Abstract: The invention provides a composition of matter of the formula (I): V—L—R where V is an organic group having binding affinity for an angiotensin II receptor site, L is a linker moiety or a bond, and R is a moiety detectable in in vivo imaging of a human or animal body, with the provisos that where V is angiotensin or a peptidic angiotensin derivative or analog then V—L—R is other than a non-metal radionuclide substituted peptide (e.g. 125I substituted angiotensin II) and L—V is other than simply a peptide with a chelating agent amide bonded to a side chain thereof. This composition of matter may be used to image cardiovascular diseases and disorders.