DIFFUSION IMAGING WITH HYPERPOLARIZED HE-3 GAS

We used MRI of hyperpolarized He-3 to demonstrate some novel aspects o f gas diffusion, Two different techniques were used, First, a slice wa s burned into a one-dimensional image by inverting the spins in the sl ice and diffusion was studied by measuring the magnetization as it fil led the depleted slice. A diffusion coefficient was determined by the fit of these data, Second, one-dimensional diffusion images were made using a Stejskal-Tanner PGSE method, This was done with and without a temperature gradient present, showing that the effect of temperature c an be dynamically monitored by such diffusion images. (C) 1997 Academi c Press.