NONINVASIVE MEASUREMENT OF RENAL HEMODYNAMIC FUNCTIONS USING GADOLINIUM-ENHANCED MAGNETIC-RESONANCE-IMAGING

A technique for the assessment of single kidney hemodynamic functions utilizing a novel MR pulse sequence in conjunction with MR contrast material administration scribed. Renal extraction fraction (EF) is derived 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 T-1 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 T-1 of blood determined. These T-1 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 T-1 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.