IN-VIVO CHARACTERIZATION OF CYTOTOXIC INTRACELLULAR EDEMA BY MULTICOMPONENT ANALYSIS OF TRANSVERSE MAGNETIZATION DECAY CURVES

Rationale and. Objectives. We investigated the multicompartmental nature of T2 decay in a specific white matter edema model. Methods. Triethyltin (TET) intoxication was produced in six male New Zealand White rabbits. Images were obtained over the 23-day study duration using a 64-echo Carr-Purcell-Meiboom-Gill (CPMG) sequence (repetition time = 3000 msec, echo time = 20 msec). T2 decay curves were extracted from 0.7 x 0.7 x 3.0 mm(3) voxels in the corpus callosum and contiguous white matter tracts, cortex, thalamic nuclei, hypothalamic nuclei, and the masseter muscles. The curves were fit with biexponential functions. Results. Increased signal intensity in the corpus callosum was evident 23 days after the first TET injection. At this time, a substantial slowly relaxing component appeared in the decay curves of the corpus callosum and, to a lesser extent, in the thalamus and hypothalamus. Changes in the rabbits' body weight, general physical condition, and neurologic state paralleled the growth and regression of the second, slowly relaxing component. Conclusion. The appearance and regression of a slowly decaying second component in the T2 decay curve is consistent with the formation and shrinkage of intracellular vesicles in the intramyelin sheaths of central white matter.