Magnetic-resonance-guided focused ultrasound treatment of non-spinal osteoid osteoma in children: multicentre experience

Background: Osteoid osteoma is a benign and painful musculoskeletal tumour that usually affects children. Current standard treatment is CT-guided radiofrequency ablation, a minimally invasive percutaneous procedure, with clinical success rates ranging between 85% and 98%. Though minimally invasive, however, this type of procedure is not free from complications. Objective: To investigate the efficacy and safety of magnetic resonance (MR)-guided focused ultrasound (MRgFUS), a needleless procedure of thermal ablation employed in the treatment of non-spinal osteoid osteoma in paediatric patients. Materials and methods: We report the results of 33 procedures of ablation of osteoid osteoma performed with MRgFUS in three university hospitals. To ablate a lesion on the bone surface, MRgFUS employs the ultrasound energy transduced along the soft tissue. The follow-up studies lasted 24 months and were performed combining clinical and imaging data. Results: Mean age of the children was 13.8 years. The clinical outcome showed a primary success of 97%. One case alone was submitted to repeat treatment because the first one failed (secondary success). No major or minor complications were recorded. During the investigation time, no relapse of symptomatology or delayed complications were observed. Conclusion: Although our study is preliminary and limited by a low number of patients, our data show that MRgFUS is effective. This suggests that it might be useful as the first-line treatment in paediatric patients with osteoid osteoma.