Magnetic resonance imaging has been traditionally used to image the structure of the brain and identify changes that may occur in pathological conditions.
One common measure that changes in the brain is the volume of particular structures. Volume, however, can only identify large (macrostructural) changes and is blind to smaller (microstructural) changes which occur beyond the spatial resolution of even the strongest MRI systems. Magnetic resonance elastography (MRE) is a technique that can potentially measure those small changes.
“MRE is a non-invasive technique that has many clinical and research applications,” said Hillary Schwarb, a research scientist at the Biomedical Imaging Center at the Beckman Institute for Advanced Science and Technology, as well as at the Interdisciplinary Health Sciences Institute.
MRE requires an MRI machine and a special pillow that is placed under the head of the person being scanned. The pillow vibrates at a very low amplitude which sends waves through the brain. “The vibration feels like when you’re on the highway and you lay your head against the window,” Schwarb said.
The nature of the waves change as they move through the brain tissue, based on the tissue composition. “We use the MRI machine to measure the displacement of those waves and build stiffness maps,” Schwarb said. “We can determine which parts of the brain are less stiff and which are more stiff, which in turn can tell us about the health of the tissue.”
In particular, Schwarb is interested in studying the hippocampus, the part of the brain that is involved in forming new memories. The hippocampus grows during childhood development and starts to shrink with age.
“The volume of the hippocampus can be correlated with memory abilities in children and older adults such that people with larger hippocampi have better memory, but this relationship has not been seen in young adulthood and middle age,” Schwarb said. “However, with MRE, we see this same positive relationship with hippocampal integrity and memory outcomes.”
Schwarb will collaborate with Ana Daugherty, an assistant professor at Wayne State University and a former Beckman Institute Postdoctoral Fellow. “We can now begin to answer decades-old questions about the organization of human memory and mechanisms of dementia,” Daugherty said.
Currently, Beckman has two 3 Tesla magnets that are used for research. The new Siemens Terra 7 Tesla MRI scanner will be located at Carle Foundation Hospital and used for both clinical and research imaging. Ultimately, the MRE techniques developed at Beckman can also be applied to Carle patients to improve diagnosis and treatment in many different neurological conditions.
“The 7 Tesla magnet is more powerful and can give you much more detailed pictures of the brain,” Schwarb said. “It opens up many opportunities to look at brain organization and brain health that are not possible with the machines we currently have.”
It also continues Beckman’s tradition of collaborative, interdisciplinary work.
“Investigating how MRE relates to cognition was developed here at Beckman and its continued success involves engineers and psychologists coming together,” Schwarb said. “The engineers and physicists will face some exciting new challenges translating MRE to the 7 Tesla MRI, but everyone is eager and excited to continue to push the field and lead the way using MRE to study cognitive health.”