Magnetic resonance imaging of time-varying magnetic fields from therapeutic devices.
While magnetic resonance imaging of static magnetic fields generated by external probes has been previously demonstrated, there is an unmet need to image time-varying magnetic fields such as those generated by transcranial magnetic stimulators and radiofrequency hyperthermia probes. A method to image such time-varying magnetic fields is introduced in this study. This article presents the theory behind the method and provides proof of concept by imaging time-varying magnetic fields generated by a figure-eight coil inside simple phantoms over a range of frequencies and intensities using a 7T small animal MRI scanner. The method was able to reconstruct the three-dimensional components of the oscillating magnetic field vector.
FMRI Laboratory, 2360 Bonisteel Blvd., Ann Arbor, MI 48109-2108, USA.
Luis
L
Hernandez-Garcia
Vivek
V
Bhatia
Krishan
K
Prem-Kumar
Magnus
M
Ulfarsson
D006801:Humans; D060526:Magnetic Fields; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D000078702:Radiofrequency Therapy; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation / Q000295:instrumentation*