The Value Of Multimodal MRI In Preoperative Diagnosis Of Rectal Cancer

Objective:The study investigated the preoperative staging and the diagnostic value of grading of rectal cancer by using high-resolution magnetic resonance imaging?HR-MRI?,dynamic contrast-enhanced magnetic resonance imaging?DCE-MRI?,and diffusion-weighted imaging?DWI?magnetic resonance scanning techniques,thus guiding the selection of clinical treatment options for rectal cancer and predicting the prognosis of patients with rectal cancer.Methods:Sixty patients who underwent colorectal cancer with colorectal biopsy from November 2017 to December 2018 in the Department of Gastrointestinal Surgery,Yijishan Hospital,Wuhu City,Anhui Province were selected.No treatment was given before.HR-MRI,DWI and DCE-MRI scans were performed using GE's 3.0T MR scanner before surgery to pre-stage and grade the tumor.Taking postoperative pathological results as the gold standard,60 patients were divided into 3 groups according to the 8th edition staging system released by the International Union Against Cancer in 2016.Among them,there were 20 patients in the?T2 phase,35 patients in the T3 phase,and 5 patients in the T4 phase.According to the degree of differentiation,60 patients with rectal cancer were divided into 5 groups,5 patients in the poorly differentiated group,10 patients in the middle-lower differentiated group,33 patients in the moderately differentiated group,and 8 in the moderate-differentiated group.Patients,4 patients in the highly differentiated group.According to whether 60 patients had lymph node metastasis,they were divided into two groups:25 patients with lymph node metastasis and 35 patients without lymph node metastasis.MRI images of all patients were evaluated by two senior MRI diagnosticians A and B.All patients'DWI and DCE-MRI images were post-processed using relevant software to obtain DCE-MRI quantitative parameter values including volume transfer constants.(K^trans),rate constant(K_ep),extracellular extravascular space volume ratio?V_e?,and ADC value.All measurement data were expressed as“mean±standard deviation”.All grouped data were in normal distribution.The accuracy,sensitivity and specificity of high-resolution MRI combined with dynamic contrast-enhanced MRI for preoperative T staging of rectal cancer were calculated.Sex,positive predictive value?PPV?,negative predictive value?NPV?,Kappa test was used to compare the consistency of preoperative image staging with postoperative pathological examination.By using one-way analysis of variance to compare the differences between the quantitative parameter values of patients with rectal cancer with different pathological T stages and different degrees of differentiation,the independent sample t test was used to compare the rectum with lymph node metastasis and no lymph node metastasis.The difference in quantitative parameter values between cancer patients,when P<0.05,the difference was considered statistically significant.Results:1,60 patients with rectal cancer who underwent MRI scans had a correct staging of 51 patients,9 of whom had a staging error.HR-MRI combined with DCE-MRI was consistent with the preoperative image T staging and postoperative pathological T staging results in patients with rectal cancer,including?T2 phase:Kappa=0.769,P<0.05,accuracy=90.00%,sensitive Sex=88.89%,specificity=90.47%,positive predictive value?PPV?=80.00%,negative predictive value?NPV?=95.00%;T3:Kappa=0.690,P<0.05,accuracy=85.00%,sensitivity=86.11%,specificity=83.33%,PPV=89.00%,NPV=80.00%;T4:Kappa=0.700,P<0.05,accuracy=95.00%,sensitivity=66.67%,specificity=98.15%,PPV=80.00%,NPV=96.00%.2,60 patients with rectal cancer who underwent multiple b-value DWI scans were divided into 5 groups according to their different degrees of differentiation:5 patients in the poorly differentiated group,10 patients in the moderate-lower differentiated group,and 33 in the moderately differentiated group.For example,there were 8 patients in the moderate-to-highly differentiated group and 4 patients in the highly differentiated group.The ADC values of rectal cancer with different pathological differentiation were:1,b value was 700 s/mm²,ADC value of low-differentiation group was 0.754±0.131x10^-3mm²/s,and ADC value of medium-low-differentiation group was 0.854±0.068 x10.^-3mm²/s,the ADC value of the moderately differentiated group was 0.889±0.076x10^-3mm²/s,the ADC value of the medium-high differentiation group was 0.983±0.093x10^-3mm²/s,and the ADC value of the highly differentiated group was 1.073±0.131 x10.^-3mm²/s,homogeneity of variance,F value is 12.619,p value<0.05,the difference is statistically significant;2,b value is 1000 s/mm2 group,ADC value of low-differentiation group is 0.637±0.054 x10^-3mm²/s The ADC value of the medium-low-differentiation group was 0.840±0.056 x10^-3mm²/s,the ADC value of the medium-differentiation group was 0.885±0.057 x10^-3mm²/s,and the ADC value of the medium-high differentiation group was 0.950±0.081 x10^-3mm²./s,the ADC value of the highly differentiated group was 1.029±0.132 x10^-3mm²/s,the variance was homogeneous,the F value was 24.900,the p value was<0.05,the difference was statistically significant;3,b value was 1500 s/mm² group,low The ADC value of the differentiation group was 0.339±0.086 x10^-3mm²/s,the ADC value of the medium-lower differentiation group was 0.714±0.117×10^-3mm²/s,and the ADC value of the moderately differentiated group was 0.718±0.062 x10^-3mm²/s.-The ADC value of the highly differentiated group is 0.853±0.091 x10^-3mm²/s,the ADC value of the highly differentiated group was 0.855±0.060 x10^-3mm²/s,the variance was homogeneous,the F value was 37.986,and the p value was<0.05.The difference was statistically significant.3,60 patients with rectal cancer who underwent DCE-MRI scan and obtained complete postoperative pathological results,including 20 patients with?pT2 phase,35 patients with pT3 phase,and 5 patients with pT4 phase.The dynamic contrast enhancement parameters of rectal cancer with different pathological T stages were:K^trans of 0.4?p68phase was 0.400±0.068 min^-1,K^trans of pT3 phase was 0.521±0.099 min^-1,and K^transrans of pT4 phase was 0.582±0.022.Min^-1,homogeneity of variance,F value is 15.801,p value<0.05,the difference is statistically significant;K_ep of 0.5?pT2 is 0.585±0.202min^-1,and K_ep of pT3 is 0.612±0.213 min^-1 The K_ep of pT4 phase was 1.498±0.321min^-1,the homogeneity of variance was 38.457,the p value was<0.05,the difference was statistically significant;the V_e of 3?pT2 phase was 0.275±0.273,and the V_e of pT3phase was 0.319±0.119,V_e of pT4 phase was 0.365±0.164,homodyne of variance,F value was 1.749,p value was equal to 0.183,the difference was not statistically significant.4,60 patients with rectal cancer were divided into 2 groups according to whether lymph node metastasis occurred,including 25 patients with lymph node metastasis and 35patients without lymph node metastasis.The dynamic contrast-enhanced quantitative parameter values for rectal cancer with lymph node metastasis and no lymph node metastasis were:1 The K^trans value of the lymph node metastasis group was 0.521±0.091min^-1,and the K^trans value of the lymph node metastasis group was not included.The mean variance was 0.463±0.105 min^-1,the t value was 2.240,p<0.05,and the difference was statistically significant.2 The Kep value of the lymph node metastasis group was0.802±0.429 min^-1,and the Kep of the lymph node metastasis group was not included.The value was 0.610±0.196 min^-1,the variance was homogeneous,the t value was 2.085,p<0.05,the difference was statistically significant;3 the lymph node metastasis group had a Ve value of 0.302±0.126,and the lymph node metastasis group had a Ve value of0.313±0.102,homodyne of variance,t value is-0.386,p value is equal to 0.701,the difference is not statistically significant.Conclusion:HR-MRI combined with DCE-MRI has important diagnostic value for preoperative T staging of rectal cancer,which helps to determine the depth of invasion of the tumor in the rectal wall and helps clinical preoperative evaluation.The ADC value has certain preoperative grade of rectal cancer.The predicted value of DCE-MRI quantitative parameters K^trans and K_ep have certain predictive value for preoperative T stage and lymph node metastasis of rectal cancer.In conclusion,the combined application of multiple MRI functional scanning techniques is of great significance for the preoperative staging and grading of rectal cancer.