Hi-def fiber tracking helps pinpoint brain damage

Researchers at the University of Pittsburgh hope the new imaging technique will help them identify neural connections broken by traumatic brain injuries and other neurological disorders.

A high definition fiber-tracking (HDFT) map of a million brain fibers. Walt Schneider Laboratory

When a 32-year-old man crashed his all-terrain vehicle without wearing a helmet, he slipped into a coma for three weeks. Though his initial CT scans revealed bleeding and swelling, and an MRI scan a week into the coma revealed bruising and swelling in the same area, neurosurgeons had no way of knowing precisely how the man would be affected if he did come out of his coma.

Three weeks later, the man awoke without the ability to move his left leg, arm, or hand. Only then were doctors able to begin planning rehabilitation.

Fortunately for the patient, a novel imaging technique called High Definition Fiber Tracking (HDFT)--developed by a team at the University of Pittsburgh--has helped identify which of his neural pathways were disrupted, according to Walter Schneider, the professor of psychology and neurosurgery who led the team that developed the tech at Pitt's Learning Research and Development Center.

HDFT, which the team reports on this month in a case study in the Journal of Neurosurgery, runs computer algorithms on data collected from MRI scans to view the brain's fiber tracts, each of which contains millions of connections.

"We can virtually dissect 40 major fiber tracts in the brain to find damaged areas and quantify the proportion of fibers lost relative to the uninjured side of the brain or to the brains of healthy individuals," Schneider reports in a school release. "Now, we can clearly see breaks and identify which parts of the brain have lost connections."

HDFT collects data from 257 directions; the state-of-the-art imaging technique called diffusion tensor imaging (DTI), by comparison, uses 51. Researchers took both types of scans of the patient at four and 10 months post-injury, but only the HDFT method revealed a lesion in a motor fiber pathway that would explain left-sided weakness and extensive fiber breaks in the region that controls his left hand.

The patient, by the way, eventually regained movement in his left leg and arm but continued to struggle to use his wrist and fingers at the 10-month mark.

While the Pitt neurosurgeons have used HDFT to map approaches to remove tumors and other abnormalities, they say much work remains to evaluate and ultimately validate HDFT as a new imaging standard. Still, they hope to some day use the fiber tracking to identify breaks that might explain not only motor problems but also memory loss and personality changes that can occur with traumatic brain injuries.

 

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