MULTIEXPONENTIAL T-2 RELAXATION IN DEGENERATING PERIPHERAL-NERVE

The multiexponential T-2 relaxation spectrum of peripheral nerve under going Wallerian degeneration has been measured both in vivo and in vit ro, Degeneration of the sciatic nerve of the amphibian Xenopus laevis was induced by crush injury, and T-2 relaxation spectra of the nerve w ere measured at several times up to 35 days following injury. Histolog ic evidence verified that the nerve underwent Wallerian degeneration, Relaxation spectra were observed to undergo measurable changes as dege neration progressed, the most evident being a reduction from three wel l-resolved T-2 components to one and a decline in the fraction of the spectra associated with the shortest T-2 component. The former appears to reflect the collapse and loss of myelinated fibers, while the latt er a combination of interstitial edema and myelin loss.