LAUSR

BACKGROUND Mechanical properties of the brain tissue are crucial to understand the mechanisms of traumatic brain injury (TBI). Injured brain tissue could induce changes of mechanical properties and anatomical structures. However, limited data is available for the injured tissue. NEW METHOD We developed a custom-built device to introduce controlled cortical impact (CCI) to brain with controlled impact velocity and direction. A study protocol for measuring the viscoelastic properties of injured brain tissue was also developed. Micro-scale morphological changes of the vasculature were quantified by analyzing confocal images of the brain tissue using CLARITY method. RESULTS Results showed significant differences of the instantaneous shear modulus of the impact region from different impact angles. However, no significant differences were found for long-term shear modulus by varying the impact angles and velocities. Analysis of the vasculature showed an increased radius of the vessels in the injured tissue compared with that in the control group. COMPARISON WITH EXISTING METHODS A combination of three different impact velocities and three different impact angles were adopted for producing injury to the brain. In addition, viscoelastic properties were compared between the injured and non-injured regions. The corresponding morphological changes of the vasculature system were also investigated. CONCLUSIONS The instantaneous shear modulus at the impact region was significantly different for the three impact angles. Compared to that of the control group, increased radius of the vasculature was also observed in the injured brain tissue. Results indicated that the biomechanical and structural changes of the injured tissue were closely related to the impact angles and velocities. Viscoelastic measurements could also help validation of computational models.