目的：探讨高分辨3.0T MRI常规扫描、扩散加权成像及动态增强扫描在直肠癌TNM分期的诊断价值。方法：2013年1月—2016年5月经结肠镜病理证实的直肠癌患者56例，男26例，女30例，年龄49~78岁，扫描序列包括：平扫矢状T2WI，轴位T2WI、T1WI、DWI、冠状T2WI、脂肪抑制轴位和冠状T2WI，动态增强T1WI轴位、矢状、冠状等序列。对各序列图像质量进行评价，将各序列进行术前MRI分期，结果与术后病理分期结果作对照。结果：高分辨MRI对直肠癌56例中正确T分期50例，错误的6例，分别有2例术后病理T1和T3期术前误诊为T2期，有2例术后T2期术前核磁误诊为T1期，总符合率为89.2%（50/56），其中T1期诊断符合率75%（6/8）；T2期诊断符合率为91%（20/22）；T3期诊断符合率为91%（20/22）；T4期诊断符合率为100%（4/4）。MRI对直肠癌诊断的总T分期准确率为89.2%（50/56）联合各序列对直肠癌的诊断敏感性和准确性优于常规序列，直肠癌的时间-信号强度曲线表现为流出型，动态增强扫描对直肠癌的检出和管壁周围的侵犯优于其他序列。结论：3.0T MRI直肠癌的理想检查组合包括：矢状T2WI、轴位T2WI、T1WI、DWI（b值为1 000 s/mm2），冠状T2WI及轴位、矢状、冠状强化扫描，可以为直肠癌患者的术前分期做出较好的评估。

Objective: To investigate the diagnostic value of high resolution 3.0T MRI conventional scan, DWI and DCE MR imaging in TNM staging of rectal cancer. Methods: Twenty-six male and thirty female patients(49~78 years old) with pathologically confirmed rectal cancer were enrolled between January 2013 to May 2016. The imaging sequences included plain sagittal T2WI, axial T2WI, T1WI, DWI, coronary T2WI, fat-suppressed axial and coronal T2WI, axial, sagittal and coronal sequences of T1WI were dynamically enhanced. The image quality of each sequence is evaluated. The results of preoperative MRI staging were compared with the results of postoperative pathological staging. Results: High-resolution MRI in 50 of 56 cases of rectal cancer showed correct T stage. Among the rest 6 cases, two cases of pathologically T1 and T3 were preoperatively misdiagnosed to be T2 respectively. Two cases of T2 were preopreatively misdiagnosed T1. The total coincidence rate was 89.2%(50/56). The coincidence rate of T1 stage was 75%(6/8). The coincidence rate of T2 stage was 91%(20/22). The coincidence rate of T3 stage was 91%(20/22). The coincidence rate of T4 stage was 100%(4/4). The accuracy of MRI in the diagnosis of total T stage were 89.2%(50/56), and the sensitivity and accuracy of combining each sequence in the diagnosis of rectal cancer were superior to that of routine sequence. The time-signal intensity curve of rectal cancer showed an outflow pattern. Dynamic contrast-enhanced scan was superior to other sequences in the detection of rectal cancer and invasion of the surrounding wall. Conclusion: The ideal combination of 3.0T MRI imaging sequences for rectal cancer consists of sagittal T2WI, axial T2WI, T1WI, DWI(b value of 1 000 s/mm2), coronary T2WI and axial, sagittal and coronary enhanced scan, which can be used for preoperative staging of rectal cancer.