title: Artifacts in T(1rho)-weighted imaging: correction with a self-compensating spin-locking pulse.
abstract: Significant artifacts arise in T(1rho)-weighted imaging when nutation angles suffer small deviations from their expected values. These artifacts vary with spin-locking time and amplitude, severely limiting attempts to perform quantitative imaging or measurement of T(1rho) relaxation times. A theoretical model explaining the origin of these artifacts is presented in the context of a T(1rho)-prepared fast spin-echo imaging sequence. Experimentally obtained artifacts are compared to those predicted by theory and related to B(1) inhomogeneity. Finally, a "self-compensating" spin-locking preparatory pulse cluster is presented, in which the second half of the spin-locking pulse is phase-shifted by 180 degrees. Use of this pulse sequence maintains relatively uniform signal intensity despite large variations in flip angle, greatly reducing artifacts in T(1rho)-weighted imaging.
authors.affiliation: B1 Stellar-Chance Laboratories, MMRRCC, Department of Radiology, University of Pennsylvania, 422 Curie Boulevard, Philadelphia, PA 19104-6100, USA. Sridhar@mail.mmrrcc.upenn.edu
authors.forename: Sridhar R
authors.initials: SR
authors.lastname: Charagundla
authors.forename: Arijitt
authors.initials: A
authors.lastname: Borthakur
authors.forename: John S
authors.initials: JS
authors.lastname: Leigh
authors.forename: Ravinder
authors.initials: R
authors.lastname: Reddy
mesh_terms: D016477:Artifacts; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*