Value Of MrTRG And ADC In Combination With Analysis For The Evaluation Of Tumor Response After Preoperative Chemoradiotherapy For Local Advanced Rectal Cancer

Obective:Retrospective analysis of magnetic resonance tumor regression grade(mrTRG)and apparent diffusion coefficient(ADC)for evaluating locally advanced rectal cancer(LARC)Value of treatment effect after Neoadjuvant Chemoradiotherapy(NCRT)).Methods:The study included 134 patients selected from the first affiliated hospital of Kunming Medical University from January 2017 to December 2019 and confirmed to have LARC by colonoscopy and magnetic resonance imaging.All patients received NCRT before surgery.Total mesorectal excision(TME)was performed after magnetic resonance assessment at week 8 after NCRT.According to Pathological Tumor Regression Grade(pTRG),patients were divided into pathological complete remission group(pCR group)and non-pathological complete remission group(non-pCR group).Two radiologists mapped the region of interest(ROI)on T2WI and DWI images,judged the MR tumor regression scale(mrTRG),and calculated the average ADC value after treatment.mrTRG 1-2 is defined as Good response.The intra-group correlation coefficient(ICC)was used to analyze the variability between the two readers' measurement results of mrTRG and ADC.Spearman correlation analysis was used to study the correlation between mrTRG,ADC and pTRG.The ROC curve was used to test the mrTRG and the average ADC to predict the accuracy of pCR.The Youden index calculated the optimal cutoff value,sensitivity,specificity,positive predictive value,and negative predictive value.Wilcoxon Signed Rank Test Compares mrTRG and ADC Changes Between pCR and Non-pCR Groups.Multi-factor stepwise Logistic regression analysis of the correlation between the main potential parameters and pCR,and ROC curve test fit model effect.DeLong test analyzes the differences in diagnostic performance of each ROC curve.P<0.05 was considered statistically significant.Results:Two observers judged good agreement between mrTRG(ICC 0.83 95%CI,0.703-0.881)and ADC measurements(ICC 0.96 95%CI,0.989-0.996).There was a positive correlation between mrTRG and pCR([rs]0.505;p<0.01),and a negative correlation between ADC value and pCR([rs]-0.693;p<0.01).The mrTRG grade of the pCR group was significantly lower than that of the non-pCR group(p<0.01),and the ADC value was significantly higher than that of the non-pCR group(p<0.01).The area under the ROC curve of the mrTRG,ADC,and fitted model for predicting pCR were 0.832,0.906,and 0.908,the sensitivity was 61.3,83.9,and 83.9,and the specificities were 98.1,84.5,and 85.4,It shows that the fitted model is better than mrTRG in predicting pCR accuracy.In predicting pCR,there was no significant difference between the ADC and the mrTRG(p=0.057),there was no significant difference between the ADC and the combined model(p=0.812),and there was a significant difference between the mrTRG and the combined model(p=0.015).Conclusions:1.After adjuvant chemoradiotherapy for locally advanced rectal cancer,some patients can achieve pCR.2.mrTRG and ADC are potential non-invasive methods to evaluate the effect of concurrent radiotherapy on locally advanced rectal cancer.mrTRG is used to identify patients with poor treatment effect(pTRG2-4).The ADC is more effective in predicting pCR.3.Adding the ADC on the basis of mrTRG can better predict pCR,and has better accuracy than using mrTRG or ADC alone.