Fig. 1.

a Time-of-flight angiography image of the circle of Willis and the anterior choroidal artery (AChA) on 7.0-Tesla MRI, transverse slab maximum intensity projection (thickness 7 mm). A line was set perpendicular to the left P1, and the corresponding intensity profile (b) is shown. c The posterior communicating artery with a perforating branch on a sagittal slab maximum intensity projection (thickness 7 mm) is shown. A line was set from the origin of the perforator to the last point at which the perforator was visible to obtain a rough estimate of the length of the perforator