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Superfine Magnetic Resonance Imaging of the Cerebrovasculature Using Self‐Assembled Branched Polyethylene Glycol–Gd Contrast Agent
Author(s) -
Mahara Atsushi,
Enmi Junichiro,
Hsu YuI,
Kobayashi Naoki,
Hirano Yoshiaki,
Iida Hidehiro,
Yamaoka Tetsuji
Publication year - 2018
Publication title -
macromolecular bioscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.924
H-Index - 105
eISSN - 1616-5195
pISSN - 1616-5187
DOI - 10.1002/mabi.201700391
Subject(s) - polyethylene glycol , peg ratio , conjugated system , magnetic resonance imaging , chemistry , chelation , ethylene glycol , gadolinium , contrast (vision) , nuclear magnetic resonance , polymer , optics , radiology , organic chemistry , medicine , physics , finance , economics
Magnetic resonance angiography is an attractive method for the visualization of the cerebrovasculature, but small‐sized vessels are hard to visualize with the current clinically approved agents. In this study, a polymeric contrast agent for the superfine imaging of the cerebrovasculature is presented. Eight‐arm polyethylene glycol with a molecular weight of ≈17 000 Da conjugated with a Gd chelate and fluorescein (F‐8‐arm PEG‐Gd) is used. The relaxivity rate is 9.3 × 10 −3 m −1 s −1 , which is threefold higher than that of free Gd chelate. Light scattering analysis reveals that F‐8‐arm PEG‐Gd is formed by self‐assembly. When the F‐8‐arm PEG‐Gd is intravenously injected, cerebrovasculature as small as 100 µm in diameter is clearly visualized. However, signals are not enhanced when Gd chelate and Gd chelate‐conjugated 8‐arm PEG are injected. Furthermore, small vasculature around infarct region in rat stroke model can be visualized. These results suggest that F‐8‐arm PEG‐Gd enhances the MR imaging of cerebrovasculature.