The myocardial mass subtended by a coronary vessel is essential when evaluating patients with coronary artery disease (CAD). Myocardial mass directly correlates with vessel size and blood flow [ ]. Moreover, patient-specific blood flow simulations incorporate myocardial mass to calculate fractional flow reserve (FFR) derived from coronary CT angiography (CCTA). Myocardial mass can be extracted from Coronary Computed Tomography Angiography (CCTA) using anatomical and flow-based methods. The anatomical method is based on Voronoi's algorithm and has been validated histologically and clinically [ ], whereas the flow-based approach has been validated against invasive flow measurements [ ]. However, the agreement between methods for vessel-specific mass calculation remains to be determined. This study assessed the agreement between two CCTA-based methods for calculating vessel-specific myocardial mass. In addition, we compared their association with invasive measurements of absolute blood flow.