Introduction High-field magnetic resonance spectroscopy (MRS) has the potential to provide enhanced neurochemical information based on increased sensitivity and higher spectral resolution. However, problems arising in high-field magnetic resonance imaging (MRI), such as more pronounced B0 and B1 inhomogeneities, may decrease spectral resolution and ultimately the quantification accuracy. A mult...

A regularized algorithm is presented for localized in vivo shimming. The technique uses first- (X,Y,Z), second- (Z(2), ZX, ZY, X(2)-Y(2), XY), and third-order (Z(3)) shim coils, and is robust when applied to arbitrarily-shaped, as well as off-center, regions of interest (ROIs). A single-shot spiral pulse sequence is used for rapid field map acquisition, and a least-squares calculation of the sh...

Introduction B1 inhomogeneity in a human body increases as the strength of static magnetic field increases and the RF wavelength becomes smaller. Recently, various RF control methods have been developed to reduce B1 inhomogeneity. For example, some methods involve devices such as dielectric pads [1,2] or coupling coils [3,4], or techniques such as B1 shimming [5,6]. However, B1 inhomogeneity st...

OBJECTIVE The purpose of this study was to evaluate the feasibility of using integrated slice-by-slice shimming (iShim) for improving the image quality of whole-body diffusion-weighted imaging (WBDWI) in patients with plasma disorder at 3 T by comparing to WBDWI using a conventional shimming (3-dimensional [3D] shim) adjustment of each body station. MATERIALS AND METHODS After approval by the...

BACKGROUND Dual-channel transmit technology improves the image quality in cardiovascular magnetic resonance (CMR) at 3 T by reducing the degree of radiofrequency (RF) shading over the heart by using RF shimming. Further improvements in image quality have been shown on a dual-transmit system using high permittivity pads. The aim of this study is to investigate the transmit field (B 1 (+)) homoge...

Introduction: While a substantially increased degree of freedom inherent of parallel RF transmit facilitates excitation profile control, it meanwhile raises concerns that poorly guided multi-port RF pulse or shimming calculations, or multi-channel hardware failure may inadvertently elevate SAR. One can address the concerns to some extent by monitoring RF power at the ports, where power sensors ...