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Sodium magnetic resonance imaging of diuresis: Spatial and kinetic response
Author(s) -
Maril Nimrod,
Margalit Raanan,
Mispelter Joel,
Degani Hadassa
Publication year - 2005
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.20359
Subject(s) - furosemide , diuretic , mannitol , sodium , chemistry , diuresis , magnetic resonance imaging , in vivo , endocrinology , medicine , renal function , biochemistry , biology , radiology , microbiology and biotechnology , organic chemistry
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.