Rat brain perfusion measurements with hyperpolarized 129Xe-NMR:: study of biological fluids for the delivery of 129Xe.

The high xenon solubility in blood and tissues makes hyperpolarized '='Xe a potential bIR tracer for tissue perfusion studies. Two biocompatible fluids were studied with a view to be used as delivery media for hyperpolarized xenon injection: the carrier agents were Xe-129 micro-bubbles in Echovist (2-3 mum in diameter), and Intralipid Xe-129 suspension. Xenon chemical shifts and longitudinal relaxation time T-1 were treasured at 2.35 T in both fluids. Xenon chemical shift of the dissolved phase in Echovist was 204.1 +/-0.5 ppm from the micro-bubbles gas phase resonance data (0 ppm). Xenon T-1 was 20.0 s in micro-bubbles in Echovist and 19.0 s for the dissolved phase. Xenon chemical shift in Intralipid was 194.6 +/-0.5 ppm. T-1 as 15.2 +/-4.9 s (n = 5) in Intralipid 20% and 20.9 +/-2.9 s (n = 4) in Intralipid 30%. Using an intra-carotid injection of a small volume (0.15 mL) of hyperpolarized xenon dissolved in Intralipid 30%, cerebral blood flow was measured in rats (160 +/- 30 mL(.)(100 g)(-1.)min(-1), n = 10). Rat brain xenon images were performed with 2-D projection-reconstruction pulse sequence, enabling regional blood flow measurements. (C) 2001 Academic des sciences/Editions scientifiques et medicales Elsevier SAS.