図１〜図６で左横隔膜下（胃左側）に中等量（厚さ１〜2cm）の腹水があり（※），図６〜図８の△は遊離ガスである．図５〜図１１の丸数字１２が十二指腸だから図６〜図１０の壁肥厚↑は胃前庭部の病変である．全周性の病変であり，やや弱いが不整に造影され進行性の悪性腫瘍を強く示唆する．図９と図１０の▲は腫大したリンパ節の可能性が高い．図９の白矢印は嚢胞か転移性病変か，病変が小さいので判断は困難だが，転移性病変を否定はできない．手術で小弯側のリンパ節転移を伴う，前庭部の巨大なBorr3型胃癌の穿孔が確認された（図A：↑が癌病変）．肝転移は認めなかった．図５〜図９の肝右葉表面の石灰化については手術記録に記載がなく詳細は不明．

参考症例１（5mmスライス，胃癌穿孔）：統合失調症の53歳女性．1ヶ月前から食欲が低下し，貧血があり，次第に腹部が膨満してきた．数時間前に上腹部痛が出現し増強したので来院．体温：37.5℃，腹部全体に腹膜刺激症状を認めた．
図１で腹水（※）と遊離ガス（△）を認め，消化管穿孔であろう．胃が食物残渣で拡張している．図２〜図１２で↑の胃壁は他部位に比べやや強く造影される壁肥厚を示し，▲は腫大したリンパ節であり，進行性胃癌の穿孔と診断する．手術と病理検査で胃癌の穿孔を認め，病変は後腹膜に強く浸潤し剥離不能であった．

参考症例２（非穿孔性胃癌）：56歳男性．食欲不振と嘔吐のため来院した．↑，▲と△が胃角部から前庭部に広がる癌病変．

文献考察：CTは胃病変の検出に有用．
１）AJR Am J Roentgenol. 1999 May;172(5):1263-70.
CT evaluation of gastric lesions with three-dimensional display and interactive virtual endoscopy: comparison with conventional barium study and endoscopy.
Ogata I, Komohara Y, Yamashita Y, Mitsuzaki K, Takahashi M, Ogawa M.

OBJECTIVE: This study was undertaken to assess the feasibility of three-dimensional (3D) CT rendering using shaded-surface display (SSD) and ray sum display and virtual endoscopic images of the stomach for simultaneous evaluation of intraluminal and extraluminal abnormalities compared with conventional upper gastrointestinal barium studies and endoscopy. SUBJECTS AND METHODS: Our prospective study consisted of 39 patients with gastric lesions (17 gastric carcinomas, nine gastric polyps, five gastric varices, five gastric submucosal tumors, one lymphoma, one case of Menetrier's disease, and one gastric erosion) detected by endoscopy and barium study. All 3D CT images were reconstructed using SSD, ray sum display, and virtual endoscopic techniques. Three-dimensional images were evaluated for ability to reveal the range and morphologic features of the gastric lesions. RESULTS: All SSD, ray sum display, and virtual endoscopic images successfully revealed five of the eight early-stage gastric carcinomas and all nine advanced-stage gastric carcinomas. Submucosal tumors were revealed on 3D CT approximately as well as on conventional endoscopy. Interactive evaluation of virtual endoscopic images and multiplanar reconstructions provided useful information regarding intraluminal and submucosal gastric involvement by gastric varices, submucosal tumor, advanced gastric carcinomas, and lymphoma. This kind of information could not be obtained by conventional endoscopy or double-contrast study. CONCLUSION: Three-dimensional CT used in conjunction with virtual CT endoscopy proved helpful in identifying gastric lesions. Also, virtual CT endoscopic images with the interactive display of multiplanar reconstructions proved useful in identifying both intraluminal and submucosal components.PMID: 10227500

２）Radiology. 2003 Jul;228(1):166-71.
Benign and malignant lesions of the stomach: evaluation of CT criteria for differentiation.
Insko EK, Levine MS, Birnbaum BA, Jacobs JE.

PURPOSE: To determine the sensitivity and specificity of computed tomographic (CT) criteria for differentiating benign from malignant stomach lesions in patients with a thickened gastric wall at CT. MATERIALS AND METHODS: A radiology department file search revealed 36 patients with a thickened gastric wall at CT who underwent double-contrast barium suspension upper gastrointestinal tract examinations within 6 weeks before or after CT. The authors reviewed the CT images without knowledge of the final radiologic, endoscopic, or pathologic findings to determine the degree of gastric wall thickening and the symmetry, distribution, and enhancement of the thickened wall. The sensitivity and specificity of these findings for detection of malignancy were calculated. RESULTS: Two of 36 patients had two gastric abnormalities each. The final diagnoses in the 38 cases were gastritis in 19, hiatal hernia in four, benign ulcer in three, benign (n = 3) or malignant (n = 8) gastric neoplasm in 11, and no gastric abnormality in one case. Mean wall thickness was 1.5 cm (range, 0.7-7.5 cm). The finding of gastric wall thickness of 1 cm or greater had a sensitivity of 100% but a specificity of only 42% for detection of malignant or potentially malignant stomach lesions. The finding of focal, eccentric, or enhancing wall thickening had a sensitivity of 93%, 71%, or 43%, respectively, and a specificity of 8%, 75%, or 88%, respectively, for detection of these lesions. Gastric wall thickening that was 1 cm or greater and was focal, eccentric, and enhancing had a specificity of 92% but a sensitivity of only 36% for detection of these lesions. CONCLUSION: Gastric wall thickness of 1 cm or greater at CT had a sensitivity of 100% but a specificity of less than 50% for detection of malignant or potentially malignant stomach lesions that necessitated further diagnostic evaluation.PMID: 12759472（full text）