title: A new coordinates system for cranial organs using magnetic resonance imaging.
abstract: CONCLUSIONS
  We developed a new coordinates system for magnetic resonance imaging (MRI) that utilizes the labyrinth and eyeballs as references to measure the spatial arrangement of cranial organs, and we verified its usefulness by observing small structures in the labyrinth in 39 ears from 33 patients. Our new coordinates system could be used for stereotactic analysis of cranial organs in MRI.
  
  
  OBJECTIVE
  To research semicircular canal anatomy in healthy organisms, we propose a method that employs references visible on MRI for stereotactic measurement of cranial structures, and we evaluated the usefulness of our method.
  
  
  METHODS
  Using the new coordinates system and vector analysis, we calculated angles among the semicircular canals and sagittal head plane from MRI volume data containing temporal bone and orbit.
  
  
  RESULTS
  The angle between the anterior semicircular canal plane and sagittal plane was 35.3 +/- 4.1 degrees; posterior semicircular canal plane and sagittal plane, 50.9 +/- 4.7 degrees; and horizontal semicircular canal plane and sagittal plane, 90.4 +/- 7.0 degrees. The angle between the anterior and posterior semicircular canal planes was 95.1 +/- 4.2 degrees; anterior and horizontal semicircular canal planes, 92.3 +/- 7.5 degrees; and posterior and horizontal semicircular canal planes, 93.5 +/- 4.9 degrees.
authors.affiliation: Department of Radiology, Medical Center East, Tokyo Women's Medical University, Tokyo, Japan. kasuzuki-rad@umin.ac.jp
authors.forename: Kazufumi
authors.initials: K
authors.lastname: Suzuki
authors.forename: Ai
authors.initials: A
authors.lastname: Masukawa
authors.forename: Sachiko
authors.initials: S
authors.lastname: Aoki
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Arai
authors.forename: Eiko
authors.initials: E
authors.lastname: Ueno
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012665:Semicircular Canals / Q000033:anatomy & histology*; D012886:Skull / Q000033:anatomy & histology*; D013238:Stereotaxic Techniques