Quantitative Analysis Of Dynamic Contrast-enhanced MRI:Use In Preoperative Diagnosis Of Rectal Cancer And Predicting Response Assessment After Neoadjuvant Chemoradiation In Locally Advanced Rectal Cancer

Part one.Applications of quantitative dynamic contrast-enhanced magnetic resonance imaging in the preoperative diagnosis of rectal cancerObjective :To investigate the Correlation of Dynamic Contrast-Enhanced MRI quantitative parameters with clinicopathological features in rectal cancer.Methods :49 patients with surgery pathologically proven rectal cancer examined with DCE-MRI were retrospectively analyzed,and obtain the perfusion parameters of the area of interest using the Tofs model,such as transfer constant(Ktrans),rate constant of back flux(Kep),extravascular extracellular volume fraction(Ve).The mean values of tumor and normal rectal wall,mucinous and nonmucinous carcinoma,T1-2 group and T3-4group,case with or without lymph node metastasis were compared using the paired t test.The cut-off values of quantitative parameters to distinguish T1-2 group and T3-4 group were analyzed by ROC curve.Results :In 49 cases,there were 41 cases of mucinous adenocarcinoma(including tubular adenocarcinoma and papillary carcinoma),and 8 cases of mucinous adenocarcinoma.There were 6 cases in T1 stage,10 cases in T2 stage,26 cases in T3 stage and 7 cases of T4 stage.There were 27 cases of N0 stage,11 cases of N1 stage and 11 cases of N2 stage.There were 45 case of M0 stage and 4 case of M1 stage.The values of Ktrans?Kep ? Ve for normal rectal wall were(0.054±0.021)/min ?(0.401±0.148)/min ?0.153±0.078,respectively.And the tumor group they were(0.316±0.141)/min ?(0.783±0.395)/min?(0.468±0.174),respectively.The differences of Ktrans,Kep and Ve between tumor and normal rectal wall were satistically significant(t =-12.905,-6.334,-11.531,all P < 0.01).The values of Ktrans?Kep ?Ve for T1-2 group were(0.208±0.688)/min ?(0.660±0.350)/min ? 0.384±0.186,respectively,for T3-4 group they were(0.369±0.136)/min?(0.843±0.406)/min?0.508±0.155,respectively.There were significant differrence of Ktrans and Ve between T1-2 group and T3-4 group(t=-5.503?-2.468,all P values < 0.05),Kep showed no statistical differences between the two groups.In T-staging,there was high sensitivity and specificity by using a cutoff value of 0.245/min in Ktrans.There was no significant difference between mucinous and nonmucinous colorectal cancer.No significant difference was found between lymphatic involvement group and without lymphatic involvement group for DCE-MRI perfusion parameters,neither was the case with or without distant metastasis.Conclusion :DCE-MRI quantitative analysis of perfusion parameters Ktrans and Ve has certain application value in T staging of rectal cancer,especially the Ktrans value,helping to distinguish between T1-2 group and T3-4 group of rectal cancer.Part two.Dynamic Contrast Enhanced MRI for the prediction of treatment response After Neoadjuvant Chemoradiation in locally advanced rectal cancerObjective:To investigate the value of dynamic contrast enhanced magnetic resonance imaging(DCE-MRI)for locally advanced rectal cancer pathological response prediction.Methods:The patients with rectal cancer with neoadjuvant chemoradiotherapy were collected from our hospital,and the surgical pathology after neoadjuvant chemoradiotherapy was confirmed as rectal cancer.The DCE-MRI perfusion parameters was obtained before CRT and surgery,including transfer constant(Ktrans),the rate constant(Kep),the volume fraction of extracellular space outside blood-vessel(Ve).The patients were divided into pathologic complete response(pCR)group and non-pCR group according to operative pathological results.The t test wse used to compare differences between the pCR and the non-pCR group before and after treatment.,and Mann-whitney U test was used to compare the differences between the two groups 'values changing before and after treatment.Results : In 37 patients,13 people obtain pathologic complete response and 24 patients with non-pCR.The final study Before neoadjuvant chemoradiation,the values of Ktrans? Kep ? Ve for pCR group were 0.443±0.063/min ? 0.959±0.387/min ?0.525±0.154,respectively,for non-CR group they were((0.261±0.050)/min ?(0.671±0.323)/min?0.592±0.447,respectively.The values of Ktrans and Kep between the two groups were stastically significant(t =9.570?2.404,respectively,all P<0.05).After neoadjuvant chemoradiation,the values of Ktrans,Kep and Ve for pCR group were(0.113±0.017)/min?(0.240±0.090)/min?0.491±0.165,respectively,for non-CR group,they were(0.193±0.044)/min?(0.559±0.233)/min?0.409±0.172,respectively.The values of Ktrans and Kep between the two groups were stastically significant(t =-5.992?-4.550,respectively,all P<0.05).The changes of all perfusion parameters before and after neoadjuvant chemoradiation in pCR groups were 0.337(0.230-0.417)/min ? 0.592(0.391-1.591)/min?-0.076(-0.261-0.472),respectively.for non-CR group,they were 0.048(-0.057-0.167)/min?0.115(-0.557-1.207)/min?0.089(-0.238-2.038).Ktrans and Kep showed significant difference between those two groups(Z values were-4.146?-4.901,respectively,all P <0.001).No significant difference was found between two group for Ve valueConclusions :DCE-MRI quantitative parameters Ktrans and Kep may help distinguish preoperatively locally advanced rectal cancer after neoadjuvant chemoradiation pCR and non-pCR group.