title: Contrast-enhanced MRI predicts local recurrence of osteoid osteoma after radiofrequency ablation.
abstract: BACKGROUND
  Osteoid osteoma is a painful benign tumour, which is commonly treated by radiofrequency ablation (RFA). The goal of this study is to assess the value of contrast-enhanced magnetic resonance imaging (MRI) for predicting clinical success after RFA of osteoid osteoma.
  
  
  METHODS
  Twenty consecutive patients (14 male, 6 female; mean age 23.3 ± 13.4 years) suffering from osteoid osteoma underwent unenhanced and contrast-enhanced T1-weighted MRI the day after RFA. Post-interventional contrast enhancement of the nidus was analyzed by comparing signal-to-noise ratios (SNR) of the nidus before and after contrast administration. The SNR between pre- and post-contrast scans was computed.
  
  
  RESULTS
  There were no significant differences in SNR between pre- and post-contrast scans in the area of ablation (P = 0.1583), while the SNR exceeded one in four patients, indicating residual contrast enhancement. In three of these patients clinical symptoms recurred, requiring re-ablation, while one patient remained free from symptoms during follow-up. In patients with a pre- and post-contrast SNR of ≤ 1.18 no local recurrence was observed.
  
  
  CONCLUSIONS
  Contrast enhancement on T1-weighted MRI imaging seems to be predictive of clinically unsuccessful RFA in osteoid osteoma. Patients with a SNR increase of ≥ 20% after contrast administration might be considered for re-ablation to avoid symptomatic tumour recurrence.
authors.affiliation: Department of Diagnostic and Interventional Radiology, RWTH Aachen, Aachen, Germany. andreas.mahnken@rwth-aachen.de
authors.forename: Andreas H
authors.initials: AH
authors.lastname: Mahnken
authors.forename: Philipp
authors.initials: P
authors.lastname: Bruners
authors.forename: Heide
authors.initials: H
authors.lastname: Delbrück
authors.forename: Rolf W
authors.initials: RW
authors.lastname: Günther
authors.forename: Cedric
authors.initials: C
authors.lastname: Plumhans
mesh_terms: D000293:Adolescent; D000328:Adult; D001859:Bone Neoplasms / Q000473:pathology* / Q000601:surgery*; D017115:Catheter Ablation / Q000379:methods*; D002648:Child; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000473:pathology* / Q000517:prevention & control; D010017:Osteoma, Osteoid / Q000473:pathology* / Q000601:surgery*; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA