微小胃癌に対するX線診断の現状と課題

Radiological Diagnosis for Minute Gastric Cancer

要旨　過去5年間に，当センターで経験した5mm以下の微小胃癌80例106病変を対象として，発見方法，組織型，腫瘍径と描出率，X線像を中心に，画像診断，特にX線検査の拾い上げについて検討した．検査方法別の病変数と平均腫瘍径は，X線検査：5病変，4.7mm，内視鏡検査：40病変，3.8mmであった．また，術後の全割標本による病理組織学的検査で診断された病変は，35例61病変，2.8mmで，すべて多発胃癌の副病変であった．組織型は，分化型97病変（tub1：90病変，tub2：7病変），未分化型9病変（sig：8病変，por1＞tub2：1病変）で，分化型が多かった．X線検査の腫瘍径別描出率は，5mmでは50％と高率であり，付着ムラのないX線撮影が行われていれば，検診でも微小胃癌を的確に診断していた．したがって，微小胃癌をX線検査で発見するためには，付着ムラのない写真を撮影し，読影では，微小胃癌のX線所見の特徴である不整形の小バリウム斑と，辺縁の微細な棘状陰影や微細顆粒状の辺縁隆起について熟知して拾い上げることが大切である．

　We investigated the detection method, histological type, tumor diameter, depiction rate, and radiographic pictures of 106 lesions in 80 cases of microgastric cancer≦5mm in diameter treated at our center over a five-year period. The numbers of lesions and mean tumor diameter indicated by different examination methods were determined. Radiography revealed 5 lesions with a mean diameter of 4.7mm, while endoscopy, indicated 40 lesions with a mean diameter of 3.8mm. Histopathological examinations using totally segmented specimens after surgery revealed 61 lesions with a mean diameter of 2.8mm in 35 cases, all of which were secondary lesions of multiple gastric cancers. Histological types were differentiated type in 97 lesions（tub1 : 90, tub2 : 7）and non-differentiated type in 9 lesions（sig : 8, por1＞tub2 : 1）; the difference was significant. The depiction rate on radiographs was high（50％）for tumors 5mm in diameter. If radiographies were conducted evenly without uneven attachment, microcancers could be diagnosed accurately even at routine health checks. Therefore, to detect microgastric cancer in radiography, it will be important to take radiographs without uneven attachment of barium, and to be familiar with small barium spots of irregular shapes and peripheral microspiny shadows and microgranular prominent borders when reading the radiographs.