Purpose: To prospectively demonstrate the feasibility of quantifying the glomerular filtration rate (GFR) by assessing the renal clearance of gadolinium-based contrast medium from the extracellular fluid volume in healthy volunteers.
Materials and methods: The study was approved by the ethics committee and the governmental drug administration department (registration number 4030139, EudraCT number 2004-002969-20, study protocol number 318/2004). Informed consent was obtained from 16 healthy volunteers (six female, 10 male; mean age, 24.5 years +/- 2.8 [standard deviation]). Thirteen volunteers (four women, nine men; mean age, 24.8 years +/- 2.7; range, 23-30 years) successfully contributed to the study. The GFR was assessed by recording the renal clearance of gadobutrol (3.75 mL, approximately 0.05 mmol per kilogram of body weight) at navigator-gated turbo fast low-angle shot magnetic resonance (MR) imaging. Time-signal intensity curves were constructed from manually drawn regions of interest in the liver, spleen, and renal cortex, and the GFR was calculated by using exponential fitting. Simultaneously obtained iopromide clearance measurements were the reference standard. Statistical evaluations included Bland-Altman plotting and analysis of the relative deviation from iopromide clearance.
Results: Evaluation of liver regions of interest revealed the lowest mean of paired differences from the iopromide clearance measurements (-5.9 mL/min per 1.73 m(2) +/- 14.6), with a mean GFR of 109.0 mL/min per 1.73 m(2) +/- 17.1 (134.1 mL/min per 1.73 m(2) +/- 35.4 for spleen, 100.7 mL/min per 1.73 m(2) +/- 25.1 for renal cortex) compared with a mean GFR of 103.1 mL/min per 1.73 m(2) +/- 9.4 measured by using iopromide clearance. The maximum deviation of MR-determined gadobutrol clearance values from iopromide clearance values was 29.2%. The mean disposition half-life of gadobutrol measured in the liver was 83.0 minutes +/- 14.2 (72.4 minutes +/- 20.2 in spleen, 92.6 minutes +/- 23.7 in renal cortex).
Conclusion: The described MR imaging method enables absolute quantification of the GFR after routine contrast material-enhanced MR imaging.