Diffusion Tensor Imaging in Acute Blast-Related Mild Traumatic Brain Injury in Injured Service Members in Afghanistan (S14.002)

OBJECTIVE: To evaluate the presence, pattern and clinical correlation of diffuse axonal injury (DAI), as evidenced using diffusion tensor imaging (DTI), in specific brain regions in blast-related mild traumatic brain injury (mTBI) in service members (SM) in Afghanistan. BACKGROUND: mTBI is a major concern for SM sustaining blast injuries in Afghanistan; the majority experience mild and transient neurological deficits and return to combat within days-weeks. DTI is an imaging technique that assesses the integrity of white matter and is thought to identify DAI, hallmark of mTBI. DTI was found to be abnormal in blast-exposed SM that were medically evacuated from combat areas (MacDonald et al, NEJM 2011), but little is known about more mildly injured SM that return to combat. DESIGN/METHODS: This is a prospective observational study of 230 US service members (115 mTBI and 115 healthy controls), enrolled between 03/14/2012 and 09/06/2012 in Afghanistan. Subjects underwent brain MRI (Phillips Achieva 1.5T), within 7 days from injury (mTBI): T1 (1x1x1 mm), T2 (1x1x1 mm), DTI (15 diffusion directions, b=1000, 2.5x2.5x2.5 mm), representing first-time use of MRI in a combat zone. Fractional anisotropy (FA), radial diffusivity, axial diffusivity and mean diffusivity were calculated for specific Regions of Interest. RESULTS: A total of 212 subjects (106 mTBI and 106 controls) completed the study. DTI data was analyzed for 76 mTBI and 86 controls as the image processing is still ongoing. FA was significantly reduced in mTBI compared to controls in the orbitofrontal white matter right (p 0.02), left (p 0.04), right superior longitudinal fasciculus (p 0.01) and middle cerebellar peduncle (p 0.03). CONCLUSIONS: The results parallel findings from previous studies (MacDonald et al, NEJM 2011), offering new evidence that white matter injury can occur even in milder forms of blast-related mTBI. Additional imaging and clinical data analysis will be available at the time of presentation. Disclosure: Dr. Adam has nothing to disclose. Dr. MacDonald has nothing to disclose. Dr. Rivet has nothing to disclose. Dr. Ritter has nothing to disclose. Dr. May has nothing to disclose. Dr. Barefield has nothing to disclose. Dr. Duckworth has nothing to disclose. Dr. La Barge has nothing to disclose. Dr. Asher has nothing to disclose. Dr. Drinkwine has nothing to disclose. Dr. Brody has nothing to disclose.