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

Abstract

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.

• Authors: Mona A Mohamed, Margaret R Lentz, Vallent Lee, Elkan F Halpern, Ned Sacktor, Ola Selnes, Peter B Barker, Martin G Pomper
• Journal: Radiology (Radiology) Vol. 254 Issue 2 Pg. 577-86 (Feb 2010) ISSN: 1527-1315 [Electronic] United States
• PMID: 20093528 (Publication Type: Journal Article)

Chemical References

• Aspartic Acid
• N-acetylaspartate
• Creatine
• Choline

Topics

• AIDS Dementia Complex (metabolism)
• Adult
• Analysis of Variance
• Aspartic Acid (analogs & derivatives, metabolism)
• Case-Control Studies
• Chi-Square Distribution
• Choline (metabolism)
• Creatine (metabolism)
• Factor Analysis, Statistical
• Female
• HIV Infections (metabolism)
• Humans
• Magnetic Resonance Spectroscopy
• Male
• Neuropsychological Tests