Lactate is one of the more important compounds assessed on MR spectroscopy, and resonates at 1.3 ppm chemical shift, with a characteristic double peak at long TEs. It is however superimposed on the lipid band, and using an intermediate TE (e.g. 144ms) will invert only lactate allowing it to be distinguished.
It is a marker of anaerobic metabolism with no peak seen in normal spectra. It is therefore elevated in necrotic areas (e.g. higher grade tumors) and infections (cerebral abscess). An elevated lactate peak may also be seen in the setting of diffuse axonal injury. In which case, it is associated with a worse prognosis .