title: High resolution NMR imaging using a high field yokeless permanent magnet.
abstract: We measured the homogeneity and stability of the magnetic field of a high field (about 1.04 tesla) yokeless permanent magnet with 40-mm gap for high resolution nuclear magnetic resonance (NMR) imaging. Homogeneity was evaluated using a 3-dimensional (3D) lattice phantom and 3D spin-echo imaging sequences. In the central sphere (20-mm diameter), peak-to-peak magnetic field inhomogeneity was about 60 ppm, and the root-mean-square was 8 ppm. We measured room temperature, magnet temperature, and NMR frequency of the magnet simultaneously every minute for about 68 hours with and without the thermal insulator of the magnet. A simple mathematical model described the magnet's thermal property. Based on magnet performance, we performed high resolution (up to [20 µm](2)) imaging with internal NMR lock sequences of several biological samples. Our results demonstrated the usefulness of the high field small yokeless permanent magnet for high resolution NMR imaging.
authors.affiliation: Institute of Applied Physics, University of Tsukuba, Ibaraki, Japan. kose@bk.tsukuba.ac.jp
authors.forename: Katsumi
authors.initials: K
authors.lastname: Kose
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Haishi
mesh_terms: D004867:Equipment Design; D005385:Fingers; D006801:Humans; D021621:Imaging, Three-Dimensional; D060526:Magnetic Fields; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation*; D019047:Phantoms, Imaging; D014675:Vegetables