Diffusion MRI has proven itself to be a rapidly evolving field for brain tissue imaging, with developments for both white matter and gray matter.

Around since the 1990s, diffusion MRI is an innovative imaging modality that utilizes the diffusive motion of water molecules to distinguish between tissues. This method can be applied to determine the orientation of brain structures, such as white matter fibers, and to gain information at much finer spatial scales than is possible with conventional MRI.

While the clinical and research applications of diffusion MRI are still expanding into many different areas, Manisha Aggarwal is particularly interested in leveraging diffusion MRI to develop techniques for microstructural imaging. With a background in electronics and instrumentation engineering, she is pursuing how different magnetic field gradients can probe different aspects of brain tissue microstructure.

“Diffusion MRI has traditionally been focused on brain white matter, but now techniques probing gray matter have been developed, and there are many areas aimed at characterization of quantitative information, such as cell sizes and additional microstructural properties,” she notes. “There is also a lot of interest in how gradient shapes can be varied to look at different effects of different parameters.”

An exciting use of diffusion MRI techniques for probing tissue microstructure would be to enable very high-resolution imaging of the human brain. Another area Aggarwal is working on is ultrahigh-resolution imaging of the human hippocampus at high field to benefit neuroimaging and advance understanding of disorders such as Alzheimer’s disease and epilepsy. However, she cautions: “The field of microstructure imaging is still a very active area of research. While the hope is that we can translate this to routine clinical use, there is still a lot of work to be done on the potential applications.”

The precedent for clinical application of diffusion MRI is strong and furthered by continuing hardware advances, with a specific technique of this imaging, called diffusion tensor imaging, now routine in clinic. For now, Aggarwal continues her work developing additional techniques and staying on the forefront of the field of diffusion MRI and advances in brain microstructural imaging.