Date of Award

12-13-2002

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

First Advisor

Robert Fulbright

Abstract

The purpose of this study was to acquire spectra using proton magnetic resonance spectroscopy (MRS) with a long echo time (TE) to measure clinically important brain metabolites in normal subjects. We aimed to determine whether these metabolites vary across brain regions and between men and women. The results of this study will constitute a normative database that will be used as a reference for MRS studies of patients with neurological disease. Single voxel proton (1H) spectra were acquired in seventy-two subjects ranging in age from twenty to forty-four years. Ten brain regions were examined. Six gray matter sites in the cerebrum included four cortical areas in the frontal, parietal, temporal, and occipital lobes, and two deep nuclear sites in the basal ganglia and the thalamus. Two cortical white matter regions were in the parietal and the frontal lobes. Two posterior fossa sites included the pons and the cerebellum. For each spectrum, the metabolites N-acetyl aspartate (NAA), creatine (Cr) and choline (Ch) were identified. Ratios of NAA/Cr and Ch/Cr were calculated for each brain region. A multifactorial analysis of variance was performed with the two metabolic ratios as dependent variables and with brain region and gender as independent variables. Post-hoc statistical analysis consisted of the Scheffés F statistic for significant difference between pairs of brain regions for both metabolic ratios. There was significant regional variation for both the NAA/Cr ratio (p < .0001) and the Ch/Cr ratio (p < .0001). The NAA/Cr ratio was consistent within cortical gray and white matter but differed between cortical gray (smaller ratio) and white matter (larger ratio). The Ch/Cr ratio was variable in the gray matter, differed between some but not all gray and white matter regions, but was consistent within cortical white matter regions. There was no difference between men and women for either metabolic ratio. These findings provide the requisite normative values to use single voxel, long TE MRS in adult patients with neurological disorders.

Comments

This is an Open Access Thesis.

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