title: Evaluation of canine intervertebral disc degeneration in colour-coded computed tomography.
abstract: BACKGROUND
  Canine intervertebral disc degeneration can lead to intervertebral disc disease. Mild degenerative changes in the structure of the canine intervertebral disc can be identified in magnetic resonance images, whereas these changes are not visible in computed tomographic images. Therefore, one aim of this study was to detect whether colour-coded computed tomography enhances the visibility of mild degenerative changes in the canine disc structure compared to non-contrast computed tomography. Furthermore, the study aimed to detect if intervertebral disc degeneration could be classified with a higher reliability in colour-coded images than in non-contrast images.
  
  
  RESULTS
  Computed tomographic image studies of 144 canine intervertebral discs were coloured using three different lookup tables. Canine intervertebral disc degeneration was evaluated by three observers using a 5-grade classification system and compared to the evaluation of non-contrast CT and MRI images. A moderate to almost perfect intraobserver and a moderate to substantial interobserver agreement were found depending on the used colour code. On comparing non-contrast and colour-coded CT significant differences were found by one observer only. Significant differences in evaluation were found in grading intervertebral disc degeneration in MRI and colour-coded CT.
  
  
  CONCLUSIONS
  Intervertebral disc degeneration could not be classified with a higher reliability on colour-coded images compared to non-contrast images. Furthermore, colour-coded CT did not enhance the visibility of mild degenerative changes in disc structure compared to non-contrast CT. However, the better intraobserver agreement and the subjective impression of the observers highlighted that the usage of colour encoded CT data sets with a wide range of tonal values of few primary and secondary colours may facilitate evaluation.
authors.affiliation: Small Animal Hospital, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, D-30559 Hannover, Germany.
authors.forename: Lisa K
authors.initials: LK
authors.lastname: Harder
authors.affiliation: Small Animal Clinic, Faculty of Veterinary Medicine, National University of Colombia, Carrera 30 45-03 (Ciudad Universitaria), Bogotá, Colombia.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Galindo-Zamora
authors.affiliation: Institut for Biometry, Epidemiology and Information Processing, University of Veterinary Medicine Hannover, Foundation, Bünteweg 2, D-30559 Hannover, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Beyerbach
authors.affiliation: Small Animal Hospital, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, D-30559 Hannover, Germany.
authors.forename: Ingo
authors.initials: I
authors.lastname: Nolte
authors.affiliation: Small Animal Hospital, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, D-30559 Hannover, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Wefstaedt
keywords: Canine; Classification; Colour; Comparison; Computed tomography; Dog; Intervertebral disc degeneration; Magnetic resonance imaging