Abstract

Functionally distinct anatomic subdivisions of the brain can often be only a few millimeters in one or more dimensions. The study of metabolic differences in such structures by means of localized in vivo MR spectroscopy is therefore challenging, if not impossible. In fact, the spatial resolution of chemical shift imaging (CSI) in humans is typically in the range of centimeters. The aim of the present study was to optimize 1H CSI in monkeys and demonstrate the feasibility of high spatial resolutions up to 1.4 ؋ 2 ؋ 1.4 mm3. The obtained spatial resolution permitted the segregation of gray and white matter in the visual cortex based on the concentration of different metabolites and neurotrans- mitters like N-acetylaspartate, glutamate, and creatine. Con- centration ratios of white matter versus gray matter tissue as well as between metabolites matched those reported in the literature from healthy human brain, demonstrating the consis- tency and reliability of the procedure. Magn Reson Med 54: 1541–1546, 2005. © 2005 Wiley-Liss, Inc. Key words: in vivo 1H NMR spectroscopy; spectroscopic imag- ing; chemical shift imaging; spatial resolution; monkey visual cortex..