A multi‐center ¹H MRS study of the AIDS dementia complex: Validation and preliminary analysis

Abstract

and the HIV MRS Consortium † Purpose: To demonstrate the technical feasibility and reliability of a multi-center study characterizing regional levels of the brain metabolite ratios choline (Cho)/creatine (Cr) and myoinositol (MI)/Cr, markers of glial cell activity, and N-acetyl aspartate (NAA)/Cr, a marker of mature neurons, in subjects with AIDS dementia complex (ADC). Materials and Methods:Using an automated protocol (GE PROBE-P), short echo time spectra (TE ϭ 35 msec) were obtained at eight sites from uniformly prepared phantoms and from three brain regions (frontal white matter, basal ganglia, and parietal cortex) of normal volunteers and ADC and HIV-negative subjects. Results:A random-effects model of the phantom and volunteer data showed no significant inter-site differences. Feasibility of a multi-center study was further validated by detection of significant differences between the metabolite ratios of ADC subjects and HIV-negative controls. ADC subjects exhibited significantly higher Cho/Cr and MI/Cr in the basal ganglia and significantly reduced NAA/Cr and significantly higher MI/Cr in the frontal white matter. These results are consistent with the predominantly subcortical distribution of the pathologic abnormalities associated with ADC. Conclusion:This is the first study to ascertain and validate the reliability and reproducibility of a short echo time 1 H-MRS acquisition sequence from multiple brain regions in a multi-center setting. It should now be possible to examine the regional effects of HIV infection in the brain in a large number of subjects and to study the metabolic effects of new therapies for the treatment of ADC in a clinical trial setting.

Relative sensitivity of magnetic resonance spectroscopy and quantitative magnetic resonance imaging to cognitive function among nondemented individuals infected with HIV

“…The imaging study protocol was directed and monitored by the central site (MGH). Initial MRS studies conducted by the consortium revealed high consistency of MRS spectra across the different imaging sites (Lee et al, 2003). T1-weighted sagittal and high-resolution proton-density images were analyzed in this study.…”

“…As described in detail previously (Lee et al, 2003), spectra data were sampled in the basal ganglia with the voxel placed in the putamen. Voxel placement verification was determined at the central processing site.…”

Assessing multiple-group diagnostic problems with multi-dimensional receiver operating characteristic surfaces: Application to proton MR Spectroscopy (MRS) in HIV-related neurological injury

“…The specifics of this study have been presented in more detail elsewhere (Lee et al 2003;Chang et al 2004). Briefly, data were collected at 11 participating imaging centers: Massachusetts General Hospital (MGH, the central site), University of California Los Angeles, Harbor-UCLA Medical Center, University of Pennsylvania, University of Washington, University of Rochester, Mt.…”

“…MRS parameters included TE=35ms, TR=3000ms, voxel size=6cm 3 (20×20×15mm 3 ), 128 acquisitions, spectral width=2500Hz, and 2k data points. For consistency, the sequence was compiled and distributed to participating sites by the MGH-NMR Center (Lee et al 2003). Spectra were localized to three brain regions corresponding to different tissue types: midline posterior parietal cortex (gray matter), mid-frontal centrum semiovale (white matter) and basal ganglia (deep gray matter).…”

“…Spectra were localized to three brain regions corresponding to different tissue types: midline posterior parietal cortex (gray matter), mid-frontal centrum semiovale (white matter) and basal ganglia (deep gray matter). Data and images from completed examinations, showing voxel placement and raw spectroscopic data, were transferred to MGH for processing (for voxel placement and spectroscopic data see (Lee et al 2003), Figure 1 and 2). All raw data were analyzed in an identical manner using the commercial software package Sage IDL (GE Medical Systems, Milwaukee, WI) (Webb et al 1994).…”