title: Measurement of single-kidney glomerular filtration rate using a contrast-enhanced dynamic gradient-echo sequence and the Rutland-Patlak plot technique.
abstract: OBJECTIVE
  To determine the accuracy of single-kidney glomerular filtration rate (GFR) determination using contrast-enhanced dynamic magnetic resonance imaging (MRI) and the Rutland-Patlak plot technique.
  
  
  METHODS
  Twenty-eight adult patients were included. As reference method, the GFR was measured by plasma clearance using a small bolus injection of iopromide. A three-dimensional gradient-echo (GRE) sequence with a flip angle of 50 degrees was used for MRI; this showed a good linear relationship between gadolinium (Gd)-DTPA concentration and signal change when measured up to a Gd-DTPA concentration of 10 mmol/liter. A slab containing both kidneys and the abdominal aorta was measured 30 times in approximately 3.5 minutes. During this measurement, 15 mL of Gd-DTPA, 0.5 mol/liter diluted to a volume of 60 mL, was injected over 60 seconds. A Rutland-Patlak plot was calculated from the signal changes in the aorta and the renal parenchyma. Single-kidney GFR was calculated for different time windows from the Rutland-Patlak plot slope.
  
  
  RESULTS
  The best correlation compared to the reference method was found with the GFR calculated from the slope of the Rutland-Patlak plot 40-110 seconds postaortic rise. Pearson's correlation coefficient was r = 0.86, SD was 14.8 mL/minute. In many of the patients, a decrease of the renal signal was observed in the excretory phase, which was probably caused by very high Gd-DTPA concentrations in the collecting tubules.
  
  
  CONCLUSIONS
  Single-kidney GFR can be calculated from dynamic contrast-enhanced MRI. We found a promising correlation of global GFR calculated by MRI compared to the reference method. In any future study, the amount of Gd-DTPA should by reduced to avoid artificial signal drop in the excretory phase induced by the T2* effect.
authors.affiliation: Department of Diagnostic Radiology, Justus-Liebig Universität Giessen, Giessen, Germany. nils.hackstein@radiol.med.uni-giessen.de
authors.forename: Nils
authors.initials: N
authors.lastname: Hackstein
authors.forename: Jan
authors.initials: J
authors.lastname: Heckrodt
authors.forename: Wigbert S
authors.initials: WS
authors.lastname: Rau
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media / Q000008:administration & dosage; D017352:Echo-Planar Imaging / Q000295:instrumentation / Q000379:methods*; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D007674:Kidney Diseases / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D019047:Phantoms, Imaging; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA