title: PedCAT for 3D-imaging in standing position allows for more accurate bone position (angle) measurement than radiographs or CT.
abstract: BACKGROUND
  PedCAT (Curvebeam, Warrington, USA) is a new technology that allows 3D-imaging with full weight bearing which is not influenced by projection and/or foot orientation (as radiographs). The aim of this study was to compare time spent of the image acquisition, and comparison of specific bone position (angle) measurements between three imaging methods (radiographs, CT, pedCAT), and to analyze and compare measurement differences and inter- and intraobserver reliability.
  
  
  METHODS
  In a prospective consecutive controlled study, 30 patients in which standard digital radiographs with full weight bearing in standing position (feet bilateral dorsoplantar and lateral views and Saltzman hindfoot view), CT without weight bearing, and pedCAT scan with full weight bearing in standing position were included, starting July 1, 2013. The following angles were measured for the right foot by three different investigators three times: 1st - 2nd intermetatarsal angle, talo-metatarsal 1-angle (TMT) both dorsoplantar and lateral projection, hindfoot angle, calcaneal pitch. The angles were digitally measured and compared (ANOVA with Post Hoc Scheffe test).
  
  
  RESULTS
  The angles differed between radiographs, CT and pedCAT (ANOVA, all p≤.01). The angles differed between pedCAT and both radiographs and CT (Post Hoc Scheffe test, each p≤.05 except for TMT dorsoplantar and calcaneal pitch angels versus radiographs).
  
  
  CONCLUSIONS
  The angles differed between radiographs, CT and pedCAT, indicating that only pedCAT is able to detect the correct angles. PedCAT includes weight bearing in contrast to CT. PedCAT prevents inaccuracies of projection and foot orientation in contrast to radiographs due to the 3D dataset which is principally independent from projection and foot orientation.
authors.affiliation: Department for Foot and Ankle Surgery Rummelsberg and Nuremberg, Germany. Electronic address: martinus.richter@sana.de.
authors.forename: Martinus
authors.initials: M
authors.lastname: Richter
authors.affiliation: Department for Foot and Ankle Surgery Rummelsberg and Nuremberg, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Seidl
authors.affiliation: Department for Foot and Ankle Surgery Rummelsberg and Nuremberg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Zech
authors.affiliation: Department for Foot and Ankle Surgery Rummelsberg and Nuremberg, Germany.
authors.forename: Sarah
authors.initials: S
authors.lastname: Hahn
mesh_terms: D000328:Adult; D001837:Body Weights and Measures; D005529:Foot Bones / Q000000981:diagnostic imaging*; D006801:Humans; D021621:Imaging, Three-Dimensional; D009140:Musculoskeletal Diseases / Q000000981:diagnostic imaging*; D015588:Observer Variation; D056888:Patient Positioning; D011187:Posture; D011446:Prospective Studies; D015203:Reproducibility of Results; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016474:Weight-Bearing
keywords: 3D-imaging; Computer tomography (CT); Radiograph; Weight bearing