Figure 12b. High-spatial-resolution MR angiography with the reduced-volume birdcage end-cap coil. Spatial resolution is 0.2 mm3 per voxel. (a) Transverse collapsed view from an SPGR 3D time-of-flight MR angiographic image (54/4; flip angle, 25°) of the circle of Willis demonstrates an aneurysm (arrow) of the P2 segment of the right posterior cerebral artery. (b) Sagittal maximum intensity projection image of the right posterior circulation in the same patient shows the aneurysm (arrow) of the P2 segment. Dual superior cerebellar arteries (arrowheads) are also visible.