Abstract
Perfluorinated gases, particularly C~2~F~6~, are potentially suitable alternatives to hyperpolarized noble gases for pulmonary airspace spin density and diffusion MRI. This work focuses mainly on ^19^F imaging of C~2~F~6~ gas in healthy and emphysematous explanted lungs, avoiding regulatory issues of human in vivo measurements. Three‐dimensional gradient echo and spin echo spin density images of human lungs can be made in 10 s with adequate signal‐to‐noise, demonstrating the feasibility for breathing dynamics to be captured during a succession of short breath holds. As expected, the spin echo images have much smaller susceptibility artifacts than the gradient echo images. ^19^F and ^3^He images of the same lungs are compared. The apparent diffusion coefficient (ADC) of C~2~F~6~ is sensitive to restrictions imposed by the lung microstructure: the average ADC is measured to be 0.018 cm^2^/s in healthy lungs versus 0.031 cm^2^/s in emphysematous lungs at a diffusion time Δ = 2.2 ms. The low free diffusivity of pure C~2~F~6~ (D~0~ = 0.033 cm^2^/s) places it in a regime where the ADC measurement allows the surface‐to‐volume ratio to be determined in each voxel, a potentially valuable quantitative characterization of regional lung tissue destruction in emphysema. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.