Introduction Proton magnetic resonance spectroscopy (H-MRS) offers attractive possibilities for the non-invasive in vivo assessment of breast lesion biochemistry, as an aid for diagnosis [1] and an early indicator of disease response to treatment [2-4]. Effective shimming to achieve a high magnetic field homogeniety over the volume of interest (VOI) is paramount for MRS to achieve sufficient sp...

PURPOSE To determine the optimal method to correct air and tissue susceptibility differences in the head and neck to allow proton ((1)H) chemical shift imaging (CSI) to be performed at 3T. MATERIALS AND METHODS Shimming protocols (iterative, first-order, and second-order) and perfluorocarbon (PFC) pads were evaluated using water peak linewidth measurements obtained from single-voxel magnetic ...

Introduction Achieving given homogeneity and SAR constraints in RF shimming process is an important problem in high field MRI. There are different studies in the literature which dealt with the optimization of these parameters by using non-convex optimization techniques. In a previous work whole body SAR constrained RF shimming problem was solved in order to achieve whole slice transmit homogen...

PURPOSE At 7 Tesla (T), conventional static field (B0 ) projection mapping techniques, e.g., FASTMAP, FASTESTMAP, lead to elevated specific absorption rates (SAR), requiring longer total acquisition times (TA). In this work, the series of adiabatic pulses needed for slab selection in FASTMAP is replaced by a single two-dimensional radiofrequency (2D-RF) pulse to minimize TA while ensuring equal...

In this paper an approach of ferromagnetic shimming for permanent MRI magnet is presented. It is designed to reduce unhomogeneity of magnetostatic field of permanent magnet to meet the stringent requirement for MRI applications. An optimal configuration of ferromagnetic pieces is generated through calculation according to the initial field map and the demanded final homogeneity specifications. ...

Introduction Increased spectral resolution and signal-to-noise ratio (SNR) and additional metabolite information not available at B0 = 1.5T are some of the benefits of magnetic resonance spectroscopy (MRS) at higher fields (≥3T) that enhance its attractiveness as an investigational tool for clinical use. However, to obtain high-quality MR spectra, reliable localized shimming is an essential pre...

PURPOSE To investigate the feasibility of high-dose dobutamine stress (HDDS) imaging using SSFP sequences at 3 T employing patient-adaptive local RF-shimming using a dual-source RF transmission system. MATERIALS AND METHODS 13 Patients underwent a HDDS protocol on a 3 T MRI scanner (Achieva 3.0T-TX, Philips Healthcare), equipped with a dual-source RF transmission system. SSFP cine sequences u...

There is evidence in the literature indicating a significant static field inhomogeneity in the human breast. A nonhomogenous field results in line broadening and frequency shifts in MRS and can cause intensity loss and spatial errors in MRI. Thus, there is a clear rationale for determining the regional variations in the static field homogeneity in the breast and providing strategies to correct ...

A spatially resolved extended phase graph (SR-EPG) framework is proposed for prediction of echo amplitudes in the presence of spatially variable radio frequency (RF) fields. The method may be used to examine any regularly repeating pulse sequence and provides a design framework for parallel transmission (PTx) systems; in this work signal homogeneity in static pseudo-steady state (SPSS) turbo sp...