title: Osteoid osteoma: MR-guided focused ultrasound for entirely noninvasive treatment.
abstract: OBJECTIVE
  To determine the preliminary feasibility, safety, and clinical efficacy of magnetic resonance (MR)-guided focused ultrasound for the treatment of painful osteoid osteoma.
  
  
  METHODS
  This prospective institutional review board-approved study involved six consecutive patients (five males and one female; mean age, 21 years) with a diagnosis of osteoid osteoma based on clinical and imaging findings. All patients underwent MR-guided focused ultrasound ablation after providing informed consent. Lesions located in the vertebral body were excluded. The number of sonications and the energy deposition were recorded. Treatment success was determined at 1, 3, and 6 months after treatment. A visual analog scale (VAS) score for pain was used to assess changes in symptoms. MR imaging features of osteoid osteoma (edema, hyperemia, and nidus vascularization) were considered at baseline and at imaging follow-up.
  
  
  RESULTS
  Treatment was performed with a mean of 4 sonications ± 1.8 (standard deviation), with a mean energy deposition of 866 J ± 211. No treatment- or anesthesia-related complications occurred. The pre- and posttreatment mean VAS scores significantly differed (7.9 ± 1.4 and 0.0 ± 0.0, respectively). At imaging, the edema and hyperemia associated with osteoid osteoma gradually disappeared in all lesions. However, nidus vascularization still persisted after treatment in four of six patients.
  
  
  CONCLUSIONS
  This limited series demonstrated that MR-guided focused ultrasound treatment of osteoid osteoma can be performed safely with a high rate of success and without apparent treatment-related morbidity.
authors: Department of Radiological, Oncological and Anatomo-pathological Sciences and Department of Orthopedics and Traumatology, Policlinico Umberto I-Sapienza University of Rome, Viale Regina Elena 324, 00161 Rome, Italy. alessandro.napoli@uniroma1.it
authors: Alessandro
authors: A
authors: Napoli
authors: Marco
authors: M
authors: Mastantuono
authors: Beatrice
authors: B
authors: Cavallo Marincola
authors: Michele
authors: M
authors: Anzidei
authors: Fulvio
authors: F
authors: Zaccagna
authors: Oreste
authors: O
authors: Moreschini
authors: Roberto
authors: R
authors: Passariello
authors: Carlo
authors: C
authors: Catalano
mesh_terms: D000328:Adult; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D053783:Magnetic Resonance Imaging, Interventional; D008297:Male; D008875:Middle Aged; D010017:Osteoma, Osteoid / Q000628:therapy*; D010147:Pain Measurement; D011446:Prospective Studies; D016896:Treatment Outcome; D014464:Ultrasonic Therapy; D055815:Young Adult