Frontier: New scanning technique diagnoses hard-to-detect brain injuries

by Ben Mauk

January, 2009

A novel screening technique that combines two existing imaging technologies can help diagnose cases of traumatic brain injury (TBI) that go undetected by standard methods, new research suggests.

Traumatic brain injury affects an estimated 1.4 million Americans. Experts classify cases as mild, moderate or severe. While more severe cases often involve loss of consciousness, debilitating headaches, nausea, seizures and lack of sleep, “Mild TBI can be difficult to diagnose because of the lack of obvious external injury,” says Mingxiong Huang, lead author of the new study.

As a result, a patient may go undiagnosed for months, though symptoms such as fatigue, headaches, and problems with memory and concentration can persist for a year or more. Current diagnostic techniques involving magnetic resonance imaging (MRI) and computed tomography (CT) fail to diagnose the brain lesions associated with TBI in an estimated 70 percent of civilian patients and 44 percent of military patients, according to Huang.

The new study combined magnetoencephalography (MEG) and diffusion tensor imaging (DTI) scanning technologies, which already have many uses in the lab and clinic. MEG scanners measure communicating neurons’ magnetic fields; DTI tracks the movement of water molecules.

In the study, 18 patients with closedhead injuries who exhibited mild-tomoderate symptoms of TBI, along with 17 healthy participants, first underwent an MEG scan, which located certain abnormal signals emitted by damaged brain tissue. Some researchers think that these signals are released by nerve cell bodies that cannot communicate because of damaged signaling pathways called axons. DTI scans then measured the extent of this damage.

“We found that MEG and DTI together were substantially more sensitive in detecting subtle neuronal injury in mild cases of TBI,” Huang says.

The study has been submitted to the Journal of Neural Trauma.