title: SQUID-detected MRI at 132 microT with T1-weighted contrast established at 10 microT--300 mT.
abstract: T(1)-weighted contrast MRI with prepolarization was detected with a superconducting quantum interference device (SQUID). A spin evolution period in a variable field between prepolarization and detection enabled the measurement of T(1) in fields between 1.7 microT and 300 mT; T(1) dispersion curves of agarose gel samples over five decades in frequency were obtained. SQUID detection at 5.6 kHz drastically reduces the field homogeneity requirements compared to conventional field-cycling methods using Faraday coil detection. This allows T(1) dispersion measurements to be easily combined with MRI, so that T(1) in a wide range of fields can be used for tissue contrast. Images of gel phantoms with T(1)-weighted contrast at four different fields between 10 microT and 300 mT demonstrated dramatic contrast enhancement in low fields. A modified inversion recovery technique further enhanced the contrast by selectively suppressing the signal contribution for a specific value of the low-field T(1).
authors.affiliation: Department of Physics, 366 LeConte Hall, University of California, Berkeley, CA 94720, USA. Isk@socrates.berkeley.edu
authors.forename: Seung Kyun
authors.initials: SK
authors.lastname: Lee
authors.forename: Michael
authors.initials: M
authors.lastname: Mössle
authors.forename: Whittier
authors.initials: W
authors.lastname: Myers
authors.forename: Nathan
authors.initials: N
authors.lastname: Kelso
authors.forename: Andreas H
authors.initials: AH
authors.lastname: Trabesinger
authors.forename: Alexander
authors.initials: A
authors.lastname: Pines
authors.forename: John
authors.initials: J
authors.lastname: Clarke
mesh_terms: D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging