Mystery of the Origin of MRI Signal in Stroke Solved

Published September 12, 2022

Diffusion MR microscopy of a sea slug neuron at 7.8 μM resolution (left) The cellular structures can also be identified using 40X traditional light microscopy (right).

MRI scans taken after a stroke show brightness around the injury, the origins of which have been a long-standing and vexatious mystery for scientists. This work suggests these MRI signal changes result from fluid changes in glial cell volumes, results that could advance our ability to distinguish reversible and irreversible stroke events or provide a better understanding for other disorders such as Parkinson's, Alzheimer's, and mood or sleep disorders.

What did the scientists discover?

Magnetic resonance imaging (MRI) is a leading diagnostic technique for neurological studies. Glial cells in the brain are responsible for maintaining water balance to ensure accurate and consistent neuron function. In MRI scans taken within the first hours after a stroke, the images appear bright around the injury, but this has been a mystery because the direct effect on neuronal swelling appears dark. In this work, a MagLab user collaboration finds that it is the changes in glial cell volumes that cause the bright effect in the MRI signal after stroke.

Why is this important?

This work is a milestone of thirty-five years of ongoing research, starting with the first MRI image of a single cell by the lead collaborator on this team. A decades-long-held belief had been that MRI image changes seen in stroke were due to neuronal swelling. Instead, the finding is that it is glial cell swelling, leading to a better understanding of the changes in MRI signals that might one day distinguish reversible and irreversible stroke events that require different treatments and may provide better diagnostics for a myriad of other brain disorders.

Who did the research?

SJ Blackband^1,2, JJ Flint¹, B Hansen³ , TM Shepherd⁴ , CH Lee^1,4, WJ Streit¹, JR Forder^1,2

¹University of Florida; ²National MagLab; ³Aarhus University, Denmark; ⁴New York University School of Medicine

Why did they need the MagLab?

Physicists and neuroscientists utilize highly sensitive MR imaging gradients and microcoils at the AMRIS Facility because they enable resolution of perfused neuronal cells and capture diffusion measurements at the microscopic cellular level. Instrumentation is being developed to improve these measurements by moving to higher magnetic fields, including the MagLab's unique 32T superconducting magnet.

Details for scientists

View or download the expert-level Science Highlight, On the Origin of MRI Signal in Stroke
Read the full-length publication, On the Origins of Diffusion MRI Signal Changes in Stroke, in Frontiers in Neurology.

Funding

This research was funded by the following grants: Boebinger (NSF DMR-1644779); Blackband (NIH R01EB012874)

For more information, contact Joanna Long.

Tools They Used

This research was conducted in the AMRIS RF capabilities including the micro-5 3000mT/m imaging gradient that enables imaging at 7.8 μm in-plane resolution, MagLab’s User Collaboration Grant Program at the MagLab's AMRIS Facility located at the University of Florida.