The invention provides for a medical imaging system (100, 300) comprising a processor (106) for controlling the medical imaging system. Execution of machine executable instructions (112) causes the processor to receive (200) a static angiographic image (114) of a region of interest (322), receive (202) a time series of angiographic images (116, 116′) of the region of interest, construct (204) an image mask (118) using the static angiographic image, determine (206) a time dependent signal (120) for each voxel within the image mask using the time series of angiographic images, construct (208) a composite angiographic image by: assigning (210) a fill time (126) to each voxel within the image mask using an extremum (124) of the time dependent signal if the extremum deviates from an average of the time dependent signal more than a predetermined threshold, and identifying (212) voxels within the image mask as being unfilled voxels.