陥凹型小胃癌の診断―X線の立場から：背景粘膜を含めて

Radiological Diagnosis of Depressed-Type Small Gastric Cancers

要旨　5mm以上10mm以下の陥凹型胃癌65例74病変を組織型，背景粘膜別に分類し，X線の立場から陥凹型小胃癌の診断について検討した．このうち二重造影法で描出良好な51病変でのX線所見の検討では，分化型癌の50.0％が線状バリウム斑として描出されていた．一方，未分化型癌では陥凹面の凹凸不整が76.9％，ひだの異常（集中・やせ・中断）が53.8％にみられたが，典型的な蚕食像の描出は乏しかった（23.1％）．陥凹型小胃癌のX線所見は，組織型にかかわらず局面を持ったバリウム斑として描出される頻度が少なく，限局性の線状バリウム斑や顆粒状粘膜，軽度のひだ先端の異常を基本所見として診断を行う必要がある．背景粘膜別の描出能では，F，P領域に比べf領域が95％で成績が最も良好だった．f領域は既存の粘膜ひだが少なく，粘膜萎縮が高度でないことから，陥凹の所見が現れやすく，小さな病変でも二重造影法で描出しやすいためと考えられた．またF領域では，ひだに埋没する病変やびらん形成のない病変が多く，P領域では特に小彎側，幽門輪近傍で二重造影像の辺縁像と圧迫法のみでしか描出されない病変が多かった．多発癌症例は29.2％であり，副病変としての陥凹型小胃癌は描出が不十分なものが多くみられた．多発癌の診断は今後の課題の1つと考えられた．

　We discussed radiological findings of depressed-type small gastric carcinomas. They were classified according to tissue form and background mucosa. The carcinomas targeted were 74 lesions, equal to or less than10mm but more than 5 mm in size.

　In well-differentiated type carcinomas, linear barium fleck was similar in 50.0％ of cases. In undifferentiated carcinomas, 76.9％ showed irregularity of the depressed area, 53.8％ showed fold abnormality, but there was poor visualization of the encroachment area image in 23.1％, so we needed to take special care when making marginal interpretation.

　The visualization rate of a lesion according to background mucosa showed that the f area was the best. In the f area (the shift zone between the fundic gland area and pyloric gland area), the radiological findings of depressive carcinomas were clear and easily expressed by double contrast method because elimination of fold and mucosal atrophy was not extensive in the background mucosa.

　Among carcinomas at the lesser curvature of the lower stomach body, or a pylorus ring neighborhood, there were many lesions expressed by a border image of the double contrast method or the pressing method. It seemed that a change of quantity of air and radiological en face view method were effective for X-ray examination of these lesions.

　There was a 29.2％ ratio of multiple cancers and visualization of these using X-ray examination was insufficient.