T2 relaxation of peripheral nerve measured in vivo.

It is demonstrated that multi-exponential transverse (T2) relaxation components can be estimated from multi-echo images of peripheral nerve. Three T2-relaxation components with T2 values +/- standard deviations (populations +/- standard deviations) of 19 +/- 7 ms (26 +/- 9%), 63 +/- 31 ms (29 +/- 11%) and 241 +/- 24 ms (45 +/- 7%) have been identified in vivo in the sciatic nerve of the amphibian Xenopus laevis. The longer-lived component, not identified previously in vivo, provides a significant contrast-to-noise ratio (CNR) between nerve and muscle in the latter-echo images. It is shown that the CNR can be further improved by the averaging of selected images from the multi-echo set.