T2 relaxometry of human median nerve.

This article examines the T2 relaxation characteristics of the median nerve. Knowledge of the T2 relaxation time is essential to optimize clinical magnetic resonance imaging (MRI) protocols and to enhance the visibility of pathophysiological changes in tissues. The T2 relaxation time of the median nerve is short relative to the T2 of other tissues like white and gray matter, for instance, and it decreases with increasing field strength of the MR scanner. A T2 relaxation time of ~50 milliseconds (ms) and ~20 ms were reported at 1.5 T and 7 T, respectively. Detailed measurements at 3.0 T revealed a biexponential decay characterized by two T2 components, at ~30 ms and ~100 ms, with normalized amplitudes of ~80% and ~20%, respectively. These two components possibly result from spatial compartmentation of water into intra-axonal and interaxonal spaces. The ability to assess microanatomical compartments within the median nerve could provide a method to study in vivo biophysical properties of nerves and could offer a means to investigate neurodegenerative diseases.