Transarterial Chemoembolization Of Hepatocellular Carcinoma: Can Early Diffusion Weighted Imaging Predict Response?

PURPOSE: We evaluated the role of early diffusion weighted imaging (DWI) in predicting response to TACE in patients with HCC and compare the results with contrast enhanced magnetic resonance imaging. Methods: 24 patients with documented HCC were taken up for TACE after a pre-procedural contrast CT and MRI. Post procedural DWI was taken on day 5-7 and the mean ADC values were documented and compared to pre procedural values. The change in ADC values was grouped into 4 categories: group 1- <25%, group 2 26-50%, group 3- 51-75% and group 4- >75%. The increase in ADC values signifying response was correlated with 5 week CEMRI scan (which has been the traditional gold standard for response evaluation) and a threshold ADC increase signifying response in majority of the cases was calculated. Results: The mean ADC of the lesions changed from 1.21× 10-3 (pre TACE) to 2.02× 10-3 mm2/sec (post TACE) [p<0.001]. Taking CE MRI as gold standard, DWI imaging had a sensitivity of 80%, specificity of 94.7% with a positive predictive value of 80%, negative predictive value of 94.7% and overall accuracy of 91.7%. Complete response was seen in19 (79%) and incomplete in 5 (21%) patients in our study. The change in ADC was significantly higher in responders (884.15 ± 161.60) as compared to non responders (564.80 ± 221.05) [p =0.001]. Conclusion: Early DWI after TACE can predict response of a HCC lesion to chemoembolization. The change in ADC values can earmark responders from non-responders. Early DWI results are concordant with CEMRI results in most of the cases. DWI can act as a substitute to CEMRI when contrast administration is not advised.