Factor analysis of proton MR spectroscopic imaging data in HIV infection: metabolite-derived factors help identify infection and dementia.

Radiology

Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, 1550 Orleans St, 492 CRB II, Baltimore, MD 21231, USA.

Published: February 2010

Purpose: To develop a relevant pathophysiologic model of human immunodeficiency virus (HIV)-associated dementia by studying regional variations in metabolite levels measured with magnetic resonance (MR) spectroscopic imaging and their relationship to immunologic measures and cognitive dysfunction.

Materials And Methods: This was a HIPAA-compliant, institutional review board-approved study involving written informed consent. Distributions of N-acetylaspartate (NAA), choline (Cho), and creatine (Cr) concentrations in 94 subjects (20 seronegative controls and 74 HIV-positive subjects; 34 of the HIV-positive subjects having HIV-associated dementia; 63 men, 31 women; mean age, 40 years) were determined with proton (hydrogen 1 [(1)H]) MR spectroscopic imaging. HIV-positive subjects underwent neuropsychological testing and blood and cerebrospinal fluid (CSF) analysis. Factor analysis was utilized to determine associations between metabolites across regions. Analysis of variance and t tests were used to isolate differences between cohorts.

Results: A "Cho factor" differentiated seronegative controls from HIV-infected cohorts, indicating elevated Cho levels across deep gray and white matter regions of HIV-positive individuals. An "NAA factor" differentiated those with dementia from those without and correlated best with psychomotor and executive function tests. A "Cr factor" indicated Cr elevations correlated with CSF monocyte chemoattractant protein-1 levels. NAA and Cr factor scores were strongly weighted to metabolite changes in white matter regions.

Conclusion: These results highlight the importance of white matter involvement in HIV-associated dementia and support the current pathogenesis model of glial cell proliferation in HIV infection, denoted by regional Cho elevations, and neuronal dysfunction and/or death, denoted by NAA decreases, associated with dementia. Factor analysis of MR spectroscopic imaging data is a useful method for determining regional metabolic variations in HIV infection and its neuropsychological correlates.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2815344PMC
http://dx.doi.org/10.1148/radiol.09081867DOI Listing

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