This is a single arm, pilot trial that evaluates the ability of a novel imaging agent (111In-ABD147) to detect metastatic cancer in participants with solid tumors. 111In-ABD147 is a high affinity Delta-like ligand 3 (DLL3) antigen binding domain fused to an engineered humanized Fc to create an antibody (VHH-Fc) that is bio-conjugated with a DOTA linker-chelator to a 111In radiometal. DLL3 is expressed on a variety of tumors, particularly those with neuroendocrine features.