title: Diffusion-weighted MR Imaging for the Assessment of Renal Function: Analysis Using Statistical Models Based on Truncated Gaussian and Gamma Distributions.
abstract: OBJECTIVE
  To determine the appropriateness of statistical models using the truncated Gaussian distribution and gamma distribution for diffusion signal decay, and to assess the correlation between the parameters obtained from the statistical models and estimated glomerular filtration rate (eGFR).
  
  
  METHODS
  Twenty-nine patients with chronic kidney disease and 21 healthy volunteers were included and classified in four groups according to eGFR (ml/min/1.73 m(2)): group 1 (90 ≤ eGFR, n = 10), group 2 (eGFR 60-90, n = 15), group 3 (eGFR 30-60, n = 17), and group 4 (eGFR < 30, n = 8). Diffusion-weighted imaging using five b-values (0, 500, 1000, 1500, and 2000 s/mm(2)) was performed. Truncated Gaussian and gamma models were compared for goodness of fit. Area fractions for the diffusion coefficient D < 1.0 × 10(-3) mm(2)/s (Frac < 1.0) and D > 3.0 × 10(-3) mm(2)/s (Frac > 3.0) obtained from the statistical model were compared among four groups. Correlation between proposed parameters and conventional apparent diffusion coefficient (ADC) with eGFR was calculated.
  
  
  RESULTS
  There was no significant difference in goodness of fit between the truncated Gaussian and gamma models. Frac < 1.0 and Frac > 3.0 showed good correlation with eGFR, as did ADC. Comparison between groups 1 and 2 showed that only Frac < 1.0 in both distribution models had significant differences.
  
  
  CONCLUSIONS
  Statistical models yield robust interpretation of diffusion magnetic resonance (MR) signals with relevance to histological changes in the kidney. The parameters of the statistical models, particularly Frac < 1.0, strongly correlated with eGFR.
authors.affiliation: Department of Radiology, National Defense Medical College.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yamada
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shinmoto
authors.forename: Koichi
authors.initials: K
authors.lastname: Oshio
authors.forename: Seigo
authors.initials: S
authors.lastname: Ito
authors.forename: Hiroo
authors.initials: H
authors.lastname: Kumagai
authors.forename: Tatsumi
authors.initials: T
authors.lastname: Kaji
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging* / Q000502:physiology*; D007677:Kidney Function Tests / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical