MRI对中低位直肠癌TaTME术前分期及可切除性评估

Preoperative staging and resectable evaluation of TaTME in low and medium rectal cancer by MRI

目的探讨1.5T MRI对中低位直肠癌经肛全直肠系膜切除术(TaTME)术前分期及可切除性评估,以指导直肠癌的TaTME个体化治疗,提高患者的保肛率和长期生存率、降低局部复发率。方法选取我院62例经结肠镜证实的中低位直肠癌患者进行盆腔高分辨平扫、DWI检查,常规序列包括:失状位T_(2)WI、斜冠状位T_(2)WI、斜轴位T_(2)WI和DWI,所有T_(2)WI序列都采用小视野、薄层扫描。DWI的b值取1000 s/mm^(2)。然后由两名腹部影像诊断医师共同阅片,矢状位测量病灶下缘距离肛门外括约肌下缘的距离、矢状位病灶最大长径、斜轴位病灶最大长径,综合所有序列对直肠癌病灶进行术前MRI-TN分期,评估直肠系膜筋膜(MRF)累及的情况,然后与手术病理结果进行对照。结果在手术病理证实的62例中低位直肠癌中,中段直肠癌38例,下段直肠癌24例。肿块下缘距肛缘的平均距离(5.2±2.5)cm,肿块矢状位最大长径(4.0±1.8)cm,肿块斜轴位最大横径(2.9±1.2)cm。MRI-T分期中正确诊断51例,错误诊断11例,正确率为82.2%。MRI-N分期中正确诊断41例,错误分期21例,正确率为66.1%。MRI判别MRF有无累及的准确率、敏感性、特异性、阳性预测值及阴性预测值分别为88.9%、88.6%、76.2%及95.1%。结论高分辨1.5T MRI可以对中低位直肠癌做出准确的术前局部分期,对手术切缘有无累及进行准确的预测,准确预判手术的可切除性,为直肠癌TaTME的临床个体化治疗提供影像依据及解剖学标记。

Objective To study the 1.5 T high-resolution MRI for low and medium rectal cancer in the transanal total mesorectal excision in preoperative staging and resectable evaluation,so at to guide the TaTME individualized treatment of rectal cancer,to improve the chance of preserving the anus and long-term survival rate,and to reduce the local recurrence rate.Methods From February 2015 to July 2019,GE HDxt 1.5 T MRI was used to perform pelvic high-resolution plain scanning and DWI examination on 62 patients with low and middle rectal cancer confirmed by colonoscopy.Routine sequences included sagittal T_(2)WI,oblique coronal T_(2)WI,oblique axial T_(2)WI and DWI,and all T_(2)WI sequences adopted small field of view and thin layer scanning.The b value of DWI was 1000 s/mm^(2).And then,two experienced abdomen radiologists read the images together in consensus,determined preoperative MRI T and N staging of rectal cancer,and predicted MRF involvement or not.Then the MRI results were compared with surgical histopathology.Results Among the 62 cases of middle and low rectal cancer confirmed by operation and pathology,these were 38 cases of middle rectal cancer,and 24 cases of lower rectal cancer.The mean distance between the lower margin of the mass and the anal margin was(5.2±2.5)cm,the maximum sagittal diameter of the mass was(4.0±1.8)cm,and the maximum transverse diameter of the mass was(2.9±1.2)cm.In MRI-T staging,51 cases were correctly diagnosed,11 cases were wrongly diagnosed,and the accuracy was 82.2%.In MRI-N staging,41 cases were correctly diagnosed,21 cases were wrong staging,and the accuracy was 66.1%.The predictive value of MRI in determining whether MRF was involved were 88.9%,88.6%,76.2%and 95.1%,respectively.Conclusion High resolution 1.5 T MRI can make accurate preoperative local staging for middle and low rectal cancer,so as to accurately predict the involvement of surgical margins,providing imaging basis and anatomical markers for clinical individualized treatment of TaTME in rectal cancer,and accurately predicting the resectability of surgery.