高分辨磁共振成像对低位直肠癌肛管浸润的判断及手术层面的界定

Anatomy of the anal canal and staging of low rectal cancer with high resolution magnetic resonance imaging

目的评估高分辨磁共振成像（MRI）对低位直肠癌肛管浸润情况的判断价值，为手术层面的界定提供参考。方法23例经病理证实的低位直肠癌患者和20例无肛管疾病的对照患者行盆腔3．0TMRI表面相控阵线圈检查。MRI扫描序列包括高分辨T2WI序列（TSE—T2WI）和三维容积内插动态增强序列（3D—VIBE）。总结正常肛管MRI高分辨图像特征及直肠癌浸润肛管影像学特征，并对直肠癌进行T分期及T—DACl分期（肿瘤浸润肛门括约肌复合体的深度）。结果20例对照组患者中，除8例联合纵肌显示欠清外，其余12例MRI下肛门括约肌复合体的7层解剖结构显示清晰。23例低位直肠癌浸润肛门括约肌复合体表现为相应解剖层面正常信号消失代之于稍高信号肿瘤组织，正常解剖层次结构消失，代之于肿块影。23例低位直肠癌患者术前影像学T分期（耻骨直肠肌上方）：T2期8例，B期7例，T4期8例；T．DACl分期（耻骨直肠肌下方）：To—DACI期10例，T1-DACI期1例，T2a-DACI期3例，T2．DACI期3例，T3-DACI期4例，T4-DACI期2例。8例影像学诊断为艮。DACI期患者行一期直肠癌切除术。其中6例术后病理学分期与术前影像学分期一致，另2例T2a-DACI病例术后病理证实为pT]期。结论高分辨MRI能够较准确地判断低位直肠癌肛管浸润情况，从而为手术层面的界定提供依据和参考。

Objective To evaluate high resolution MR in imaging of the anatomy and tumor invasion of the anal canal. Methods Twenty-three patients with low rectal cancer confirmed by pathology results were recruited as the study group and 20 patients without history of anal canal diseases were recruited as the control group. All patients received MRI examinations containing three TSE-T2WI sequences and three 3D-VIBE sequences. The distance between the tumor and the anal margin was measured in the study group. Two radiologists finished T staging of the tumor independently. Results MRI had a clear demonstration of the anatomy of the anal canal in all 20 control patients. The T staging of 23 patients of study group was T2 （n=8）, T3 （n=7）, and T4 （n=8）, and the depth of anal canal invasion （T-DACI） was T0-DACI （n=10）, T1-DACI （n=l）, T2a-DACI （n=3）, T2-DACI （n=3）, T3-DACI （n=4） and T4-DACI （n=2）. Eight patients received surgery and the consistency between pathological staging and imaging staging was 75%. Conclusion High resolution MRI has the capacity of demonstrating the complex anatomy of the anal canal, and can provide evidence of anal canal invasion for low rectal cancer.