Off-resonance effects can cause image blurring in spiral scanning and various forms of image degradation in other MRI methods. Off-resonance effects can be caused by both B0 inhomogeneity and concomitant gradient fields. Previously developed off-resonance correction methods focus on the correction of a single source of off-resonance. This work introduces a computationally efficient method of co...

We demonstrate quantitative experimental evidence for a weak localization correction to the conductivity in monolayer and bilayer graphene systems. We show how inter- and intra-valley elastic scattering control the correction in small magnetic fields in a way which is unique to graphene. A clear difference in the forms of the correction is observed in the two systems, which shows the importance...

FIELD INHOMOGENEITY COMPENSATION IN HIGH FIELD MAGNETIC RESONANCE IMAGING (MRI) Zhenghui Zhang, PhD University of Pittsburgh, 2006 This thesis concentrates on the reduction of field (both main field B0 and RF field B1) inhomogeneity in MRI, especially at high B0 field. B0 and B1 field inhomogeneity are major hindrances in high B0 field MRI applications. B1 inhomogeneity will lead to spatially v...

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 B0 magnetic field and the B1 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 B1 RF inhomogeneity effects in T(1)(ρ) imaging. T...

Brain image segmentation is one of the most important parts of clinical diagnostic tools. However, accurate segmentation of brain images is a very difficult task due to the noise, inhomogeneity and sometimes deviation in brain images. Wells model incorporates the brain image segmentation and inhomogeneity correction into one framework to overcome influences from the intensity inhomogeneity and ...

A fast parallel excitation pulse design algorithm to select and to order phase-encoding (PE) locations (also known as "spokes") of an Echo-Volumar excitation k-space trajectory considering B(0) field inhomogeneity is presented. Recently, other groups have conducted research to choose optimal PE locations, but the potential benefit of considering B(0) field inhomogeneity during PE location selec...

Recent studies have proposed that glycosaminoglycan chemical exchange saturation transfer (gagCEST) is associated with a loss of glycosaminoglycans (GAGs), which may be an initiating factor in intervertebral disc (IVD) degeneration. Despite its promising potential, this application has not been reported in human in vivo IVD studies because of the challenges of B(0) magnetic field inhomogeneity ...

The simultaneous use of linear spatial encoding magnetic fields (L-SEMs) and nonlinear spatial encoding magnetic fields (N-SEMs) in B1+ inhomogeneity problems is formulated and demonstrated with both simulations and experiments. Independent excitation k-space variables for N-SEMs are formulated for the simultaneous use of L-SEMs and N-SEMs by assuming a small tip angle. The formulation shows th...