Measurement of single-kidney glomerular filtration rate using a contrast-enhanced dynamic gradient-echo sequence and the Rutland-Patlak plot technique

Purpose: 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. Materials and 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 50degrees 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. Conclusion: 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 GdDTPA should by reduced to avoid artificial signal drop in the excretory phase induced by the T2* effect.