Noninvasive measurement of renal hemodynamic functions using gadolinium enhanced magnetic resonance imaging

Abstract

A technique for the assessment of single kidney hemodynamic functions utilizing a novel MR pulse sequence in conjunction with MR contrast material administration is described. Renal extraction fraction (EF) is derived by measuring the concentration of the incoming contrast agent in the renal artery and the outgoing concentration in the renal vein. The glomerular filtration rate (GFR) can then be determined by the product of EF and renal plasma flow. A modified inversion recovery MR pulse sequence is used to measure the T1 of moving blood. This pulse sequence uses a spatially nonselective inversion pulse. A series of small flip angle detection pulses are then used to monitor the recovery of longitudinal spin magnetization in an image plane intersecting the renal vessels. The recovery rate is measured in each vessel and the T1 of blood determined. These T1 measurements are then used to determine the ratio of contrast concentration in the renal arteries and veins. Blood flow measurements can be obtained simultaneously with T1 measurements by inserting flow-encoding magnetic field gradients into the pulse sequence. Preliminary results in human volunteers suggest the feasibility of noninvasively determining hemodynamic functions with magnetic resonance.

Functional MRI of the kidney: tools for translational studies of pathophysiology of renal disease

“…Several groups have published results based on this approach to measure single-kidney GFR (22,31,96). The major disadvantage of this approach is the necessity for concentration and blood flow measurements in relatively small vessels.…”

“…Several approaches have been proposed to measure tissue pH by magnetic resonance. Some exploit the difference in 31 P or 1 H resonances (90,142,149). However, these are limited in terms of imaging applications.…”

T1 measurement of flowing blood and arterial input function determination for quantitative 3D T1‐weighted DCE‐MRI

“…The latter manifests as a signal enhancement due to the flow of fresh blood with fully relaxed spins into the imaging slice, which results in an apparent T 1 shortening and falsely measured high contrast concentrations. Nonselective inversion of all blood magnetization within the subject can be applied, but this in-flow correction method is limited to single-slice acquisitions (2). The simplest and most common solution is to assume a T 1 value and ignore errors due to variations in hematocrit, temperature, and blood oxygen.…”

Magnetic Resonance Imaging of Renal Disease: Recent Developments and Future Applications

“…Early developments of MRR-based single kidney function validated the technique by establishing the correlation with elevated serum creatinine level and with dynamic gamma-camera scintigraphy [36]. One recently published approach to measuring single kidney GFR by using MRI was proposed by Dumoulin et al [37], who calculated GFR by multiplying renal plasma flow (determined with MR PC imaging) by gadopentetate dimeglumine extraction fraction (calculated by using T1 relaxation measurements of blood in the renal artery or aorta and renal vein or inferior vena cava during steady-state intravenous infusions of gadolinium-based contrast material). It has to be mentioned that Gd doses should be <0.1 mmol/kg, as the T2* effects of gadolinium chelates result in decreased rather than increased signal intensity in areas of concentrated contrast material such as the renal medulla [38].…”