title: Evaluation of renal allograft function early after transplantation with diffusion-weighted MR imaging.
abstract: OBJECTIVE
  To determine the inter-patient variability of apparent diffusion coefficients (ADC) and concurrent micro-circulation contributions from diffusion-weighted MR imaging (DW-MRI) in renal allografts early after transplantation, and to obtain initial information on whether these measures are altered in histologically proven acute allograft rejection (AR).
  
  
  METHODS
  DW-MRI was performed in 15 renal allograft recipients 5-19 days after transplantation. Four patients presented with AR and one with acute tubular necrosis (ATN). Total ADC (ADC(T)) was determined, which includes diffusion and micro-circulation contributions. Furthermore, diffusion and micro-circulation contributions were separated, yielding the "perfusion fraction" (F(P)), and "perfusion-free" diffusion (ADC(D)).
  
  
  RESULTS
  Diffusion parameters in the ten allografts with stable function early after transplantation demonstrated low variabilities. Values for ADC(T) and ADC(D) were (x10(-5) mm(2)/s) 228 +/- 14 and 203 +/- 9, respectively, in cortex and 226 +/- 16 and 199 +/- 9, respectively, in medulla. F(P) values were 18 +/- 5% in cortex and 19 +/- 5% in medulla. F(P) values were strongly reduced to less than 12% in cortex and medulla of renal transplants with AR and ATN. F(P) values correlated with creatinine clearance.
  
  
  CONCLUSIONS
  DW-MRI allows reliable determination of diffusion and micro-circulation contributions in renal allografts shortly after transplantation; deviations in AR indicate potential clinical utility of this method to non-invasively monitor derangements in renal allografts.
authors.affiliation: Department of Nephrology and Hypertension, University Hospital of Bern, Bern, Switzerland.
authors.forename: Ute
authors.initials: U
authors.lastname: Eisenberger
authors.forename: Harriet C
authors.initials: HC
authors.lastname: Thoeny
authors.forename: Tobias
authors.initials: T
authors.lastname: Binser
authors.forename: Mathias
authors.initials: M
authors.lastname: Gugger
authors.forename: Felix J
authors.initials: FJ
authors.lastname: Frey
authors.forename: Chris
authors.initials: C
authors.lastname: Boesch
authors.forename: Peter
authors.initials: P
authors.lastname: Vermathen
mesh_terms: D000328:Adult; D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D016030:Kidney Transplantation / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D051437:Renal Insufficiency / Q000175:diagnosis* / Q000601:surgery*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome