title: Information theoretic ranking of four models of diffusion attenuation in fresh and fixed prostate tissue ex vivo.
abstract: OBJECTIVE
  To compare the theoretical information content of four popular models of diffusion-weighted signal attenuation.
  
  
  METHODS
  Four whole prostates were imaged fresh unfixed and fixed at 9.4T. Biexponential, kurtosis, stretched exponential, and monoexponential models were ranked using Akaike's Information Criterion (AIC) with validation by a leave-one-out test of model prediction error.
  
  
  RESULTS
  For unfixed tissue measurements (b-value range: 17-2104 s/mm(2)) the biexponential and kurtosis models had similar information content to each other and this was distinctly higher than for the stretched and monoexponential models. In fixed-tissue measurements (b-value range: 17-8252 s/mm(2)), the biexponential model had much higher information content than the three other models.
  
  
  CONCLUSIONS
  AIC-based model ranking is consistent with an independent prediction accuracy test. Biexponential and kurtosis models consistently perform better than stretched and monoexponential models. The biexponential model has increasing superiority over all three other models as maximum b-value increases above ∼2000 s/mm(2).
authors.affiliation: Roger Bourne, Discipline of Medical Radiation Sciences, Faculty of Health Sciences, University of Sydney, Lidcombe, Australia.
authors.forename: Roger M
authors.initials: RM
authors.lastname: Bourne
authors.forename: Eleftheria
authors.initials: E
authors.lastname: Panagiotaki
authors.forename: Andre
authors.initials: A
authors.lastname: Bongers
authors.forename: Paul
authors.initials: P
authors.lastname: Sved
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Watson
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Alexander
mesh_terms: D000465:Algorithms; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D011467:Prostate / Q000033:anatomy & histology*; D015203:Reproducibility of Results
keywords: Akaike Information Criterion; diffusion; modelling; prostate