破裂内頚動脈血マメ状動脈瘤の診断に造影MR vessel wall imagingが有用であった1例

Magnetic Resonance Vessel Wall Imaging Reveals a Ruptured Blood Blister-like Aneurysm:A Case Report

Ⅰ．はじめに

　内頚動脈血マメ状動脈瘤（blood blister-like aneurysm：BBA）は，頭蓋内動脈瘤の0.3〜1%，内頚動脈瘤の0.9〜6.6%の頻度で発生する比較的稀な動脈瘤であり，主に硬膜内内頚動脈前壁に発生し，小さい半球形の脆弱な瘤壁を有する¹⁾．BBA破裂によるくも膜下出血（subarachnoid hemorrhage：SAH）の診断は，画像診断技術の進歩した現在においてもしばしば難渋するが，今回われわれは，血管内の血液信号を抑制して血管壁の性状を評価できるmotion-sensitized driven-equilibrium（MSDE）法を用いた造影magnetic resonance vessel wall imaging（MR-VWI）が，破裂部動脈瘤の診断に有用であった1例を経験したので報告する．

　Recent advances in digital subtraction angiography（DSA）and 3D-CT angiography（3D-CTA）have enabled the identification of tiny intracranial aneurysms. However, the imaging of blood blister-like aneurysms（BBAs）in the internal carotid artery（ICA）is still challenging. We report the case of a subarachnoid hemorrhage（SAH）with a ruptured BBA in the ICA that was revealed by magnetic resonance vessel wall imaging（MR-VWI). A 68-year-old woman presented with SAH. CT showed diffuse SAH（Fisher group 3). 3D-CTA and DSA showed a small bulge in the right ICA. MR-VWI with gadolinium showed thick wall enhancement in the supraclinoid portion of the right ICA；hence, we diagnosed SAH because of the ruptured BBA of the right ICA. Trapping combined with high-flow bypass was performed for the ruptured BBA. We concluded that MR-VWI may be useful for diagnosing ruptured BBAs under strict blood pressure management.