Regional cerebral blood flow and FDG uptake in asymptomatic HIV-1 men

Abstract

Despite advances in the treatment of patients with human immunodeficiency virus (HIV), HIV-associated neurocognitive disorder occurs in 15-50% of HIV-infected individuals, and may become more apparent as ageing advances. In the present study we investigated regional cerebral blood flow (rCBF) and regional cerebral metabolic rate of glucose uptake (rCMRglc) in medically and psychiatrically stable HIV-1-infected participants in two age-groups. Positron emission tomography (PET) and magnetic resonance imaging (MRI)-based arterial spin labeling (ASL) were used to measure rCMRglc and rCBF, respectively, in 35 HIV-infected participants and 37 HIV-negative matched controls. All participants were currently asymptomatic with undetectable HIV-1 viral loads, without medical or psychiatric comorbidity, alcohol or substance misuse, stable on medication for at least 6 months before enrolment in the study. We found significant age effects on both ASL and PET with reduced rCBF and rCMRglc in related frontal brain regions, and consistent, although small, reductions in rCBF and rCMRglc in the anterior cingulate cortex (ACC) in HIV, a finding of potential clinical significance. There was no significant interaction between HIV status and the ageing process, and no significant HIV-related changes elsewhere in the brain on PET or ASL. This is the first paper to combine evidence from ASL and PET method in HIV participants. These finding provide evidence of crossvalidity between the two techniques, both in ageing and a clinical condition (HIV).

Keywords: ASL; HIV; PET; ageing; glucose uptake; rCBF.

Figure 1

Study recruitment.

Figure 2

ASL: Areas of significantly (cluster level corrected P < 0.05) reduced regional cerebral blood flow (rCBF) in older relative to younger participants in three clusters in the frontal lobes in the midline and left dorso‐lateral frontal regions. Slides in radiological convention with left hemisphere to the right of the image.

Figure 3

ASL: Areas of significantly (cluster level corrected P < 0.05) increased regional cerebral blood flow (rCBF) in older relative to younger participants in four clusters situated in sub cortical white matter bilateral putamen (lenticular nucleus) and bilateral pulvinar (posterior thalamus). Slides in radiological convention.

Figure 4

PET: Area of significantly (cluster level corrected P < 0.05) reduced regional cerebral metabolic rate of glucose (rCMRglc) in older relative to younger participants in left dorsolateral and bilateral midline frontal/anterior cingulate regions. Slides in radiological convention.

Figure 5

PET: Areas of significantly (cluster level corrected p < 0.05) increased regional cerebral metabolic rate of glucose (rCMRglc) in older relative to younger participants in bilateral pulvinar and white matter, upper brain stem, and cerebellar regions. Slides in radiological convention.

Figure 6

Area of reduced (A) regional cerebral blood flow (rCBF) and (B) regional cerebral metabolic rate of glucose (rCMRglc) in HIV‐infected participants relative to HIV‐negative controls in the right anterior and inferior region of anterior cingulate cortex (cluster level uncorrected P < 0.05). Slides in radiological convention.