The powerful new imaging technique called High Definition Fiber Tracking (HDFT) will allow doctors to clearly see for the first time neural connections broken by traumatic brain injury (TBI) and other disorders. As reported in Discover Magazine
by Bijal P. Trivedi, MS, MA, head bumps, jolts, or exposure to a blast can snap fragile nerves in the brain that carry signals from one part of the body to another. But there is no diagnostic technique that can visualize which nerve fibers, or neurons, are broken. When a nerve snaps, communication between different brain regions is disrupted, just like a damaged circuit in a computer. Not being able to locate the damage is an enormous setback to recovery and rehabilitation for the approximately 1.7 million people who suffer TBI each year in the U.S. That number doesn’t include the more than 300,000 soldiers with brain damage inflicted during military combat between 2000 and 2014.
Often such damage is invisible on CT scans, which use X-rays to visualize blockages, bleeds, tumors, and skull fractures. MRI uses radio waves to create more detailed images, revealing bleeds, tumors, and crude structural damage, but it cannot detect broken nerves. Even functional MRI (fMRI), which measures brain activity by tracking blood flow, can’t detect the loss of neurons.
McGowan Institute for Regenerative Medicine
affiliated faculty member David Okonkwo, MD, PhD (pictured), Professor and Executive Vice Chair of Neurological Surgery, and Professor of Sports Medicine and Nutrition at the University of Pittsburgh, Director of Neurotrauma and of the Scoliosis and Spinal Deformity Program at UPMC, and the Clinical Director of the Brain Trauma Research Center, knew that brain injuries were easily overlooked. Even today, when a head injury or coma patient is brought to the ER, the person gets a CT scan to determine if there is a blood clot in the brain that requires surgery. The problem, says Dr. Okonkwo, is that in 9 out of 10 cases, those patients have a normal CT scan and are told they’re fine. “But in many cases, they are not normal,” he adds. “And they will be the first ones to share with you 3 months, 6 months later, the ways in which their life has changed.” He says that in most hospitals, trying to diagnose a TBI is pretty much like trying to find a bone fracture before X-ray machines were invented.
But that changed for Dr. Okonkwo in fall 2009 when Walter Schneider, PhD, a psychologist at Pitt, visited from across campus. Dr. Schneider is fascinated by technology, and he’d come to talk about a new way to image the major tracts of the brain. Tracts are bundled cables of axons that link one region of the brain to another — like superhighways — and conduct information. An axon is the long, skinny “tail” of a nerve cell, or neuron, which transmits electrical signals from one neuron to another elsewhere in the brain. Within a specific tract, all the nerve cells begin in the same location and end in a common location. Each tract has a predominant function: The corticospinal tract controls movement; the cingulate tract, memory; and the arcuate handles language. When an axon is injured, communication between particular neurons is lost; when an entire tract is severed, two brain regions can no longer talk to each other.
With financing from the Defense Advanced Research Projects Agency, Dr. Schneider launched the 2009 Pittsburgh Brain Competition to lure the best minds to work on brain connectivity mapping. Dr. Okonkwo began collaborating with Dr. Schneider to test the HDFT technology in a research trial by recruiting patients with brain injuries. Other team members then worked with Dr. Okonkwo and Juan Fernandez-Miranda, MD, a Pittsburgh neurosurgeon and neuroanatomist and the Director of the Fiber Tractography (HDFT) Lab, on an iPad app to create a tool that was clinically relevant and useful to neurosurgeons as they performed brain surgery or searched for damage in an injured patient. Seeing a detailed scan of the brain is clinically important, both in a diagnostic sense as well as a therapeutic one, says Dr. Okonkwo.
Part of the process of pushing this new technology is building the technical infrastructure that will allow Drs. Okonkwo and Schneider to better acquire MRI data, analyze and interpret it, and present brain images to clinicians and patients in a way that’s intuitive. The scan now takes 22 minutes, the analysis just 4 hours. Currently the only way to get a high-definition scan of brain fibers is to participate in a research trial. That will remain true for the next 3 to 5 years until the FDA approves the technology. But already, Drs. Okonkwo and Schneider are glimpsing the fruits of their efforts: They’re helping patients understand the consequences of their brain injuries.
Illustration: McGowan Institute for Regenerative Medicine.
Discover Magazine (08/03/15)
Media Video Library - UPMC/University of Pittsburgh Schools of the Health Sciences: High Definition Fiber Tracking
Bio: Dr. David Okonkwo