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Updated: Jul 17, 2025
Registered Bioimaging of Nanomaterials for Diagnostic and Therapeutic Monitoring
Published on: December 9, 2010
Multishell diffusion MRI reveals whole-brain white matter changes in HIV
Silvia Minosse1, Eliseo Picchi1,2, Allegra Conti2
1Diagnostic Imaging Unit, University Hospital Rome Tor Vergata, Rome, Italy.
Abstract:
Diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) have been previously used to explore white matter related to human immunodeficiency virus (HIV) infection. While DTI and DKI suffer from low specificity, the Combined Hindered and Restricted Model of Diffusion (CHARMED) provides additional microstructural specificity. We used these three models to evaluate microstructural differences between 35 HIV-positive patients without neurological impairment and 20 healthy controls who underwent diffusion-weighted imaging using three b-values. While significant group effects were found in all diffusion metrics, CHARMED and DKI analyses uncovered wider involvement (80% vs. 20%) of all white matter tracts in HIV infection compared with DTI. In restricted fraction (FR) analysis, we found significant differences in the left corticospinal tract, middle cerebellar peduncle, right inferior cerebellar peduncle, right corticospinal tract, splenium of the corpus callosum, left superior cerebellar peduncle, left superior cerebellar peduncle, pontine crossing tract, left posterior limb of the internal capsule, and left/right medial lemniscus. These are involved in language, motor, equilibrium, behavior, and proprioception, supporting the functional integration that is frequently impaired in HIV-positivity. Additionally, we employed a machine learning algorithm (XGBoost) to discriminate HIV-positive patients from healthy controls using DTI and CHARMED metrics on an ROIwise basis, and unique contributions to this discrimination were examined using Shapley Explanation values. The CHARMED and DKI estimates produced the best performance. Our results suggest that biophysical multishell imaging, combining additional sensitivity and built-in specificity, provides further information about the brain microstructural changes in multimodal areas involved in attentive, emotional and memory networks often impaired in HIV patients.
Insights
Combined Hindered and Restricted Model of Diffusion (CHARMED) and diffusion kurtosis imaging (DKI) reveal widespread white matter changes in HIV infection, outperforming diffusion tensor imaging (DTI) in detecting microstructural differences.
Area of Science:
- Neuroimaging
- Biophysics
- Medical Science
Background:
- Diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) have limitations in specificity for detecting white matter alterations in HIV infection.
- The Combined Hindered and Restricted Model of Diffusion (CHARMED) offers enhanced microstructural specificity.
Purpose of the Study:
- To evaluate microstructural differences in white matter between HIV-positive patients and healthy controls using DTI, DKI, and CHARMED.
- To assess the utility of these diffusion models, particularly CHARMED and DKI, in identifying widespread brain changes associated with HIV.
- To employ machine learning for discriminating HIV patients from controls using diffusion imaging metrics.
Main Methods:
- Diffusion-weighted imaging with three b-values was performed on 35 HIV-positive patients and 20 healthy controls.
- Analysis included DTI, DKI, and CHARMED models to assess white matter microstructural integrity.
- An XGBoost machine learning algorithm with Shapley Explanation values was used for classification and feature importance analysis.
Main Results:
- Significant group differences in diffusion metrics were observed across all models.
- CHARMED and DKI revealed broader white matter tract involvement (80%) in HIV infection compared to DTI (20%).
- Restricted fraction analysis identified specific tract differences, impacting functions like motor control, proprioception, and equilibrium.
- CHARMED and DKI metrics, analyzed via machine learning, demonstrated superior performance in discriminating HIV patients from controls.
Conclusions:
- Biophysical multishell imaging, particularly CHARMED and DKI, provides greater sensitivity and specificity for detecting microstructural brain changes in HIV infection.
- These advanced diffusion models highlight widespread white matter alterations affecting cognitive and attentive networks often impaired in HIV.
- CHARMED and DKI show promise as advanced neuroimaging biomarkers for understanding and potentially managing HIV-associated neurological complications.
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