Early Diagnosis And Quantitative Evaluation Of DWI In The Lesions After Radiofrequency Ablation Of Hepatic Carcinoma

Objective: To evaluate the clinic value of DW-MRI in the early diagnosis of residual lesions or new lesions and the quantitative evaluation of DWI for the lesions after RFA of hepatic carcinoma.Materials and methods: The data of DW-MRI of 31 patients with hepatic carcinoma before and after RFA and of 20 normal persons were analyzed. The lesions after RFA in the DWI and the change of signal of ROI were analyzed in the DWI and ADC imaging, and ADC values of lesions were measured before RFA and different organizations after RFA. The limiting value of ADC was obtained with pathology or DSA images in control.Results: The sensitivity, specificity, PPV and NPV of CT images in 28 cases and enhanced MRI in 31 cases before RFA were analyed, which showed the highest sensitivity (100%) of contrast-enhanced MRI(CE-MRI)combined with DWI. Results showed that the signal of lesions was more accurate when b value was 600 and 800s/mm~2 in DWI. Thirty one patients with 38 lesions before and after RFA were analyzed in the routine MRI, CE-MRI and DWI, and ADC values of image were measured. ADC values of lesions were acquired by using of overall level measurement and high and low signal area measurement, the differences of ADC values between lesions and normal liver in the ADC imaging with b value 800 s/mm~2 were significant (P< 0.05). Differences of ADC values between lesions and liver tissue around lesions, the lesions and inflammation tissue, the lesions before RFA and after's, were significant in the ADC imaging with b value 600 and 800 s/mm~2 (P<0.05), where the differences of ADC values were no statistically significant in the ADC imaging with b value 400 s/mm~2 (P>0.05). Differences of ADC values between lesions and coagulation necrotic tissue, lesions and liquefaction necrosis after RFA were significant in the ADC imaging with b value 400, 600 and 800 s/mm~2 (P<0.05).Conclusion: DWI displays a higher sensitivity for tumor detection. And the detection capacity could be even improved by combination of DWI and MRI. ADC value measured is near to the true DC value in the ADC imaging when b value was 800 s/mm~2, if the lesion showed a clear boundary. DWI combined with ADC imaging could show signal differences between tumors and other tissues, such as normal liver parenchyma, inflammatory tissue, and necrotic tissue. A various of pathological types have a relatively specific range of ADC values, which could be as the quantitative evaluation for the RFA efficacy.