title: CT-guided radiofrequency ablation of osteoid osteoma: correlation of clinical outcome and imaging features.
abstract: OBJECTIVE
  We aimed to retrospectively evaluate the computed tomography (CT) and magnetic resonance imaging (MRI) findings of patients with osteoid osteoma treated with CT-guided radiofrequency ablation (RFA) along with the clinical outcome and long-term success.
  
  
  METHODS
  Seventy-three CT-guided RFA procedures were performed in 72 patients. The long-term success was assessed using a questionnaire including several visual analog scale scores. The CT evaluation included pre- and immediate postprocedural imaging of all 72 patients, and MRI was performed in 18 patients with follow-up imaging (mean, 3.4±2.2 months). The evaluation criteria included nidus morphology and a correlation with markers of clinical success.
  
  
  RESULTS
  The primary technique effectiveness rate was 71/72 (99%). One relapse was successfully retreated, leading to a secondary technique effectiveness rate of 72/72 (100%). The long-term follow-up (mean, 51.2±31.2 months; range, 3-109 months) revealed a highly significant reduction of all assessed limitation scores (P < 0.001). The CT morphology was typical in all cases and did not change during the short-term follow-up. The follow-up MRI patterns varied considerably, including persistent nidus contrast enhancement in one-third (6/18) and persistent marrow edema in half (9/18) of the patients. None of the investigated MRI and CT patterns correlated with the clinical outcome.
  
  
  CONCLUSIONS
  The long-term outcome of CT-guided RFA of osteoid osteoma is excellent. There is no correlation of the CT and MRI patterns with the clinical outcome. Thus, the treatment decisions should not be solely based on the imaging findings. Investigators should also be aware of the variety of imaging patterns after RFA.
authors.affiliation: Departments of Diagnostic and Interventional Radiology, University of Heidelberg, Heidelberg, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Rehnitz
authors.forename: Simon David
authors.initials: SD
authors.lastname: Sprengel
authors.forename: Burkhard
authors.initials: B
authors.lastname: Lehner
authors.forename: Karl
authors.initials: K
authors.lastname: Ludwig
authors.forename: Georg
authors.initials: G
authors.lastname: Omlor
authors.forename: Christian
authors.initials: C
authors.lastname: Merle
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Kauczor
authors.forename: Volker
authors.initials: V
authors.lastname: Ewerbeck
authors.forename: Marc-André
authors.initials: MA
authors.lastname: Weber
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D017115:Catheter Ablation / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D010017:Osteoma, Osteoid / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D015641:Radiography, Interventional / Q000379:methods; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome; D055815:Young Adult