Estimation of Fractional Flow Reserve in Coronary Artery Based on Serial Intravascular Ultrasound Images*

Fractional flow reserve (FFR) is used to determine the indication of percutaneous coronary intervention (PCI). Serial intravascular ultrasound (IVUS) images were obtained with an IVUS system with the central frequency of 60-MHz using an automatic pull-back (0.5 mm/s) system. 1) Lumen of coronary artery was segmented by U-Net neural network to optimize the intersection over union (IoU) loss function. 2) The centroid of the segmented lumen was used to reconstruct 3D morphology of coronary artery. 3) Finally, computed fluid dynamics (CFD) was applied to the 3D morphology of coronary artery to visualize the pressure distribution in coronary artery. IVUS provides the mechanical properties of the vascular wall by elastography or palpography techniques. Because both the 3D geometry and the wall properties are obtainable with serial IVUS images, better CFD simulation would be available. This study showed that the principles of intracoronary blood flow and pressure drop estimation were possible from serial IVUS images. Clinical application of IVUS-based estimation of FFR is expected in the near future.