Diffusion magnetic resonance imaging in multiple sclerosis.

This paper reviews the use of magnetic resonance diffusion imaging in studies of multiple sclerosis. Firstly, the principles of diffusion imaging are explained together with a discussion of the hardware and techniques required. The concept of diffusion tensor imaging is introduced and images obtained using this method are presented. Studies that have used diffusion imaging in patients with multiple sclerosis and the implications of the results are discussed. There is an increase in the diffusion coefficient of water molecules in the plaques of patients with multiple sclerosis, compared with healthy brain. Some workers also report increased diffusion in the normal appearing white matter of some patients with multiple sclerosis. Possible mechanisms are given for these findings, together with the experimental evidence to support them.