REVIEWARTICLE METABOLIC BRAINMAPPING VariousMRS Application Tools for Alzheimer Disease andMild Cognitive Impairment

SUMMARY: MR spectroscopy is a noninvasive technique that allows the detection of several naturally occurring compounds (metabo-lites) from well-defined regions of interest within the human brain. Alzheimer disease, a progressive neurodegenerative disorder, is the most common cause of dementia in the elderly. During the past 20 years, multiple studies have been performed on MR spectroscopy in patients with both mild cognitive impairment and Alzheimer disease. Generally, MR spectroscopy studies have found decreased N-acetylaspartate and increased myo-inositol in both patients with mild cognitive impairment and Alzheimer disease, with greater changes in Alzheimer disease than inmild cognitive impairment. This review summarizes the information content of proton brainMR spectroscopy and its related technical aspects, as well as applications ofMR spectroscopy tomild cognitive impairment andAlzheimer disease.WhileMR spectroscopymay have some value in the differential diagnosis of dementias and assessing prognosis, more likely its role in the near future will be predominantly as a tool formonitoring disease response or progression in treatment trials.Morework is needed to evaluate the role of MR spectroscopy as a biomarker in Alzheimer disease and its relationship to other imaging modalities. ABBREVIATIONS: ADAlzheimer disease; GABA -aminobutyric acid; Glu glutamate; 1H-MR spectroscopy protonMR spectroscopy; LASER localization by adiabatic selective refocusing; MCI mild cognitive impairment; mI myo-inositol; MRSI MR spectroscopic imaging; PRESS point-resolved spectroscopy sequence; SENSE sensitivity encoded; tCr total creatine; tNAA total N-acetyl aspartate; TMA trimethylamines MR spectroscopy is a noninvasive technique that permits theestimation of the concentrations of various compound