Determinants of tissue delivery for 129Xe magnetic resonance in humans.

Magnetic resonance imaging using laser-polarized 129Xe is a new technique first demonstrated by Albert et. al. (Nature 370, 1994) who obtained a 129Xe image of an excised mouse lung. This paper describes the factors influencing the accumulation of inhaled, polarized 129Xe in human tissue. The resulting model predicts the 129Xe magnetization in different tissues as a function of the time from the start of inhalation, the tissue perfusion rate and partition coefficient for xenon, and the relevant T1 decay times. The relaxation times of 129Xe in biological tissues are not yet known precisely. Substitution of estimated values for these parameters results in an expected signal-to-noise ratio (SNR) from polarized 129Xe MR in the brain of approximately 2% of the equivalent SNR from proton MR.