Fig. 3

Example simulated segmentation variations containing error combinations and corresponding visual scores. a This simulated segmentation variation contains 6 errors: severe orbit error, severe skull error, subtle merge/separation error, omission of the internal carotid artery, severe boundary error of the M1 segment of the middle cerebral artery and posterior communicating artery. Due to the high number and severity of errors, a visual score of 10 is assigned to this segmentation, indicating low quality. b This simulated segmentation variation contains 2 errors: a severe omission error of the small vessels and a subtle false-positive segmentation of parts of the superior sagittal sinus. This segmentation gets a visual score of 3, corresponding to moderate quality. Please see Table 2 for the subjective scoring system and Table 1 for a detailed description of errors. Red: True positive voxels, Green: False-positive voxels, Blue: False-negative voxels