The NMR signal decay characteristics of cerebral oedema.

Quantitative magnetic resonance (MR) imaging has been used to characterize vasogenic and triethyltin-induced cytotoxic cerebral oedema in cats, and the findings have been compared with the ultrastructural features of the lesions. Both normal and oedematous white matter yield non-linear T2 signal decay curves. The derived biexponential functions comprised a short T2 component representing intracellular water, and a long T2 component representing oedema fluid whose T2 was increased by an increase in free water of these tissue compartments. The relative sizes of the long T2 components were compatible with the sizes of the oedema spaces as determined ultrastructurally. Quantitative MR imaging can provide information which reflects the size and relaxation behaviour of the major tissue water compartments.