Three-dimensional triple-quantum-filtered 23Na imaging of the dog head in vivo.
Multiple-quantum (MQ) -filtered 23Na NMR has been proposed as a means to partially discriminate between intracellular and extracellular sodium. However, low signal-to-noise ratio (SNR) has been a major obstacle to MQ-filtered 23Na imaging becoming an important technique for biological and clinical applications. We compared the various MQ-filtered 23Na imaging pulse sequences to select the optimum sequence that provides the best SNR. The results of phantom experiments show that the gradient-echo MQ-filtered 23Na imaging sequence produces the best SNR. We also report, for the first time, three-dimensional single-quantum (SQ) and triple-quantum (TQ) -filtered 23Na images of the live dog brain and demonstrate the sensitivity of these images to ischemia produced by euthanizing the animal. The SQ images showed a 10% to 15% decrease in signal intensity from the brain post-mortem, whereas the TQ-filtered images showed a 40% to 50% increase. These changes in signal intensities are consistent with the influx of Na+ into the cells upon death. The feasibility of obtaining TQ-filtered 23Na images of in situ dog brain encourages us to apply this technique to humans.
Kalyanapuram
R
R
Department of Biomedical Engineering Program, University of Texas Southwestern Medical Center, Dallas 75235-9085, USA.
Seshan
V
V
Bansal
N
N
D000818:Animals; D001921:Brain / Q000033:anatomy & histology* / Q000378:metabolism*; D002545:Brain Ischemia / Q000378:metabolism; D004285:Dogs; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D012964:Sodium / Q000378:metabolism; D012975:Sodium Isotopes
D012975:Sodium Isotopes; D012964:Sodium