Paramagnetic enhanced proton magnetic resonance measurement in rats: Correlates with renal function

Abstract

Renal cortical, medullar and papillary T 1 and T 2 relaxation times were measured in rats with normal ( n = 13) and impaired renal function ( n = 11) with a Bruker Multispec, 20 MHz at 37°C. In one group of seven rats, decreased renal function was obtained by 50% glycerol solution administration (10 ml/kg-body weight) 24 hours before the experiment, while in another group of four rats the renal function was decreased, by ureteral ligation for 72 hours. Immediately after the excision of one kidney, Gadolinium-DTPA (70 μmole/kg body weight) was injected intravenously. The second kidney was excised 5 min later. From the T 1 and T 2 relaxation times measured in the cortex, medulla, and papilla, their respective ratios before and after GdDTPA administration were calculated and correlated with GFR determined by creatinine clearance ( C cr range was between 0 and 850 μl/min/g kidney weight). For T 1: the ratios in the cortex, medulla, and papilla the correlation coefficients were r = 0.81 ( p < 0.001), r = 0.85 ( p < 0.001), and r = 0.87 ( p < 0.0001), respectively. The respective correlation coefficient r values for T 2 were r = 0.38 (NS), r = 0.76 ( p < 0.001), and r = 0.73 ( p < 0.001). The present study indicates that a combination of MR measurements, with and without GdDTPA paramagnetic enhancement, can offer a new possibility for obtaining information on renal function and suggest the possibility of concomitant anatomo functional magnetic resonance imaging.