Technical aspects of osteoid osteoma ablation in children using MR-guided high intensity focussed ultrasound

AbstractBackground: Osteoid osteoma (OO) is a painful bone tumour occurring in children and young adults. Magnetic resonance imaging-guided high intensity focussed ultrasound (MR-HIFU) allows non-invasive treatment without ionising radiation exposure, in contrast to the current standard of care treatment with radiofrequency ablation (RFA). This report describes technical aspects of MR-HIFU ablation in the first 8 paediatric OO patients treated in a safety and feasibility clinical trial (total enrolment of up to 12 patients).Materials and methods: OO lesions and adjacent periosteum were treated with MR-HIFU ablation in 5–20 sonications (sonication duration = 16–48 s, frequency = 1.2 MHz, acoustic power = 20–160 W). Detailed treatment workflow, patient positioning and coupling strategies, as well as temperature and tissue perfusion changes were summarised and correlated.Results: MR-HIFU ablation was feasible in all eight cases. Ultrasound standoff pads were shaped to conform to extremity contours providing ...