# Novel Radial Diffusion-Weighted MR Spectroscopic Imaging of HIV: Biomarker Detection Using Functional Imaging and Neurocognitive Correlates

> **NIH NIH R21** · UNIVERSITY OF CALIFORNIA LOS ANGELES · 2020 · $194,144

## Abstract

Project Summary/Abstract
HIV-induced immune activity in the central nervous system (CNS) is believed to lead to permanent brain
changes, neurocognitive dysfunction and functional impairment. MR Spectroscopy (MRS) is a powerful non-
invasive tool for assessing neurochemical changes in multiple brain locations of HIV+ patients. In contrast to
diffusivity of water recorded using diffusion weighted imaging (DWI), diffusion-weighted (DW)-MR spectroscopy
can detect the diffusivity of intracellular metabolites such as, N-acetylaspartate, creatine, and choline, which are
exclusively located in the intracellular space, with a slow exchange between intra- and extra-cellular
compartments; therefore, the detected apparent diffusion coefficients (ADCs) of cerebral metabolites can only
be attributed to diffusion in the intracellular space. The outcome would provide more information (diffusivity of
metabolites) than averaged water diffusivity from DTI. Earlier attempts have investigated the ADCs of three
metabolites using single-voxel localized MRS in mostly healthy human subjects. MR imaging using radial
sampling has been shown to be less sensitive to motion and off-resonance effects. Earlier work on DW line scan
echo planar spectroscopic imaging (DW-LSEPSI) for motion robustness suffered from reduced SNR. Extending
radial sampling to hyperpolarized carbon-13 (13C) MRSI has been demonstrated; however, implementation in
1H MRSI has not been demonstrated. We propose to develop volumetric radial-based echo-planar diffusion-
weighted spectroscopic imaging (r-DW-EPSI), to evaluate diffusion of intracellular metabolites such as NAA, Cr,
Cho, and Glu/glutamine (Glx). Alterations in metabolite ADC values may generate additional information about
mechanisms underlying HIV, even after anti-retroviral therapy (ART). By exploiting strategies of acquisition
acceleration of spatial encoding using FISTA with variable acceleration reconstruction, the radial EPI readout in
the DW-EPSI sequence will enable recording of multi-voxel DW-spectra an order of magnitude faster than when
using conventional phase-encoding. Specific aims of this study are: (1) Develop accelerated r-DW-EPSI using
semi-LASER localization, and optimize it in brain phantoms and 10 healthy adults. (2) Determine ADCs of Cr,
NAA, Cho, mI and Glx in 25 HIV+ subjects, and assess their differences compared to 25 age-/sex-matched
healthy adults. The outcome will be correlated with DTI metrics, neuropsychological test results, and other
disease variables. We will test the following hypotheses: 1) The accelerated 3D r-DW-EPSI acquisition will be
less sensitive to motion and chemical shift off-resonance effects due to oversampling in the central k-space.
Altered ADCs of non-water molecules will be measured in multiple brain regions as markers of microstructural
abnormalities as well as relative metabolite concentrations. 2) Metabolite ADCs and relative concentrations will
support DTI findings correlating with neurocog...

## Key facts

- **NIH application ID:** 10126403
- **Project number:** 1R21MH125349-01
- **Recipient organization:** UNIVERSITY OF CALIFORNIA LOS ANGELES
- **Principal Investigator:** MICHAEL Albert THOMAS
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $194,144
- **Award type:** 1
- **Project period:** 2020-09-08 → 2022-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10126403

## Citation

> US National Institutes of Health, RePORTER application 10126403, Novel Radial Diffusion-Weighted MR Spectroscopic Imaging of HIV: Biomarker Detection Using Functional Imaging and Neurocognitive Correlates (1R21MH125349-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10126403. Licensed CC0.

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