title: Estimation of single-kidney glomerular filtration rate without exogenous contrast agent.
abstract: OBJECTIVE
  Measurement of single-kidney filtration fraction and glomerular filtration rate (GFR) without exogenous contrast is clinically important to assess renal function and pathophysiology, especially for patients with comprised renal function. The objective of this study is to develop a novel MR-based tool for noninvasive quantification of renal function using conventional MR arterial spin labeling water as endogenous tracer.
  
  
  METHODS
  The regional differentiation of the arterial spin labeling water between the glomerular capsular space and the renal parenchyma was characterized and measured according to their MR relaxation properties (T1ρ or T2 ), and applied to the estimation of filtration fraction and single-kidney GFR. The proposed approach was tested to quantify GFR in healthy volunteers at baseline and after a protein-loading challenge.
  
  
  RESULTS
  Biexponential decay of the cortical arterial spin labeling water MR signal was observed. The major component decays the same as parenchyma water; the minor component decays much slower as expected from glomerular ultra-filtrates. The mean single-kidney GFR was estimated to be 49 ± 9 mL/min at baseline and increased by 28% after a protein-loading challenge.
  
  
  CONCLUSIONS
  We developed an arterial spin labeling-based MR imaging method that allows us to estimate renal filtration fraction and singe-kidney GFR without use of exogenous contrast.
authors.affiliation: Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Xiang
authors.initials: X
authors.lastname: He
authors.forename: Ayaz
authors.initials: A
authors.lastname: Aghayev
authors.forename: Serter
authors.initials: S
authors.lastname: Gumus
authors.forename: K
authors.initials: K
authors.lastname: Ty Bae
mesh_terms: D000465:Algorithms; D003287:Contrast Media; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007668:Kidney / Q000033:anatomy & histology* / Q000502:physiology*; D007677:Kidney Function Tests / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels
chemical_list: D003287:Contrast Media; D013113:Spin Labels
keywords: T1ρ; T2; arterial spin labeling (ASL); renal filtration fraction; single-kidney GFR