能谱CT在鉴别T3及T4a期胃癌中的应用价值

Application of spectral CT in the differentiation of stage T3 and T4a gastric carcinoma

目的探讨能谱CT对T3期及T4a期胃癌鉴别诊断的应用价值。方法回顾性收集2013年12月至2014年12月期间于郑州大学第一附属医院行腹部能谱CT检查的62例T3期及T4a期胃癌患者的参数资料，男38例，女24例，年龄33—77（58．6±10．4）岁；均经手术病理确诊，其中L期胃癌20例，T4a期42例。采用宝石能谱成像双期动态增强扫描，测量动脉和静脉两期胃癌病灶邻近周围脂肪间隙的碘浓度（100μg／ml）、水浓度（100μg／ml）及同层腹主动脉的碘浓度，计算得出标准化碘浓度（标准化碘浓度：碘浓度／同层腹主动脉碘浓度）。采用两独立样本t检验分别比较动脉和静脉期L及T4a期胃癌病灶邻近周围脂肪间隙的碘浓度、水浓度和标准化碘浓度，并与患者的病理结果对照，绘制ROC曲线评估能谱CT的诊断效能。结果动脉期：T1a期胃癌测量的碘浓度为-5．19±0．81，标准化碘浓度为-0．05±0．01；明显高于T1期的-3．44±1．54（P=0．000）和-0．03±0．01（P=0．000）。静脉期：T4a期胃癌测量的碘浓度为-3．78±0．94，标准化碘浓度为-0．04±0．01，亦明显高于T3期的-1．62±1．43（P=0．000）和-0．02±0．02（P-0．000）。T4a期动脉和静脉期的水浓度分别为955．72±15．68和949．86±17．36，T3期则分别为947．77±18．43和942．46±18．53，T4a期与L期水浓度比较，差异均无统计学意义（分别为P=0．106和P=0．143）。ROC曲线显示，动脉期的碘浓度和标准化碘浓度曲线下面积分别为0．829和0．867，以标准化碘浓度=-0．039作为阈值鉴别胃癌的T1期及T4a期时，相应的诊断敏感度为83．3％，特异度为75．0％。静脉期的碘浓度和标准化碘浓度曲线下面积分别为0．873和0．905。选取标准化碘浓度为-0．031作为阈值判断胃癌的L期及T4a期时，相应的诊断敏感度为81．0％，特异度为85．0％。结论腹部能谱CT检查能够较好地鉴别T3期及T4a期胃癌；T4a期胃癌病灶邻近脂肪间隙碘浓度更高。以静脉期标准化碘浓度-0．031作为阈值，鉴别诊断效能较高。

Objective To investigate the application value of spectral CT in the differentiation of stage T3 and T4a gastric carcinoma. Methods Data of 62 gastric cancer patients of stage T3 and T4a undergoing abdominal spectral CT examination in the First Affiliated Hospital of Zhengzhou University from December 2013 to December 2014 were collected retrospectively. There were 38 male and 24 female patients, with age of 33 to 77 （58.6± 10.4） years old. Abdominal double-phase enhanced scanning in gemstone spectral imaging mode was used to measure Iodine concentration （IC, 100 μg/ml） and water concentration （WC, 100 Ixg/ml） of perigastric fat tissue adjacent to the lesion during arterial phase （AP） and venous phase （VP）, and normalized iodine concentration （nIC） calculated respectively （nIC=IC/IC of aorta on the same slice）. IC, WC, nIC of arterial phase venous phase between stage T3 and T4a lesions were compared with double independent sample t was and test and compared with pathology. The diagnostic efficacy was evaluated using receiver operating characteristic （ROC） curve analysis. Results During arterial phase in stage T4a cases, IC （100 μg/ml） was -5.19 ± 0.81 and nIC was -0.05 ± 0.01, which was significantly higher than -3.44± 1.54 （P = 0.000） and -0.03 ± 0.01 （P = 0.000） in stage T3 cases. During venous phase in T4a cases, IC （100 μg/ml） was -3.78± 0.94 and nIC was -0.04 ± 0.01, which was significantly higher than -1.62±1.43 （P = 0.000） and -0.02 ±0.02 （P = 0.000） in stage T3 cases. As compared to arterial phase, IC and nlC of stage T4a and T3 of venous phase were more significantly different （all P 〈 0.05）. WC of stage T4a during arterial and venous phase was 955.72 ± 15.68 and 949.86 ± 17.36 respectively, while WC of stage T3 during arterial and venous phase was 947.77 ±18.43 and 942.46 ± 18.53 respectively. There were no significant differences in WC between two stage cases during arterial and venous phase （P= 0.106, P = 0.143）. ROC analysis showed that area under the ROC of IC and nIC during arterial phase was 0.829 and 0.867 respectively, and cut-off value of nIC was -0.039 for differentiation of stage T3 and T4a with corresponding 83.3% of sensitivity and 75.0% of specificity; area under the ROC of IC and nIC during venous phase was 0.873 and 0.905 respectively, and cut-off value of nIC was -0.031 for differentiation of stage T3 and T4a with corresponding 81.0% of sensitivity and 85.0% of specificity. Conclusions Abdominal spectral CT scan is useful in the differentiation of stage T3 and T4a gastric carcinoma. The IC of perigastric fat tissue is significantly higher in stage T4a gastric carcinoma compared to stage T3 gastric carcinoma. Higher diagnostic efficacy can be obtained when taking -0.031 as the cutoff value of nIC during venous phase.