Patent ID: 6869591

Claim:
A contrast agent for magnetic resonance imaging (MRI), which agent comprises particles, wherein said particles are coupled to a chelator containing a paramagnetic ion which ion is positioned offset from the surface of the particles, so as to provide said ion substantial access to hydrogen nuclei in a surrounding liquid, whereby the relaxivity of said nuclei is enhanced, wherein said particles are microparticles or nanoparticles comprised of an inert core comprising fluorocarbon liquid surrounded by a lipid/surfactant coating, and wherein said offset is such that the particle provides a ρ 1 of at least about 0.5×10 6 (s*mM) −1 or a ρ 2 of at least about 1×10 6 (s*mM) −1 at a field strenth of 1.5 T on a per particle basis; and wherein the particles are emulsified in a liquid emulsion.