title: Mass screening for retrocochlear disorders: low-field-strength (0.2-T) versus high-field-strength (1.5-T) MR imaging.
abstract: OBJECTIVE
  In patients with clinical symptoms suggestive of a retrocochlear disorder, contrast-enhanced T1-weighted spin-echo (SE) high-field-strength MR imaging is considered the criterion standard in assessing vestibular schwannoma. However, only 10-20% of its findings are pathologic. Our purpose was to prospectively compare the performance of low-field-strength MR imaging in screening for retrocochlear disorders, with high-field-strength MR imaging as the criterion standard.
  
  
  METHODS
  A total of 287 patients with suspected retrocochlear disease underwent axial 1.5-T MR imaging with a T1-weighted SE sequence before and after contrast enhancement and with a high-resolution T2-weighted construction interference in steady state sequence. At immediate follow-up, the same patients underwent axial 0.2-T T1-weighted SE imaging without additional contrast enhancement. Results were classified as negative, positive, or uncertain and were analyzed in light of the patients' clinical symptoms.
  
  
  RESULTS
  MR imaging at 1.5 T depicted 63 disorders (21.95%), including 53 schwannomas, three other tumors, and seven other disorders (ie, gadolinium-enhancing inner ear, facial nerve, or meninges). MR imaging at 0.2 T showed evidence of 58 disorders; five disorders were not detected, although all schwannomas and other tumors were seen, including those smaller than 2 mm, and only two (28.6%) of the other disorders were detected. When correlated with clinical data, results showed that the five undetected disorders occurred in patients with unusual clinical signs.
  
  
  CONCLUSIONS
  MR imaging at 0.2 T provided high sensitivity in detecting vestibular schwannoma of the internal auditory canal or cerebellopontine angle; it can be used for mass screening for this disease. Positive and uncertain imaging findings should be followed up with high-field-strength MR imaging.
authors.affiliation: Department of Radiology, Hopital Huriez, Centre Hospitalier Universitaire de Lille, France.
authors.forename: Frédérique
authors.initials: F
authors.lastname: Dubrulle
authors.forename: Julia
authors.initials: J
authors.lastname: Delomez
authors.forename: Alireza
authors.initials: A
authors.lastname: Kiaei
authors.forename: Pierre
authors.initials: P
authors.lastname: Berger
authors.forename: Christophe
authors.initials: C
authors.lastname: Vincent
authors.forename: François-Michel M
authors.initials: FM
authors.lastname: Vaneecloo
authors.forename: Laurent
authors.initials: L
authors.lastname: Lemaitre
mesh_terms: D002530:Cerebellopontine Angle; D007758:Ear, Inner; D005188:False Negative Reactions; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008403:Mass Screening / Q000379:methods*; D009464:Neuroma, Acoustic / Q000175:diagnosis; D011446:Prospective Studies; D012181:Retrocochlear Diseases / Q000175:diagnosis*; D012680:Sensitivity and Specificity