双源CT标准化碘浓度及能谱曲线在胃癌周围侵犯诊断中的应用价值

The application value of dual source CT standardized iodine concentration and energy spectrum curve in the diagnosis of peripheral invasion of gastric cancer

目的探讨双源CT双能量成像在胃癌淋巴结转移诊断中的应用价值。方法收集我院2016年11月~2017年6月间于我院放射科行双源CT双能量扫描检测的45例经手术病理证实的进展期胃癌患者的影像资料,根据病理结果将淋巴结分为有转移组与无转移组(正常组),分别测量胃癌淋巴结转移与正常淋巴结动脉期和静脉期的碘浓度及同层主动脉碘浓度,比较胃癌转移淋巴结与正常淋巴结标准化碘浓度(normalized iodine concentration,NIC)的差异;分析淋巴结转移与正常淋巴结能谱曲线斜率的特征。结果最佳单能量图像是70keV。转移性淋巴结与非转移淋巴结动脉期的NIC值是0.545±0.087、0.143±0.078,差异有统计学意义(P<0.05);静脉期的转移性淋巴结与非转移淋巴结NIC值是0.478±0.014、0.306±0.083,差异有统计学意义(P<0.05)。胃癌转移淋巴结与正常淋巴结的双期能谱曲线均为下降型,二者于40~80keV时差异较明显;于80~140keV对应的能谱曲线差异较小。动脉期曲线斜率k为6.86时,诊断胃癌转移淋巴结的灵敏度是83.2%,特异度是84.7%;静脉期斜率k为6.66时,灵敏度是64.6%,特异度是97.7%。结论 NIC和能谱曲线走行趋势对胃癌淋巴结转移的定性及定量诊断有较大的帮助。

Objective To investigate the value of dual energy CT dual energy imaging in the diagnosis of lymph node metastasis of gastric cancer.Methods We collected the imaging data of 45 patients with advanced gastric cancer confirmed by operation and pathology,who underwent dual source CT double energy scanning in the department of radiology of our hospital from November 2016 to June 2017.According to the pathological results,those patients were divided into the lymph node metastasis group and non-metastasis group.The iodine concentrations in the lymph node metastasis of gastric cancer and the normal lymph node at arterial phase and portal venous phase as well as that in the same layer of aorta were determined respectively.The difference of the normalized iodine concentration(NIC)between the lymph node metastasis of gastric cancer and normal lymph node was compared.Then,the characteristics of energy spectrum curve slope of the lymph node metastasis and normal lymph node were analyzed in this work.Results The best single energy image was 70 keV.The NIC value of metastatic lymph node at arterial phase was 0.545±0.087 and that of non-metastatic lymph node was 0.143±0.078,with statistically significant difference(P<0.05);The NIC value of metastatic lymph node at venous phase was 0.478±0.014 and that of non-metastatic lymph node was 0.306±0.083,the difference was statistically significant(P<0.05).The energy spectrum curve in the metastatic lymph node of gastric carcinoma and normal lymph nodes at the arterial phase and venous phase was both decreased.The spectrum curve of lymph node metastasis of gastric cancer was above that of the normal lymph node and the corresponding spectrum curve was more steep;The difference of the two characteristics from 40 to 80 keV was obvious and that of corresponding energy spectrum curve from 80 to 140 keV was smaller.When the curve slope k at arterial phase was 6.86,the sensitivity and specificity for the diagnosis of lymph node metastasis was 83.2%,and 84.7%,respectively.When the slope k at the venous phase was 6.66,the sensitivity was 64.6%,and the specificity was 97.7%.Conclusion The trend of NIC and energy spectrum curve is helpful for qualitative and quantitative diagnosis of lymph node metastasis of gastric cancer.