Rationale and objectivesThe authors demonstrate the feasibility of monitoring renal status continuously and noninvasively at a patient's bedside, avoiding both radioactivity and blood and urine samples.MethodsGadolinium-153-labeled ProHance and a glomerular filtration rate (GFR) standard technetium-99m-DTPA were coadministered to anesthetized normal and nephrectomized rats with their tails hanging in a PC 20 spin analyzer. Blood samples and T1 measurements were collected and analyzed.ResultsLog time plots of153Gd,99mTc (from blood samples) and T1 of the rat tails were all linear and parallel. Halftimes were 32 plusmn; 2, 32 plusmn; 6, and 32 plusmn; 6 minutes for the decay of the T1,153Gd and99mTc, respectively. The halftime of the nephrectomized animal was 2000 plusmn; 4000 minutes.ConclusionsT1 of an appendage remote from the kidneys reflects the concentration of gadolinium in the blood, which is in rapid equilibrium with tissue interstitial space gadolinium. The decay in T1 of the appendage reflects glomerular filtration. Thus, it is feasible to detect changes in renal status at a patient's bedside by monitoring T1 of a finger or wrist using a small, inexpensive magnet.
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