Daily Bulletin 2015

DTI Could Help Those at Risk for Long-term Problems Resulting from Head Injury

Tuesday, Dec. 01, 2015

Unlike standard imaging techniques, diffusion tensor imaging (DTI) can uncover the underlying pathology for traumatic brain injury (TBI) and mild traumatic brain injury (mTBI). Two studies presented Monday showed the potential role DTI could play in helping people most at risk for persistent, long-term problems that result from a head injury.

Sara B. Rosenbaum, M.D.

Sara B. Rosenbaum, M.D.

Eva Catenaccio

Eva Catenaccio

Between 15 and 30 percent of people suffering TBI or mTBI (concussion) will have continued problems resulting from the injury, a group termed the "miserable minority," according to Michael L. Lipton, M.D., Ph.D., the principal investigator for both studies.

"The biggest conundrum in TBI research and clinical care is who is going to recover and who is part of that miserable minority," said Dr. Lipton, the associate director of the Gruss Magnetic Resonance Research Center and director of radiology research at Albert Einstein College of Medicine (Einstein) and Montefiore Medical Center in the Bronx, New York.

"We'd like to know who they are up front rather than waiting it out for the effects to present," he added. "Then maybe we can protect people who may be more vulnerable or intervene early to arrest the degeneration of axons that underpins long term neurobehavioral problems."

Early Signs of Abnormalities Relate to Long-Term Outcomes

DTI abnormalities around the time of injury are significantly related to long-term outcomes, according to Sara B. Rosenbaum, M.D., a radiology resident at Montefiore Medical Center who presented one of the studies.

"Prospective identification of those at risk may allow for improved patient management and inform treatment trials," Dr. Rosenbaum said.

The researchers recruited 31 mTBI patients from a local emergency center as well as 40 healthy volunteers. DTI at 3 Tesla was performed within two weeks of injury, and cognition was tested at one year post-injury.

Subjects were classified based on presence or absence of abnormally high radial diffusivity (RD) within two weeks of injury in selected brain regions (left frontal, right frontal, left temporal, right temporal and corpus callosum). T-tests compared cognitive outcomes between subjects with or without abnormally high RD in each region.

The results showed subjects with abnormally high RD in the left temporal and right temporal lobes performed worse on cognitive tasks at one year post-injury.

"These results suggest that individualized quantitative analysis of DTI in the setting of mTBI might ultimately aid in mTBI prognostication," Dr. Rosenbaum said. "DTI could thus, if further study confirms its prognostic value, be used as a noninvasive biomarker in the acute setting to identify those who will have poor long-term outcome."

Gender Plays Role in Negative Long-term Effects of TBI

In a related study done at Einstein, researchers found that gender is a potential risk elevator for the negative long-term effects of TBI, specifically that women have a higher risk than men.

The researchers studied 41 females and 41 age- and education-matched males (ages 18-52) drawn from an ongoing longitudinal study of repetitive head impacts on amateur soccer players. Their inclusion included a questionnaire that estimated the number of headers performed over the prior 12 months.

Analysis following 3T DTI imaging and neurocognitive testing revealed that women appear to have a greater response to repetitive head impacts for the same amount of heading. The researchers found more evidence of white matter microstructural damage and worse cognitive performance in women compared to men.

"The overall goal is to generate guidelines for safe heading exposure," said Eva Catenaccio, a fourth-year medical student at Einstein who presented the research. "These results demonstrate that these guidelines need to be sex-specific."

The potential impact of the study's results, though preliminary, could extend beyond sports. It could help end a persistent myth that women have worse TBI outcomes than men because they are more likely to complain about the symptoms.

"Women aren't making it up or exaggerating," Catenaccio said. "Many of the symptoms are vague, so they are hard to quantify, thus easier to dismiss. This research shows that there really is something going on organically in the brain that underlies these symptoms. And, it affects women to a greater extent than men."

Question of the Day:

I want to change the MR imaging parameters for a new protocol based on a research paper I read, but the console says the SAR is too high. What is SAR?

Tip of the day:

Patients who have many follow-up head CTs should be assessed for dose to the eyes as they swiftly become at risk for cataracts.

The RSNA 2015 Daily Bulletin is owned and published by the Radiological Society of North America, Inc., 820 Jorie Blvd., Oak Brook, IL 60523.