Xenon-129 MR imaging and spectroscopy of rat brain using arterial deliveryof hyperpolarized xenon in a lipid emulsion

Hyperpolarized Xe-129 dissolved in a lipid emulsion constitutes an NMR trac er that can be injected into the blood stream, enabling blood-flow measurem ent and perfusion imaging. A small volume (0.15 ml) of this tracer was inje cted in 1.5 s in rat carotid and Xe-129 MR spectra and images were acquired at 2.35 T to evaluate the potential of this approach for cerebral studies. Xenon spectra consistently showed two resonances, at 194.5 ppm and 199.0 p pm relative to the gas peak. The signal-to-noise ratio (SNR) obtained for t he two peaks was sufficient (ranging from 12 to 90) to follow their time co urses. 2D transverse-projection xenon images were obtained with an in-plane resolution of 900 mum per pixel (SNR range 8-15). Histological analysis re vealed no brain damage except in two rats that had received three injection s. (C) 2001 Wiley-Liss, Inc.