DIFFUSION-WEIGHTED IMAGING IN EPILEPSY

Diffusion-weighted imaging (DWI) is a relatively new magnetic resonanc e imaging (MRI) technique that can be used to probe the microenvironme nt of water. Contrast in DWI depends on properties different from trad itional T-1 and T-2 contrast, and is derived from the translational mo tion of water molecules. Since it is reasonable to think that a change in the microenvironment of water might be reflected in a change in wa ter diffusion characteristics, the quantitative assessment of the (app arent) diffusion coefficient ADCw may represent a unique means of asse ssing tissue status. DWI has already shown great utility in the study of cerebral ischemia in animal models and has proved useful in the ear ly identification of cerebral ischemia in patients. More recent report s have indicated a potential for DWI in studying epilepsy. Here, we br iefly review some of what is known about the measurement of ADCw in is chemia and compare these results with what has recently been reported for epilepsy. In this manner we hope to better understand the underlyi ng mechanisms behind changes in water diffusion associated with specif ic pathologies.