title: Three-dimensional computed tomographic analysis of the relationship between the arcuate eminence and the superior semicircular canal.
abstract: OBJECTIVE
  The location of the superior semicircular canal (SSC) is often determined intraoperatively based on its topographic association with the arcuate eminence (AE). This determination is not always possible because of the potential variability in the relationship between these two structures. The goal of this study was to describe the three-dimensional (3-D) relationship between the AE and SSC using 3-D computed tomography (CT) and to evaluate the utility of 3-D CT for preoperative planning for surgical approaches to the middle cranial fossa.
  
  
  METHODS
  We studied 11 patients (22 sides) radiographically using 0.8- to 1-mm thick reconstructed CT images. A standard set of structural relationships was measured between the AE, SSC, and other regional landmarks.
  
  
  RESULTS
  3-D CT clearly demonstrated the relationships between traditional landmarks along the petrous ridge and middle cranial fossa. The relationship between the arcuate eminence and SSC was found to be highly variable. The average distance between the tips of the two structures was found to be 5.7 mm (range, 2.7-10.4 mm).
  
  
  CONCLUSIONS
  There is significant variability in the relationship between the AE and the SSC. The AE is not a consistent or reliable landmark for identifying the precise position of the SSC. Detailed preoperative information regarding the relationship between the AE, SSC, and other bony landmarks can be easily and quickly assessed using 3-D CT.
authors.affiliation: Division of Neurosurgery, University of Missouri-Columbia, Columbia, Missouri. USA. ketanbulsara@hotmail.com
authors.forename: Ketan R
authors.initials: KR
authors.lastname: Bulsara
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Leveque
authors.forename: Linda
authors.initials: L
authors.lastname: Gray
authors.forename: Takanori
authors.initials: T
authors.lastname: Fukushima
authors.forename: Allan H
authors.initials: AH
authors.lastname: Friedman
authors.forename: Alan T
authors.initials: AT
authors.lastname: Villavicencio
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002941:Circle of Willis / Q000000981:diagnostic imaging; D035301:Cranial Fossa, Middle / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D004432:Ear, Middle / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D007431:Intraoperative Complications / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D038361:Neuronavigation / Q000191:economics / Q000379:methods*; D010579:Petrous Bone / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D011300:Preoperative Care / Q000379:methods*; D011446:Prospective Studies; D015203:Reproducibility of Results; D012665:Semicircular Canals / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D012984:Software; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000592:standards; D000159:Vestibulocochlear Nerve / Q000033:anatomy & histology / Q000601:surgery