Abstract: A lyophilized imaging agent formulation and methods for making same are disclosed, such formulations comprise a targeting molecule such as antibody or chemotactic peptide, a linker such as diethylenetriaminepentaacetic acid (DTPA) or succinimidyl 6-hydrazinium nicotinate hydrochloride (SHNH), drying protectant such as mannitol, maltose or tricine, and excipient such as polysorbate 80, in citrate buffer. The formulations of the invention are lyophilized and may be stored stably for extended periods of time. Following reconstitution with diluent, the formulations are administered to a subject for scintigraphic imaging or therapeutic use. Also contemplated is a kit comprising a two-vial system wherein a first vial comprises a lyophilized formulation of imaging agent in the form of a lyophilized cake, and a second vial comprises a pharmaceutically acceptable carrier or diluent.