A dendrimer conjugate according to Formula (I), or its pharmaceutically acceptable salt, or solvate thereof: and complexes of Formula I conjugates with metals radionuclides of elements such as rhenium, technetium, yttrium, lutetium and others to provide a complex for imaging tissues or for the radiotherapeutic treatment of cancer tissue. Such complexes are specific to PSMA protein and can therefore be used in imaging or treating cancer of the prostate and other tissue where the protein is expressed.
