Objective: To compare the diagnostic value of T2 weighted imaging (T2WI), diffusion-weighted imaging (DWI), and T2WI+ DWI magnetic resonance imaging (MRI) for staging of rectal cancers for improving the accuracy of tumor staging. Methods: From January 2011 to December 2013, 120 cases of rectal cancers proved by colonoscopy without receiving any anti-tumor treatment were enrolled retrospectively. The MRI data for these patients were divided into three groups, ie., T2WI, DWI and T2WI+ DWI, for evaluating the tumor stages. The results were compared with histopathologic findings. The sensitivity and specificity were calculated and compared with chi-square test. The nodal staging was predicted by using T2WI+ DWI. Results: The accuracy for prediction of tumor staging was 83.3%, 65.0% and 92.5% for T2WI, DWI, and T2WI+ DWI respectively. The specificity for evaluating T1 and T2 stage, and the sensitivity for evaluating T3 by DWI was significantly lower than those using T2WI and T2WI+ DWI in rectal cancers. The sensitivity for evaluation of T2 by DWI was lower than that using T2WI+ DWI (63.0% vs. 88.9%). The sensitivity for evaluation T2 and specificity for T3 by T2WI+ DWI was higher than thouse using T2WI only (88.9% vs. 51.9%, 94.0% vs. 72.0%). The accuracy for prediction of nodal staging by using T2WI+ DWI was 62.1% (72/116). Conclusions: T2WI is the key sequence for staging of rectal cancers. Although the diagnostic accuracy was not good by using DWI alone, the combination of T2WI and DWI can improve the accuracy significantly for tumor staging in rectal cancers, whereas the nodal staging was still a hard task for radiologists.
目的： 探讨T2加权成像(T2WI)、扩散加权成像(DWI)及T2WI＋DWI在直肠癌分期中的诊断价值。 方法： 收集2011年1月至2013年12月间经手术病理证实且术前未行任何抗肿瘤治疗的直肠癌患者120例，根据术前MRI资料分为T2WI、DWI和T2WI＋DWI 3组，分别对肿瘤T分期进行评价，并与病理结果进行比较，计算不同序列T分期的敏感度和特异度。应用T2WI＋DWI序列对N分期进行评价，并与病理结果进行比较。 结果： T2WI、DWI和T2WI＋DWI序列诊断直肠癌T分期的准确率分别为83.3%(100/120)、65.0%(78/120)和92.5%(111/120)。与T2WI和T2WI＋DWI比较，DWI序列诊断直肠癌T1、T2期的特异度、T3期的敏感度均较低，差异有统计学意义(P<0.05)。DWI序列诊断直肠癌T2期的敏感度(63.0%)低于T2WI＋DWI序列(88.9%)。T2WI＋DWI序列对诊断直肠癌T2期的敏感度(88.9%)和T3期的特异度(94.0%)高于T2WI序列(分别为51.9%和72.0%)。T2WI＋DWI序列诊断直肠癌N分期的准确率为62.1%(72/116)。 结论： 高分辨T2WI是直肠癌治疗前分期的关键序列，单独DWI序列尚不能进行准确分期，但T2WI联合DWI可以提高直肠癌T分期的准确率。T2WI＋DWI评价直肠癌N分期尚需进一步研究。.
Keywords: Diffusion-weighted imaging; Magnetic resonance imaging; Rectal neoplasms; Tumor staging.