Clinical Study Of 3.0T MR High-resolution T₂WI And DWI For Preperative T Staging And Pathology Classification Of Rectal Cancer

Objective:To explore the value of the 3.0T magnetic resonance（MR）high-resolution T₂WI combined with diffusion weighted imaging（DWI）in preoperative T stage diagnosis of primary rectal cancer and apparent diffusion coefficient（ADC）value in the prediction of the degree of pathological differentiation of rectal cancer.Methods:1.Select 48 patients with rectal cancer who underwent surgical resection without neoadjuvant treatment who received initial MRI and diffusion-weighted imaging（DWI）for high-resolution T₂WI and DWI examinations;DWI sequence selects the region of interest（ROI）and measures the mean ADC value.Combine the specimen data obtained from surgery for comparative analysis（analysis includes: tumor pathological classification,tumor pathological degree,classification,tumor TNM staging）;2.Through statistical analysis,show the accuracy,sensitivity（Se）,specificity（Sp）,Positive predictive value（PPV）,negative predictive value（NPV）of diagnosis T staging by high-resolution T₂WI examination method,DWI examination method and high-resolution T₂WI combined DWI examination method.The Kappa test was used to test the consistency between the results of the three methods and the postoperative pathological T staging results.Using χ² test to compare the results of the three imaging methods,P <0.05 was considered statistically significant.The consistency of the measurement of tumor mean ADC value between two observers was evaluated usingICC test and Bland-Altman map.The Student t test（independent sample t test）was used to compare the difference in mean ADC value between mucinous adenocarcinoma and non-mucinous adenocarcinoma.The ANOVA test and the Student t test was used to compare the difference in mean ADC value between the groups of non-mucinous adenocarcinoma.P<0.05 was considered statistically significant.Result:1.A total of 48 cases of rectal cancer were analyzed.High-resolution T₂WI sequence examination results:T1,T2,T3 and T4 diagnostic accuracy was93.75%,81.25%,79.16%and 93.75%,kappa=0.572.DWI sequence examination results:T1,T2,T3 and T4 diagnostic accuracy was 89.58%,83.33%,77.08%and83.33%,kappa=0.481.High-resolution T₂WI combined DWI sequence examination results:T1,T2,T3 and T4 diagnostic accuracy was 93.75%,87.5%,87.5%and 93.75%;kappa=0.704,High-resolution T₂WI sequence examination results were not statistically significant with DWI sequence examination results（χ²=0.364,p=0.549）.The results of DWI sequence examination were statistically significant with the results of High-resolution T₂WI combined with DWI sequence examination（χ²=5.143,p=0.016）.The results of high resolution T₂WI sequence examination were not statistically significant with the results of High-resolution T₂WI combined with DWI sequence examination（χ²=2.250,p=0.125）.2.In the same DWI sequence,A significant interobserver difference was not observed in the mean ADC measurements,ICC=0.752,p <0.05.Among the 48 patients,5 cases of mucinous adenocarcinoma,43 cases of adenocarcinoma（including 7 cases of well-differentiated,33 cases of moderately differentiated,and 3 cases of poorly differentiated carcinoma）.The mean ADC value of mucinous adenocarcinoma was（1.068±0.186）×10^-3mm²/s,which was higher than that of non-mucinous adenocarcinoma,and the mean ADC value of non-mucinous adenocarcinoma,was（0.848±0.123）×10^-3mm²/s.The difference between the two was statistically significant（t=-3.486,p=0.001）,As a threshold To diagnose mucinous adenocarcinoma,the mean ADC value was ≥0.98510×10^-3mm²/s,the sensitivity,specificity and ROC curve were90.7%,p=0.011,80% and 0.851.Among the non-mucinous adenocarcinoma,the ADC value of well-differentiated adenocarcinoma is（0.927±0.082）×10^-3mm²/s,that of moderately differentiated adenocarcinoma is（0.843±0.123）×10^-3mm²/s,and that of poorly differentiated adenocarcinoma is（0.723±0.036）× 10^-3mm²/s,the difference is statistically significant（F=3.295,p=0.047）.The results of well-differentiated adenocarcinoma were not statistically significant with the results of moderately differentiated adenocarcinoma,（t=-1.680,p=0.101）,The results of well-differentiated adenocarcinoma were statistically significant with the results of poorly differentiated adenocarcinoma,（t=3.677,p=0.006）,The results of moderately differentiated adenocarcinoma were not statistically significant with the results of poorly differentiated adenocarcinoma,（t=1.626,p=0.113）.Conclusion: 3.0T MR high-resolution T₂WI combined with DWI sequence examination has a strong clinical value in evaluating preoperative T staging of primary rectal cancer;the DWI sequence is an effective supplementary sequence.The mean ADC value of DWI sequence has strong correlation with histological type and pathological differentiation of rectal cancer and has certain clinical predictive value.