Non-invasive Quantifications of the Stenosis Severity of Coronary Artery Disease, Using Cardiac Computed Tomography Angiography and Computational Fluid Dynamics

Abstract

Fractional flow reserve (FFR) is directly measured by inserting pressure wire inside the catheter during invasive coronary angiography (ICA). It is the gold standard to identify severity of stenosis as hemodynamically significant stenosis (HSS) or hemodynamically insignificant stenosis (HIS) of coronary artery disease (CAD). However, FFR is invasive, leads to several risks and complications, high x-ray exposure, expensive, takes more time and needs of contrast agent administration during procedure. The goal of this study was to overcome those problems by computing FFR non-invasively from coronary computed tomography angiography (CCTA-FFR) by combining 3D coronary artery geometry reconstruction (3D-CAGR) from 2D CT image data semi-automatically and computational fluid dynamics (CFD) methods to derive coronary blood flow simulation (CBFS) for the reconstructed geometries. In this study, Materialise mimics and ANSYS software’s were used to compute 3D-CAGR and CBFS, respectively. Blood flow was considered as laminar, incompressible and Newtonian during CBFS, and the wall of the coronary artery (CA) was considered as rigid. Proper meshing the geometry, setting ups of appropriate boundary conditions, physical and physiological models have very significant roles during CBFS to obtain accurate CCTA-FFR result. In this study, patient-specific parameters known as mean arterial pressure (MAP) was used during CBFS and CCTA-FFR computation. Pressure profile or wall pressure distribution were computed to calculate CCTA-FFR during 3D-CFD simulation. Finally, the calculated CCTA-FFR results were compared with coronary computed tomography (CCTA) and ICA results obtained during clinical diagnosis at MCM general hospital by the radiologist and cardiologist, for verification and validation of CFD model. We have achieved 83.3% accuracy by comparing our results of some patients with the gold standard (ICA) computed by the cardiologist at MCM general hospital. Therefore, this study has significant roles to advance CAD patient’s management, reduce unnecessary catheterization, support radiologist and cardiologist decision-making, interpretation of CCTA, and minimizes diagnosis costs, time, and ICA related risks