能谱CT定量参数对胃癌淋巴结的定性评估价值

Preoperative assessment value of spectral CT quantitative parameters in lymph node metastasis of gastric cancer

目的 探讨能谱CT定量参数对胃癌淋巴结的定性评估价值。方法 前瞻性收集2013年12月至2015年6月郑州大学第一附属医院经病理确诊的且资料完整的86例胃癌患者的临床及影像资料。患者均采用Discover GSI CT机行腹部（自膈顶至耻骨联合上缘）常规平扫和能谱双期增强扫描；在后处理工作站上对1.25 mm层厚的平扫、动静脉期70 keV单能量图像、动静脉期碘基图像进行分析，测量并记录淋巴结的长径、短径、短长径比、动脉期和静脉期CT值、动脉期和静脉期碘基值。以手术病理结果为金标准，对转移和非转移淋巴结各定量参数进行独立样本t检验，对于差异有统计学意义的参数绘制ROC曲线，以约登指数最大时的界值作为诊断阈值，计算各参数的诊断灵敏度和特异度。本临床研究注册号：81271573。结果 86例患者中男53例，女33例，年龄22~87（中位数53）岁；胃上区癌28例，胃中区癌12例，胃下区癌27例，累及两个区以上者19例；分化型胃癌35例，未分化型51例。术中检出淋巴结1 072枚，其中阳性淋巴结412枚，阴性淋巴结660枚。CT图像共检出淋巴结552枚，检出率51.5%；其中阳性淋巴结338枚（82.0%，338/412）；阴性淋巴结214枚（32.4%，214/660）。相比非转移性淋巴结，胃癌转移性淋巴结短径[（9.52 ± 3.58）mm比（6.48 ± 2.94）mm，t= 4.639，P= 0.000]、短长径比[（0.82 ± 0.14）比（0.61 ± 0.08），t= 13.514，P= 0.000]、平扫CT值[（20.44 ± 6.77）Hu比（16.06 ± 7.14）Hu，t= 3.154，P= 0.002]、动脉期CT值[（61.71 ± 11.78）Hu比（40.11 ± 10.18）Hu，t= 9.588，P= 0.000]、静脉期CT值[（71.34 ± 13.03）Hu比（53.81 ± 11.39）Hu，t= 7.888，P= 0.000]、动脉期碘基值[（16.17 ± 4.22）× 100 μg/cm3比（8.03 ± 3.10）× 100 μg/cm3，t= 9.781，P= 0.000]和静脉期碘基值[（20.13 ± 6.04）× 100 μg/cm3比（11.58 ± 4.13）× 100 μg/cm3，t= 10.147，P= 0.000]均较高，差异具有统计学意义；但两者长径的差异无统计学意义[（11.71 ± 5.63）mm比（10.64 ± 3.20）mm，t= 1.380，P= 0.169]。胃癌淋巴结短径、短长径比、平扫CT值、动脉期CT值、静脉期CT值、动脉期碘基值和静脉期碘基值的ROC曲线的曲线下面积分别为0.600、0.880、0.648、0.832、0.755、0.864和0.835。短长径比〉0.72的诊断灵敏度为75.6%，特异度为93.5%；动脉期CT值〉 49.75 Hu的诊断灵敏度为66.9%，特异度为88.8%；静脉期CT值〉59.80 Hu的诊断灵敏度为69.9%，特异度为77.6%；动脉期碘基值〉 9.65 × 100 μg/cm3的诊断灵敏度为80.4%，特异度为82.2%；静脉期碘基值〉 15.65 × 100 μg/cm3的诊断灵敏度为69.9%，特异度为86.9；短长径比与动脉期碘基值联合诊断灵敏度为95.2%，特异度为76.9%。结论 能谱CT图像上胃癌患者淋巴结短长径比、动静脉期碘基值、动静脉期CT值是评估其转移性的主要参数；其中淋巴结短长径比和动脉期碘基值诊断效能较高，两者联合可以明显提高诊断灵敏度。

Objective To investigate the preoperative assessment value of spectral CT quantitative parameters in lymph node metastasis of gastric cancer.Methods From December 2013 to June 2015, clinical and image data of 86 patients with gastric cancer confirmed by gastroscope pathology undergoing preoperative enhanced CT were prospectively collected. Enhanced CT included nonenhanced CT of conventional 120 kVp mode, arterial phase （AP） and venous phase （VP） with GSI mode on Discover GSI CT scanner. The raw data were transferred to ADW4.6 workstation to reconstruct the monochromatic images at 70 keV and iodine-based images in AP and VP with 1.25 mm thickness. The short diameter, long diameter, ratio of short to long diameter, CT attenuation and iodine value of lymph nodes in each phase were measured and recorded. Pathology results were used as golden standard. The spectral CT quantitative parameters of positive and negative lymph nodes were compared by t test and the sensitivity and specificity analyses were performed by ROC curves. This clinical study registration number 81271573.Results Among these 86 gastric cancer patients （53 male and 33 female） , tumors of 28 cases were in upper part, of 12 cases in middle part, of 27 cases in distal part and of 19 cases involved two parts. Thirty-five cases were differentiated type and 51 cases were undifferentiated type. A total of 1 072 lymph nodes were found in operation, of which 412 nodes were positive and 660 were negative. Among 552 lymph nodes found in CT images, 338 nodes were positive and 214 were negative. Compared to negative lymph nodes, short diameter[ （9.52 ± 3.58） mm vs. （6.48 ± 2.94） mm, t= 4.639, P= 0.000], ratio of short to long diameter （0.82 ± 0.14 vs. 0.61 ± 0.08, t= 13.514, P= 0.000） , CT attenuation in precontrast[ （20.44 ± 6.77） Hu vs. （16.06 ± 7.14） Hu, t= 3.154, P= 0.002], CT attenuation in AP [ （61.71 ± 11.78） Hu vs. （40.11 ± 10.18） Hu, t= 9.588, P= 0.000], CT attenuation in VP[ （71.34 ± 13.03） Hu vs. （53.81 ± 11.39） Hu, t= 7.888, P= 0.000], iodine value in AP[ （16.17 ± 4.22） 100 μg/cm3 vs. （8.03 ± 3.10） 100 μg/cm3, t= 9.781, P= 0.000], the iodine value in VP[ （20.13 ± 6.04） 100 μg/cm3 vs. （11.58 ± 4.13） 100 μg/cm3, t= 10.147, P= 0.000] of positive lymph nodes were greater. The long diameter was not significantly different between positive and negative lymph nodes [ （11.71 ± 5.63） mm vs. （10.64 ± 3.20） mm, t= 1.380, P= 0.169]. The area under ROC curve of short diameter, ratio of short to long diameter, CT attenuation in precontrast, AP and VP, iodine value in AP and VP of lymph nodes was 0.600, 0.880, 0.648, 0.832, 0.755, 0.864, 0.835, respectively. Taking the ratio of short to long diameter over 0.72 as diagnosis standard, the sensitivity was 75.6% and the specificity was 93.5%. Taking the CT number in AP over 49.75 Hu, the sensitivity was 66.9% and the specificity was 88.8%. Taking the CT number in VP over 59.80 Hu, the sensitivity was 69.9% and the specificity was 77.6%. Taking the iodine value in AP over 9.65 （100 μg/cm3） , the sensitivity was 80.4% and the specificity was 82.2%. Taking the iodine value in VP over 15.65 （100 μg/cm3） , the sensitivity was 69.9% and the specificity was 86.9%. Combinong the ratio of short to long diameter with the iodine value in AP, the sensitivity was 95.2% and the specificity was 76.9%.Conclusions The ratio of short to long diameter, the iodine value and CT attenuation in AP and VP of lymph nodes in spectral CT are important criteria to evaluate the metastasis of gastric cancer. Combining the ratio of short to long diameter with the iodine value in AP can obviously improve the sensitivity.