A contrast agent of formula I: V-L-R (I) where V is an organic group having binding affinity for an angiotensin II receptor site, L is a linear or branched amino acid-comprising biomodifier or linker moiety, and R is a reporter moiety detectable in in vivo imaging of a human or animal body.
1. A contrast agent which is 99m Tc (Losartan-Leu-diglycolyl-cPn216), 99m Tc (Losartan-Leu-Gly-diglycolyl-cPn216), 99m Tc (Losartan-Leu-β-Ala-diglycolyl-cPn216) or 99m Tc (Losartan-Leu-Lys(Propionyl-PEG(12)-Ac)-Diglycoloyl-cPn216).
2. A pharmaceutical composition comprising an effective amount of a contrast agent of claim 1 or a salt thereof, together with one or more pharmaceutically acceptable adjuvants, excipients or diluents for use in enhancing image contrast in in vivo imaging.
3. A method of generating enhanced images of a human or animal body previously administered with a contrast agent composition comprising a contrast agent of claim 1 , which method comprises generating an image of at least part of said body.