Objective
The purpose of this study was to determine whether ¹H magnetic resonance spectroscopy (MRS) is a potential tool for the detection of microscopic diffuse axonal injury (DAI) and for the evaluation of functional status of patients with traumatic brain injury (TBI).

Method
Seven patients with severe TBI and fourteen normal control volunteers were examined. Image guided spectra of localized in vivo ¹H MRS were obtained from parietal white matter (PWM) and occipital gray matter (OGM) in which definite abnormality was not detected in MR imaging. The severity of TBI was evaluated by the initial Glasgow Coma Scale (GCS), and the functional status was evaluated by Functional Independence Measure (FIM) at the time of the MRS examination, approximately 2 months after onset.

Results
In PWM, the [N-acetylaspartate(NAA)/Creatine(Cr)] ratio was significantly lower, and the [Choline(Cho)/Cr] and [myo-Inositol(mI)/Cr] ratios were significantly higher in the patients with TBI than those of normal volunteers. There was no significant correlation between the ratios of metabolites and GCS scores. However, interestingly, a significant correlation between the [NAA/Cr] ratio in PWM and the FIM scores was observed.

Conclusion
We could conclude that decreased [NAA/Cr], increased [Cho/Cr], and increased [mI/Cr] ratios in PWM can be considered as markers for DAI. Localized ¹H MRS has a potential to be used for the detection of DAI in vivo and evaluation of functional status of the patients with TBI.