Glomerular filtration rate measured using the Patlak plot technique and contrast-enhanced dynamic MRI with different amounts of gadolinium-DTPA

We determined the optimum gadolinium (Gd)-DTPA dose and time window for calculating the glomerular filtration rate (GFR) using contrast-enhanced (CE) dynamic MRI and the Patlak plot technique. Twelve adult volunteers with healthy kidneys were included in the study. As a reference method the GFR was measured by iopromide plasma clearance. A three-dimensional gradient-echo (GRE) sequence with a flip angle of 50 degrees was used for MRI. Signal was measured using a body surface coil with four elements. Each volunteer was examined on four days using 2 mL, 4 mL, 8 mL, or 16 mL of Gd-DTPA 0.5 mmol/mL dissolved with sodium chloride (NaCl) 0.9% to a total of 60 mL. The injection rate was 1 mL/second. A Patlak plot was calculated from the kidney and aorta signals. The mean reference GFR was 133 mL/min (min-max, 116-153 mL/min). The best correlation of GFR calculated from MRI data compared to the reference method was found in a time window 30-90 seconds after aortic signal rise using 16 mL Gd-DTPA. Pearson's correlation coefficient was r = 0.83, and the standard deviation (SD) from the line of regression was 10.5 mL/minute. We found a significantly lower average GFR(MR) using 16 mL Gd-DTPA compared to 4 mL and 2 mL in the late time window 60-120 seconds post aortic rise. A dose of 16 mL Gd-DTPA was optimal for measuring GFR using dynamic MRI and the Patlak plot technique. The slope should be measured in a time window of 30-90 seconds post aortic rise.