title: Effect of arterial deprivation on growing femoral epiphysis: quantitative magnetic resonance imaging using a piglet model.
abstract: OBJECTIVE
  To investigate the usefulness of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion MRI for the evaluation of femoral head ischemia.
  
  
  METHODS
  Unilateral femoral head ischemia was induced by selective embolization of the medial circumflex femoral artery in 10 piglets. All MRIs were performed immediately (1 hour) and after embolization (1, 2, and 4 weeks). Apparent diffusion coefficients (ADCs) were calculated for the femoral head. The estimated pharmacokinetic parameters (Kep and Ve from two-compartment model) and semi-quantitative parameters including peak enhancement, time-to-peak (TTP), and contrast washout were evaluated.
  
  
  RESULTS
  The epiphyseal ADC values of the ischemic hip decreased immediately (1 hour) after embolization. However, they increased rapidly at 1 week after embolization and remained elevated until 4 weeks after embolization. Perfusion MRI of ischemic hips showed decreased epiphyseal perfusion with decreased Kep immediately after embolization. Signal intensity-time curves showed delayed TTP with limited contrast washout immediately post-embolization. At 1-2 weeks after embolization, spontaneous reperfusion was observed in ischemic epiphyses. The change of ADC (p = 0.043) and Kep (p = 0.043) were significantly different between immediate (1 hour) after embolization and 1 week post-embolization.
  
  
  CONCLUSIONS
  Diffusion MRI and pharmacokinetic model obtained from the DCE-MRI are useful in depicting early changes of perfusion and tissue damage using the model of femoral head ischemia in skeletally immature piglets.
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, and Institute of Radiation Medicine, SNUMRC, Seoul 110-744, Korea.
authors.forename: Jung-Eun
authors.initials: JE
authors.lastname: Cheon
authors.affiliation: Department of Orthopedic Surgery, Seoul National University College of Medicine, Seoul 110-744, Korea.
authors.forename: Won Joon
authors.initials: WJ
authors.lastname: Yoo
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, and Institute of Radiation Medicine, SNUMRC, Seoul 110-744, Korea.
authors.forename: In-One
authors.initials: IO
authors.lastname: Kim
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, and Institute of Radiation Medicine, SNUMRC, Seoul 110-744, Korea.
authors.forename: Woo Sun
authors.initials: WS
authors.lastname: Kim
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, and Institute of Radiation Medicine, SNUMRC, Seoul 110-744, Korea.
authors.forename: Young Hun
authors.initials: YH
authors.lastname: Choi
mesh_terms: D000818:Animals; D001158:Arteries / Q000503:physiopathology; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004195:Disease Models, Animal; D004617:Embolism / Q000150:complications; D004838:Epiphyses / Q000098:blood supply* / Q000473:pathology*; D005270:Femur Head / Q000098:blood supply* / Q000473:pathology*; D008297:Male; D010020:Osteonecrosis / Q000473:pathology; D010384:Pelvic Bones / Q000098:blood supply / Q000473:pathology; D015427:Reperfusion Injury / Q000150:complications / Q000175:diagnosis*; D013552:Swine
keywords: Diffusion-weighted imaging; Dynamic contrast enhanced MRI; Femoral head ischemia