OBJECTIVETo investigate the value of pretreatment and posttreatment changes of apparent diffusion coefficients (ADCs) in predicting response to chemoembolization in liver cancer.

METHODSPatients with liver cancer were examined with diffusion-weighted MRI at two b values (0 and 500 s/mm(2)) before and after chemoemblization. Quantitative ADC maps were calculated using images under b values of 0 and 500 s/mm(2). The mean ADC values of lesions before and after chemoemblization were compared. The correlation of response to chemoembolization with ADC value was analyzed.

RESULTSThe mean value of pretreatment ADC in non-responding lesions were significantly higher than that in the responding lesions (1.687 x 10(-3) mm(2)/s vs. 1.278 x 10(-3) mm(2)/s, P < 0.05). The results of receiver operator characteristic (ROC) analysis showed that when a threshold ADC value was set on 1.618 x 10(-3) mm(2)/s, the sensitivity and specificity for identification of non-responding lesions were 96.0% and 77.8%, respectively. After transarterial chemoembolization, the responding lesions had a significant increase in ADC values than non-responding lesions (32.6% vs. 5.2%, P = 0.025). The results of ROC analysis indicated that when the changes of ADC value for identification of responding lesions before and after transarterial chemoembolization was > or = 16.2%, the sensitivity and specificity were 72% and 100%, respectively. However, no significant change was observed in normal liver parenchyma and spleen (P > 0.05).

CONCLUSIONPretreatment mean ADC value can be used to predict the response to chemoembolization, and for selection of therapy in liver cancer. A significant increase in mean ADC can be observed if the lesions responds to chemoembolization.