Better Diagnoses for Brain Disorders

Neurodegenerative diseases such as Alzheimer's and Parkinson's are not only devastating to victims and their families, but also baffling to scientists and doctors. Medical professionals don't yet fully understand what causes these diseases or what happens in the brain when they strike. They are also notoriously difficult to diagnose; doctors rely largely on patient behavior to make their determinations because there is no way to identify the diseases with certainty. Although positron emission tomography (PET) scans can help, the information those scans yield is limited: They reveal which areas of the brain are functional, but can't provide structural information and lack high resolution.

Researchers at the Mayo Clinic and the MagLab hope to help change that.

In the first collaboration of its kind, the MagLab's Sam Grant and Florida State University have teamed up with the Mayo Clinic in Jacksonville, Florida to see how effective MRI scans can be in detecting these disorders.

The clinic and Drs. Katherine Schweitzer, Dennis Dickson and Zbigniew Wszolek have provided dozens of samples of brain tissue from deceased Alzheimer's and Parkinson's patients who have donated their bodies to science. Grant and his colleagues are making highly detailed MRI scans of these samples in the powerful 900 MHz ultra-wide-bore magnet, hoping to find biomarkers that doctors can one day use to diagnose living patients.

In the samples from Alzheimer's patients, the researchers are zeroing in on the hippocampus, a curved structure located deep in the brain's temporal lobe that is the center for memory and learning. Long before patients exhibit any behavioral symptoms, Alzheimer's disease attacks the hippocampus, destroying nerve cells and the synapses between them. By the time a patient starts to have noticeable symptoms (memory loss, confusion, mood swings), tissue destruction has spread to other areas of the brain.

The disease leaves traces in the form of protein deposits. Beta-amyloid plaque builds up between neurons, clogging neural pathways. That "gunk" is one of the features that the researchers hope to identify on the MRI scans.

Grant, an assistant professor at the FAMU-FSU College of Engineering who performs MRI work at the lab, is hoping the 900 MHz magnet will be able to identify deposits of metals such as iron, copper and zinc that tend to get stuck in the plaque. Also, the MRI scans should reveal the shrinkage that a diseased brain undergoes as the cells die off.

Grant hopes MRIs will reveal signs of Alzheimer's in the hippocampus
and signs of Parkinson's in the basal ganglia of the human brain.

"I'm hoping that the strength of the 900 magnet can be leveraged to help diagnose these diseases in the future," said Grant, "and I'm excited about the prospect of translating this research into a technique that physicians can use with patients."

For Parkinson's patients, the researchers hone in small structures in the basal ganglia, a group of nuclei at the base of the forebrain. One of these structures, the substantia nigra, produces dopamine, a neurotransmitter that controls movement and balance. When Parkinson's attacks this structure, dopamine levels in the brain drop, eventually resulting in the telltale Parkinson's symptoms – stiffness, tremors, difficulty moving.

Previous studies have shown heavy deposits of proteins and iron in the Parkinsonian brain. The 900 scanner, powered by a massive 21.1-tesla magnet, should pinpoint those areas where metal accumulation has impacted neurons, Grant says.

After making MRI scans of the Mayo Clinic brain samples, pathologists from the clinic will do histological studies on the tissue to see if they find on a cellular level what the researchers suspect they can identify on a structural level.

If the findings are confirmed, much work still lies ahead. After all, the goal is not diagnosing the dead, but the living. One day, perhaps, doctors will be able to identify and track these diseases with high-resolution MRI scanners, possibly identifying them far earlier in their progression than is now possible.

"We're hoping to prove that you can do this work in vivo as well – if you have the resolution in order to do it," said Grant.

This article has discussed only a few of the research projects in the world's largest MRI scanner. You can take a look at some of the other research being done in the instrument in our list of some of the other MRI research projects at the MagLab. Also, check out our Links & Resources page for more information on MRI, the MagLab and more.

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Thanks to the Magnet Academy's scientific adviser on this article Sam Grant, an assistant professor of engineering with the Florida A&M University/Florida State University College of Engineering and an expert in MRI at the Magnet Lab.

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