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Updated: May 7, 2026
Advanced Diffusion Imaging in The Hippocampus of Rats with Mild Traumatic Brain Injury
Published on: August 14, 2019
A macroscopic view of microstructure: using diffusion-weighted images to infer damage, repair, and plasticity of
1Instituto de Neurobiología, Universidad Nacional Autónoma de México, Mexico.
Abstract:
Since its introduction in the early 1990s, diffusion-weighted magnetic resonance imaging (MRI) has played a crucial role in the non-invasive evaluation of tissue microstructure of brain parenchyma in vivo. Diffusion anisotropy, in particular, has been extensively used to infer histological changes due to brain maturation and pathology, as it shows a clear dependence on tissue architecture. Although the resolution used in most studies lies in the macroscopic range, the information provided originates at the microscopic level and, as such, diffusion MRI serves as a microscope that can reveal profound details of tissue with direct clinical and research applications. The interpretation of diffusion parameters of white matter rests on what is known to drive diffusion anisotropy, namely axonal membranes, density and coherence, as well as myelin sheaths. However, these factors interact to modulate anisotropy, making interpretations potentially difficult. While there are numerous publications that report diffusion changes in response to particular, histologically confirmed tissue abnormalities in animal models of disease, the microscopic correlates of altered diffusion parameters due to neurological disorders in humans have been difficult to characterize. Animal models may provide insight into the mechanisms involved, but do not necessarily provide accurate representations of the human condition, making human diffusion MRI studies with direct histological confirmation crucial for our understanding of tissue changes secondary to neurodevelopment and disease. This work provides a synopsis of tissue characteristics that give rise to highly informative, specific diffusion patterns, and also of how methodological and artifactual aspects can provide erroneous diffusion measurements that do not accurately reflect tissue and may lead to misinterpretation of results. Examples of diffusion changes due to human conditions are provided to illustrate the wealth of applications of diffusion MRI in clinical and research fields.
Insights
Diffusion-weighted magnetic resonance imaging (dMRI) non-invasively reveals brain tissue microstructure. This review clarifies how dMRI reflects tissue characteristics and discusses potential interpretation errors for clinical applications.
Area of Science:
- Neuroimaging
- Biophysics
- Histology
Background:
- Diffusion-weighted magnetic resonance imaging (dMRI) has been pivotal in non-invasively assessing brain microstructure since the 1990s.
- Diffusion anisotropy, a key dMRI metric, correlates with tissue architecture, enabling inference of maturation and pathological changes.
- Understanding the microscopic basis of dMRI signals is crucial for accurate interpretation of white matter properties.
Purpose of the Study:
- To elucidate the relationship between specific tissue characteristics and diffusion patterns observed in dMRI.
- To highlight methodological and artifactual factors that can lead to misinterpretation of dMRI measurements.
- To underscore the importance of human dMRI studies with histological correlation for understanding neurodevelopment and disease.
Main Methods:
- Review of existing literature on diffusion MRI principles and applications.
- Synopsis of tissue microstructural features influencing diffusion anisotropy (e.g., axonal membranes, myelin).
- Discussion of potential sources of error and artifacts in dMRI acquisition and analysis.
Main Results:
- Diffusion MRI provides microscopic insights into tissue with macroscopic resolution.
- Interpretation of diffusion parameters is complex due to the interplay of microstructural factors.
- Methodological issues can yield erroneous diffusion measurements, complicating clinical and research findings.
Conclusions:
- Diffusion MRI is a powerful tool for investigating brain tissue microstructure in vivo.
- Accurate interpretation requires understanding the link between tissue properties and dMRI signals.
- Human studies with histological validation are essential for advancing the clinical utility of dMRI in neurological disorders.
