脳動脈瘤に関する画像診断の最新事情

Update on Vessel Wall Imaging of Intracranial Aneurysm

Point

・血管壁イメージングMRIにおいて，未破裂瘤に比べ破裂瘤でより強い瘤壁造影効果を有することが明らかとなっている．

・破裂瘤の強い瘤壁造影効果は，多発瘤合併くも膜下出血のみならず，微小動脈瘤や脳動静脈奇形における出血源診断にも応用できる可能性がある．

・未破裂瘤における瘤壁造影効果は，破裂の危険因子や治療介入後の再発予測因子として注目されている．

　Intracranial aneurysms occur frequently; however, only a few of these rupture to cause subarachnoid hemorrhage. This presents a dilemma regarding the course of appropriate treatment. In the last decade, the wide utilization of magnetic resonance imaging-based vessel wall imaging（VWI）has facilitated the assessment of aneurysm wall enhancement（AWE）, which has garnered significant attention. In 2013, initial reports highlighted that AWE was characteristic of ruptured aneurysms whereas, in 2014, AWE was identified as a characteristic feature of unruptured aneurysms with a high risk of rupture. Several studies have supported these findings since then. VWI, a novel modality that visualizes the inflammation of the aneurysmal wall, is considered highly useful for the diagnosis of aneurysms. This review discusses the key literature on AWE. Long-term prospective studies are warranted to determine whether AWE is an independent risk factor for aneurysmal progression.