双源CT能谱成像定性评估胃癌转移淋巴结

目的 探讨双源CT能谱成像定性评估胃癌转移淋巴结的价值。方法 收集病理确诊为胃癌的67例患者资料，术前均接受双源CT腹部平扫和能谱双期增强扫描，测量并记录淋巴结长径、短径、短长径比、动脉期和静脉期标准化碘浓度，绘制能谱衰减曲线，并计算其斜率。对转移淋巴结和非转移淋巴结间差异有统计学意义的参数绘制ROC曲线，确定诊断胃癌转移淋巴结的阈值、敏感度和特异度。结果 胃癌转移淋巴结与非转移淋巴结的短径、短长径比、动脉期和静脉期标准化碘浓度差异均有统计学意义（P均<0.05），ROC曲线下面积分别为0.601（P=0.006）、0.881（P<0.001）、0.865（P<0.001）和0.834（P<0.001）。以短长径比=0.734为阈值，双源CT能谱成像诊断胃癌转移淋巴结的敏感度75.72%、特异度93.64%；以动脉期标准化碘浓度0.223为阈值，敏感度69.81%，特异度91.20%；以静脉期标准化碘浓度0.392为阈值，敏感度78.33%，特异度85.63%。胃癌转移淋巴结与非淋巴结的双期能谱曲线呈下降型，动脉期曲线斜率为6.860时，诊断胃癌转移淋巴结的敏感度为83.24%，特异度为84.72%；静脉期斜率为6.660时，敏感度为64.62%，特异度为97.70%。淋巴结短长径比、动脉期标准化碘浓度及能谱曲线斜率联合诊断胃癌转移淋巴结的敏感度和特异度分别为97.34%和87.83%；淋巴结短长径比、静脉期标准化碘浓度及能谱曲线斜率联合诊断诊断胃癌转移淋巴结敏感度80.13%，特异度90.31%。结论 胃癌患者淋巴结短长径比、动静脉期标准化碘浓度、动静脉期斜率是评估其转移性的主要参数；三者联合可明显提高双源CT能谱成像诊断胃癌淋巴结转移的效能。

Dual-source CT energy spectral imaging in qualitative evaluation of metastatic lymph nodes in patients with gastric cancer

Objective To observe the value of dual-source CT energy spectral imaging in qualitative evaluation of metastatic lymph nodes in patients with gastric cancer. Methods Data of patients with pathologically diagnosed gastric cancer were collected, who underwent both dual-source CT abdomen plain scanning and energy spectrum double-phase enhanced scanning. The long diameter, short diameter, short length-diameter ratio, arterial phase and venous phase standardized iodine concentration of lymph nodes were measured and recorded. Energy spectrum attenuation curves were drawn, and the slopes were calculated. Parameters with statistical significant differences between metastatic and non-metastatic lymph nodes were used to plot ROC curves, and the thresholds for diagnosing metastatic lymph nodes of gastric cancer, and their diagnostic sensitivity and specificity were calculated. Results There were significant differences in short axis, short aspect ratio, normalized iodine concentration in arterial phase and venous phase between metastatic and non-metastatic lymph nodes in patients with gastric cancer (all P<0.05), the area under the curve of ROC curve was 0.601 (P=0.006), 0.881 (P<0.001), 0.865 (P<0.001) and 0.834 (P<0.001), respectively. When the short length to diameter ratio was 0.730, the sensitivity and specificity in diagnosis of metastatic lymph nodes of gastric cancer was 75.72% and 93.64%. When standardized iodine concentration was 0.223 in arterial phase, the sensitivity and specificity in diagnosis of metastatic lymph nodes of gastric cancer was 69.81% and 91.20%. When the standardized iodine concentration was 0.392 in the venous phase, the sensitivity and specificity in diagnosis of metastatic lymph nodes of gastric cancer was 78.33% and 85.63%. Dual-phase energy spectrum curve of both gastric metastatic lymph nodes and non-lymph node decreased. Taken the arterial curve slope k=6.860 as the threshold, the sensitivity and specificity in diagnosis of metastatic lymph nodes was 83.24% and 84.72%.When the threshold venous phase slope k was set at 6.660, the sensitivity and specificity in diagnosis of metastatic lymph nodes was 64.62% and 97.70%, respectively. Combining arterial phase length-to-diameter ratio, arterial phase standardized iodine concentration and spectral curve slope, the sensitivity and specificity in diagnosing metastatic lymph nodes was 97.34% and 87.83%, which was 80.13% and 90.31% when combining venous phase short length-diameter ratio, venous phase standardized iodine concentration and spectral curve slope. Conclusion The short-length-to-diameter ratio, arterial-venous phase standardized iodine concentration and arterial-venous phase slope of lymph nodes are the main parameters for evaluating metastatic lymph nodes in patients with gastric cancer. Combination of the above three parameters can obviously improve the sensitivity and specificity in diagnosis of metastatic lymph nodes in patients with gastric cancer.