The role of early MRI in assessing the risk of local tumor progression following irreversible electroporation for hepatocellular carcinoma treatment.

[BACKGROUND] Irreversible electroporation (IRE) in hepatocellular carcinoma (HCC) triggers apoptosis instead of thermal coagulation, resulting in specific modifications within ablation zones. Aim of this study is to evaluate the diagnostic value of MRI performed three days post-IRE (D3MRI).

[METHODS] This single-institution retrospective study examined patients with HCC treated by IRE from 2012-2017. Criteria included no prior HCC treatment, available D3MRI and one-month MRI (M1MRI) without residual tumor and at least one follow-up MRI after 3 months. We measured the peripheral hyperemia (IREPZ) and central necrotic zone (IRECZ) in the ablation area along with the minimum thickness of IREPZ (min.Th/IREPZ) on both D3MRI and M1MRI. The duration of follow-up and instances of local tumor progression (LTP) were recorded.

[RESULTS] Forty-eight patients (median age: 68 years) with 65 treated nodules (median diameter: 19 mm) were included. The median follow-up was 37 months. D3MRI median dimensions were 67 mm for IREPZ, 19 mm for IRECZ, and 5 mm for min.Th/IREPZ. LTP occurred in 25 nodules after 18 months. 52% had LTP at min.Th/IREPZ. A min.Th/IREPZ ≤ 5 mm on D3MRI indicated a 24-fold higher risk of LTP (95% CI [2.25-255.95],  < .01), conversely, the min.Th/IREPZ on M1MRI had no predictive value.

[CONCLUSION] D3MRI appears to be a valuable tool for assessing the true ablation margins in HCC nodules treated with IRE and for identifying potential sites of local recurrence. It may, therefore, be considered for integration into the follow-up protocol for patients undergoing IRE treatment for HCC.