title: Correlation of biexponential diffusion parameters with arterial spin-labeling perfusion MRI: results in transplanted kidneys.
abstract: OBJECTIVE
  The purpose of the present study was to explore the correlation between diffusion parameters assessed by biexponential analysis and the tissue perfusion measured by arterial spin labeling (ASL) imaging in renal allografts.
  
  
  METHODS
  Seventeen recipients of renal allograft (11 men and 6 women; mean [SD] age, 53.6 [14.1] years) were included in this study. For diffusion-weighted imaging, a paracoronal echo-planar imaging sequence was acquired with 16 b values (range, b = 0-750 s/mm²) and 6 averages at 1.5 T. For the quantitative assessment of transplanted kidney perfusion, a flow-sensitive alternating inversion recovery true fast imaging with steady precession-ASL technique was applied. No respiratory gating was used. For quantitative analysis, region of interest measurements were performed on parameter maps. The Spearman correlation coefficients were calculated to determine the association between mean serum creatinine levels, estimated glomerular filtration rate, the apparent diffusion coefficient (ADC) of pure diffusion, the ADC of pseudodiffusion, the monoexponential ADC, the fraction of pseudodiffusion, and the tissue perfusion ASL values.
  
  
  RESULTS
  In the renal cortex, the fraction of pseudodiffusion was 17.4% ± 4.0%, the apparent diffusion coefficient of pure diffusion was 160.7 ± 15.0 × 10⁻⁵ mm²/s, the monoexponential ADC was 193.2 ± 16.7 × 10⁻⁵ mm²/s, and the ADC of pseudodiffusion was 1421.0 ± 237.7 × 10⁻⁵ mm²/s. Mean cortical perfusion of renal allografts, as assessed with ASL imaging, was 247.2 ± 75.0 mL/100 g/min. There was a significant correlation between ASL perfusion and the fraction of pseudodiffusion (r = 0.68; P < 0.005) but not with the other diffusion coefficients. Both ASL perfusion and the fraction of pseudodiffusion exhibited a significant correlation with serum creatinine levels (r = 0.51 and r= 0.53, respectively; P < 0.05) and estimated glomerular filtration rate (r = 0.63 and r = 0.54, respectively; P < 0.05).
  
  
  CONCLUSIONS
  This is the first study that shows a significant correlation between renal allograft perfusion, as assessed with ASL perfusion measurements, and the fraction of pseudodiffusion derived from biexponential diffusion-weighted imaging measurements.
authors.affiliation: Department of Diagnostic and Interventional Radiology, Medical Faculty, University of Dusseldorf, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Heusch
authors.forename: Hans-Jörg
authors.initials: HJ
authors.lastname: Wittsack
authors.forename: Till
authors.initials: T
authors.lastname: Heusner
authors.forename: Christian
authors.initials: C
authors.lastname: Buchbender
authors.forename: Michael Nguyen
authors.initials: MN
authors.lastname: Quang
authors.forename: Petros
authors.initials: P
authors.lastname: Martirosian
authors.forename: Philip
authors.initials: P
authors.lastname: Bilk
authors.forename: Patric
authors.initials: P
authors.lastname: Kröpil
authors.forename: Dirk
authors.initials: D
authors.lastname: Blondin
authors.forename: Gerald
authors.initials: G
authors.lastname: Antoch
authors.forename: Rotem S
authors.initials: RS
authors.lastname: Lanzman
mesh_terms: D001783:Blood Flow Velocity; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D016030:Kidney Transplantation; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012077:Renal Artery / Q000503:physiopathology*; D012079:Renal Circulation; D051436:Renal Insufficiency, Chronic / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels; D013223:Statistics as Topic
chemical_list: D013113:Spin Labels