Imaging the Distribution of Magnetic Nanoparticles With Ultrasound

Magnetic nanoparticles can be caused to oscillate under the influence of an incident ultrasonic wave. If the particles are momentarily aligned with a magnetizing pulse creating a macroscopic magnetization, this oscillation will result in a time-varying magnetic moment which should be detectable as an induced voltage in a nearby pickup coil. In this way, focused ultrasound can be used to map, or image, the spatial distribution of the magnetic particles after these particles have been introduced into the body. The magnetic particles could be antibody-labeled to target tumor cells or used as a cardiovascular contrast agent, among other applications. The magnitude of the induced signal is estimated for one micron particles with a Fe/tissue volume fraction of 10-6, which is about the limit of detectability for MRI superparamagnetic contrast agents consisting of single domain iron-oxide particles. One advantage of this method compared to conventional MRI is potentially greater sensitivity due to the absence of a large background signal

[1]  H. Bryant,et al.  A biomagnetic system for in vivo cancer imaging , 2005, Physics in medicine and biology.

[2]  J. Chalmers,et al.  Analytical magnetapheresis of ferritin-labeled lymphocytes. , 1995, Analytical chemistry.

[3]  P. Lauterbur,et al.  The sensitivity of the zeugmatographic experiment involving human samples , 1979 .

[4]  Thomas L. Szabo,et al.  Diagnostic Ultrasound Imaging: Inside Out , 2004 .

[5]  R Weissleder,et al.  Monocrystalline iron oxide nanocompounds (MION): Physicochemical properties , 1993, Magnetic resonance in medicine.

[6]  T. Ibrahim.  Analytical approach to the MR signal , 2005, Magnetic resonance in medicine.

[7]  Jeff W M Bulte,et al.  Clinically applicable labeling of mammalian and stem cells by combining superparamagnetic iron oxides and transfection agents. , 2003, Radiology.

[8]  Q. Pankhurst,et al.  Applications of magnetic nanoparticles in biomedicine , 2003 .

[9]  R. Weissleder,et al.  Pancreatic receptors: initial feasibility studies with a targeted contrast agent for MR imaging. , 1994, Radiology.

[10]  R Weissleder,et al.  Improved delineation of human brain tumors on MR images using a long‐circulating, superparamagnetic iron oxide agent , 1999, Journal of magnetic resonance imaging : JMRI.

[11]  A. Bjørnerud,et al.  NC100150 injection, a preparation of optimized iron oxide nanoparticles for positive‐contrast MR angiography , 2000, Journal of magnetic resonance imaging : JMRI.

[12]  R. Harrington.  Time-Harmonic Electromagnetic Fields , 1961 .

[13]  J. Barger,et al.  Elements of acoustics , 1998 .

[14]  R. Chow,et al.  ELECTROKINETIC MEASUREMENTS BY ELECTROACOUSTICAL METHODS , 1989 .

[15]  Alan P Koretsky,et al.  Sizing it up: Cellular MRI using micron‐sized iron oxide particles , 2005, Magnetic resonance in medicine.