One‐month apparent diffusion coefficient correlates with response to radiofrequency ablation of hepatocellular carcinoma

Purpose To assess whether apparent diffusion coefficient (ADC) values at 1 and 3 months after radiofrequency ablation (RFA) may be associated with a favorable response to therapy for hepatocellular carcinoma (HCC) and liver metastases. Materials and Methods Fifty‐nine patients with HCC ( n  = 35) or liver metastases ( n  = 24) who underwent 1.5T diffusion‐weighted magnetic resonance imaging (DWMRI) at 1 and 3 months post‐RFA were included. ADC values of patients with local tumor recurrence were compared to those without local recurrence. A subgroup analysis was performed for HCC and metastases. Results Thirty‐eight HCC and 27 metastases were evaluated. The ADC value of HCC at 1 month after RFA was lower in recurrent tumors (0.957 ± 0.229 [SD] × 10 −3 mm 2 ) compared to tumors with complete response (1.414 ± 0.322 [SD] × 10 −3 mm 2 /s, P  = 0.006). At multivariate analysis, ADC at 1 month was the single independent variable associated with recurrence for HCC (area under the receiver operating characteristic curve = 0.860). No significant association was observed for liver metastases ( P  = 0.089). Conclusion A low ADC value at 1 month after RFA is associated with an early local recurrence of HCC. This study does not confirm that such association exists for hepatic metastases. Level of Evidence : 3 Technical Efficacy : Stage 2 J. MAGN. RESON. IMAGING 2017;45:1648–1658