目的探讨MRI对直肠癌及局部 淋巴结转移的诊断价值。方法 选取我院 2015年4月-2017年4月收治的180例经病理 证实的直肠癌患者的临床资料，均有完整 的MRI影像资料，以病理诊断为金标准， 分析MRI对直肠癌患者术前评估及局部淋 巴结转移的诊断准确性。结果 MRI的T分 期中T≤2期准确度为88.9%、T3期准确度 82.1%、T4期准确度86.7%，T分期总准确 度为85.0%；N分期中N0期准确度79.7%、 N1期准确度64.9%、N2期准确度61.9%，N 分期总准确度为69.4%。本组180例患者 病理诊断结果显示，淋巴结阳性患者102 例，阴性78例，术前MRI诊断淋巴结转移 的敏感性为79.4%，特异性为69.2%，其中 假阳性率30.8%，假阴性率20.6%，阳性预 测值为77.1%，阴性预测值为72.0%。淋巴 结转移MRI表现特征：转移的淋巴结边缘 呈分叶状或毛刺状，部分淋巴结信号具有 不均匀的表现。结论 MRI检查对直肠癌术 前分期有重要价值，可为术前病情评估和 治疗方案的制定提供依据，MRI对直肠癌 局部淋巴结转移的判断有一定价值，但仍 存在一定局限性，临床实践中应结合其他 影像学检查方式，以提高诊断准确度。

Objective To discuss the diagnostic value of MRI for local lymph node metastasis and rectal cancer. Methods The clinical data of 180 cases of rectal cancer confirmed by pathology were selected in our hospital in April -2017 April 2015, there are complete MRI image data. With pathological diagnosis as the gold standard, the diagnostic accuracy of MRI for preoperative evaluation and local lymph node metastasis was analyzed. Results The accuracy of T≤2 in T stage of MRI was 88.9%, the accuracy of T3 was 82.1%, the accuracy of T4 was 86.7% , T staging total accuracy of 85.0%. N staging N0 accuracy 79.7%, N1 accuracy 64.9%, N2 accuracy 61.9%, N staging the total accuracy of 69.4%. The group of 180 patients pathological diagnosis showed that 102 patients with positive node, the negative in 78 cases, the sensitivity and specificity of preoperative MRI in diagnosing lymph node metastasis were 79.4% and 69.2% respectively. The false positive rate was 30.8%, the false negative rate was 20.6%, the positive predictive value was 77.1% and the negative predictive value was 72.0%. Lymph node metastasis MRI features: The lymph node metastasis was lobulated or burr-like, part of the lymph node signal has a non-uniform performance. Conclusion Preoperative MRI examination of the staging of rectal cancer has important value for preoperative evaluation of the disease and provide a basis for the development of treatment options, MRI has some value in judging the local lymph node metastasis of rectal cancer, but there are still some limitations, clinical practice should be combined with other imaging methods to improve the diagnostic accuracy.