Combination antiretroviral therapy modulates the blood oxygen level-dependent amplitude in human immunodeficiency virus-seropositive patients.

Combination antiretroviral therapy (cART) limits human immunodeficiency virus (HIV) replication in the central nervous system (CNS) and prevents progressive neurological dysfunction. We examined if the degree of CNS penetration by cART, as estimated by the CNS penetration effectiveness (CPE) score, affects brain activity as measured by the amplitude of the blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) response. HIV+ patients on low-CPE cART (n=12) had a significantly greater BOLD fMRI response amplitude than HIV+ patients on high-CPE cART (n=12) or seronegative controls (n=10).

Detection of human immunodeficiency virus induced inflammation and oxidative stress in lenticular nuclei with magnetic resonance spectroscopy despite antiretroviral therapy.

Background: Single-voxel magnetic resonance spectroscopy measurements of N-acetyl aspartate, choline, and creatine (Cr) are affected in patients with human immunodeficiency virus (HIV) and neurocognitive impairment. However, these metabolic markers are often normalized in affected central nervous system regions, such as the lenticular nuclei, after initiation of highly active antiretroviral therapy (HAART).

Objective: To examine whether lactate (Lac), a marker of inflammation and anaerobic glycolysis, and lipid, an indicator of cell membrane turnover resulting from oxidative stress, could serve as surrogate biomarkers within the lenticular nuclei of HIV-positive patients with different degrees of neurocognitive impairment.

Altered hemodynamics and regional cerebral blood flow in patients with hemodynamically significant stenoses.

Background And Purpose: Blood oxygen level-dependent (BOLD) contrast largely depends on changes in cerebral blood flow (CBF). Because cerebrovascular disease may result in altered CBF, we assessed the temporal dynamics and magnitude of the BOLD response in patients with major arterial stenoses.

Methods: Seven patients with hemodynamically significant stenoses affecting the anterior circulation (primarily left internal carotid and middle cerebral arteries) were compared with 7 neurologically healthy subjects.

Amplitude-modulated continuous arterial spin-labeling 3.0-T perfusion MR imaging with a single coil: feasibility study.

Written informed consent was obtained prior to all human studies after the institutional review board approved the protocol. A continuous arterial spin-labeling technique with an amplitude-modulated control was implemented by using a single coil at 3.0 T.

Reduced susceptibility effects in perfusion fMRI with single-shot spin-echo EPI acquisitions at 1.5 Tesla.

Arterial spin labeling (ASL) perfusion contrast is not based on susceptibility effects and can therefore be used to study brain function in regions of high static inhomogeneity. As a proof of concept, single-shot spin-echo echo-planar imaging (EPI) acquisition was carried out with a multislice continuous ASL (CASL) method at 1.5T.

Arterial spin labeling perfusion fMRI with very low task frequency.

Functional magnetic resonance imaging (fMRI) has become the most widely used modality for visualizing regional brain activation in response to sensorimotor or cognitive tasks. While the majority of fMRI studies have used blood oxygenation level-dependent (BOLD) contrast as a marker for neural activation, baseline drift effects result in poor sensitivity for detecting slow variations in neural activity. By contrast, drift effects are minimized in arterial spin labeling (ASL) perfusion contrast, primarily as a result of successive pairwise subtraction between images acquired with and without labeling.