Post-TACE changes in ADC histogram predict overall and transplant-free survival in patients with well-defined HCC: a retrospective cohort with up to 10 years follow-up.

Objectives: To evaluate the role of change in apparent diffusion coefficient (ADC) histogram after the first transarterial chemoembolization (TACE) in predicting overall and transplant-free survival in well-circumscribed hepatocellular carcinoma (HCC).

Methods: Institution database was searched for HCC patients who got conventional TACE during 2005-2016. One hundred four patients with well-circumscribed HCC and complete pre- and post-TACE liver MRI were included. Volumetric MRI metrics including tumor volume, mean ADC, skewness, and kurtosis of ADC histograms were measured. Univariate and multivariable Cox models were used to test the independent role of change in imaging parameters to predict survival. P values < 0.05 were considered significant.

Results: In total, 367 person-years follow-up data were analyzed. After adjusting for baseline liver function, tumor volume, and treatment modality, incremental percent change in ADC (ΔADC) was an independent predictor of longer overall and transplant-free survival (p = 0.009). Overall, a decrease in ADC-kurtosis (ΔkADC) showed a strong role in predicting longer survival (p = 0.021). Patients in the responder group (ΔADC ≥ 35%) had the best survival profile, compared with non-responders (ΔADC < 35%) (p < 0.001). ΔkADC, as an indicator of change in tissue homogeneity, could distinguish between poor and fair survival in non-responders (p < 0.001). It was not a measure of difference among responders (p = 0.244). Non-responders with ΔkADC ≥ 1 (homogeneous post-TACE tumor) had the worst survival outcome (HR = 5.70, p < 0.001), and non-responders with ΔkADC < 1 had a fair survival outcome (HR = 2.51, p = 0.029), compared with responders.

Conclusions: Changes in mean ADC and ADC kurtosis, as a measure of change in tissue heterogeneity, can be used to predict overall and transplant-free survival in well-circumscribed HCC, in order to monitor early response to TACE and identify patients with treatment failure and poor survival outcome.

Key Points: • Changes in the mean and kurtosis of ADC histograms, as the measures of change in tissue heterogeneity, can be used to predict overall and transplant-free survival in patients with well-defined HCC. • A ≥ 35% increase in volumetric ADC after TACE is an independent predictor of good survival, regardless of the change in ADC histogram kurtosis. • In patients with < 35% ADC change, a decrease in ADC histogram kurtosis indicates partial response and fair survival, while ∆kurtosis ≥ 1 correlates with the worst survival outcome.