High intensity focused ultrasound periosteal ablation in an animal model: potential for palliation of bone metastases.

Purpose: Radiotherapy is standard-of-care for painful bone metastases yet has limitations and associated side effects. Ablation of sensory nerves endings along the periosteum with magnetic resonance imaging guided high intensity focused ultrasound (MRgFUS) proved safe and clinically effective for pain relief in patients with bone metastases, received FDA and CE approval, but has not gained widespread adoption due to significant cost and procedural and logistical complexity. This preclinical study evaluated the safety and feasibility of a fluoroscopy-guided high intensity focused ultrasound platform to ablate a targeted region along the surface of bones.

Methods: Two healthy adult pigs received 6 kJ to 10 kJ sonications to the femur, ileum, and ribs. Animals were followed-up for 3 months. Longitudinal clinical observation and follow up magnetic resonance imaging (MRI), and computed tomography (CT) scans were performed. After sacrifice, the targeted bone and adjacent tissues were sent for histopathological evaluation to confirm thermal ablation.

Results: Clinical observations revealed no neurological or musculoskeletal deficits. MRI scans on day 5 demonstrated robust ablation in all targeted sites. At 12 weeks, CT scans and histopathological evaluation showed complete healing of ablated regions.

Conclusions: Periosteal bone ablation using the Neurolyser XR in a healthy porcine model is feasible with no adverse events, and no radiological or histological evidence of lasting injury or fracture to the targeted bones.