Tokyo Nuclear Services Co. Ltd. 1 article published in JoVE Medicine Semi-quantitative Assessment Using [18F]FDG Tracer in Patients with Severe Brain Injury Tomohiro Yamaki1,2, Shinji Onodera2, Tomoki Uchida2, Yoshihiro Ozaki2, Kazuaki Yokoyama3, Haruko Henmi2, Mizuho Kamezawa2, Miyoko Hayakawa2, Daisuke Itou1, Nobuo Oka1,2, Masaru Odaki1, Yasuo Iwadate4, Shigeki Kobayashi1 1 [18F]-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography is useful for studying glucose metabolism related to brain function. Here, we present a protocol for an [18F]FDG tracer set-up and semiquantitative assessment of the region-of-interest analysis for targeted brain areas associated with clinical manifestations in patients with severe traumatic brain injury.