SUPERPARAMAGNETIC NANOPARTICLES CONTAINING LIPOSOMES AS POTENTIAL SPECIFIC CONTRAST AGENT FOR BRAIN MR-IMAGING - INITIAL FEASIBILITY STUDY BY A COMBINED APPROACH WITH FE-59-ACTIVATED TRACK-AUTORADIOGRAPHY

The present study is focused on the feasibility of a specific brain MR imaging. In this context, we used magnetite-dextran nanoparticles lab elled with Fe-59 encapsulated within mannose coated liposomes. These l iposomes are particularly well suited to such studies since they act b oth as a contrast agent and a radiotracer, thus permitting an unambigu ous correlation between in vivo macroscopic MR imaging signals and in vitro microlocalizations by Fe-59-activated track-autoradiography. MR imaging 48 h after intravenous injection of these liposomes in Lewis r ats suggested a specific fixation in choroid plexus, around large cere bral veins and in meninges. The histopathological significance of thes e MR signals was confirmed by validation at the cellular level using a specifically developed low-signal Fe-59-activated track-autoradiograp hic approach. This investigation model constitutes a promising approac h in neurobiology.