脳動脈瘤のスクリーニングにおける三次元CT画像の評価

Value of three-dimensional computed tomography in screening cerebral aneurysms

　脳動脈瘤6名について三次元CTを行い，脳血管写による検出率と比較した。脳動脈瘤の総数は17個であった。三次元CTでは，予備知識なしに10個（59％）の脳動脈瘤が検出された。最大径が10mm以上の動脈瘤は，ウイリス輪近傍であっても発見できた。7mm以下の動脈瘤は，その部位に関係なく検出が困難であった。三次元CTは，特に血管走行が複雑なウイリス輪近傍にある場合に脳動脈瘤の検出能力が劣り，眼運動神経麻痺では脳動脈瘤以外の原因検索が必要なために，まずMRIを行った後にこれを行うべきであると結論された。

We performed three-dimensional computed tomography (3D-CT) in 6 patients of cerebral aneurysm. Prior cerebral angiography showed a total of 17 aneurysms. 3D-CT alone detected 10 cerebral aneurysm (59%) . It was possible to identify aneurysms lager than 10 mm even when located near the circle of Willis. It was difficult to identify aneurysms when smaller than 7 mm regardless of their location. 3D-CT was of limited value in detecting cerebral aneurysms, particularly when located near the circle of Willis with complex vascular network. As cases of oculomotor palsy may be caused by lesions other than cerebral aneurysm, we advocate that 3D-CT be performed after magnetic resonance imaging (MRI) in screening cases of suspected cerebral aneurysm.