TSPO and injury: Using PET with TSPO-targeting radiotracers, such as carbon 11–labeled ([11C])–(R)-PK11195 or [11C]PBR28, high TSPO has been found in the brains of individuals 6 months after a traumatic brain injury,9,10 with evidence of high TSPO for up to 17 years after a moderate to severe brain insult.11 Further understanding of the microglial response to repeated mTBI in collision sport promises to inform future guidelines for game safety and clinical practices to promote brain healing.