Predictive Value Of MRI In The Complete Response After Preoperative Nneoadjuvant Chemoradiation For Advanced Rectal Cancer

Objective:To investigate the volume reduction rate,diffusion weighted imaging?DWI?and dynamic contrast-enhanced magnetic resonance imaging?DCE-MRI?predicting local advanced rectal cancer?locally advanced rectal cancer,LARC?The value of complete remission after preoperative neoadjuvant chemoradiation therapy?CRT?.Materials and Methods:Retrospective analysis of total mesorectal excision?TME?4 to 8 weeks after CRT in our hospital from January 2015 to December2017 was performed.54 patients with LARC who were pathologically confirmed were collected.Our hospital Siemens Magnetom Verio3.0T magnetic resonance imaging technology to evaluate the efficacy of preoperative CRT for rectal cancer.Of the 54 patients,37 were males and 17 were females,aged 31 to72 years,with a median age of 53 years.All patients underwent rectal MRI within 1 week before CRT?before CRT?and 1 week before TME?before TME?.Axis high resolution T2-weighted and DWI images are passed to the ziostion workstation.The DWI and DCE-MRI images were transferred to a Siemens3.0T workstation and special software was used for post-processing and recording of the values of various parameters.After surgery,the pathologic tumor stage was determined according to the TNM classification system recommended by the International Union against Cancer and the AJCC,7th ed.^[1]All histopathologic cases were evaluated by a gastrointestinal pathologist with 8years of experience.The tumor length after CRT was defined by the largest tumor length at pathological specimen examination.pCR was defined as the absence of viable adenocarcinoma cells in the surgical specimen?ypT0N0,the"yp"prefix indicates final staging after CRT[y]and postoperative pathologic examination[p]?.In the present study we classified the patients into pCR and non-pCR groups.The t-test was used to compare the differences in parameters(Volume,ADC,and K^trans)between the pCR group and the non-pCR group and before and after treatment.The Mann-Whitney test was used to compare the rate of change of tumor parameters after CRT in the pCR and non-p CR groups.Using the receiver characteristic curve?ROC?to evaluate the rate of change of each parameter after treatment to identify the efficacy of pCR and non-pCR?the U-test was used for the comparison of diagnostic efficacy?,and the diagnostic threshold was determined.The combined sensitivity of the combined test and the pairwise test[=method A sensitivity+?1-method A sensitivity?×method B sensitivity]and joint specificity?=method A specific×method B specific?.P<0.05 was considered statistically significant.Results:Of the 54 patients,17 were in the p CR group and 37 in the non-pCR group.After CRT,the tumor volume in patients with rectal cancer was reduced and the ADC value of tumors showed a tendency to increase?Table 1?.In the pCR group,the volume reduction ratio,tumor ADC,and K^transchange rate after CRT were higher than those in the non-pCR group?P<0.05?.Although K^trans%was statistically significant in the pCR and non-p CR groups,its sensitivity and specificity were low?Table 2?.The pre-and post-treatment volume,ADC values,and K^transvalues in this study were not statistically different between patients with pCR and non-pCR?Table 2?.The correlation test showed a weak correlationbetween?volumeand?ADC?Pearson'scorrelation coefficient=0.669,p<0.001?,and there was no correlation among other variables.ROC analysis showed that?ADC was the best diagnostic method for good pathological response in both response analyses.After the CRT,the tumor volume reduction rate and the best cut-off value of?ADC were 73.11%and0.64×10-3,respectively.The area under the ROC curve of pCR after CRT prediction was 0.970 and 0.971 for p CR.The sensitivity,specificity,positive predictive value?PPv?,and negative predictive value?NPv?used to predict pCR were 88%,98%,89%,100%,and 88%,52%,88%,and 94%,respectively?Table3?.After CRT,tumor?volume%and?ADC showed no significant difference in the diagnostic efficacy of pCR?Z=-1.000,P=0.317?.The combination of the two tests,the combined sensitivity of 93.1%,combined specificity of 59.5%.Conclusion:The tumor?volume%and?ADC have higher diagnostic efficacy in predicting the curative effect of rectal cancer after CRT.Predicting pCR has certain value.The combination of the two did not improve the sensitivity and specificity of the diagnosis of pCR.