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

Abstract

Purpose:To determine the accuracy of single-kidney glomerular filtration rate (GFR) determination using contrastenhanced 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 50°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 ϭ 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 Gd-DTPA should by reduced to avoid artificial signal drop in the excretory phase induced by the T2* effect.

Kidney transplantation: Structural and functional evaluation using MR Nephro‐Urography

“…Implementation of highly accelerated postcontrast 3D GRE has also been shown useful for the quantitative evaluation of renal function (19,21,22). Advances in imaging technology have reduced imaging times such that a coronal volume of images through the kidney can now be acquired in approximately 1 second, while maintaining an isotropic resolution of 3 mm (22).…”

“…Glomerular filtration rate has been computed from this postprocessed data using the Rutland-Patlak plot, which assumes a two-compartment model of the vascular and nephron spaces (19). There are significant theoretical limitations of the 2-compartment model, which considers only the intravascular compartment and the filtered contrast within the renal tubules, but does not account for interstitial distribution.…”

Comparison of Gd‐DTPA and Gd‐BOPTA for studying renal perfusion and filtration

“…[8] are not directly measurable. A DCE-MRI measurement produces R 1 -weighted signals S(t), and an extra calculation and measurement is required to derive R 1 (t) from S(t).…”

“…Low molecular weight gadolinium chelates have a predominantly renal elimination by glomerular filtration without any tubular secretion or reabsorption (7). These substances have similar pharmacokinetics as tracers like inulin, EDTA, or iodinated contrast agents, and therefore allow for glomerular filtration rate (GFR) assessment with magnetic resonance imaging (MRI) (8)(9)(10)(11)(12). One potentially confounding factor is the interaction of the contrast agent and serum proteins.…”

“…[8] is the most general operational equation for MR renography. It relates the measurable quantities DR 1 (t) and DR 1A (t) to the four measurable parameters: the blood flow F P /(1-H), the tracer mean transit times T P and T T , and a parameter E (r 1T /r 1P ) proportional to the tracer extraction fraction E. The hematocrit H can be determined from blood tests, but other parameters, in particular the tubular flow or GFR, can only be determined when further assumptions are made on (1-k)b and the relaxivity ratio r 1T /r 1P .…”