"maging region; and an instrument for use with the target object in the imaging region, said instrument including a body sized for use in the target object and a polymeric-paramagnetic ion complex coating thereon in which said complex is represented by formula (I): P-X-L-Mn+(I) wherein P is a polymer, X is a surface functional group, L is a chelate, M is a paramagnetic ion and n is an integer that" . . . .