Sodium magnetic resonance imaging of diuresis: Spatial and kinetic response

✍ Scribed by Nimrod Maril; Raanan Margalit; Joel Mispelter; Hadassa Degani

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 547 KB
• Volume: 53
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.20359

✦ Synopsis

Abstract

Renal function is highly correlated with the sodium concentration gradient along the corticomedullary axis. The application of 3D high‐resolution sodium magnetic resonance imaging (MRI) provided a means to quantify in vivo the spatial and temporal changes in renal tissue sodium concentration under normal and diuretic conditions. A detailed, pixel‐by‐pixel analysis of the intact rat kidney sodium MR images yielded a quantitative measure of the corticomedullary sodium gradient before and at early and later times after the administration of two distinct diuretic agents, furosemide and mannitol. Furosemide, a loop diuretic, induced a fivefold reduction in the cortical‐outer medullary sodium gradient, whereas mannitol, an osmotic diuretic, did not affect this gradient. Both diuretics induced a 50% decrease in the sodium concentration of the inner medulla; however, mannitol exerted its effect twice as fast as furosemide with a 2.5‐min exponential decay constant. These specific changes were attributed to the different mechanism of action and site of activity of each diuretic agent. Thus, high‐resolution ^23^Na MRI offers a unique, noninvasive tool for functional imaging of the kidney physiology. Magn Reson Med 53:545–552, 2005. © 2005 Wiley‐Liss, Inc.