目的 探讨CT征象对胃肠道神经鞘瘤(GIS)与胃肠道间质瘤(GIST)的鉴别诊断价值.方法 选取 58 例经病理证实的GIS(13 例)和GIST(45 例)患者的CT影像资料,包括病灶的大小、形态和边界、强化方式、肿瘤血管、病灶内坏死、出血、钙化等征象,并测量肿瘤及同层主动脉/大动脉平扫、动脉期、静脉期CT值,观察病灶内有无粗大肿瘤血管,计算动脉期、静脉期标化密度(CTS-A、CTS-P)、强化CT值(ΔCTA、ΔCTP).采用受试者操作特征曲线(ROC)分析CT征象的鉴别诊断效能.结果 GIS组坏死比例(38.5%)、粗大肿瘤血管比例(0%)、平扫密度[(29.00±8.57)HU]、平扫标化密度(0.71±0.23)、动脉期密度[(50.92±11.43)HU]、动脉期标化密度(0.16±0.05)、动脉期强化值[(21.92±11.85)HU]、静脉期密度[(76.08±19.56)HU]、静脉期标化密度(0.48±0.08)均低于GIST组.平扫密度阈值为 34HU时诊断GIS的敏感度和特异度分别为 84.6%、79.3%.结论 瘤内是否存在粗大肿瘤血管、坏死能够将大部分GIS与GIST区分开来.联合平扫密度低及病灶内无粗大肿瘤血管的特征能提高GIS与GIST鉴别诊断准确率;另外,动脉期轻度均匀强化、静脉期轻中度均匀强化等特征也有助于鉴别GIS与GIST.
Objective To investigate the value of CT features in the differential diagnosis of gastrointestinal schwannoma(GIS)and gastrointestinal stromal tumor(GIST).Methods The CT signs of 58 cases of pathologically proved GIS(n=13)and GIST(n=45)were analyzed retrospectively in terms of size,shape,border,enhancement pattern,tumor vessels,intrafocal ne-crosis,hemorrhage,calcification and so on.We measured the CT values of tumor and homolayer aorta/aorta on plain scanand calculated the standardized density(CTS-A,CTS-P)and the enhanced CT value(ΔCTA,ΔCTP)in the arterial phase and venous phase.The receiver operating characteristic curve(ROC)was used to analyze the differential diagnostic efficacy of CT signs.Result In GIS group,necrosis ratio(38.5%),large tumor vessel ratio(0%),plain scan density[(29.00±8.57)HU],plain scan standardized density(0.71±0.23),arterial phase density[(50.92±11.43)HU],arterial phase standardized density(0.16±0.05),arterial phase enhancement value[(21.92±11.85)HU],venous phase density[(76.08±19.56)HU],or the standard-ized density of venous phase standardized density(0.48±0.08)was lower than that of GIST group.When the threshold of plain scan density was 34HU,the sensitivity and specificity of diagnosing GIS were 84.6%and 79.3%,respectively.Conclusion The presence of large tumor vessels and necrosis in tumor can distinguish most GIS from GIST.The combination of low density on the plain scan and no large tumor vessels in the lesions can improve the accuracy of differential diagnosis between GIS and GIST.In addition,mild homogeneous enhancement in arterial phase and mild to moderate homogeneous enhancement in venous phase are also helpful to distinguish between GIS and GIST.