title: Compensation for spin-lock artifacts using an off-resonance rotary echo in T1rhooff-weighted imaging.
abstract: The origin of image artifacts in an off-resonance spin-locking experiment is shown to be imperfections in the excitation flip angle. A pulse sequence for off-resonance spin locking is implemented that compensates for imperfections in the excitation flip angle through an off-resonance rotary echo. The off-resonance rotary echo alternates the frequency offset and phase of the RF transmitter during two spin-locking pulses of equal duration. The underlying theory is detailed, and MR images demonstrate the effectiveness of the technique in agarose gel phantoms and in in vivo human brain at 3T.
authors.affiliation: Department of Biochemistry & Molecular Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6100, USA. witschey@med.upenn.edu
authors.forename: Walter R T
authors.initials: WR
authors.lastname: Witschey
authors.forename: Arijitt
authors.initials: A
authors.lastname: Borthakur
authors.forename: Mark A
authors.initials: MA
authors.lastname: Elliott
authors.forename: Eric
authors.initials: E
authors.lastname: Mellon
authors.forename: Sampreet
authors.initials: S
authors.lastname: Niyogi
authors.forename: Chenyang
authors.initials: C
authors.lastname: Wang
authors.forename: Ravinder
authors.initials: R
authors.lastname: Reddy
mesh_terms: D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008962:Models, Theoretical; D019047:Phantoms, Imaging; D012016:Reference Values