Brain lesions with elevated lactic acid peaks on magnetic resonance spectroscopy.

Magnetic resonance (MR) spectroscopy is a noninvasive imaging tool that provides information on various metabolite concentrations within brain lesions. The biochemical information obtained with MR spectroscopy, along with the morphologic appearance of a lesion on MR imaging, allows for better characterization and improved diagnostic ability. Lactic acid is an end product of anaerobic metabolism. Under conditions of anaerobic metabolism or inflammation, lactate levels become elevated and a characteristic peak at 1.3 ppm is detected on MR spectroscopy. This review will discuss the significance of lactate as a metabolite and will describe various brain lesions and disease conditions in which elevated lactate levels are detected.