Diffusion tensor imaging of acute mild traumatic brain injury in adolescents

TLDR

Despite normal CT imaging, many adolescents with mild traumatic brain injury report persistent postconcussion symptoms, a dissociation that has long puzzled clinicians. The study aimed to assess diffusion tensor imaging tractography of the corpus callosum in adolescents with MTBI within six days postinjury to identify microstructural changes. DTI tractography of the corpus callosum was performed on 10 adolescents with MTBI and 10 matched controls, and symptom questionnaires were administered to evaluate cognitive, affective, and somatic complaints. Adolescents with MTBI exhibited increased fractional anisotropy and decreased apparent diffusion coefficient and radial diffusivity, which correlated with symptom severity, indicating cytotoxic edema and suggesting that DTI is more sensitive than conventional imaging for detecting clinically relevant changes. Abbreviations used include ADC, BSI, CC, DTI, ED, EPI, FA, FFE, FOV, GCS, ICC, MTBI, PTA, RD, ROI, RPCSQ, SWI, TE, TI, and TR.

Abstract

Background: Despite normal CT imaging and neurologic functioning, many individuals report postconcussion symptoms following mild traumatic brain injury (MTBI). This dissociation has been enigmatic for clinicians and investigators. Methods: Diffusion tensor imaging tractography of the corpus callosum was performed in 10 adolescents (14 to 19 years of age) with MTBI 1 to 6 days postinjury with Glasgow Coma Scale score of 15 and negative CT, and 10 age- and gender-equivalent uninjured controls. Subjects were administered the Rivermead Post Concussion Symptoms Questionnaire and the Brief Symptom Inventory to assess self-reported cognitive, affective, and somatic symptoms. Results: The MTBI group demonstrated increased fractional anisotropy and decreased apparent diffusion coefficient and radial diffusivity, and more intense postconcussion symptoms and emotional distress compared to the control group. Increased fractional anisotropy and decreased radial diffusivity were correlated with severity of postconcussion symptoms in the MTBI group, but not in the control group. Conclusions: In adolescents with mild traumatic brain injury (MTBI) with Glasgow Coma Scale score of 15 and negative CT, diffusion tensor imaging (DTI) performed within 6 days postinjury showed increased fractional anisotropy and decreased diffusivity suggestive of cytotoxic edema. Advanced MRI-based DTI methods may enhance our understanding of the neuropathology of TBI, including MTBI. Additionally, DTI may prove more sensitive than conventional imaging methods in detecting subtle, but clinically meaningful, changes following MTBI and may be critical in refining MTBI diagnosis, prognosis, and management. ADC= : apparent diffusion coefficient; BSI= : Brief Symptom Inventory; CC= : corpus callosum; DTI= : diffusion tensor imaging; ED= : Emergency Department; EPI= : echoplanar imaging; FA= : fractional anisotropy; FFE= : fast field echo; FOV= : field of view; GCS= : Glasgow Coma Scale; ICC= : intraclass correlation coefficients; MTBI= : mild traumatic brain injury; PTA= : post-traumatic amnesia; RD= : radial diffusivity; ROI= : region of interest; RPCSQ= : Rivermead Post Concussion Symptoms Questionnaire; SWI= : susceptibility weighted imaging; TAI= : traumatic axonal injury; TE= : echo time; TI= : inversion time; TR= : repetition time.