[Fusion imaging of 3D MR cisternography/angiography for differential diagnosis of internal carotid-posterior communicating artery aneurysms and infundibular dilations].

By using a fusion imaging of three-dimensional (3D) magnetic resonance cisternography (MRC) and coregistered magnetic resonance angiography (MRA), protrusions at the bifurcation of the internal carotid-posterior communication artery, detected by MRA, were investigated to differentiate between the infundibular dilations and aneurysms. The MRA, obtained by the 3D time-of-flight sequence, showed the flow-related arterial structures by means of an inflow effect mainly induced by the peak systolic flow velocity. The MRC, obtained by 3D fast spin-echo sequence, depicted the contours of the vascular structures within the cisternal space in contrast to the surrounding cerebrospinal fluid. Fusion images of 3D MRC/MRA showed the anatomy of protrusions from the different viewpoints with flow-related intraluminal images (MRA) in conjunction with outer-wall configuration images of the vascular structures (MRC). This imaging technique may be useful to differentiate the infundibular dilations from the internal carotid-posterior communicating artery aneurysms.