Post-traumatic stress disorder (PTSD) and traumatic brain injury (TBI) are common conditions afflicting U.S. military veterans, yet they are difficult to distinguish clinically. A new study using brain perfusion SPECT, however, has demonstrated the ability of the modality to differentiate the conditions.

If SPECT can be used to identify which patients have PTSD versus TBI, it could alter treatment decisions and lead to better outcomes. The results were published in the April issue of Brain Imaging and Behavior, a special edition devoted to veteran’s issues.

Authors Cyrus A. Raji, MD, PhD, of the Department of Radiology at UCLA Medical Center, and colleagues looked at a group of 196 veterans: 36 with PTSD, 115 with TBI and 45 with PTSD/TBI. The study population included peacetime and wartime veterans, regardless of service branch, and TBI did not have to be service related.

SPECT was performed at rest and during a concentration task, and the researchers analyzed the response in default mode network regions where abnormal findings are present in many neurological and psychiatric disorders.

Baseline quantitative regions with SPECT separated PTSD from TBI with 94 percent accuracy, according to the authors. Sensitivity was 92 percent and specificity was 85 percent. Concentration scans yielded an accuracy of 89 percent. Visual readings of the baselines scans resulted in 83 percent accuracy in separating TBI from PTSD/TBI.

"Now we can differentiate two common disorders which often overlap based on clinical examination in our veteran population,” said co-author Theodore Henderson, MD, PhD, of the International Society of Applied Neuroimaging and president of Denver-based neuroimaging consulting firm The Synaptic Space, in a press release. "Improved diagnosis can lead to better treatment, particularly for TBI, since we have been developing specific treatments for TBI."

Since 2001, more than 400,000 military personnel and veterans have been diagnosed with PTSD or TBI.