Bo Zhu1,2, Thomas
Witzel1,2, Shan Jiang3, Daniel G. Anderson3,
Robert S. Langer3, Bruce R. Rosen1,2,
1Harvard-MIT Division of Health Sciences & Technology, Massachusetts Institute of Technology, Cambridge, MA, USA; 2Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA; 3Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
A novel contrast mechanism for imaging iron oxide contrast agents is described based on the Rotary Saturation effect, whereby the oscillating magnetic fields generated from vibrating iron oxide nanoparticles resonantly couples with the spin system to produce tunable signal changes. We demonstrate this active contrast modulation with a block-design experiment interleaving vibration of the contrast agent on and off resonance relative to the rotating frame resonance frequency, and observe statistically significant signal changes only for ROIs adjacent to the nanoparticles. We envision contrast modulation of iron oxide nanoparticles in-vivo using sound waves or endogenous motion to generate the nanoparticle vibration.