Changes in cerebral metabolism are detected prior to perfusion changes in early HIV-CMC: A coregistered H-1 MRS and SPECT study

Human immunodeficiency virus-cognitive motor complex (HIV-CMC), a common co mplication of the acquired Immunodeficiency syndrome (AIDS), is characteriz ed by progressive cognitive impairment and motor dysfunction. Functional im aging methods, such as single-photon emission computed tomography (SPELT) a nd proton magnetic resonance spectroscopy (H-1-MRS), have been applied to a ssess the severity of brain injury. However, it is unclear which of these t wo methods is more sensitive in detecting brain abnormalities in patients w ith early HIV-CMC. Twenty-four HIV-CMC patients were compared with 34 healt hy subjects; each had quantitative SPELT ((133)Xenon-calibrated Tc-99m-HMPA O) and quantitative 1H-MRS. Both modalities were co-registered in order to assess regional cerebral blood flow (rCBF) and metabolite concentrations wi thin the same voxel of interest in four brain regions (midfrontal and midpa rietal gray matter, temporoparietal white matter, and basal ganglia). On SP ELT, only the temporoparietal white matter showed a trend for decreased rCB F in HIV-CMC patients (-13%, P = 0.06). On MRS, HIV-CMC patients showed sig nificantly reduced creatine concentration in the basal ganglia (-8%, P = 0. 008), as well as Increased myoinositol concentrations in the basal ganglia (+25%, P = 0.01) and the temporoparietal white matter (+18%, P = 0.08). The re was no significant correlation between SPELT and MRS variables in the pa tients in any region. H-1 MRS showed abnormal neurochemistry in the basal g anglia, whereas rCBF on SPELT was normal in the same region. This finding s uggests that metabolite concentrations on 1H MRS are better surrogate marke rs than rCBF measurements with SPELT for the evaluation of brain injury in early HIV-CMC. (C) 2000 Wiley-Liss, Inc.