Perfusion and diffusion imaging

This article reviews the measurement of perfusion and diffusion and discusses the implications of the observed anisotropy of diffusion of water molecules in some tissues. An experiment is described which shows how observations of diffusion anisotropy can be used to obtain structural information for a model system and to estimate tissue propertiesin vivo. Differences between perfusion and diffusion are highlighted, and the impact of the former on temperature measurementsin vivo based on MRI is discussed. The article concludes that the observation of these phenomena are worth very substantial effort in order to elucidate a number of quite significant problems in the practice of magnetic resonance imaging today.