The signals of
lactate and
lipids partially overlap in single-voxel
proton MR spectroscopy (1HMRS), sometimes making them difficult to differentiate in clinical settings. Our aim in this study was to identify
lactate and
lipids by varying the echo time (TE). We expect that the accurate detection of
lactate and
lipids will have high diagnostic value in the diagnosis of
brain tumors. Following our protocol, we obtained meaningful 1HMRS spectra from 213 patients, including 163 patients with
brain tumors, between August 1999 and February 2004. 1HMRS was performed with a TE of 144 ms followed by a TE of 30 ms and/or a TE of 288 ms, if necessary. For the 213 patients,
lactate level was "negative" in 47 patients, "positive" in 131 patients, and "strongly positive" in 35 patients. The
lipid level was "negative" in 90 patients, "positive" in 56 patients, and "strongly positive" in 67 patients. Based on logistic discriminant analyses of neuro-epithelial
tumor WHO grade and
lactate and
lipid levels,
lactate and
lipid levels were significant between WHO grades 2 and 3 (P=0.0239) and between grades 3 and 4 (P=0.0347).
Lipids are a more significant factor for the discrimination between WHO grades 2 and 3 (P=0.0073) and between grades 3 and 4 (P=0.0048). With our method of varying the TE, it is possible accurately and efficiently to detect
lactate and
lipids in the brain. We found a significant correlation between
lactate and
lipid expression and WHO grade of neuro-epithelial
tumors.