Noninvasive magnetic resonance imaging stratifies injury severity in a rodent model of male juvenile traumatic brain injury

• Published in: Journal of neuroscience research 2020-01, Vol.98 (1), p.129-140
• Main Authors: Badaut, Jerome, Adami, Arash, Huang, Lei, Obenaus, André
• Format: Article
• Language: English
• Subjects: Animals; Apoptosis; Blood; Brain; Brain - diagnostic imaging; Brain Edema - diagnostic imaging; Brain Injuries, Traumatic - diagnostic imaging; Cell death; Cognitive science; Computed tomography; Corpus callosum; Cortex; Edema; Head injuries; hemorrhage; Histology; Injury Severity Score; Magnetic permeability; Magnetic Resonance Imaging; Medical imaging; Models, Animal; Mortality; Neuroimaging; Neuroscience; NMR; Nuclear magnetic resonance; rat; Rats; Rats, Sprague-Dawley; Resonance; Therapeutic applications; Tomography, X-Ray Computed; Traumatic brain injury; white matter; White Matter - diagnostic imaging
• ISSN: 0360-4012; 1097-4547
• DOI: 10.1002/jnr.24415

Age and severity are significant predictors of traumatic brain injury (TBI) outcomes in the immature brain. TBI studies have segregated TBI injury into three severity groups: mild, moderate, and severe. While mild TBI is most frequent form in children and adults, there is debate over the indicators used to denote mild injury. Clinically, magnetic resonance imaging (MRI) and computed tomography (CT) are used to diagnose the TBI severity when medically warranted. Herein, we induced mild, moderate, and severe TBI in juvenile rats (jTBI) using the controlled cortical impact model. We characterized the temporal and spatial injury after graded jTBI in vivo using high‐field MRI at 0.25 (6 hr), 1 and 3 days post‐injury (dpi) with comparative histology. Susceptibility‐weighted imaging (SWI) for blood and T2‐weighted imaging (T2WI) for edema were quantified over the 0.25–3 dpi. Edema volumes increased linearly with severity at 0.25 dpi that slowly continued to decrease over the 3 dpi. In contrast, blood volumes did not decrease over time. Mild TBI had the least amount of blood visible on SWI. Fluoro‐jade B (FJB) staining for cell death confirmed increased cellular death with increasing severity and increased FJB + cells in the corpus callosum (CC). Interestingly, the strongest correlation was observed for cell death and the presence of extravascular blood. A clear understanding of acute brain injury (jTBI) and how blood/edema contribute to mild, moderate, and severe jTBI is needed prior to embarking on therapeutic interventions. Noninvasive imaging should be used in mild jTBI to verify lack of overt injury. Juvenile TBI results in blood (red) and edema (blue) deposition and can be visualized on MRI. Increasing severity of injury results in increasing levels of fluoro‐jade B (FJB) positive cell death which extends from the cortex at impact site into CC.