MRI拡散強調画像により術前診断が可能であった硬膜内伸展を示したDiploic Epidermoidの1例

A Case of Diploic Epidermoid Invading Intradurally, Which was Diagnosed by MR Diffusion-weighted Image

I．はじめに

　MRI拡散強調画像は，生体内の水分子の拡散運動を画像化させたもので，近年脳梗塞超急性期症例に対する早期診断にその有用性が報告されている^4,6,13）．一方で，脳腫瘍性病変については報告例が少なく未だ検討段階である．しかし，類上皮腫についてはその有用性が報告されている．今回われわれは頭頂骨から硬膜内にかけ発生した板間層類上皮腫（diploic epidermoid）の手術例を経験し，その術前診断にMRI拡散強調画像が有効であったため，考察を加え報告する．

A case of diploic epidermoid in the right parietal bone was presented.

A 66-year-old male was admitted to our hospital because of aphasia. Plain skull radiogram showed anosteolytic lesion in the right parietal bone. Computed tomography revealed a mass with destruction of theparietal bone extending from an inner to an outer table. The mass was shown by MR imaging as hypoin-tensity on the T1-weighted image and as hyperintensity on the T2-weighted image. The hyperintensity became more remarkable by using a diffusion technique. Based on these findings, a preoperative diagnosisof right parietal epidermoid was made. The mass was totally removed and diagnosed pathologically asepidermoid. It was concluded that diploic epidermoid invading intradurally could be differentiated fromother osteolytic tumors by using MR diffusion-weighted image.