Hyperpolarized 129Xe as a novel probe agent of lung functions in MRI and MRS. Experimental results with mice at 9.4 T

Abstract

Two-dimensional nuclear magnetic resonance (2D-NMR) of hyperpolarized 129Xe has been measured under a high magnetic field of 9.4 T. A homemade glassware-based apparatus was utilized to produce the hyperpolarized noble gas. The degree of polarization was 3–5% with the Xe gas in natural isotopic abundance. The Exchange Spectroscopy (EXSY) version of the 2D-NMR was first applied to systems in vivo. The exchange phenomenon on the surface of alveoli in mouse lungs was observed, after a preliminary application of the method to porous materials used in analytical chemistry, to test the successful performance of the 2D-EXSY experiment with hyperpolarized noble gas. The EXSY experiments have proven the existence of the exchange phenomenon between the gas phase and the adsorbed or dissolved phase, and the exchange rate constants have been estimated from the quantitative treatment of the EXSY data. The rate constants are expected to be used as an alternative novel indicator of lung functions since the rate constants reflect the properties of both the gas phase and the dissolved phase in lungs. This is in contrast with the apparent diffusion coefficient (ADC) hitherto proposed, which monitors diffusion only in the gas phase. © 2004 Elsevier B.V.