title: Obstacles in spatial evaluation of CBCT-reformatted panoramic imaging.
abstract: OBJECTIVE
  Conventional panoramic radiography (cPR) underlines procedure-related limitations in the display of objects. CBCT is presumed to overcome these constraints. To virtualize a cPR view, reformatted panoramic images (rPIs) can be generated. This study evaluated the rPI with regard to its susceptibility to sterical object deposition in comparison with cPR.
  
  
  METHODS
  A specially developed implant model with dental implants each of 4.0-mm diameter and 11.0-mm length was depositioned by shift, rotation and tilt of 5.00 mm (±0.01 mm) of horizontal shift and 5.0° (±0.167°), respectively, on a highly precise goniometer rotation table, and cPRs and rPIs were generated. Automated evaluation of the cPRs was carried out using a specially developed software. rPIs were processed and analyzed by a semi-automated image analysis.
  
  
  RESULTS
  Object deposition lead to distortive effects in the rPI analogue to cPR, but they appear in display only. Objects illustrated in the rPI were dimensionally correct, but sterical relations are elusive. Results are obtained for the horizontal shift, declination and reclination, lateral tilt and rotation.
  
  
  CONCLUSIONS
  Distortions within the rPI represent the illustration of the hyperbolic-shaped layer out of the three-dimensional data set. With this study, we demonstrated these procedure-related inherent but practically underestimated consequences. Effects of sterical object malpositioning must be compensated by the observer by adequate virtual adjustment of the processed layer. Accurate virtual adjustment leads to vertical dimensions. Sterical relations, e.g. angulation of two objects, are irretraceable unless precisely referenced.
authors.affiliation: 1 Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Wikner
authors.affiliation: 1 Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Reinhard E
authors.initials: RE
authors.lastname: Friedrich
authors.affiliation: 1 Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Ashkan
authors.initials: A
authors.lastname: Rashad
authors.affiliation: 2 Department of Diagnostic and Interventional Neuroradiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Schulze
authors.affiliation: 1 Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Henning
authors.initials: H
authors.lastname: Hanken
authors.affiliation: 1 Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Max
authors.initials: M
authors.lastname: Heiland
authors.affiliation: 1 Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Gröbe
authors.affiliation: 1 Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Björn
authors.initials: B
authors.lastname: Riecke
mesh_terms: D054893:Cone-Beam Computed Tomography / Q000379:methods* / Q000706:statistics & numerical data; D015921:Dental Implants; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods* / Q000706:statistics & numerical data; D021621:Imaging, Three-Dimensional / Q000379:methods / Q000706:statistics & numerical data; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D011862:Radiography, Panoramic / Q000379:methods* / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D012399:Rotation; D014584:User-Computer Interface
chemical_list: D015921:Dental Implants
keywords: cone-beam computed tomography; dental implant; multiplanar reconstructions; panoramic radiography; reformatted panoramic image