FOLH1 and central nervous system cancer: These include PET tracers targeting epidermal growth factor receptor (EGFR) expression in gliomas, chemokine receptor type 4 (CXCR4) in lymphoma, translocator protein (TSPO), and prostate-specific membrane antigen (PSMA).130Imaging of hypoxia and other amino acids are growing applications, and PET probes targeting the immune system, specifically the metabolic reprogramming of T-cells,130represent an exciting frontier in the age of immunotherapy.