title: Intravoxel incoherent motion and diffusion-tensor imaging in renal tissue under hydration and furosemide flow challenges.
abstract: OBJECTIVE
  To assess the reproducibility and the distribution of intravoxel incoherent motion (IVIM) and diffusion-tensor (DT) imaging parameters in healthy renal cortex and medulla at baseline and after hydration or furosemide challenges.
  
  
  METHODS
  Using an institutional review board-approved HIPAA-compliant protocol with written informed consent, IVIM and DT imaging were performed at 3 T in 10 volunteers before and after water loading or furosemide administration. IVIM (apparent diffusion coefficient [ADC], tissue diffusivity [D(t)], perfusion fraction [f(p)], pseudodiffusivity [D(p)]) and DT (mean diffusivity [MD], fractional anisotropy [FA], eigenvalues [λ(i)]) imaging parameters and urine output from serial bladder volumes were calculated. (a)Reproducibility was quantified with coefficient of variation, intraclass correlation coefficient, and Bland-Altman limits of agreement; (b) contrast and challenge response were quantified with analysis of variance; and (c) Pearson correlations were quantified with urine output.
  
  
  RESULTS
  Good reproducibility was found for ADC, D(t), MD, FA, and λ(i) (average coefficient of variation, 3.7% [cortex] and 5.0% [medulla]), and moderate reproducibility was found for D(p), f(p), and f(p) · D(p) (average coefficient of variation, 18.7% [cortex] and 25.9% [medulla]). Baseline cortical diffusivities significantly exceeded medullary values except D(p), for which medullary values significantly exceeded cortical values, and λ(1,) which showed no contrast. ADC, D(t), MD, and λ(i) increased significantly for both challenges. Medullary diffusivity increases were dominated by transverse diffusion (1.72 ± 0.09 [baseline] to 1.79 ± 0.10 [hydration] μm(2)/msec, P = .0059; or 1.86 ± 0.07 [furosemide] μm(2)/msec, P = .0094). Urine output correlated with cortical ADC with furosemide (r = 0.7, P = .034) and with medullary λ(1) (r = 0.83, P = .0418), λ(2) (r = 0.85, P = .0301), and MD (r = 0.82, P = .045) with hydration.
  
  
  CONCLUSIONS
  Diffusion MR metrics are sensitive to flow changes in kidney induced by diuretic challenges. The results of this study suggest that vascular flow, tubular dilation, water reabsorption, and intratubular flow all play important roles in diffusion-weighted imaging contrast.
authors.affiliation: Department of Radiology, NYU Langone Medical Center, 660 First Ave, 4th Floor, New York, NY 10016, USA. eric.sigmund@nyumc.org
authors.forename: Eric E
authors.initials: EE
authors.lastname: Sigmund
authors.forename: Pierre-Hugues
authors.initials: PH
authors.lastname: Vivier
authors.forename: Dabang
authors.initials: D
authors.lastname: Sui
authors.forename: Nicole A
authors.initials: NA
authors.lastname: Lamparello
authors.forename: Kristopher
authors.initials: K
authors.lastname: Tantillo
authors.forename: Artem
authors.initials: A
authors.lastname: Mikheev
authors.forename: Henry
authors.initials: H
authors.lastname: Rusinek
authors.forename: James S
authors.initials: JS
authors.lastname: Babb
authors.forename: Pippa
authors.initials: P
authors.lastname: Storey
authors.forename: Vivian S
authors.initials: VS
authors.lastname: Lee
authors.forename: Hersh
authors.initials: H
authors.lastname: Chandarana
mesh_terms: D000328:Adult; D000465:Algorithms; D000704:Analysis of Variance; D016880:Anisotropy; D056324:Diffusion Tensor Imaging / Q000379:methods*; D004232:Diuretics / Q000008:administration & dosage*; D005260:Female; D005665:Furosemide / Q000008:administration & dosage* / Q000378:metabolism*; D006801:Humans; D007275:Injections, Intravenous; D007668:Kidney / Q000378:metabolism*; D008297:Male; D009038:Motion; D015203:Reproducibility of Results
chemical_list: D004232:Diuretics; D005665:Furosemide