title: Three-Dimensional Assessment of Temporomandibular Joint Using MRI-CBCT Image Registration.
abstract: OBJECTIVE
  To introduce a new approach to reconstruct a 3D model of the TMJ using magnetic resonance imaging (MRI) and cone-beam computed tomography (CBCT) registered images, and to evaluate the intra-examiner reproducibility values of reconstructing the 3D models of the TMJ.
  
  
  METHODS
  MRI and CBCT images of five patients (10 TMJs) were obtained. Multiple MRIs and CBCT images were registered using a mutual information based algorithm. The articular disc, condylar head and glenoid fossa were segmented at two different occasions, at least one-week apart, by one investigator, and 3D models were reconstructed. Differences between the segmentation at two occasions were automatically measured using the surface contours (Average Perpendicular Distance) and the volume overlap (Dice Similarity Index) of the 3D models. Descriptive analysis of the changes at 2 occasions, including means and standard deviation (SD) were reported to describe the intra-examiner reproducibility.
  
  
  RESULTS
  The automatic segmentation of the condyle revealed maximum distance change of 1.9±0.93 mm, similarity index of 98% and root mean squared distance of 0.1±0.08 mm, and the glenoid fossa revealed maximum distance change of 2±0.52 mm, similarity index of 96% and root mean squared distance of 0.2±0.04 mm. The manual segmentation of the articular disc revealed maximum distance change of 3.6±0.32 mm, similarity index of 80% and root mean squared distance of 0.3±0.1 mm.
  
  
  CONCLUSIONS
  The MRI-CBCT registration provides a reliable tool to reconstruct 3D models of the TMJ's soft and hard tissues, allows quantification of the articular disc morphology and position changes with associated differences of the condylar head and glenoid fossa, and facilitates measuring tissue changes over time.
authors.affiliation: Department of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada.
authors.forename: Mohammed A Q
authors.identifier: http://orcid.org/0000-0001-5620-2873
authors.initials: MA
authors.lastname: Al-Saleh
authors.affiliation: Servier Virtual Cardiac Centre, University of Alberta, Edmonton, Alberta, Canada.|Department of Computing Science, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Kumaradevan
authors.initials: K
authors.lastname: Punithakumar
authors.affiliation: Department of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada.
authors.forename: Manuel
authors.initials: M
authors.lastname: Lagravere
authors.affiliation: Servier Virtual Cardiac Centre, University of Alberta, Edmonton, Alberta, Canada.|Department of Computing Science, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Pierre
authors.initials: P
authors.lastname: Boulanger
authors.affiliation: Department of Radiology and Diagnostic Imaging, Faculty of Science, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Jacob L
authors.initials: JL
authors.lastname: Jaremko
authors.affiliation: Department of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Major
mesh_terms: D000328:Adult; D000465:Algorithms; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D064847:Multimodal Imaging / Q000379:methods*; D015203:Reproducibility of Results; D013705:Temporomandibular Joint Disorders / Q000000981:diagnostic imaging*