Feasibility Study The Residue Of Rabbit Liver VX2 Model Under RFA By IVIM-DWI

Objective: This study was to investigate the feasibility and value of diffusion-weighted in-vivo non-coherent motion(IVIM-DWI)parameters in assessing residual VX2 in rabbit liver.Methods: This study was approved by Medical Ethics Committee and Animal Management Committee of Shengjing Hospital,China Medical University.Twenty-nine VX2 tumor-bearing rabbits were selected.When before radiofrequency and one week after operation,have taken the routine hepatic scan and IVIM-DWI examination,in which IVIM selected b: 0,10,20,30,40,50,75,100,150,300,500,800,1000 and 1200seconds/mm2;then according to combined with the MRI images and postoperative pathology(one week after operation),the appropriate regions of interest(ROIs)were selected.With same related softwares,the lesions were divided into two regions :Ablation(before and after treatment,Ab and Aa),Residual(before andafter treatment,Rb and Ra),would obtain true diffusion coefficient(D),pseudodiffusion coefficient(D*)and tissue perfusion score(f).Simultaneously the variables were calculated(after-before,D,D*,f).The Paired Test was used to analyze the statistical significance of the parameters in each group.The area under the ROC curve(AUC)was used to evaluate the diagnostic value of each variables.Result: The f and D* decreased in radiofrequency ablation after RFA(P<0.05),meanwhile the D increased(P<0.05);the f of residual tumor area increased significantly compared with before(P<0.05).But the changes of D* and D were not statistically significant(P>0.05).By plotting the ROC curve of the variables,the f curve was closer to the upper left corner and had better evaluation of residuals(AUC: 0.807;P <0.01;95% CI: 0.693-0.921).Conclusion: The parameters f,D and D* obtained by IVIM-DWI can both show the necrosis changes of radiofrequency ablation in VX2 tumor with a certain extent.The measurement of variables in f can also effectively evaluate the potential of residual tumor after RFA.This study further enhances the confidence of DWI in the clinical evaluation of the efficacy of radiofrequency ablation of liver tumors.