title: A system for low field imaging of laser-polarized noble gas.
abstract: We describe a device for performing MRI with laser-polarized noble gas at low magnetic fields (<50 G). The system is robust, portable, inexpensive, and provides gas-phase imaging resolution comparable to that of high field clinical instruments. At 20.6 G, we have imaged laser-polarized (3)He (Larmor frequency of 67 kHz) in both sealed glass cells and excised rat lungs, using approximately 0.1 G/cm gradients to achieve approximately 1 mm(2) resolution. In addition, we measured (3)He T(2)(*) times greater than 100 ms in excised rat lungs, which is roughly 20 times longer than typical values observed at high ( approximately 2 T) fields. We include a discussion of the practical considerations for working at low magnetic fields and conclude with evidence of radiation damping in this system.
authors.affiliation: Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA.
authors.forename: G P
authors.initials: GP
authors.lastname: Wong
authors.forename: C H
authors.initials: CH
authors.lastname: Tseng
authors.forename: V R
authors.initials: VR
authors.lastname: Pomeroy
authors.forename: R W
authors.initials: RW
authors.lastname: Mair
authors.forename: D P
authors.initials: DP
authors.lastname: Hinton
authors.forename: D
authors.initials: D
authors.lastname: Hoffmann
authors.forename: R E
authors.initials: RE
authors.lastname: Stoner
authors.forename: F W
authors.initials: FW
authors.lastname: Hersman
authors.forename: D G
authors.initials: DG
authors.lastname: Cory
authors.forename: R L
authors.initials: RL
authors.lastname: Walsworth
mesh_terms: D000818:Animals; D004867:Equipment Design; D006371:Helium; D007554:Isotopes; D007834:Lasers; D008168:Lung / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008280:Magnetics; D008297:Male; D008433:Mathematics; D019047:Phantoms, Imaging; D011846:Radio Waves; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D007554:Isotopes; D006371:Helium