title: A constant gradient unilateral magnet for near-surface MRI profiling.
abstract: The design and construction of a unilateral NMR (UMR) magnet assembly for near-surface 1D profiling is presented. The arrangement consists of a single permanent magnet topped with a shaped iron pole cap. The analytically determined profile of the pole cap shapes the field over the magnet, giving a constant gradient of 31 G/cm over a 8mm depth at a 1H frequency of 4.26 MHz in a spot approximately 5 mm wide. The moderate gradient allows 1D profiling of planar samples with a frequency encoded spin-echo experiment. The curvature of the magnetic field limits the available resolution to 100's of microm. The device is suitable for profiling planar samples in which a coarse resolution but large spatial extent is desired.
authors.affiliation: MRI Centre, Department of Physics, PO Box 4400, University of New Brunswick, Fredericton, New Brunswick, Canada E3B 5A3.
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Marble
authors.forename: Igor V
authors.initials: IV
authors.lastname: Mastikhin
authors.forename: Bruce G
authors.initials: BG
authors.lastname: Colpitts
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Balcom
mesh_terms: D000465:Algorithms; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D008280:Magnetics / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013499:Surface Properties; D014159:Transducers