Compounds for targeting endothelial cells, compositions containing the same and methods for their use

1. A method of imaging endothelial cells, tumor cells or other cells that express NP-1 in a human or animal comprising:

a) administering to said human or animal a composition comprising a compound of the formula (I)

A-L-B  (I)

in which:

A is a monomer of TKPPR (SEQ ID NO:2) or a monomer of a TKPPR (SEQ ID NO:2) analogue which contains TKPPR (SEQ ID NO:2) and which

specifically binds to NP-1 or cells which express NP-1 with avidity that is equal to or greater than TKPPR (SEQ ID NO:2);

L is a linker; and

B is a phospholipid; and

b) detecting said compound.

2. The method of claim 1 wherein a tumor in a human or an animal is staged.