Mapping microglia and astrocyte activation in vivo using diffusion MRI
Raquel Garcia-Hernandez1, Antonio Cerdán Cerdá1, Alejandro Trouve Carpena1
1Instituto de Neurociencias, CSIC/UMH, San Juan de Alicante, Alicante, Spain.
Abstract:
While glia are increasingly implicated in the pathophysiology of psychiatric and neurodegenerative disorders, available methods for imaging these cells in vivo involve either invasive procedures or positron emission tomography radiotracers, which afford low resolution and specificity. Here, we present a noninvasive diffusion-weighted magnetic resonance imaging (MRI) method to image changes in glia morphology. Using rat models of neuroinflammation, degeneration, and demyelination, we demonstrate that diffusion-weighted MRI carries a fingerprint of microglia and astrocyte activation and that specific signatures from each population can be quantified noninvasively. The method is sensitive to changes in glia morphology and proliferation, providing a quantitative account of neuroinflammation, regardless of the existence of a concomitant neuronal loss or demyelinating injury. We prove the translational value of the approach showing significant associations between MRI and histological microglia markers in humans. This framework holds the potential to transform basic and clinical research by clarifying the role of inflammation in health and disease.
Insights
A new noninvasive diffusion-weighted MRI technique can image glial cell changes in the brain. This method quantifies neuroinflammation and glial activation, offering a powerful tool for psychiatric and neurodegenerative disease research.
Area of Science:
- Neuroscience
- Medical Imaging
- Cell Biology
Background:
- Glia play a crucial role in psychiatric and neurodegenerative disorders.
- Current in vivo imaging methods for glia are invasive or lack resolution and specificity.
- Positron emission tomography (PET) has limitations in imaging glial changes.
Purpose of the Study:
- To develop and validate a noninvasive diffusion-weighted magnetic resonance imaging (MRI) method for assessing glial cell morphology and activation.
- To demonstrate the method's sensitivity to neuroinflammation, degeneration, and demyelination.
- To establish the translational potential of the MRI technique in human studies.
Main Methods:
- Utilized diffusion-weighted MRI in rat models of neuroinflammation, degeneration, and demyelination.
- Quantified noninvasive signatures of microglia and astrocyte activation.
- Correlated MRI findings with histological markers in both animal models and human subjects.
Main Results:
- Diffusion-weighted MRI successfully captured distinct fingerprints of microglia and astrocyte activation.
- The method demonstrated sensitivity to glial morphology and proliferation changes.
- MRI-histology correlations confirmed the translational validity of the approach in humans.
- The technique provided a quantitative measure of neuroinflammation independent of neuronal loss or demyelination.
Conclusions:
- Noninvasive diffusion-weighted MRI offers a novel approach to image glial cell dynamics in vivo.
- This technique can quantitatively assess neuroinflammation and glial activation, aiding in the study of neurological diseases.
- The MRI method has significant potential to advance both basic and clinical research on glia's role in health and disease.
