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Imaging Shows How Brain Structures Deteriorate in Parkinson's Disease

A novel MRI technique may help researchers track how patients respond to treatment.


 

A new imaging technique may offer the first glimpse of the degeneration of two brain structures affected by Parkinson’s disease, researchers reported in the November 26 online Archives of Neurology.

The technique, which combines several types of MRI, could allow physicians to better monitor patients’ progression and track the effectiveness of potential new treatments, according to coauthor Suzanne Corkin, PhD, Professor Emerita of Neuroscience, Massachusetts Institute of Technology (MIT) in Cambridge.

The study is also the first to provide clinical evidence for the theory that Parkinson’s neurodegeneration begins deep in the brain and advances upward.

“This progression has never been shown in living people, and that’s what was special about this study,” said Dr. Corkin. “With our new imaging methods, we can see these structures more clearly than anyone had seen them before. A major obstacle to research on the causes and progression of this disease has been a lack of effective brain imaging methods for the areas affected by the disease.”

In 2004, Heiko Braak proposed that during the earliest stages of disease, the substantia nigra begins to degenerate and that the degeneration then spreads outward to the basal forebrain. Neuropathologists had found evidence for this sequence of events, but it had never been observed in living patients, because the substantia nigra is difficult to image with conventional MRI.

To overcome this obstacle, the MIT team used four types of MRI scans, each with different magnetic fields, thus generating different images. By combining these scans, the researchers created composite images of each patient’s brain that clearly show the substantia nigra and basal forebrain. “Our new MRI methods provide an unparalleled view of these two structures, allowing us to calculate the precise volumes of each structure,” said lead author David A. Ziegler, PhD, postdoctoral researcher at the University of California, San Francisco.

After scanning normal brains, the researchers studied 29 early-stage Parkinson’s disease patients and found significant loss of volume in the substantia nigra early on, followed by loss of basal forebrain volume later in the disease.

In future studies, this MRI technique could be used to follow patients over time and measure whether degeneration of the two areas is correlated or if they deteriorate independently of one another, noted Dr. Corkin. This approach could also give physicians a new way to monitor how their patients are responding to treatment, she said. Researchers could use the new imaging tools to determine the effects of potential new treatments.


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