A double-tuned (1)H/(23)Na dual resonator system for tissue sodium concentration measurements in the rat brain via Na-MRI.
A method for quantifying the tissue sodium concentration (TSC) in the rat brain from ²³Na-MR images was developed. TSC is known to change in a variety of common human diseases and holds considerable potential to contribute to their study; however, its accurate measurement in small laboratory animals has been hindered by the extremely low signal to noise ratio (SNR) in ²³Na images. To address this, the design, construction and characterization of a double-tuned ¹H/²³Na dual resonator system for ¹H-guided quantitative ²³Na-MRI are described. This system comprises an SNR-optimized surface detector coil for ²³Na image acquisition, and a volume resonator producing a highly homogeneous B₁ field (<5% inhomogeneity) for the Na channel across the rat head. The resonators incorporated channel-independent balanced matching and tuning capabilities with active decoupling circuitry at the ²³Na resonance frequency. A quantification accuracy of TSC of <10 mM was achieved in Na-images with 1.2 µl voxel resolution acquired in 10 min. The potential of the quantification technique was demonstrated in an in vivo experiment of a rat model of cerebral stroke, where the evolution of the TSC was successfully monitored for 8 h after the stroke was induced.
School of Physics, Trinity College Dublin, University of Dublin, Ireland. Computer Assisted Clinical Medicine, Medical Faculty Mannheim, University of Heidelberg, Germany.
Friedrich
F
Wetterling
Martin
M
Tabbert
Sven
S
Junge
Lindsay
L
Gallagher
I Mhairi
IM
Macrae
Andrew J
AJ
Fagan
D000818:Animals; D001921:Brain / Q000378:metabolism*; D002545:Brain Ischemia / Q000175:diagnosis / Q000378:metabolism; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D008297:Male; D019047:Phantoms, Imaging; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000378:metabolism*; D013499:Surface Properties
D012964:Sodium