title: Modified brix model analysis of bone perfusion in subjects of varying bone mineral density.
abstract: OBJECTIVE
  To apply pharmacokinetic modeling to the investigation of bone perfusion in subjects of varying bone mineral density.
  
  
  METHODS
  This study re-analyzed previous experimental data. A modified pharmacokinetic model was applied to data obtained from two prior studies of dynamic contrast-enhanced MR imaging of L3 vertebral body in 165 subjects (65 males, 100 females), classified into three groups (normal, osteopenia, and osteoporosis) according to bone mineral density. Three parameters, amplitude A, exchange rate (k(ep)), and elimination rate (k(el)), were obtained by fitting the signal intensity to the pharmacokinetic model. These parameters were compared across the three groups for males and females, respectively.
  
  
  RESULTS
  Perfusion parameters, amplitude A was found to be reduced in osteoporotic subjects with additional, though less pronounced, reductions found in the permeability constant (A*k(ep)) and the elimination rate (k(el)). Increased marrow fat content was found in osteoporotic bone, which helped to partially explain the observed reduction in interstitial space.
  
  
  CONCLUSIONS
  By pharmacokinetic model, bone perfusion can be quantitatively analyzed with alteration in functional parameters related to microcirculation in subjects of varying bone mineral density. Developing bone marrow specific pharmacokinetic models should help to deepen knowledge of physiological and pathological perfusion changes occurring in bone.
authors.affiliation: Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong, China. mheather@hitsz.edu.cn
authors.forename: Heather Ting
authors.initials: HT
authors.lastname: Ma
authors.forename: James F
authors.initials: JF
authors.lastname: Griffith
authors.forename: David K
authors.initials: DK
authors.lastname: Yeung
authors.forename: P C
authors.initials: PC
authors.lastname: Leung
mesh_terms: D000368:Aged; D000465:Algorithms; D015519:Bone Density; D001851:Bone Diseases, Metabolic / Q000503:physiopathology*; D003198:Computer Simulation; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008159:Lumbar Vertebrae / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008954:Models, Biological; D010024:Osteoporosis / Q000503:physiopathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity