TSPO and neoplasm: Fig. 4 demonstrates representative imaging and immunohistochemistry from a patient with a fast growing tumor and high 11C-(R)-PK11195 specific binding. Fig. 4B-D documents the spatial correspondence between Iba1 and TSPO expression within this tumor, and double immunostaining (Fig. 4E) demonstrated colocalization of TSPO expression within the cytoplasm of Iba1+ macrophages.