Clinical Application Of Multi-parametric Mr In Re-evaluation Of Rectal Carcinoma After Neoadjuvant Chemoradiation

Part I Application of multi-parametric MRI in the evaluation of the response to chemoradiation and the optimal predictor Objective:The aim is to explore the value of diffusion-weighted magnetic resonance imaging and volume measurement based on DCE-MR images in evaluating the response to neoadjuvant therapy for local advanced rectal cancer and to analyze and compare different results in order to find the optimal predictor.Methods:A total of 92 patients with rectal cancer of T3 and T4 between 2015.9-2018.12 were collected.All patients underwent two MR examinations before neoadjuvant therapy and before surgery.The diffusion sequence included two sets of b-value combinations,b(0,800)and b(0,1000).On the MR images,the volume and ADC values before and after the neoadjuvant treatment were measured.The patients were divided into two groups according to the postoperative pathological tumor regression grading score.Patients with pathological tumor regression grade(1-2)were classified as good responder group,and patients with pathological tumor regression grade(3-5)were classified as poor responder group.Volume and ADC value related indicators were compared between the two groups.ADC value related indicators for b=800 and b=1000 were compared.Finally,the ROC curve was drawn to evaluate the diagnostic efficacy of each index for the evaluation of the response to neoadjuvant therapy.Result:A total of 92 patients with rectal cancer were included in the study.Among them,there were 37 patients in the good responder group(pTRG1-2)and 55 patients in the poor responder group(pTRG3-5).In the good responder group and the poor responder group,the ADC value measured at b=1000 was significantly higher than the ADC value measured at b=800.In the good responder group and the poor responder group,there was no statistically significant difference in percentage of ADC increase for b=800 and b=1000.The percentage of ADC increase(b=800)has the largest area under the curve,and area under the curve is 0.957,and the cut-off value is 29.10%.The area under the curve for percentage of ADC increase(b=1000)is 0.893,and the cut-off value is 28.67%.The area under the curve of the ?ADC value for b=800 and b=1000 was 0.879 and 0.866,respectively.The area under the TVRR curve is 0.726.Conclusion: Percentage of ADC increase,as optimal predictor unaffected by b values,is useful to screen out patients with good response to neoadjuvant chemoradiation.Part II Clinical application of DWI,DCE-MRI and T2 WI in the evaluation of the staging of rectal cancer after neoadjuvant chemoradiotherapy Objective:In Part II,the aim is to evaluated the accuracy of different MR sequences and combinations for T staging after neoadjuvant therapy,and provided more accurate perioperative information for the formulation of surgical procedures.Methods:There were 92 patients with T3 and T4 rectal cancer between 2015.9-2018.12.The enrolled patients underwent MR examination within 3 days prior to surgery.The T-stage of neoadjuvant chemotherapy for rectal cancer was performed with different MR sequences or sequence combinations and compared with pathological T stage.The accuracy of different MR sequences or sequence combinations for rectal cancer T staging was calculated,and the consistency was analyzed by Kappa test..The sensitivity,specificity,negative predictive value,and positive predictive value of different MR sequences or combination of sequences for evaluating rectal mesangial fascia invasion after neoadjuvant therapy were calculated.Result:A total of 92 patients with rectal cancer were included in the study,including 61 males and 31 females.The accuracy of high-resolution T2 WI for T-stage after neoadjuvant chemotherapy for rectal cancer was 50.0%,and the Kappa value was 0.252.The accuracy of high-resolution T2 WI combined with DWI for T-stage after neoadjuvant chemotherapy for rectal cancer was 58.7%,Kappa value was 0.303;the accuracy of DCE-MR image for T was 82.6%,Kappa value was 0.78;The sensitivity and specificity of HR-T2 WI combined with DCE-MR for the evaluation of rectal mesangial fascia were 81.8% and 96.3%,respectively.The sensitivity and specificity of HR-T2 WI combined with DWI were 63.6% and 72.8%,respectively.Sensitivity of HR-T2 WI Degree and specificity were 54.5% and 64.1%,respectively.Conclusion:DCE-MR has the highest accuracy of T-stage after N-CRT in rectal cancer,and has high consistency with pathological T stage.It is the best sequence combination of T stage after rectal cancer CRT.DCE-MRI combined with T2 WI to assess the sensitivity and specificity of rectal mesangial fascia invasion can provide accurate perioperative information for the development of surgical plans.