Quantitative T1ρ imaging using phase cycling for B0 and B1 field inhomogeneity compensation

Abstract

T 1 ρ imaging is useful in a number of clinical applications. T 1 ρ preparation methods, however, are sensitive to non-uniformities of the B 0 magnetic field and the B 1 RF field. These common system imperfections can result in image artifacts and quantification errors in T 1 ρ imaging. We report on a phase-cycling method which can eliminate B 1 RF inhomogeneity effects in T 1 ρ imaging. This method does not only correct for image artifacts but also for T 2 ρ contamination caused by B 1 RF inhomogeneity. The presence of B 0 magnetic field inhomogeneity can compromise the effectiveness of this method for B 1 RF inhomogeneity correction. We demonstrate that, by combining the spin-locking scheme reported by Dixon et al. (Myocardial suppression in vivo by spin locking with composite pulses. Magn Reson Med 1996; 36:90–94) with phase cycling, we can simultaneously correct B 0 magnetic field inhomogeneity effects and B 1 RF inhomogeneity effects in T 1 ρ imaging. Phantom and in vivo data sets are used to demonstrate the proposed methods and to compare them with other existing T 1 ρ preparation methods.