Lactate (Lac) is absent in normal brain tissue and its presence is indicative of anerobic glycolysis at the cellular level. Elevated levels are associated with ischemic conditions or metabolic disorders (where anerobic glycolysis predominates) but is also noted at the edges of large brain tumours. The peak is very sensitive to the technique employed and unless the correct echo time is employed, it may be artifactually suppressed. The spectral peak lies at 1:33 ppm. The peak is often inverted or bifid.