Introduction In principle, two different approaches are reported to diminish wave propagation effects, and thus, improve B1 homogeneity with parallel transmission. The first approach is given by "basic" RF shimming, adjusting amplitude and phase of the different transmit channels to obtain a homogeneous B1 distribution [1]. The second approach is given by "tailored" RF shimming, i.e., multidime...

Target audience: Researchers and engineers who have interest in RF transmit technology in high field MRI. Purpose: The B1 inhomogeneity is one of the problems for breast imaging at 3 T. Various methods using multiple channel RF transmit coil or using some additional dielectric absorptive material are investigated to overcome this problem [1, 2]. These studies showed the number of channels of RF...

• Halbach magnet adapted with rings for mechanical shimming. Novel passive magnetic field shimming method based on ferrofluid suspensions in microvolumes. Small size light-weight assembly suitable mobile resonance applications. A novel principle of permanent assemblies is introduced, defined amounts a suspension contained microliter volume plastic container that accurately positioned within the...

Introduction In high field MRI, the increased interactions between the electromagnetic waves and the biological tissues may give rise to heat and thermal hazards. This is clearly apparent for multi-transmit array applications where the electromagnetic fields are heavily manipulated in the subject to be imaged. In this work we provide complete 3D predictions of the B1 + fields, MRI images, energ...

MOTIVATION Functional renal imaging is an area of growing interest [1]. BOLD imaging of the kidneys is one of the functional techniques explored. This technique has the potential to study changes in blood flow and oxygenation in the hypoxic renal medulla. Depending on the amount of hypoxia in the medulla, the BOLD contrast between renal cortex and medulla changes. This change in contrast can be...

Introduction The B1 transmit field inhomogeneity represents a serious problem in whole-body high field MRI (≥3T). B1 shimming based on measured B1 maps is a promising approach to cope with this problem and represents the primary application for parallel transmission at this point in time [1,2]. However, B1 mapping is still an error-prone and time consuming process [3], potentially resulting in ...

METHODS: Currently, among other means, modifications of the applied RF pulses are investigated to cope with the mentioned B1 inhomogeneities. First, using a coil array for RF transmission, standard slice selective pulses can be transmitted with different weights in the different array elements (see, e.g., [2-4]). These weights, i.e., amplitude and phase of each element, are designed to yield a ...

Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany Combining PET and MRI into a hybrid device is challenging since both systems might influence each other. A typical interference problem of such a combined device is the distortion of the MRI’s B0 field distribution due to the material brought inside the MRI’s...