Instead, our focus shifted to the studies that explore the imaging of tumor-associated stroma and including programmed cell death protein-1 (PD-1) and its ligand (PD-L1) [38–40], carbonic anhydrase IX (CAIX) [41], and macrophage mannose receptor (MMR, or CD206) [42–44]. This evidence concerns the gene PDCD1 and neoplasm.