高分辨率MRI对直肠癌系膜淋巴结转移的诊断价值

Diagnostic Value of High Resolution MRI on Mesenteric Lymph Node Metastasis of Rectal Cancer

目的:分析高分辨率T2加权成像(T2WI)上直肠癌系膜淋巴结的MRI特点,探讨应用磁共振成像(MRI)诊断直肠系膜淋巴结转移的依据,旨在提高直肠癌术前N分期的诊断效能。方法:回顾性分析本院2016年4月至2017年3月收治的62例直肠癌患者MRI影像学资料。分别以淋巴结短径≥3 mm及≥5 mm为基准,结合内部信号(分为信号混杂及信号均匀)、边缘情况(分为边缘光整及边缘毛糙),对直肠癌系膜脂肪筋膜内淋巴结进行N分期。影像学诊断结果与病理诊断结果对照,统计分析MRI在诊断直肠癌的术前N分期的准确度、敏感度、特异度、阳性预测值以及阴性预测值。结果:62例患者,以淋巴结≥5 mm为阳性指标时,诊断准确度为77.42%,敏感度为62.50%,特异度86.84%,阳性预测值为75.00%,阴性预测值为78.57%;以淋巴结≥3 mm作为阳性指标时,诊断准确度为75.80%,敏感度为87.50%,特异度68.00%,阳性预测值为63.60%,阴性预测值为89.66%;淋巴结≥3 mm组的敏感度高于≥5 mm组的,差异有统计学意义(P<0.05),诊断效能差异无统计学意义(P>0.05)。两者间结合内部信号特点及边缘情况后,淋巴结≥5 mm组诊断准确度为83.87%,敏感度为62.50%,特异度97.37%,阳性预测值为93.75%,阴性预测值为83.43%;淋巴结≥3 mm组诊断准确度为90.32%,敏感度为83.33%,特异度94.74%,阳性预测值为90.91%,阴性预测值为90.00%;两者诊断效能均较单纯淋巴结大小为阳性指标时有所提高,尤其以淋巴结≥3 mm组诊断效能更佳,其准确度、特异度、阳性预测值升高明显,差异有统计学意义(P<0.05)。结论:单纯以淋巴结大小作为转移标准时,3 mm较5 mm敏感度高,但特异度低;结合淋巴结的信号及边缘情况,可明显提高诊断效能,而且3 mm时更加明显。因此,在判定淋巴结是否转移时,应依据淋巴结大小,结合信号以及边缘情况进行综合分析。

Objective： to analyze the MRI features of the mesentery lymph nodes of rectal carcinoma with high resolution T2 weighted imaging（T2 WI）, and to investigate the basis of using MRI to diagnose the lymph node metastasis of rectal cancer, so as to improve the preoperative N staging of rectal cancer. Methods： A retrospectiveanalysis of 62 cases of rectal carcinoma patients with MRI imaging in our hospital in April 2016~2017 year in March from data, respectively in the lymph node short diameter is greater than or equal to 3 mm and over 5 mm for reference, combined with the internal signal（divided into mixed signal and signal edge（uniform）, divided into smooth edge and rough edge）, the mesorectal fascia fat in lymph nodes were N staging, imaging diagnosis and pathological diagnosis Results, statistical analysis of MRI in the diagnosis of colorectal cancer preoperative N staging accuracy, sensitivity, specificity, positive predictive value and negative predictive value. Results： 62 patients only with lymph node positive index was greater than 5 mm, the diagnostic accuracy was 77.42%,sensitivity was 62.50%, specificity 86.84%, positive predictive value was 75%, the negative predictive value was78.57%; the lymph node is greater than or equal to 3 mm as a positive index, the diagnostic accuracy was 75.80%,sensitivity 87.50%, specificity 68%, positive predictive value was 63.60%, the negative predictive value was89.66%; the sensitivity is higher than that of the former, the difference was statistically significant（P〈0.05）, no significant differences in the remaining diagnostic efficiency（P〈0.05）. The combination of internal signal characteristics and the edge of the situation, 5 mm group, the accuracy was 83.87% more than the lymph node, the sensitivity was 62.50%, specificity 97.37%, positive predictive value was 93.75%, the negative predictive value was 83.43%; the 3 group mm diagnostic accuracy was 90.32% more than the lymph node, the sensitivity was83.33%, specificity was 94.74%., the positive predictive value was 90.91%, the negative predictive value was 90%;the diagnostic efficiency was higher than the simple lymph node size for positive index improved, especially in lymph nodes more than 3 group mm diagnostic performance better, accuracy, specificity, positive predictive value of elevated significantly, the difference was statistically significant（P〈0.05）. Conclusion： only by the size of lymph node metastasis as standard, 3 mm, 5 mm with high sensitivity, but the specificity is low; the combined signal and the edge of lymph nodes, can significantly improve the diagnostic efficiency, and 3 mm more obvious.Therefore, in the determination of lymph node metastasis, a comprehensive analysis should be performed based on the size of the lymph nodes, combined with signal and marginal conditions.