Denatured albumin complexes for radioscintigraphic imaging and evaluation of reticuloendothelial systems

Small sized material (less than 0.2 mu m, preferably less than 1 mu m) comprising a complex of (1) denatured albumi particularly human serum albumin and (2) a metal reducing agent, particularly a stannous reducing agent, preferably formed in the presence of a stabilizing ligand, which complex, when labelled with technetium-99m provides an excellent agent for imaging or otherwise evaluating reticuloendothelial systems (res) and/or components thereof, particularly the bone marrow, liver and/or lymphatic system; methods of making and using the same; a complex (physical or chemical) of technetium-99m with such materials and methods of using such latter complex