title: Automatic image registration of three-dimensional images of the head of cats and dogs by use of maximization of mutual information.
abstract: OBJECTIVE
  To validate mutual information criterion as a ready-to-use technique for automated alignment (ie, registration) of 3-dimensional (3-D) multimodal image data of the head of cats and dogs.
  
  
  METHODS
  Corresponding 3-D magnetic resonance imaging (MRI) and computed tomography (CT) brain scans of a 6-month-old Doberman Pinscher with a brain cyst; CT images of the head of a European shorthair cat with a meningioma before and immediately, 3, and 6 months after surgical resection; and CT and corresponding stacked anatomic cryosection images of the entire head of a 2-year-old sexually intact female Beagle.
  
  
  METHODS
  All images were matched retrospectively by use of an in-house computer program developed on the basis of a mutual information image registration algorithm. Accuracy of the resulting registrations was evaluated by visual inspection.
  
  
  RESULTS
  All registrations were judged to be highly accurate. Additional manual corrections were not necessary.
  
  
  CONCLUSIONS
  Mutual information registration criterion can by applied to 3-D multimodal head images of cats and dogs for full automatic rigid-body image registration. The combination of such aligned images would considerably facilitate efforts of veterinary clinicians as indicated by its widespread use in brain surgery and radiation therapy of humans.
authors.affiliation: Department of Small Animal Surgery, Faculty of Veterinary Medicine, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Böttcher
authors.forename: Johann
authors.initials: J
authors.lastname: Maierl
authors.forename: Silke
authors.initials: S
authors.lastname: Hecht
authors.forename: Ulrike
authors.initials: U
authors.lastname: Matis
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Liebich
mesh_terms: D000818:Animals; D001927:Brain Diseases / Q000175:diagnosis / Q000601:surgery / Q000662:veterinary*; D002371:Cat Diseases / Q000175:diagnosis* / Q000601:surgery; D002415:Cats; D003560:Cysts / Q000175:diagnosis / Q000601:surgery / Q000662:veterinary*; D004283:Dog Diseases / Q000175:diagnosis* / Q000601:surgery; D004285:Dogs; D005260:Female; D021621:Imaging, Three-Dimensional / Q000662:veterinary*; D008279:Magnetic Resonance Imaging / Q000662:veterinary; D008577:Meningeal Neoplasms / Q000175:diagnosis / Q000601:surgery / Q000662:veterinary*; D008579:Meningioma / Q000175:diagnosis / Q000601:surgery / Q000662:veterinary*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000662:veterinary