L-COSY spectra. A) Age-matched healthy control; B) Athlete with history of RBT. Spectroscopy was performed at 3 T using a 32 channel head coil and voxel size of 3 × 3 × 3 cm3 in the PCG; increment size 0.8 ms; 64 increments with 8 averages resulting in an acquisition time of 12.8 minutes; acquired vector 1,024 points; acquisition time 512 ms; spectral width in F2 2,000 Hz and spectral width in F1 1,250 Hz. Assigned neurochemicals are according to Ramadan et al.  and Lean . For presentation, the spectra were calibrated to the lysine cross peak at 3.00–1.67 ppm. Abbreviations: N-acetylaspartate (NAA), choline (Cho); creatine (Cr); glutamate (Glu) and glutamine together (Glx); aspartate (Asp); myoinsitol (mI); lysine (Lys); threonine (Thr), gamma-aminobutyric acid (GABA). L-COSY, localized correlated spectroscopy; PCG, posterior cingulate gyrus; RBT, repetitive brain trauma.