The Value Of DCE-MRI And DWI In Evaluating The Efficacy Of Microwave Ablation For Liver Malignant Tumors

PartⅠFeasibility Study of Obtaining Mean ADC Values of Liver Malignant Tumors after Microwave Ablation by Measuring ROI Values of PACS Objective:To investigate the feasibility of measuring ROI values by PACS after microwave ablation(MWA)for liver malignant tumors to obtain the mean ADC values of lesions.Methods:30 patients with liver malignant tumors who underwent DWI examination in our hospital between August 2020 and December 2020 were selected for review after MWA,including 48 lesions,and all patients had good image quality.The mean ADC values of the lesions were measured on GE3.0T MRI Advantage Workstation(the same lesion was measured for 3 times and the mean values was obtained).Then,the mean ROI values of lesions on the same ROI were measured from PACS(the same lesion was measured for 3 times and the mean value was obtained).Linear correlation analysis was carried out for the mean ADC values and mean ROI values of the same ROI,and the regression equation was preliminary established.Results:The mean ADC values measured on GE3.0T MRI Advantage Workstation were normally distributed,the mean ROI values and ADC values of the same ROI were positively correlated(r=0.975,P<0.05).The linear regression equation was preliminary established as:Y = 0.0009 X + 0.122.Conclusion:There was a significant correlation between the ADC values measured by MR Advantage Workstation and the ROI values measured by the ADC map in PACS of liver malignant tumors after MWA.It was feasible to obtain the mean ADC values of liver malignant tumors after MWA simply by measuring ROI values of PACS.Part Ⅱ The Value of MRI Examination in Evaluating the Curative Effect of Microwave Ablation for Liver Malignant TumorsObjective:To explore the evaluation value of DCE-MRI and DWI in the efficacy of MWA surgery for liver malignant tumors.Methods:A retrospective analysis was performed on 64 patients with liver malignant tumors who underwent DCE-MRI and DWI examination after MWA in our hospital from August 2018 to December 2020,including 99 lesions.According to the clinical diagnosis of the existence of active tumor tissue in the liver,they were divided into active tumor tissue group and inactive tumor tissue group.The ADC values of each group were counted respectively.The imaging evaluation results were compared with the clinical diagnosis results,and the diagnostic efficacy of the three methods of DWI alone diagnosis,DCE-MRI alone diagnosis,and DWI and DCE-MRI combined diagnosis were analyzed.Two-sample t-test was used to analyze the differences of the mean ADC value of the two groups.The ROC curve was used to obtain the cut-off point of ADC values.Chi-square test and Fisher’s exact probabilities test were used to evaluate the diagnostic efficacy of the three methods.Results:The mean ADC values between active and inactive tumor tissue groups were 0.99×10-3mm2/S and 1.53×10-3mm2/S,the difference was statistically significant(t=6.653,P<0.05).The ROC curve of ADC value for predicting liver active tumor tissue after MWA showed that the AUC was 0.89;When the cut-off value was 1.25×10-3mm2/S,the sensitivity and specificity were 89.5% and81.2%.A total of 99 lesions were analyzed,and 27 active lesions were diagnosed by DWI scan,10 of which were inconsistent with clinical diagnosis;72 inactive lesions were diagnosed,2 of which were inconsistent with clinical diagnosis.17 active lesions were diagnosed by DCE-MRI scan,2 of which were inconsistent with clinical diagnosis;82 inactive lesions were diagnosed,4 of which were inconsistent with clinical diagnosis.19 active lesions were diagnosed by DWI combined with DCE-MRI scan,1 of which was inconsistent with clinical diagnosis;80 inactive lesions were diagnosed,1 of which was inconsistent with clinical diagnosis.Chi-square test and Fisher’s exact probabilities test showed that there was no statistically significant difference in the sensitivity of the three test methods.The diagnostic accuracy of DCE-MRI combined with DWI was higher than DWI diagnosis,and the difference was statistically significant(χ~2=7.686,P=0.006 < 0.05),the pairwise comparison of the remaining accuracy showed no statistically significant difference.The specificity of DCE-MRI alone diagnosis and DWI combined with DCE-MRI diagnosis were higher than that of DWI diagnosis,and the difference was statistically significant(χ~2=5.766,P=0.016 < 0.05;χ~2=7.907,P=0.005 < 0.05);The specificity of DCE-MRI alone and DWI combined with DCE-MRI had no statistical significance。Conclusion:The mean value of ADC in the group with active tumor in the liver after MWA was significantly lower than that in the group without active tumor.The values of ADC were high effective in predicting the presence of active tumor lesions in the liver after MWA.DCE-MRI combined with DWI examination has a high accuracy in the evaluation of postoperative efficacy of liver malignant tumors MWA,which can be used as a routine imaging examination method for postoperative follow-up of liver malignant tumors with MWA.