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MRI Agents (mri + agent)
Selected AbstractsFluorinated Polymer Nanoparticles as a Novel 19F MRI Contrast Agent Prepared by Dendrimer-Initiated Living Radical PolymerizationMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 12 2010Michihiro Ogawa Abstract Novel fluorinated polymer nanoparticles (PNPs) for 19F MRI were prepared by living radical polymerization initiated by a dendrimer. The dendritic macroinitiator with Br substituents was synthesized from hydroxy-group-terminated G2 polyamidoamine dendrimers. The arborescent fluorinated polymers of 2,2,3,3-tetrafluoropropyl methacrylate and 2,2,2-trifluoroethyl methacrylate were characterized in molecular weight, the number of arms, the degree of polymerization per arm, and the diameter as a whole. The PNP diameter was precisely controlled by the molecular weight in the range of 3,25,nm. In addition, the fluorinated PNP gave a narrow resonance by 19F NMR spectroscopy. These results indicate that the fluorinated PNP can be used as a new type of 19F MRI agent. [source] Safety update on the possible causal relationship between gadolinium-containing MRI agents and nephrogenic systemic fibrosisJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2007Michael Pedersen PhD [source] PAMAM dendrimer-based contrast agents for MR imaging of Her-2/neu receptors by a three-step pretargeting approachMAGNETIC RESONANCE IN MEDICINE, Issue 4 2008Wenlian Zhu Abstract Pretargeting of receptors is a useful approach in molecular imaging and therapy to reduce background noise or toxicity and enhance selectivity. In this study a three-step pretargeting approach that includes a biotinylated antibody, avidin/streptavidin, and a biotinylated imaging agent is described. A PAMAM dendrimer generation 4 (G4D)-based MRI T1 agent biotin-G4D-DTPA-Gd (bG4D-Gd) and its sister compound with remaining free surface amine groups blocked by succinic anhydride to reduce positive charges (bG4D-Gd-SA) were synthesized. Limited selective enhancement in MRI was observed in a Her-2/neu mouse tumor xenograft by this three-step pretargeting approach that includes biotinylated trastuzumab, avidin and bG4D-Gd, or bG4D-Gd-SA. However, these dendrimer-based MRI agents with molecular weight around 29 kD reached and remained in the tumor through the enhanced permeability and retention effect. Prolonged and extensive accumulation of both bG4D-Gd and b-G4-Gd-SA in the kidneys was also observed. Magn Reson Med, 2008. © 2008 Wiley-Liss, Inc. [source] Paramagnetic Liposomes as Innovative Contrast Agents for Magnetic Resonance (MR) Molecular Imaging ApplicationsCHEMISTRY & BIODIVERSITY, Issue 10 2008Enzo Terreno Abstract This article illustrates some innovative applications of liposomes loaded with paramagnetic lanthanide-based complexes in MR molecular imaging field. When a relatively high amount of a GdIII chelate is encapsulated in the vesicle, the nanosystem can simultaneously affect both the longitudinal (R1) and the transverse (R2) relaxation rate of the bulk H2O H-atoms, and this finding can be exploited to design improved thermosensitive liposomes whose MRI response is not longer dependent on the concentration of the probe. The observation that the liposome compartmentalization of a paramagnetic LnIII complex induce a significant R2 enhancement, primarily caused by magnetic susceptibility effects, prompted us to test the potential of such agents in cell-targeting MR experiments. The results obtained indicated that these nanoprobes may have a great potential for the MR visualization of cellular targets (like the glutamine membrane transporters) overexpressing in tumor cells. Liposomes loaded with paramagnetic complexes acting as NMR shift reagents have been recently proposed as highly sensitive CEST MRI agents. The main peculiarity of CEST probes is to allow the MR visualization of different agents present in the same region of interest, and this article provides an illustrative example of the in vivo potential of liposome-based CEST agents. [source] | ||||||||||