Using 3D Amide Proton Transfer MR Imaging To Assess Different Pathological Prognostic Factors Of Rectal Adenocarcinoma

ObjectiveTo investigate the feasibility of three-dimensional amide proton transfer weighted magnetic resonance imaging(3D-APTw-MRI)in assessing WHO grading,tumor stage(pT),lymph node metastasis(pN)stage,p53 and Ki-67 expression of rectal adenocarcinoma,in comparison with conventional diffusion-weighted imaging(DWI).Materials and MethodsThe magnetic resonance imaging(MRI)data and postoperative pathological data of patients with rectal adenocarcinoma were enrolled to analyze their invasiveness in this retrospectively study,Where our hospital from January 2019 to September 2020.MR scan were performed by Philips 3.0T MRI scanner.The Sequences included conventional T1WI,high-resolution T2WI,DWI,enhanced T1WI and 3D-APTw.Mean APT signal intensity(APT SI)and mean apparent diffusion coefficient(ADC)values of tumors were calculated on 3D-APTw and DWI maps,respectively.The inter-group correlation coefficient was used to evaluate the consistency of the APT value and ADC value measured by two observers.Pathological analysis included WHO grades,pT stages,pN stages,and p53 label index and Ki-67 label index.SPSS 20.0 and MedCalc software were used to analyze the pathological indexes,mean APT SI value and mean ADC value,including the differences of mean APT SI value and mean ADC value in rectal adenocarcinoma with different WHO grades,pTstages,pN stages,p53 protein and Ki-67 label index.Statistical test included Student’s t-test,One-way analysis of variance(ANOVA),rank sum test,Chi-square test,Spearman’s correlation coeffificient and receiver operating characteristic(ROC)curve analysis.ResultsClinical and MRI data of 87 patients were collected in this study.According to the inclusion and exclusion criteria,43 patients were finally enrolled(average age:61 years,range:34-85 years),including 12 females and 31 males.According to the WHO grading criteria,28 patienrs were diagnosed as low-grade rectal adenocarcinomas(G1=6,G2=22),15 patienrs were diagnosed as high-grade rectal adenocarcinomas(G3 tumors).According to the analysis of histopathological specimens and pathologic TNM staging of colorectal carcinoma(AJCC 8th edition),10 tumors did not extend beyond the rectal muscularis propria(pT2),20 tumors invaded through the muscularis propria into the pericolorectal tissues(pT3),9 tumors invaded through the visceral peritoneum(pT4a),and 4 tumors invaded other adjacent organs or stuctures(pT4b);No regional lymph node metastasis was found in 23 patients(pN0),whereas 11 patients had metastasis in fewer than three lymph nodes(pN1),and 9 patients had metastasis in four or more regional lymph nodes(pN2).High-grade tumors,more advanced stage tumors,tumors with lymph node involvement showed significantly higher mean APT SI values.Mean ADC differences were found in tumors with different pT stage,but not in tumors with different histologic grade.Tumor with p53 positive status had higher mean APT SI than tumor with negative p53 status.There was no difference in mean ADC with p53 status.Mean APT SI and mean ADC were signifificantly different in tumors with low and high Ki-67 status.Mean APT SI exhibited a positive correlation with p53 label index and Ki-67 label index.Mean ADC showed no correlation with p53 label index,but a negative correlation with Ki-67 label index.ROC curves demonstrated that mean APT SI had signifificantly higher diagnostic ability for differentiation of high Ki-67 expression of rectal adenocarcinoma than mean ADC,while no difference was found in predicting p53 status.ConclusionMean APT SI was related to WHO grade,tumor stage(pT),lymph node metastasis stage(pN),p5 3 and Ki-67 expression levels in rectal adenocarcinoma,compared with DWI imaging,3D-APTw imaging was more effective in evaluating the invasive biological characteristics of rectal adenocarcinoma.Therefore,3D-APTw imaging may serve as a non-invasive imaging indicators for assessing genetic prognostic factors of rectal adenocarcinoma.