Intra-operative High Intensity Focused Ultrasound (HIFU) for Fast and Large Volume Liver Ablation. Final Results of a Phase II Study

Abstract

Introduction: High intensity focused ultrasound (HIFU) is a recent, non-ionizing and non-invasive technology of focal destruction. Independence from perfusion makes HIFU a promising technique for focal ablation of liver tumors. Current technology is based on extra-corporeal treatment which limits use of HIFU for the treatment of liver tumors. Moreover, elementary ablations are small and must be juxtaposed to treat supra-centimetric tumors, resulting in long-time treatment. Method: We developed an HIFU probe for intra-operative use and assessed the feasibility and efficacy of this device in patients with colorectal liver metastases (<30 mm). This study was a ablate-and-resect prospective, single-center phase II study. All ablations were performed in the area of liver scheduled for liver resection to avoid loss of chance. Results: Between May 2014 and July 2020, 15 patients were enrolled and 26 CLM were targeted. HIFU ablations were created to ablate metastases with safety margins in all directions. The exposure time was 370 seconds. In total, 24 out of 26 liver metastases were successfully treated with safety margins (>3 mm) in all directions in 15 patients. HIFU ablations were round-shaped with an average long axis of 44.3 ± 6.1 mm and an average shortest axis of 35.9 ± 6.7 mm. On gross examination, the average diameter of the treated metastasis was 12.2 ± 4.8 mm. No damage occurred to neighboring tissues. Conclusions: Intra-operative HIFU can produce large ablations in 6 minutes with a precision of 1-2 mm and real-time monitoring (NCT01489787).