MR imaging of diffusion of He-3 gas in healthy and diseased lungs

Hyperpolarized He-3 gas MRI was used to form maps of the effective diffusiv ity of gas in human lungs. Images of diffusion as well as spin density are presented from a study of 11 healthy volunteers and 5 patients with severe emphysema. The effective rate of diffusion, D-e, of the gas is reduced by t he alveolar walls; tissue destruction in emphysema is hypothesized to resul t in larger D-e. Indeed, the mean value of D-e in the emphysematous lungs i s found here to be about 2.5 times that of healthy lungs, although still sm aller than the unrestricted diffusivity of He-3 in free air. Histograms of D-e values across coronal slices are presented. The results are discussed i n terms of spatial variations, variations among individuals, healthy and di seased, and variations due to changes in lung volume. Magn Reson Med 44:174 -179, 2000. (C) 2000 Wiley-Liss, Inc.