title: Detection of weak magnetic fields induced by electrical currents with MRI: theoretical and practical limits of sensitivity.
abstract: Detection of weak magnetic fields induced by neuronal electrical activities with magnetic resonance imaging (MRI) is a potentially effective method for functional imaging of the brain. In this study, we compared the theoretical and practical limits of sensitivity for detecting weak magnetic fields with a columnar phantom. The theoretical limit of sensitivity was estimated from signal and noise intensities in magnetic resonance images. The theoretical limit of sensitivity was approximately 10(-8)T. The practical limit was 10 times the theoretical limit. The dependence of the theoretical limit of sensitivity on acquisition parameters, such as the repetition time (TR), echo time (TE), number of pixels, and spectral width, was quantitatively evaluated. The results indicated the existence of an optimal value in T(E)/T2*.
authors.affiliation: Department of Biomedical Engineering, Graduate School of Medicine, University of Tokyo, Japan.
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Hatada
authors.forename: Masaki
authors.initials: M
authors.lastname: Sekino
authors.forename: Shoogo
authors.initials: S
authors.lastname: Ueno
mesh_terms: D001931:Brain Mapping / Q000379:methods; D004574:Electromagnetic Fields; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D012680:Sensitivity and Specificity; D013997:Time Factors