title: Automated method for small-animal PET image registration with intrinsic validation.
abstract: OBJECTIVE
  We propose and compare different registration approaches to align small-animal PET studies and a procedure to validate the results by means of objective registration consistency measurements.
  
  
  METHODS
  We have applied a registration algorithm based on information theory, using different approaches to mask the reference image. The registration consistency allows for the detection of incorrect registrations. This methodology has been evaluated on a test dataset (FDG-PET rat brain images).
  
  
  RESULTS
  The results show that a multiresolution two-step registration approach based on the use of the whole image at the low resolution step, while masking the brain at the high resolution step, provides the best robustness (87.5% registration success) and highest accuracy (0.67-mm average).
  
  
  CONCLUSIONS
  The major advantages of our approach are minimal user interaction and automatic assessment of the registration error, avoiding visual inspection of the results, thus facilitating the accurate, objective, and rapid analysis of large groups of rodent PET images.
authors.affiliation: Unidad de Medicina y Cirugía Experimental, Hospital General Universitario Gregorio Marañón, C/ Doctor Esquerdo 46, 28007, Madrid, Spain. jpascau@mce.hggm.es
authors.forename: Javier
authors.initials: J
authors.lastname: Pascau
authors.forename: Juan Domingo
authors.initials: JD
authors.lastname: Gispert
authors.forename: Michael
authors.initials: M
authors.lastname: Michaelides
authors.forename: Panayotis K
authors.initials: PK
authors.lastname: Thanos
authors.forename: Nora D
authors.initials: ND
authors.lastname: Volkow
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Vaquero
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Soto-Montenegro
authors.forename: Manuel
authors.initials: M
authors.lastname: Desco
mesh_terms: D000465:Algorithms; D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism; D001923:Brain Chemistry; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D049268:Positron-Emission Tomography / Q000379:methods*; D051381:Rats; D011924:Rats, Zucker; D015203:Reproducibility of Results
chemical_list: D019788:Fluorodeoxyglucose F18