| BackgroundMRI is the most commonly used for staging of rectal cancer in current clinical practice based on T2WI(T2-Weighted Imaging)and DWI(Diffusion Weighted Imaging).T2 WI is recommended as the first line for the staging of rectal cancer,because T2 WI has relatively high soft tissue contrast,which in turn helps the accurate evaluation of tumor aggeressiveness and differentiate the relationship between tumor and the rectal mesenteric fascia and sphincter.However,it is difficult for radiologist to stage most of patients with rectal cancer depending on solely parameter of MRI.DWI and its quantitative parameter of ADC(Apparent Diffusion Coefficient),which indicates the speed of movement of water molecules diffusion in the tissue,can show the diffusion information of tumor and adjacent tissue microenvironment,and indirectly reflect the tissue structure and function.Therefore,the value of ADC can be used for the differentiate diagnosis of different lesions.With the development of MRI technology,the application of T2 WI and dynamic enhancement can provide excellent resolution and accuracy in the staging of rectal cancer,which is now widely used in the preoperative diagnosis of rectal cancer.Compared with using T2 or DWI alone for T/N staging of rectal cancer,T2 WI combined with DWI and dynamic enhancement can provide more structural and physiological information.By comparing T2 WI,DWI,and dynamic contrast enhanced(DCE)imaging with T2 WI + DWI and T2WI+ DCE,this study aimed to obtain a more accurate assessment method for rectal cancer staging.ObjectiveTo investigate and compare the diagnostic value of the following sequences including T2 WI,DWI,DCE,T2 WI combined with DWI,T2 WI conbined with DCE.MethodsThe study was approved by the institution ethics committee and an informed consent form was abtained for each patient.Between January 2019 and June 2020,in total of one hundred and fifty-five patients with surgically pathology confirmed as rectal adenocarcinoma in Henan Cancer Hospital were finally enrolled in this study.There are 72 females and 83 males,mean age of 52.6 ± 10.8 years.All of whom underwent rectal MRI on the same 3.0 MRI and had surgical pathology results.Patients underwent MR T2 WI,DWI and multi-phase enhancement sequences of pelvic scans within two weeks prior to the procedure.The depth of tumour infiltration(T-stage)and local lymph node metastasis(N-stage)were determined based on the MRI findings and compared with the postoperative pathological findings.Statistical analysis were performed using SPSS(21.0)software.Agreement between MRI diagnosis for T and N staging and pathologic T and N staging was evaluated by Kappa test,Kappa value of 0-0.4 is defiend as poor consisitency,0.4-0.6 as moderate consisitency,0.6-0.8 as good consisitency and 0.8 or more as perfect.ROC curves were plotted for different sequences of T-stage.Compare the accuracy,sensitivity,specificity and AUC values of different sequences and different stages.ResultsIn total of 155 rectal cancer patients were enrolled,of whom 62 were diagnosed by postoperative pathology as in T1-2 stage,77 in T3,and 16 in T4.Five sequences including T2 WI,DWI,DCE,T2WI+DWI and T2WI+DCE were used for evalation.(1)In terms of the comparing between above sequences in preoperative T staging,the Kappa value of consisitency test between MRI diagnoses and pathological results was as follows: 0.680 for T2WI;0.553 for DWI;0.562 for DCE;0.658 for T2WI+DWI;0.553 for T2WI+DCE,T2 WI and T2WI+DWI showed better agreement between pathological diagnosis than the other sequences.(2)In term of the accuracy,sensitivity and specificity of T2 WI,DWI,DCE,T2WI+DWI,T2WI+DCE for the T staging is as follow:(1)the accuracy of T2 WI in differentaiting T1-2,T3 and T4 stages was 80.9%,81.3% and 98.6% respectively,the overall diagnostic accuracy was 81.2%.(2)The accuracy of DWI in diagnosing T1-2,T3 and T4 stages was 79.3%,74.9% and 77.8% respectively,the overall diagnostic accuracy was 74.8%.(3)The accuracy of T2 WI + DWI in assessing T1-2,T3 and T4 stages was80.1%,80.1% and 98.2%,respectively,the overall diagnostic accuracy was 80%.(4)The accuracy of T2 WI + DCE in evaluating T1-2,T3 and T4 stages was 79.0%,78.8% and98.2%,respectively,the overall diagnostic accuracy was 78.7%.The diagnostic sensitivitities of T2 WI for T3 and T4 were 89.6% and 100%.The sensitivity of T2 WI combined with DWI or multi-stage enhancement to assess T3 and T4 stages of rectal cancer was 88.3% and 100%,with no significant improvement(P > 0.05).The specificity of all sequences for assessing T3 stage of rectal cancer was low,ranging from 64.5% to73.1%,the specificity of the rest T1-2 and T4 were all higher than 86%,there is no statistical differences(P > 0.05).(3)ROC analyses: the sequence with the highest AUC value for assessing pathological T1-2 staging was T2 WI with an AUC value of 0.809,and the diagnostic accuracy was 80.9%,DWI yielded the highest sensitivety,whereas T2 WI and T2WI+DWI yielded better specificity.The sequence with the highest AUC value for assessing pathological T3 staging was T2 WI with an AUC value of 0.813.The sequence with the highest AUC value for the assessment of pathological T4 stage was T2 WI with an AUC value of 0.986.(4)In terms of N staging,the total accuracy of T2 WI was 75.5% with kappa=0.664,the total accuracy of DWI was 77.4% with kappa=0.673,the total accuracy of multi-stage enhancement was 74.2% with kappa=0.648,the total accuracy of T2WI+DWI was 77.4% with kappa=0.675 and the total accuracy of T2WI+multi-stage enhancement was 78.5%,kappa=0.681.T2WI+DCE showed realative good efficacy for N staging.(5)Three sequences of T2 WI,T2WI+DWI DCE were used to assess the involvement of rectal mesenteric fascia with surgical results as the gold standard.the overall accuracy of T2 WI in determining the involvement of rectal mesenteric fascia was74.2% with kappa=0.588;the overall accuracy of T2WI+DWI was 78.1% with kappa=0.598;and the overall accuracy of T2WI+multi-stage enhancement was 80.0% with kappa=0.608.The results showed that T2 WI combined with multi-stage enhancement was more accurate in determining the involvement of rectal mesenteric fascia in rectal cancer patients before surgery.Conclusions We investigated the diagnostic efficacy of five sequences including T2 WI,DWI,DCE,T2WI+DWI and T2WI+ DCE in the application of MRI in the preoperative staging of rectal cancer,and the results showed that T2 WI was more consistent than other sequences in T staging,with an overall accuracy rate of 81.2%,which was higher than other sequence combinations.By comparing the ROC curves of each sequence combination for T-staging,the largest AUC for each stage was T2 WI,p<0.001,again demonstrating the importance of T2 WI in T-staging;T2WI+multiphasic enhancement in N-staging had an overall accuracy of 78.1%,kappa=0.681,with better agreement than other sequences;T2WI+multiphasic enhancement in assessing tethered fascial involvement The overall accuracy was 80.0%,with kappa=0.608,which was more consistent and better than the other sequences.This demonstrates the accuracy of MRI in the staging of rectal cancer and the value of combining multiple sequences over T2 WI alone,which can help in the formulation of comprehensive clinical treatment plans. |
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