[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-fl ight sequence, showed the fl ow-related arterial structures by means of an infl ow effect mainly induced by the peak systolic fl ow 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 fl uid. Fusion images of 3D MRC/MRA showed the anatomy of protrusions from the different viewpoints with fl ow-related intraluminal images (MRA) in conjunction with outer-wall confi guration 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. （Received : July 28, 2005, Accepted : January 23, 2006）