H-1 MR SPECTROSCOPY OF THE BRAIN IN HIV-1-SEROPOSITIVE SUBJECTS - EVIDENCE FOR DIFFUSE METABOLIC ABNORMALITIES

PURPOSE: To analyze brain metabolite changes in HIV-1-seropositive sub jects in order to define whether the neuronal impairment is a localize d or more diffuse process. MATERIALS and METHODS: 15 patients and 18 v olunteers underwent multivoxel proton magnetic resonance (MR) spectros copy at 1.5T. Nine patients were classified as being neuropsychiatrica lly unimpaired and six as having HIV-1-associated dementia on the basi s of a full neuropsychological examination. Spectra were analysed from multiple voxels located in the fronto-parietal cortex and white matte r at the level of centrum semiovale. RESULTS: A significant reduction in mean peak area ratios of NAA/Cr (p<0.005 in the grey matter, p<0.01 in the white matter) and an elevation in mean Cho/Cr (p<0.005 in both grey matter and white matter) were observed in patients with HIV-1-as sociated dementia when compared to healthy volunteers. No significant metabolite abnormalities were detected in the neuropsychiatrically uni mpaired group, although there was a similar trend in the metabolite ra tios. The changes in metabolite ratios were of the same order of magni tude in the cortical grey matter and subcortical white matter as in th e deeper white matter in all patients. There were also no significant regional variations in mean metabolite ratios between right and left h emispheres or anterior and posterior voxels at the level of the brain studied. There were no abnormalities in Glx/Cr in any spectra analysed from either patient group. CONCLUSION: The absence of significant reg ional variation in metabolite ratios at the level of the centrum semio vale provides some evidence that abnormalities of cerebral metabolites in HIV-infected patients may be part of a diffuse process.