Introduction: Magnetic resonance imaging (MRI) is emerging as a powerful tool for diagnosis in patients with mild traumatic brain injury (mTBI). We report the preliminary findings from a prospective imaging study using conventional diffusion tensor imaging (DTI) and a new myelin sensitive sequence, mcDESPOT, in athletes sustaining mTBI.

Methods: Prospective consent was obtained from right-handed college football and rugby athletes. Fourteen (14) athletes with sports-related concussions (GCS 13-15) underwent 3T-MR imaging <72 hours post-injury, including T1, FLAIR, SWI, DTI and mcDESPOT sequences. Eight of the 14 athletes had >3-month follow-up DTI MRI and 4 of 8 had follow-up mcDESPOT. T1/FLAIR and SWI MR were reviewed blindly by a CAQ Neuroradiologist. DTI region of interest (ROI) analysis was performed in the following regions: splenium and genu of the corpus callosum, bilateral uncinate, bilateral inferior longitudinal fasciculi, bilateral cingulum and bilateral corona radiata. Changes in myelin content were analyzed in the same ROIs with the mcDESPOT sequence.

Results: Conventional imaging was normal, however, 2/14 subjects had punctate SWI hemorrhages. DTI analysis comparing initial and >3-month follow-up scans demonstrated statistically significant decreased fraction anisotropy (FA) at >3 months in the splenium (p=0.02), left uncinate (p=0.05) and left cingulum (p=0.02), as well as increased mean diffusivity (MD) in the left cingulum (p=0.005) and left corona radiata (p=0.001). McDESPOT analysis of myelin content showed a trend towards increased myelination in the left uncinate (p=0.07).

Conclusions: DTI findings in this study corroborate other studies by showing longitudinal decreased FA and increased MD in specific white matter tracts following mTBI. The left uncinate myelination changes revealed by mcDESPOT correlate well with the changes seen by DTI. As increased myelination has not previously been demonstrated with mTBI, the trend towards increased myelination in the left uncinate fasciculus warrants further investigation.

Patient Care: It will help in the diagnosis and potential prognostication for mild traumatic brain injury in athletes.

Learning Objectives: By the conclusion of this session, participants should be able to 1) discuss the importance of MRI in diagnosing mild traumatic brain injury 2) understand diffusion tensor and myelin imaging findings in mild traumatic brain injury

References: 1: Shenton ME, Hamoda HM, Schneiderman JS, Bouix S, Pasternak O, Rathi Y, Vu MA, Purohit MP, Helmer K, Koerte I, Lin AP, Westin CF, Kikinis R, Kubicki M, Stern RA, Zafonte R. A review of magnetic resonance imaging and diffusion tensor imaging findings in mild traumatic brain injury. Brain Imaging Behav. 2012 Jun;6(2):137-92. 2: Deoni SC, Dean DC 3rd, O'Muircheartaigh J, Dirks H, Jerskey BA. Investigating white matter development in infancy and early childhood using myelin water faction and relaxation time mapping. Neuroimage. 2012 Nov 15;63(3):1038-53.