Brain metabolism and cognitive impairment in HIV infection: a 3-T magnetic resonance spectroscopy study

• Published in: Magnetic resonance imaging 2010-11, Vol.28 (9), p.1251-1257
• Main Authors: Mohamed, Mona A, Barker, Peter B, Skolasky, Richard L, Selnes, Ola A, Moxley, Richard T, Pomper, Martin G, Sacktor, Ned C
• Format: Article
• Language: English
• Subjects: Adult; Antiretroviral Therapy, Highly Active; Attention; Brain - metabolism; Cognition Disorders - complications; Cognition Disorders - pathology; Cognition Disorders - virology; Cohort Studies; Female; Glutamate; Glutamic Acid - chemistry; Glutamine - chemistry; Glx; HIV dementia; HIV Infections - complications; HIV Infections - pathology; HIV Seropositivity; Human immunodeficiency virus; Humans; Magnetic Resonance Spectroscopy - methods; Male; Middle Aged; MR spectroscopy; Radiology
• ISSN: 0730-725X; 1873-5894
• DOI: 10.1016/j.mri.2010.06.007

Abstract Background and Purpose Human immunodeficiency virus (HIV)-associated dementia (HAD) has been extensively studied using magnetic resonance spectroscopy (MRS) at field strengths of 1.5 T. Higher magnetic field strengths (such as 3 T) allow for more reliable determination of certain compounds, such as glutamate (Glu) and glutamine (Gln). The current study was undertaken to investigate the utility of 3-T MRS for evaluating HIV+ patients with different levels of cognitive impairment with emphasis on the measurement of Glu and Glx (the sum of Glu and Gln). Methods Eighty-six HIV+ subjects were evaluated at 3 T using quantitative short echo time single-voxel MRS of frontal white matter (FWM) and basal ganglia (BG). Subjects were divided into three groups according to the Memorial Sloan Kettering (MSK) HIV dementia stage: 21 had normal cognition (NC) (MSK 0), 31 had mild cognitive impairment (MCI) without dementia (clinical MSK stage=0.5), and 34 had dementia (HAD) (MSK≥1). HIV+ subjects had also undergone standardized cognitive testing covering the domains of executive function, verbal memory, attention, information processing speed and motor and psychomotor speed. Between-group differences in metabolite levels in FWM and BG were evaluated using ANOVA. Pearson correlation coefficients were used to explore the associations between the Glu and Glx metabolites and neurocognitive results. Results FWM Glx was lower in HAD (8.1±2.1 mM) compared to both the MCI (9.17±2.1 mM) and NC groups (10.0±1.6 mM) ( P =.006). FWM myo-inositol (mI) was higher in HAD (4.15±0.75 mM) compared to both MCI (3.86±0.85 mM) and NC status (3.4±0.67 mM) ( P =.006). FWM Glx/creatine (Cr) was lower and FWM mI/Cr was significantly higher in the HAD compared to the MCI and NC groups ( P =.01 and P =.004, respectively). BG N -acetyl aspartate (NAA) was lower in the HAD group (6.79±1.53 mM), compared to the MCI (7.5±1.06 mM) and NC (7.6±1.01 mM) groups ( P =.036). Significant negative correlations were observed between Glu, Glx and NAA concentrations with Trail-Making Test B ( P =.006, P =.0001 and P =.007, respectively), and significant positive correlation was found with the Digit symbol test ( P =.02, P =.002 and P =.008, respectively). FWM Glx and NAA concentrations showed negative correlation with Grooved Pegboard nondominant hand ( P =.02 and P =.04, respectively). Conclusion Patients with HAD have lower levels of Glx concentrations and Glx/Cr ratio in FWM, which was associated with