24) Frequently, diffuse or focal leptomeningeal enhancement (predominantly involving the basilar cisterns, craniocervical junction, or pericallosal
regions) is seen on postcontrast gadolinium images (25,26) (Figures 11,12).
At that time, cranial MRI showed hyperintense signal abnormality in the corpus callosum and in the pericallosal
areas on T2-weighted images.
The choroidal type occurs when arterial feeders originate from the pericallosal
, choroidal or thalamoperforaters.
of California, San Francisco) details the basic concepts and tenets of aneurysm microsurgery, various craniotomies and exposures for successful clipping, and microsurgical anatomy, dissection strategies, and clipping techniques for each of the seven most common aneurysm types: posterior and anterior communicating artery, middle cerebral artery, ophthalmic artery, basilar bifurcation, pericallosal
artery, and posterior inferior cerebellar artery aneurysms.
Distribution of coiled aneurysms Anterior choroidal 1 Anterior communicating 7 Basilar tip 11 Carotid termination 3 Intracavernous 3 Superior hypophyseal 1 Middle cerebral artery 13 Ophthalmic 2 Posterior cerebral 1 Posterior communicating 36 Pericallosal
1 Superior cerebellar 1 Vertebral 4 Total 84 Table II.
and interhemispheric lipomas may show calcification of the fibrous capsule with rim or eggshell appearance.