目的 研究磁共振T2加权成像（T2WI）结合弥散加权成像（DWI）对直肠癌术前分期的价值,以及其与病理的相关性。方法 纳入2020年6月—2023年6月就诊的208例影像学、病理资料完整直肠癌患者进行回顾性分析。所有患者在术前行直肠标准方案MRI检查,通过平扫和增强提示肿瘤的位置和大小,DWI信号测量肿瘤的表观弥散系数（ADC）值。对比T2WI单独和联合DWI对于直肠癌术前分期的诊断效能。获得不同病理分级肿瘤组织的平均及最小ADC值,分析两者与病理分级之间的相关性。结果 T2WI联合DWI对于T2、T3期直肠癌的诊断准确度高于T2WI单独评估,差异具有统计学意义（P<0.05）。低分化直肠癌平均及最小ADC值明显低于中、高分化直肠癌,差异有统计学意义（P<0.05）,且最小ADC值与病理分级呈负相关（r=–0.422, P<0.05）。结论 T2WI联合DWI对于直肠癌分期的诊断效能好于单独应用T2WI;最小 ADC 值对于术前肿瘤的病理分级具有较好的应用价值。

Objective To study the value of magnetic resonance （MR） T2 weighted imaging （T2WI） combined with diffusion weighted imaging （DWI） in preoperative staging of rectal cancer and its correlation with pathology. Methods This retrospective analysis was conducted on 208 patients of rectal cancer with complete imaging and pathological data from June 2020 to June 2023. All patients underwent preoperative rectal standard protocol of MRI examination, with plain and enhanced scans indicating the location and size of the tumor and DWI signals measuring the apparent diffusion coefficient （ADC） value of the tumor. We compared the diagnostic efficacy of T2WI alone and the combination of T2WI and DWI, obtained the average and minimum ADC values of tumor tissues with different pathological grades, and analyzed the correlation between the two values and pathological grades. Results The diagnostic accuracy of combined T2WI and DWI for T2 and T3 stages of rectal cancer was significantly higher than that of T2WI alone （P<0.05）. The average and minimum ADC values of low differentiated rectal cancer were significantly lower than those of medium and high differentiated rectal cancers （P<0.05）, and the minimum ADC value was negatively correlated with pathological grade（r=–0.422, P<0.05）. Conclusions The combination of T2WI and DWI has a higher diagnostic efficiency for rectal cancer than T2WI alone. In addition, the minimum ADC value has a good value for preoperative pathological grading of tumors.