title: Individualized oblique-axial magnetic resonance imaging for improved visualization of mediolateral TMJ disc displacement.
abstract: OBJECTIVE
  A new individualized oblique-axial orientation of magnetic resonance imaging scans of the temporomandibular joint (TMJ), corrected to be perpendicular to the tangent of the posterior slope of the articular eminence, has been proposed to improve the representation of the disc. The aim of this study was to evaluate the quality of the images obtained with this new type of scanning plane and to assess the factors that can affect the scans.
  
  
  METHODS
  Twenty-nine TMJs were scanned by the use of sagittal, conventional coronal, and individualized oblique-axial scanning planes. On the sagittal images, the angle alpha between the tangent of the posterior slope of the articular eminence and the vertical was measured, and the disc position was evaluated. For both imaging planes, 2 examiners, blind to the scanning techniques, counted the number of conventional coronal and oblique-axial scans in which the disc was visible and in which the medial and lateral disc borders were well demarcated and evaluated the mediolateral disc position.
  
  
  RESULTS
  The individualized oblique-axial technique was superior to the conventional coronal technique in depicting the disc and its medial and lateral demarcations (paired t test, P < 0.05). The possibility of correct diagnosis of the mediolateral disc position and the agreement between the observers in this evaluation were better with the oblique-axial technique than with the conventional technique (P < 0.05). This was particularly evident when the disc was anteriorly displaced.
  
  
  CONCLUSIONS
  The individualized oblique-axial scanning planes should be used for a better representation of the disc/condyle complex mediolaterally if the disc is anteriorly displaced.
authors.affiliation: Clinic for Masticatory Disorders and Complete Denture, Center for Dental and Oral Medicine and Maxillofacial Surgery, University of Zurich, Zurich, Switzerland.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Chen
authors.forename: L M
authors.initials: LM
authors.lastname: Gallo
authors.forename: D
authors.initials: D
authors.lastname: Meier
authors.forename: S
authors.initials: S
authors.lastname: Palla
mesh_terms: D000293:Adolescent; D000328:Adult; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D004204:Joint Dislocations / Q000175:diagnosis* / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008335:Mandibular Condyle / Q000473:pathology; D015588:Observer Variation; D016037:Single-Blind Method; D013223:Statistics as Topic; D013701:Temporal Bone / Q000473:pathology; D019224:Temporomandibular Joint Disc / Q000473:pathology*