特異な頭部MRI T2*強調画像所見を呈した感染性心内膜炎の1例

A Case of Specific MRI T2* Weighted Image Associated with Bacterial Endocarditis

Ⅰ．はじめに

　細菌性動脈瘤は感染性心内膜炎を有する患者に合併しやすく⁴⁾，破裂した場合の死亡率が高いため^2,7)，迅速な診断および厳密かつ頻回のフォローアップが必要となる．また，経過中，動脈瘤のサイズの変化だけでなく，自然消失したり新規発生したりすることも報告されている⁷⁾．今回われわれは，脳内出血で発症した細菌性動脈瘤の患者において，MRI T2^*強調画像にて多発するsignal loss lesionを呈した1例を経験したので，文献的考察も加え報告する．

　We report a case of multiple signal loss lesions detected by T2^＊ weighted image associated with bacterial endocarditis. A 23 year-old woman, who had undergone surgical closure of ventricular septal defect at age 2, suffered headache and general fatigue after dental treatment. She was admitted to another institution, and examinations revealed bacterial endcarditis. She was transferred to our hospital, and underwent aortic valve replacement. After the valve replacement, CT revealed parenchymal hematoma in the left frontal lobe. CT angiography (CTA) and cerebral angiography (CAG) demonstrated an aneurysm at the distal branch of the left middle cerebral artery. T2^＊ weighted image demonstrated multiple signal loss lesions, which were not revealed by CAG and CTA. We speculated that these signal loss lesions were thrombosed mycotic intracranial aneurysms. She underwent left frontotemporal craniotomy, and the aneurysm was resected.

　Mycotic aneurysms are rare neurovascular lesions but their mortality and morbidity are high, so careful follow-up examinations are required. T2^＊ weighted image was useful to detect mycotic aneurysms and plan the surgical strategy.