Each year, approximately 18,000 Americans suffer from spinal cord injuries. These injuries can result in devastating loss of mobility, often causing lifelong struggles to regain independence and quality of life. During the initial months after injury, there are rapid degenerative changes, such as demyelination at and around the lesion, which are associated with a less favorable recovery outcome.

“Recovery outcomes for spinal cord injuries can be highly unpredictable, and current imaging techniques don’t always provide clear answers about who might recover,” said Clas Linnman, Ph.D., assistant professor at Spaulding Rehabilitation Hospital and Harvard Medical School in Boston, Massachusetts. “Our study investigated whether PET imaging could detect spared nerve connections in the injured spinal cord that may indicate a better chance of recovery.”

A novel PET tracer, ¹⁸F-3F4AP, was developed to image demyelinated axons (damaged nerve fibers) in spinal cord injuries. In a preclinical research model, rats with incomplete spinal contusion injuries were imaged with ¹⁸F-3F4AP PET at multiple time points up to one month after injury. PET imaging results were then compared with autoradiography and immunohistochemistry of postmortem spinal cord tissue. Additionally, a proof-of-concept study of ¹⁸F-3F4AP PET in two human patients with spinal cord injuries of different severities was performed.