title: Can MRI replace CT in evaluating semicircular canal dehiscence?
abstract: OBJECTIVE
  Patients with symptoms of semicircular canal dehiscence often undergo both CT and MR imaging. We assessed whether FIESTA can replace temporal bone CT in evaluating patients for SC dehiscence.
  
  
  METHODS
  We retrospectively reviewed 112 consecutive patients (224 ears) with vestibulocochlear symptoms who underwent concurrent MR imaging and CT of the temporal bones between 2007 and 2009. MR imaging protocol included a FIESTA sequence covering the temporal bone (axial 0.8-mm section thickness, 0.4-mm spacing, coronal/oblique reformations; 41 patients at 1.5T, 71 patients at 3T). CT was performed on a 64-row multidetector row scanner (0.625-mm axial acquisition, with coronal/oblique reformations). Both ears of each patient were evaluated for dehiscence of the superior and posterior semicircular canals in consensual fashion by 2 neuroradiologists. Analysis of the FIESTA sequence and reformations was performed first for the MR imaging evaluation. CT evaluation was performed at least 2 weeks after the MR imaging review, resulting in a blinded comparison of CT with MR imaging. CT was used as the reference standard to evaluate the MR imaging results.
  
  
  RESULTS
  For SSC dehiscence, MR imaging sensitivity was 100%, specificity was 96.5%, positive predictive value was 61.1%, and negative predictive value was 100% in comparison with CT. For PSC dehiscence, MR imaging sensitivity was 100%, specificity was 99.1%, positive predictive value was 33.3%, and negative predictive value was 100% in comparison with CT.
  
  
  CONCLUSIONS
  MR imaging, with a sensitivity and negative predictive value of 100%, conclusively excludes SSC or PSC dehiscence. Negative findings on MR imaging preclude the need for CT to detect SC dehiscence. Only patients with positive findings on MR imaging should undergo CT evaluation.
authors.affiliation: Department of Radiology, University Hospital, Lausanne, Switzerland. patrick.browaeys@skynet.be
authors.forename: P
authors.initials: P
authors.lastname: Browaeys
authors.forename: T L
authors.initials: TL
authors.lastname: Larson
authors.forename: M L
authors.initials: ML
authors.lastname: Wong
authors.forename: U
authors.initials: U
authors.lastname: Patel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004244:Dizziness / Q000175:diagnosis / Q000000981:diagnostic imaging; D005260:Female; D005500:Follow-Up Studies; D034381:Hearing Loss / Q000175:diagnosis / Q000000981:diagnostic imaging; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007759:Labyrinth Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012665:Semicircular Canals / Q000000981:diagnostic imaging / Q000473:pathology*; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D013701:Temporal Bone / Q000000981:diagnostic imaging; D014012:Tinnitus / Q000175:diagnosis / Q000000981:diagnostic imaging; D036542:Tomography, Spiral Computed / Q000379:methods*; D014717:Vertigo / Q000175:diagnosis / Q000000981:diagnostic imaging; D055815:Young Adult