guide to clinical application

The aim of this paper is to provide a guide to the clinical application of the functional computed tomography (CT) techniques fractional flow reserve (CT FFR) and myocardial perfusion (CTP) in patients presenting for the evaluation of coronary artery disease (CAD). Both techniques have recently been introduced to complement coronary CT angiography (CTA) with physiological information. Evidence supporting their diagnostic accuracy accumulates at a fast pace, and both techniques are moving from research tools to clinical applications for specific subgroups of patients. As a consequence, the question that now emerges is how to optimally implement these techniques in the daily clinical workflow to maximize the benefit to patients. Given the inherent differences between both techniques in their underlying physical principles and methodology, as well as the types of pathophysiological information they provide, these techniques are not interchangeable. Rather, within the broad spectrum of patients presenting for CAD evaluation, both CT FFR and CTP may have their own optimized application where the highest benefit at the lowest risk and cost may be achieved. Therefore, we will review the physical principles and available clinical evidence of each technique, and propose how this information can be applied to the individual patient. Moreover, as techniques continue to mature, the combination of coronary CTA with CT FFR and/or CTP likely will become a powerful and accessible diagnostic tool for the detailed characterization of atherosclerotic disease providing a potentially more precise and personalized approach to patients with suspected CAD.