title: Quantitative renal cortical perfusion in human subjects with magnetic resonance imaging using iron-oxide nanoparticles: influence of T1 shortening.
abstract: BACKGROUND
  Using conventional contrast agents, the technique of quantitative perfusion by observing the transport of a bolus with magnetic resonance imaging (MRI) is limited to the brain due to extravascular leakage.
  
  
  OBJECTIVE
  To perform quantitative perfusion measurements in humans with an intravascular contrast agent, and to estimate the influence of the T1 relaxivity of the contrast agent on the first-pass response.
  
  
  METHODS
  Renal cortical perfusion was measured quantitatively in six patients with unilateral renal artery stenosis using a rapid gradient double-echo sequence in combination with an intravenous bolus injection of NC100150 Injection, an intravascular contrast agent based on iron-oxide nanoparticles. The influence of T1 relaxivity was measured by comparing perfusion results based on single- and double-echo data.
  
  
  RESULTS
  The mean values of cortical blood flow, cortical blood volume, and mean transit time in the normal kidneys were measured to 339+/-60 ml/min/100 g, 41+/-8 ml/100 g, and 7.3+/-1.0 s, respectively, based on double-echo data. The corresponding results based on single-echo data, which are not compensated for the T1 relaxivity, were 254+/-47 ml/min/100 g, 27+/-3 ml/100 g, and 6+/-1.2 s, respectively.
  
  
  CONCLUSIONS
  The use of a double-echo sequence enabled elimination of confounding T1 effects and consequent systematic underestimation of the perfusion.
authors.affiliation: Department of Diagnostic Radiology, Uppsala University Hospital, Uppsala, Sweden. arvid.morell@radiol.uu.se
authors.forename: A
authors.initials: A
authors.lastname: Morell
authors.forename: H
authors.initials: H
authors.lastname: Ahlstrom
authors.forename: S O
authors.initials: SO
authors.lastname: Schoenberg
authors.forename: A
authors.initials: A
authors.lastname: Abildgaard
authors.forename: M
authors.initials: M
authors.lastname: Bock
authors.forename: A
authors.initials: A
authors.lastname: Bjørnerud
mesh_terms: D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics*; D003911:Dextrans; D052203:Ferrosoferric Oxide; D006801:Humans; D007501:Iron / Q000008:administration & dosage / Q000493:pharmacokinetics*; D007672:Kidney Cortex / Q000098:blood supply* / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D010087:Oxides / Q000008:administration & dosage / Q000493:pharmacokinetics*; D012078:Renal Artery Obstruction / Q000503:physiopathology*; D012079:Renal Circulation
chemical_list: D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; C097921:ferumoxtran-10; D007501:Iron; D052203:Ferrosoferric Oxide