目的 探讨胃肠间质瘤CT和MRI表现、分析漏诊和误诊的原因。方法 回顾性分析20例经病理证实的胃肠道间质瘤CT 和MRI表现，15例行CT检查，5例行MRI检查。结果 单发19例(发生于胃12例，小肠4例，直肠1例，肠系膜2例)；多 发1例(发生于乙状结肠系膜和空肠)。表现为圆形或类圆形肿物，边界清晰,向腔外、腔内或跨壁生长的肿物，长径 约2-10cm。CT平扫密度不均匀，多有坏死、囊变，可见Torri-celli-Bernoulli征；T1WI为不均匀低信号，T2WI为 不均匀高信号，DWI为高信号。增强扫描肿物实性部分不均匀明显延迟强化。漏诊2例，均位于充盈不佳的胃体部。 误诊3例，2例误诊为囊腺癌；1例误诊为直肠癌。结论 胃肠间质瘤发生部位多变，充分的肠道准备和掌握其CT和 MRI的表现，有助于避免漏诊和误诊。

Objective To discuss the CT and MRI features of gastrointestinal stromal tumor(GIST) and analyse the reasons of missed diagnosis and misdiagnosis. Methods The CT and MRI imaging of 20 cases with GIST proved by pathology were retrospectively analyzed, of which 15 cases and 5 cases underwent CT and MRI respectively. Results 19 cases had solitary masses (12 in stomach, 2 in small intestine, 3 in colon and 2 in mesentery), Multiple was 2 case which were found in mesocolon pelvinum and jejunum. They were round or oval shapes from 3 to 10 cm with clear boundary, growth intraluminal, exophytic or dumbbell. With CT non-enhanced scan, the tumors were non-homogeneous texture with cystic or necrotic changes, some of them could see “Torri-celli-Bernoulli" sign. With MRI, the tumors appeared as heterogeneous hypointensity on T1WI, heterogeneous hyperintensity on T2WI and hyperintensity on DWI. With contrast enhanced scan. The parenchyma of tumors were intensified and enhancement was more obvious in the venous phase than in the arterial. 2cases were missed diagnosis which in the body of stomach. 3 cases were misdiagnosis, which 2 cases as cystadenocarcinoma and 1 case as rectal carcinoma. Conclusion The location of GIST is changeable. Adequate bowel preparation and master of their CT and MRI features, which are helpful to avoid missed diagnosis and misdiagnosis.