Prostate cancer treated with irreversible electroporation: MRI-based volumetric analysis and oncological outcome

To assess multiparametric magnetic resonance imaging (mpMRI) characteristics in prostate cancer (PCa) before and after irreversible electroporation (IRE) and to investigate their correlation with the presence of post-operative recurrence of PCa.

MpMRI was performed in 30 men with PCa prior to treatment, after 10 days and at 6 months. An additional scan at 1 year was available for 18 men. Two radiologists assessed retrospectively the following parameters by planimetry: tumour volume, necrotic volume (early post-treatment scan) and residual fibrosis. Residual tumour/recurrence were defined as a suspicious area within the treatment field scored ≥ 4 on a 1-to-5 scale. Oncological outcome was also assessed.

The median follow-up of the entire study was 16 months. Six men were undertreated and showed mpMRI recurrence after 6 months. At 1-year, three additional men had recurrence. Overall, four of these 9 men (44%) were retreated. The other five men did not receive any further treatment. Median time to re-treatment was 15 months. Median pre-treatment lesion volume was 0.65 cc, 0.66 cc and 0.43 cc on the different mpMRI sequences (T2-weighted, diffusion-weighted and dynamic contrast enhanced imaging). Median necrotic volume was 10.77 cc. Median overall residual fibrosis volumes were 0.84 cc and 0.95 cc at 6-month and 1-year mpMRI. Pre-treatment, necrotic and residual fibrosis volumes were significantly different (p < 0.001). Pre-treatment tumour volumes on diffusion-weighted imaging and necrotic volumes were correlated (r = 0.18; p = 0.02).

MpMRI is able to visualise the IRE ablation effects in men with PCa. MpMRI-derived parameters - such as tumour, necrotic and fibrosis volumes - can be measured and are potentially useful for assessing efficacy in the medium term, as with other ablative techniques.