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Steering of aggregating magnetic microparticles using propulsion gradients coils in an MRI Scanner
Author(s) -
Mathieu JeanBaptiste,
Martel Sylvain
Publication year - 2010
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.22279
Subject(s) - materials science , scanner , magnetic nanoparticles , perpendicular , electromagnetic coil , amplitude , microfluidics , suspension (topology) , nuclear magnetic resonance , magnetic field , spectroscopy , analytical chemistry (journal) , mechanics , physics , chemistry , optics , nanotechnology , nanoparticle , geometry , mathematics , chromatography , quantum mechanics , homotopy , pure mathematics
Upgraded gradient coils can effectively enhance the MRI steering of magnetic microparticles in a branching channel. Applications of this method include MRI targeting of magnetic embolization agents for oncologic therapy. A magnetic suspension of Fe 3 O 4 magnetic particles was injected inside a y‐shaped microfluidic channel. Magnetic gradients of 0, 50, 100, 200, and 400 mT/m were applied to the magnetic particles perpendicularly to the flow by a custom‐built gradient coil inside a 1.5‐T MRI scanner. Measurement of the steering ratio was performed both by video analyses and quantification of the mass of the particles collected at each outlet of the microfluidic channel, using atomic absorption spectroscopy. Magnetic particles steering ratios of 0.99 and 0.75 were reached with 400 mT/m gradient amplitude and measured by video analyses and atomic absorption spectroscopy, respectively. Experimental data shows that the steering ratio increases with higher magnetic gradients. Moreover, theory suggests that larger particles (or aggregates), higher magnetizations, and lower flows can also be used to improve the steering ratio. The technological limitation of the approach is that an MRI gradient amplitude increase to a few hundred milliteslas per meter is needed. A simple analytical method based on magnetophoretic velocity predictions and geometric considerations is proposed for steering ratio calculation. Magn Reson Med 63:1336–1345, 2010. © 2010 Wiley‐Liss, Inc.