PET trumps MRI in detecting damaged nerves in MS patients

Myelin, a fatty substance that sheaths nerves, is often damaged or missing in individuals with multiple sclerosis (MS). Physicians have depended on MR to detect demyelination, but the modality is incapable of differentiating between lost or damaged myelin and inflammation.

But recent research may show potential for positron emission tomography to detect voltage-gated potassium channels, which can be detected by PET and provide quantitative data on demyelination.

"In healthy myelinated neurons, potassium channels are usually buried underneath the myelin sheath," explained study author Brian Popko, PhD, director of the center for peripheral neuropathy at the University of Chicago. "When there is loss of myelin, these channels become exposed. They migrate throughout the demyelinated segment and their levels increase."

The study—led by Pedro Brugarolas, PhD, a faculty member at Massachusetts General Hospital/Harvard Medical School—was published online Jan. 12 in Scientific Reports.

Researchers administered 4-aminopyridine, an existing MS medication, to mice. The drug accumulated in demyelinated areas of the brain.

"We were able to show, in rats, that the tracer accumulated to a higher degree in demyelinated areas than in control areas," Popko said.