Quantitative proton MRS predicts outcome after traumatic brain injury

Objective: To determine whether proton MRS (H-1-MRS) neurochemical measurem ents predict neuropsychological outcome of patients with traumatic brain in jury (TBI). Background: Although clinical indices and conventional imaging techniques provide critical information for TBI patient triage and acute ca re, none accurately predicts individual patient outcome, Methods: The autho rs studied 14 patients with TBI soon after injury (45 +/- 21 days postinjur y) and again at 6 months (172 +/- 43 days) and 14 age-, sex;, and education -matched control subjects. N-acetylaspartate (NAA), creatine, and choline w ere measured in normal-appearing occipitoparietal white and gray matter usi ng quantitative H-1-NIRS. Outcome was assessed with the Glasgow Outcome Sca le (GOS) and a battery of neuropsychological tests. A composite measure of neuropsychological function was calculated from individual test z-scores pr obing the major functional domains commonly impaired after head trauma. Res ults: Early NAA concentrations in gray matter predicted overall neuropsycho logical performance (r = 0.74, p = 0.01) and GOS (F = 11.93, p = 0.007). Ot her metabolite measures were not related to behavioral function at outcome. Conclusion: H-1-MRS provides a rapid, noninvasive tool to assess the exten t of diffuse injury after head trauma, a component of injury that may be th e most critical factor in evaluating resultant neuropsychological dysfuncti on. H-1-MRS can be added to conventional MR examinations with minimal addit ional time, and may prove useful in assessing injury severity, golding pati ent care, and predicting patient outcome.