Tuesday  |  Salon 8  |  09:40 AM–10:00 AM

#15741, Intrasulcal Cavitation and Stress Concentration Consistent with Chronic Traumatic Encephalopathy

Subjects with Chronic Traumatic Encephalopathy (CTE) consistently present scar tissue around the sulcal depths of their brain. Cavitation in the cerebrospinal fluid (CSF) has been hypothesized as a mechanism for Traumatic Brain Injury, but its connection with CTE has remained elusive. Cavitation in the sulci has the added complexity of the increased confinement of vapor bubbles between parallel compliant walls. This added constraint could modify bubble dynamics to completely alter the classic micro-jetting induced by a semi-confinement near solid walls. How the geometrical differences and material characteristics of the sulci affect the onset and magnitude of cavitation is to be studied. An axial cut of an MRI scan of the brain of a 50-percentile middle-aged adult is utilized to determine statistically relevant size and geometry of the brain. This information is used to create a simplified biofidelic polyacrylamide hydrogel brain phantom. Gray and white matter are mimicked by utilizing 12% and 10% solutions of polyacrylamide respectively.
Tinted polyacrylamide particles are embedded in the mid-plane of the phantoms to serve as motion tracers. These phantoms are submerged in degassed and deionized water serving as an approximation to CSF. The phantoms are enclosed in a 3D-printed skull with acrylic windows for optical access. High-speed imaging (25 000 fps) is used to record the output response of the tracer particles due to blunt impacts delivered by a free-falling load. The strain and strain-rate fields are calculated in a Lagrangian frame of reference using Particle Tracking Velocimetry (PTV). Digital segmentation is used to segregate regions of gray and white matter, and to determine their corresponding stress fields. Intrasulcal cavitation is observed to expand the sulci, inducing stress concentration in the sulcal depths as evidenced from the PTV measurements. This observation is consistent with scar tissue present in subjects with Chronic Traumatic Encephalopathy.

Bianca Davila-Montero   Michigan State University
Emma Todd   Michigan State University
Joseph Kerwin   Los Alamos National Laboratory
Michaelann Tartis   New Mexico Tech
Adam Willis   U.S. Air Force
Ricardo Mejia-Alvarez   Michigan State University