Contrast agents

1. A composition of matter of formula I

V-L-R  (Formula I)

wherein

L is a linker moiety or a bond;

R is a moiety comprising one to ten detectable labels; and

V is selected from the list of non-peptidic organic groups consisting of:

N 2 -[3S-hydroxy-4-(N-hydroxyamino)2R-isobutylsuccinyl]-L-(4-oxymethylcarboxy)phenylalanine-N 1 -methylamide,

N-(4-octylphenyl)-3-(2-carboxyethyl)-6,7-dihydro-5H-thiazolo[3,2-a]pyrimidine-2-carboxamide,

N 2 -[3S-hydroxy-4-hydroxyamino)-2R-isobutylsuccinyl]-L-phenylalanine-N 1 -methylamide,

N-(6-aminohexyl)-[4-(6,7-dimethoxy-quinazolin-4-ylamino)phenyl]acetamide hydrochloride,

3-Oxo-2-[2-(pyridin-2-ylamino)-ethyl]-2,3-dihydro-1H-isoindole-5-carboxylic acid [2-(2-amino-ethylcarbamoyl)-ethyl]-amide, and

N-(6-amino-hexyl)-2-{3-[2-(4-chloro-benzyloxy)-2-(2,4-dichloro-phenyl)-ethyl]-3H-imidazol-1-yl}-acetamide.

2. A composition of matter of claim 1 labelled with Gd(III), 99m Tc or 111 In chelates of DTPA.

3. A composition of matter as claimed in claim 1 wherein R is a radionuclide.

4. A composition of matter as claimed in claim 3 wherein R is an iodine or metal radionuclide.

5. A pharmaceutical composition comprising a composition of matter of formula I as defined in claim 1 together with at least one pharmaceutically acceptable carrier or excipient.

6. A method of generating an image of an animate human or non-human animal subject involving administering a contrast agent to said subject and generating an image of at least a part of said subject to which said contrast agent has distributed, characterised in that as said contrast agent is used as a composition of matter of formula I as defined in claim 1 .

7. A process for the preparation of a composition of a matter of formula I

V-L-R

of claim 1 , said process comprising conjugating moiety V with moiety R via the linker or bond L.