High-resolution MRI characterization of human thrombus using a novel fibrin-targeted paramagnetic nanoparticle contrast agent

In this study, the sensitivity of a novel fibrin-targeted contrast agent fo r fibrin defection was defined in vitro on human thrombus, The contrast age nt was a lipid-encapsulated perfluorocarbon nanoparticle with numerous Gd-D TPA complexes incorporated into the outer surface, After binding to fibrin clots, scanning electron microscopy of treated clots revealed dense accumul ation of nanoparticles on the clot surfaces, Fibrin clots with sizes rangin g from 0.5-7.0 mm were imaged at 4.7 T with or without treatment with the t argeted contrast agent, Regardless of sizes, untreated clots were not detec table by T-1-weighted MRI, while targeted contrast agent dramatically impro ved the detectability of all clots, Decreases in T-1 and T-2 relaxation tim es (20-40%) were measured relative to the surrounding media and the control clots. These results suggest the potential for sensitive and specific dete ction of microthrombi that form on the intimal surfaces of unstable atheros clerotic plaque. (C) 2000 Wiley-Liss, Inc.