CD69 and central nervous system cancer: noninvasive visualization of targets like PD-L1 (present on tumor and immune cells), CD4/CD8 (on T-cell subsets), CD11b (on myeloid-lineage cells), CD69 (on early activated T-cells), and OX40 or TIGIT (as co-stimulatory/co-inhibitory checkpoint molecules) provides a window into multiple facets of the glioma immune reaction, offering richer insights than tumor-centered imaging alone.