23Na magnetic resonance imaging of tissue sodium

Abstract

Hypertension is linked to disturbed total-body sodium (Na +) regulation; however, measuring Na + disposition in the body is difficult. We implemented 23Na + magnetic resonance spectroscopy ( 23Na +-MR) and imaging technique ( 23Na +-MRI) at 9.4T for animals and 3T for humans to quantify Na + content in skeletal muscle and skin. We compared 23Na +-MRI data with actual tissue Na + content measured by chemical analysis in animal and human tissue. We then quantified tissue Na + content in normal humans and in patients with primary aldosteronism. We found a 29% increase in muscle Na + content in patients with aldosteronism compared with normal women and men. This tissue Na + was mobilized after successful treatment without accompanying weight loss. We suggest that, after further refinements, this tool could facilitate understanding the relationships between Na accumulation and hypertension. Furthermore, with additional technical advances, a future clinical use may be possible. © 2011 American Heart Association, Inc.