Computing intracoronary blood flow rate under incomplete boundary conditions: Combing coronary anatomy and fractional flow reserve

•An easy and accurate way to measure the mean intracoronary flow rate was proposed by combining coronary angiography images and fractional flow reserve.•Flow rate can be calculated under the incomplete boundary conditions obtained by fractional flow reserve.•The proposed method was validated in both idealized and reconstructed 3D models of coronary branches.