Detection of Elastase-Induced Emphysema in Rat Lungs by Measuring Diffusion of Hyperpolarized 3 He , X.J. Chen, L.W. Hedlund, M.S. Chawla, H.E. Mller and G.A. Johnson, Duke University Medical Center, Durham, NC, USA and Westflische Wilhelms-Universitt, Mnster, Germany.