title: In-vivo Imaging of Magnetic Fields Induced by Transcranial Direct Current Stimulation (tDCS) in Human Brain using MRI.
abstract: Transcranial direct current stimulation (tDCS) is an emerging non-invasive neuromodulation technique that applies mA currents at the scalp to modulate cortical excitability. Here, we present a novel magnetic resonance imaging (MRI) technique, which detects magnetic fields induced by tDCS currents. This technique is based on Ampere's law and exploits the linear relationship between direct current and induced magnetic fields. Following validation on a phantom with a known path of electric current and induced magnetic field, the proposed MRI technique was applied to a human limb (to demonstrate in-vivo feasibility using simple biological tissue) and human heads (to demonstrate feasibility in standard tDCS applications). The results show that the proposed technique detects tDCS induced magnetic fields as small as a nanotesla at millimeter spatial resolution. Through measurements of magnetic fields linearly proportional to the applied tDCS current, our approach opens a new avenue for direct in-vivo visualization of tDCS target engagement.
authors.affiliation: BioMedical Engineering Inter-Departmental Program (BME-IDP), University of California Los Angeles, Los Angeles, California, United States.|Laboratory of FMRI Technology (LOFT), Department of Neurology, University of California Los Angeles, Los Angeles, California, United States.
authors.forename: Mayank V
authors.initials: MV
authors.lastname: Jog
authors.affiliation: Laboratory of FMRI Technology (LOFT), Department of Neurology, University of California Los Angeles, Los Angeles, California, United States.
authors.forename: Robert X
authors.initials: RX
authors.lastname: Smith
authors.affiliation: Laboratory of FMRI Technology (LOFT), Department of Neurology, University of California Los Angeles, Los Angeles, California, United States.|Stevens Neuroimaging and Informatics Institute, University of Southern California, Los Angeles, California, United States.
authors.forename: Kay
authors.initials: K
authors.lastname: Jann
authors.affiliation: Department of Psychiatry, University of California Los Angeles, Los Angeles, California, United States.
authors.forename: Walter
authors.initials: W
authors.lastname: Dunn
authors.affiliation: Department of Biomedical Engineering, The City College of The City University of New York, New York, United States.
authors.forename: Belen
authors.initials: B
authors.lastname: Lafon
authors.affiliation: Department of Biomedical Engineering, The City College of The City University of New York, New York, United States.
authors.forename: Dennis
authors.initials: D
authors.lastname: Truong
authors.affiliation: Laboratory of FMRI Technology (LOFT), Department of Neurology, University of California Los Angeles, Los Angeles, California, United States.
authors.forename: Allan
authors.initials: A
authors.lastname: Wu
authors.affiliation: Department of Biomedical Engineering, The City College of The City University of New York, New York, United States.
authors.forename: Lucas
authors.initials: L
authors.lastname: Parra
authors.affiliation: Department of Biomedical Engineering, The City College of The City University of New York, New York, United States.
authors.forename: Marom
authors.initials: M
authors.lastname: Bikson
authors.affiliation: Laboratory of FMRI Technology (LOFT), Department of Neurology, University of California Los Angeles, Los Angeles, California, United States.|Stevens Neuroimaging and Informatics Institute, University of Southern California, Los Angeles, California, United States.
authors.forename: Danny J J
authors.initials: DJ
authors.lastname: Wang
mesh_terms: D000328:Adult; D002540:Cerebral Cortex / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D060526:Magnetic Fields; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D050781:Transcranial Magnetic Stimulation