PET Imaging of Translocator Protein in Subjects With Traumatic Brain Injury

Objective:

Brain damage following traumatic injury (TBI) results from both direct (e.g., mechanical injury to the brain and vasculature) and indirect mechanisms (e.g., secondary mechanisms such as inflammation). While CT and MRI can help visualize the result of inflammatory processes in the brain for instance, the development of cerebral edema neither method can be used to document active inflammation itself. The translocator protein (TSPO), which is highly expressed in microglia and reactive astrocytes, has been used as a biomarker in positron emission tomography (PET) to identify active inflammatory processes. Recently, our laboratory developed PBR28, a new PET ligand that images TSPO with high levels of specific binding. We have successfully used PBR28 to investigate a number of brain disorders such as epilepsy, multiple sclerosis, and HIV infection with minor cognitive motor disorder, and are detecting neuroinflammation. The current protocol aims to explore whether PBR28 PET imaging can show changes in subjects with TBI who have shown MRI abnormalities in the acute phase and also in those who are in the chronic phase of TBI.

Study population: The following three groups will be studied:

TBI subjects who had brain injury within approximately 3 months and have exhibited MRI abnormalities consistent with TBI and who are enrolled in "Evaluation, Pathogenesis, and Outcome of Subjects with or Suspected Traumatic Brain Injury" (10-N-N122, PI Latour), "Evaluation and Diagnosis of Potential Research Subjects with Traumatic Brain Injury (TBI), (11-N-0084, PI: Lawrence Latour), or other CNRM protocols. N = 20

TBI subjects who had brain injury more than approximately 5 month ago, are enrolled in 11-N-0084, and meet criteria of TBI established by CNRM. N = 20