潰瘍合併早期胃癌の画像診断―潰瘍合併早期胃癌のX線診断

Radiological Diagnosis for Early Gastric Cancer with Ulceration

要旨　2007年4月から2012年3月までの5年間に，当センターで経験した5mm以上の陥凹型早期胃癌442例471病変（分化型：374病変，未分化型：97病変）を対象として，病理組織学的に潰瘍合併の有無を分析した．潰瘍合併率は，分化型30.2％，未分化型54.6％と未分化型で高率であった．「胃癌治療ガイドライン」では，深達度と潰瘍の有無で治療法選択を行うため，ESD適応・非適応の境界となる腫瘍径で比較検討した．深達度pMの潰瘍合併率は，分化型癌では，30mm以下で18.4％，31mm以上で53.3％，未分化型癌では，20mm以下で13.6％，21mm以上で51.8％であり，ESD非適応の境界となる腫瘍径以上で高率であった．精密X線検査での潰瘍の存在診断率は，分化型癌の31mm以上，未分化型癌の20mm以上ではともに80％以上と高率であった．潰瘍の存在診断が不良であったのは，萎縮型のU・M領域小彎に存在する腫瘍径20mm以下の分化型癌に多かった．潰瘍合併早期胃癌の検診X線によるX線検査良悪性の拾い上げ正診率は，69.2％と高率であったが，潰瘍の形態だけでなく，潰瘍周囲の0-IIcあるいはIIb病変が描出されている場合に正確に診断されており，適切な追加撮影が有効であった．精密X線検査による深達度の正診率は，分化型pM＋pSM1：72.9％，未分化型pM＋pSM1：41.7％で，とくに未分化型癌で深達度を深読みする傾向があり，正診率が低率であった．二重造影法では空気を少量から増量し過伸展まで撮影して，バリウム斑の濃度，ひだ集中や粘膜集中の程度，粘膜像を詳細に読影し，圧迫撮影では，圧迫の強弱による形態の変化に注意して読影することが重要であった．

　In this study, we histopathologically analyzed the presence of ulcer complications in 471 lesions from 442 cases of depressed type early gastric cancer with diameter exceeding 5mm（differentiated : 374 ; non-differentiated : 97）encountered at our center. The rates of ulcer complications were 30.2％and 54.6％in differentiated and non-differentiated cases, respectively, and this difference was significant. For diagnosis of ESD（endoscopic submucosal dissection）candidate lesions, it is necessary to diagnose tissue form, tumor size, and invasion depth in addition to the presence of ulcer and its depth. The rate of diagnosis of the presence of ulcers through detailed X-ray examination was high, with over 80％ detection of ulcers exceeding 31mm and 20mm in diameter for differentiated and non-differentiated cancer, respectively. The rate of diagnosis of the presence of ulcers was poor mainly in atrophy from differentiated cancer with tumors smaller than 20mm in diameter located in the lesser curvature of the U and M regions. At medical checkup, the accurate diagnosis rate for distinction of benign vs. malignant lesions was high（69.2％）, and the accuracy increased when IIc or IIb lesions located around the ulcer were also seen in addition to the form of ulcer, indicating that appropriate additional imaging is effective. The correct diagnosis rates for invasion depth of pM cancer through detailed X-ray examination were 72.9％ and 41.7％ for differentiated and non-differentiated cases, respectively. The invasion depth tended to be estimated as deeper than the actual case in non-differentiated cancer. In double contrast study, the amount of air inside the stomach was increased until the stomach was stretched, and detailed diagnostic reading was performed on images of darkness of the barium spot, degree of convergence of mucosal fold or mucosa, and image of the mucosa. For imaging while applying pressure to the stomach area, it was important to perform diagnostic reading while focusing on the change in configuration due to the strength of pressure.