早期胃癌の内視鏡的粘膜切除術における超音波内視鏡検査の役割

The Utility of Endoscopic Ultrasonography (EUS) to Evaluate the Indication for Endoscopic Mucosal Resection (EMR)

要旨　早期胃癌に対して超音波内視鏡検査（EUS）を行い，内視鏡的粘膜切除術（EMR）への適応との観点から深達度診断能および癌巣内潰瘍・潰瘍瘢痕の有無，癌巣近傍の壁内血管の存在診断への応用について検討した．使用機種は，周波数7.5/12MHzおよび20MHzのEUSを用いた．早期胃癌143病変の検討で，深達度診断能は7.5/12MHzEUSを用いた病変ではm癌72％，sm癌86％（sm₁癌62％），20MHzEUSを用いた病変ではm癌76％，sm癌62％（sm₁癌75％）であった．高周波数EUSは粘膜層，粘膜下層のより詳細な検討が可能なため，EMRの適応をより厳密に判定することが可能であった．深達度診断を誤った症例は潰瘍または潰瘍瘢痕を伴った病変に多くみられた．EUSは深達度診断のみならず，癌巣内潰瘍・潰瘍瘢痕の有無や周囲の血管の有無を含めての診断が可能で，治療法を選択するうえで有用と考えられた．

　With 7.5/12 MHz-EUS and 20 MHz-EUS, we studied early gastric cancer concerning the depth of cancerous invasion, the presence of fibrosis accompanying the ulcer or ulcer scar and vessels around the carcinoma. In addition, we evaluated the indication for EMR. Of 143 lesions of early gastric cancer, the accuracy of estimating the depth invasion using 7.5/12 MHz-EUS and 20 MHz-EUS was 72% (50/69 cases) versus 76% (19/25 cases) for the mucosal (m) cancer group ; 86% (31/36 cases) versus 62% (8/13 cases) for the submucosal (sm) cancer group ; especially 62% (5/8 cases) versus 75% (3/4 cases) for the sm₁-cancer group respectively.

　The mucosal layer and the submucosal layer could be better visualized by 20 MHz-EUS than by 7.5 MHz-EUS, because the former apparatus has higher frequency than the latter and the indication for EMR was clearly diagnosed. There was a tendency misdiagnose cancerous lesions, accompanied with ulcer or ulcer scar. EUS was useful for diagnosis of the depth of invasion, the presence of fibrosis accompanying ulcer or ulcer scar, and the vessels around the lesion.