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.