局部进展期直肠癌新辅助放化疗后肿瘤退缩分级:MRI与病理对照研究

Tumor regression grade after neoadjuvant chemoradiotherapy for locally advanced rectal cancer:MRI and pathological control study

目的探讨磁共振肿瘤退缩分级(magnetic resonance tumor regression grade,mrTRG)的诊断效能及影响因素。材料与方法本研究回顾性分析2017年10月至2021年6月期间天津市人民医院肛肠诊疗中心收治的局部进展期中低位直肠癌患者病例129例。所有病例均行常规长程同步放化疗加根治性手术治疗,分别于同步放化疗前1周及结束后4周进行MRI扫描。以病理肿瘤退缩分级(pathologic tumor regression grade,pTRG)作为金标准,采用Kappa检验分析mrTRG的诊断效能。采用分层分析,评估不同MR因素[扩散加权成像(diffusion-weighted imaging,DWI)、T分期、T2WI高信号、直肠系膜筋膜(mesorectal fascia,MRF)侵犯阳性(MRF+)、壁外血管侵犯(extramural vascular invasion,EMVI)阳性(EMVI+)]对mrTRG诊断效能的影响。结果单独采用T2WI进行评估,mrTRG 1~2级57例,3~5级72例。采用T2WI联合DWI进行评估,mrTRG 1~2级70例,3~5级59例。病理结果显示,pTRG 0~1级66例,2~3级63例。mrTRG与pTRG间一致性中等(单纯T2WI:Kappa=0.602,P<0.001;T2WI+DWI:Kappa=0.693,P<0.001)。与单纯T2WI相比,T2WI联合DWI提高了mrTRG的敏感度(86.4%vs.82.9%)、特异度(83.9%vs.77.1%)、阴性预测值(89.7%vs.79.4%)、约登指数(70.3%vs.60.0%)、总符合率(84.9%vs.80.2%)。T分期高、T2WI高信号、MRF+、EMVI+使mrTRG的敏感度、特异度、阳性预测值、阴性预测值、约登指数、总符合率不同程度减低(T2WI高信号对mrTRG的敏感度影响除外)。结论T2WI联合DWI能够提高mrTRG的诊断效能,新辅助放化疗前T分期高、T2WI高信号、MRF+、EMVI+会降低mrTRG评估的准确性。

Objective:To investigate the diagnostic efficacy of magnetic resonance tumor regression grade(mrTRG)and affecting factors.Materials andMethods:Aretrospective study was conducted in 129 cases with locally advanced low rectal cancer admitted to theAnorectal Disease Diagnosis and Treatment Center of Tianjin Union Medical Center from October 2017 to June 2021.All patients received conventional long-term concurrent chemoradiotherapy and radical surgery.MRI scans were performed 1 week before and 4 weeks after the end of concurrent chemoradiotherapy.Using pathologic tumor regression grade(pTRG)as the gold standard,Kappa test was used to analyze the diagnostic efficacy of mrTRG.The effects of differentMR factors[diffusion-weighted imaging(DWI),T staging,high signal intensity on T2WI,mesorectal fascia invasion positive(MRF+),extramural vascular invasion positive(EMVI+)]on the diagnostic efficacy of mrTRG were evaluated by stratified analysis.Results:Using T2WI alone,57 cases were mrTRG 1-2 and 72 cases were mrTRG 3-5.Using T2WI combined with DWI,70 cases were mrTRG 1-2 and 59 cases were mrTRG 3-5.The pathological results showed that 66 cases were pTRG 0-1 and 63 cases were pTRG 2-3.mrTRG was moderately consistent with pTRG(T2WI alone:Kappa=0.602,P<0.001;T2WI+DWI:Kappa=0.693,P<0.001).Compared with T2WI,T2WI combined with DWI increased the sensitivity(86.4%vs.82.9%),specificity(83.9%vs.77.1%),negative predictive value(89.7%vs.79.4%),Jorden index(70.3%vs.60.0%)and total coincidence rate(84.9%vs.80.2%)of mrTRG.High T stage,T2WI high signal intensity,MRF+and EMVI+reduced the sensitivity,specificity,positive predictive value,negative predictive value,Jordon index and total coincidence rate of mrTRG in varying degrees(except the effect of high T2WI signal on mrTRG sensitivity).Conclusions:T2WI combined with DWI can improve the diagnostic efficiency of mrTRG.High T stage,T2WI high signal intensity,MRF+,EMVI+before neoadjuvant chemoradiotherapy will reduce the accuracy ofmrTRG assessment.