Because gas diffusion rapidly senses alveolar boundaries, the low diffusion constant of xenon offers advantages over hyperpolarized helium. This advantage can be extended by further reducing the diffusion constant of xenon atoms by preparing the residual gas in the lungs with an inert low diffusion component like sulfurhexafluoride. Furthermore, if the concentration of this component is properly prepared, then the diffusion constant of xenon in the residual lung gas can be matched to that of the inspired gas. This matching eliminates any uncertainty in the gas diffusion constant.

The use of sulfurhexafluoride to reduce the diffusion constant of hyperpolarized Helium-3 in lungs may be similarly beneficial.