Pathophysiological Concepts in Mild Traumatic Brain Injury: Diffusion Tensor Imaging Related to Acute Perfusion CT Imaging

Abstract

BackgroundA subgroup of patients with mild traumatic brain injury (TBI) experiences residual symptoms interfering with their return to work. The pathophysiological substrate of the suboptimal outcome in these patients is a source of debate.ObjectiveTo provide greater insight into the pathophysiological mechanisms of mild TBI.MethodsDiffusion tensor imaging (DTI) was performed during follow-up of 18 patients with mild TBI and compared with healthy control subjects. DTI data of the patient group were also compared with perfusion CT imaging in the acute phase of injury.ResultsIn patients with mild TBI, a trend was observed for a decreased fractional anisotropy (FA) in widespread bilateral frontal white matter areas with increased mean diffusivity (MD) in the parieto-temporal regions, compared to healthy control subjects. Cerebral blood volume (CBV) correlated significantly with FA in several white matter tracts including the corpus callosum, the internal capsule, the inferior fronto-occipital fascicle, the corticospinal tract, the superior and the inferior longitudinal fascicle.ConclusionIn mild TBI with normal conventional imaging significant associations between cerebral perfusion in the acute phase of injury and DTI analyses in the chronic phase of injury were discerned. The pathophysiological concept of these findings is being outlined.

MR Imaging Applications in Mild Traumatic Brain Injury: An Imaging Update

“…The literature on glutamate (Glu), glutamine blood flow in mTBI patients has been demonstrated by using arterial spin labeling MR techniques (139,140). MR findings of cerebral hypoperfusion in the anterior cingulate and frontal lobes are also supported by single photon emission computed tomography (141)(142)(143)(144), as well as CT perfusion studies (145)(146)(147). Although causation is difficult to establish, perfusion abnormalities have been described in concert with metabolic changes (148) and DTI abnormalities (145), and it is conceivable that hypoxia secondary to hypoperfusion may play a role in perpetuating metabolic disturbance and neuronal injury.…”

“…Although causation is difficult to establish, perfusion abnormalities have been described in concert with metabolic changes (148) and DTI abnormalities (145), and it is conceivable that hypoxia secondary to hypoperfusion may play a role in perpetuating metabolic disturbance and neuronal injury. Furthermore, these perfusion abnormalities have been linked to clinical metrics of injury (141,145,146), suggesting that the pathogenesis of mTBI likely results from complex interactions between perfusion, functional, structural, and metabolic changes after traumatic injury.…”

Imaging Evidence and Recommendations for Traumatic Brain Injury: Advanced Neuro- and Neurovascular Imaging Techniques

“…109,110,112,119,122,132,133 Evidence and Recommendations for Perfusion Imaging. All the studies above have involved only limited numbers of patients, and further research is required to validate the findings described above and determine how relevant they are in the management of individual patients with TBI (class IIb recommendation).…”

A Review of the Effectiveness of Neuroimaging Modalities for the Detection of Traumatic Brain Injury

“…Even in patients with mild TBI and normal non-contrast CT, perfusion CT imaging can identify regional decreases in CBV, 49 which correlate with abnormalities detected in diffusion tensor magnetic resonance imaging. 50 These techniques may have value in evaluating select TBI patients and for clinical research, but are not considered routine clinical practice.…”