术前MRI对直肠癌分期和侧切缘的预测价值

Value of preoperative MRI in prediction of pathological stage and circumferential resection margin in rectal cancer

目的:评估术前MRI预测直肠癌T、N分期和侧切缘(Circumferential resection margin,CRM)受累的准确程度。方法:术前肠镜活检病理证实直肠癌28例,MRI检查前经肛门插入三腔管气囊(内注水或气适量),采用Siemens Avanto 1.5T磁共振系统,用MRI评估肿瘤T分期﹑系膜淋巴结转移N分期和CRM受累,所有病例均行全直肠系膜切除术TME,对照术前MRI分期和术后病理结果,评估MRI能否准确预测直肠癌T、N分期及CRM受累。结果:MRI正确T分期24例,错误4例,其中3例T1～T2期高估为T3期,1例T3期低估为T1～T2期,T分期的总准确率为85.7%(24/28),其中T1～T2期的预测准确率为66.7%(6/9),T3期的准确率为92.3%(12/13),T4期的准确率为100%(6/6),MRI可以对T分期进行准确预测(Kappa值为0.773,P<0.001)。MRI对直肠系膜淋巴结正确分期22例,错误分期6例,其中高估4例,低估2例,准确率为78.6%(22/28),灵敏度为89.5%(17/19),特异度为55.6%(5/9),MR对系膜淋巴结转移可做出一般性预测(Kappa值为0.478,P=0.01)。MRI正确预测CRM 26例,错误2例,其中高估1例,低估1例,准确率为92.9%(26/28),灵敏度为85.7%(6/7),特异度为95.2%(20/21)。MRI可以准确预测CRM是否受累(Kappa值为0.81,P<0.001)。结论:使用三腔管气囊进行术前MRI检查能准确预测直肠癌T分期,并可靠地预测CRM是否受累,对N分期只能一般性预测。

Objective： To evaluate the accuracy of preoperative MRI in prediction of pathological staging and involvement of circumferential resection margin （CRM） in rectal cancer. Methods： Twenty-eight patients were biopsy-proven to be rectal cancer through preoperaitive eolonoscopy. All patients were inserted with a triple cavity catheter with balloon inflated with air to the anus before MRI examining, Siemens Magnetom Avanto 1.5T were used. All patients underwent total mesoreetal excision and were assessed prospectively using high-resolution MRI for tumour（T） and mesorectal nodal（N） staging as well as CRM sta- tus using the depth of turnout spread, tumour node metastasis and CRM involvement. Preoperative MRI assessment of these prognostic factors was compared with the histopathological findings by carefully correlated with pathologic specimen. Results： MRI correctly staged the tumor in 24 patients, had 4 mistakes, understaged in 1 case, and overstaged in 3 cases. The accu- racy of T stage was 85.7%（24/28）. There was an accurate correlation between pathologic and MRI tumor staging （Kappa=0.773, P〈O.001）. Node status was correctly staged in 22 patients, overstaged in 4 cases, and understaged in 2 cases. The accuracy of＇ node staging was 78.6%（22/28）, sensitivity was 89.5%（17/19）, and specificity was 55.6%（5/9）. The correlation between patholog- ic and MRI node staging was generic（Kappa=0.478, P=0.01）. The CRM status was correctly reported in 26 patients, overstaged in 1 case, and understaged in 1 case. The accuracy of CRM status was 92.9%（26/28）, sensitivity was 85.7%（6/7）, and speci- ficity was 95.2%（20/21）. There was a good correlation between pathologic and MRI CRM involvement （Kappa=0.81, P〈0.001）. Conclusion： Preoperative MRI provides generic predictive data as to mesorectal node stage, but does produce reliable predic- tion of clear CRM and tumor staging.