Diffusion-weighted imaging of hepatocellular carcinoma before and after transarterial chemoembolization: role in survival prediction and response evaluation

Background: Survival outcomes of patients with hepatocellular carcinoma (HCC) treated with transarterial chemoembolization (TACE) are heterogeneous. Measuring the apparent diffusion coefficient (ADC) using diffusion-weighted imaging (DWI) may improve overall survival prediction.

Aim: To assess the value of measuring the ADC before and after TACE in predicting overall survival.

Methods: A retrospective analysis was performed in HCC patients treated with TACE at a tertiary referral center between 2008 and 2017. The ADC values and changes in ADC value (ΔADC) of HCC lesions (≥ 1 cm) and liver parenchyma were assessed by DWI ≤ 3 months before and after first TACE. Pre- and post-TACE ADC values were compared with tumor response according to mRECIST and correlated with overall survival (OS) in a univariable and multivariable Cox-regression analysis.

Results: A total of 89 patients were included, mostly Child-Pugh A (85%) and BCLC stage B (53%) with a median OS of 21.7 months (95% CI 17.6-25.9). Tumor ADC increased from 1081 mm²/s before (IQR 964-1225) to 1328 mm²/s (IQR 1197-1560) after TACE (p < 0.001). Responders according to mRECIST showed a higher ΔADC after first TACE than non-responders (26 vs. 14%, p = 0.048). Pre-TACE ADC and ΔADC were not significantly associated with OS in both univariable and multivariable analysis, whereas response according to mRECIST remained an independent predictor of OS.

Conclusion: mRECIST was confirmed as an independent prognostic factor of OS, but pre- or post-TACE ADC measurements were not. Response according to mRECIST was associated with a higher increase in ADC than non-response.