In this paper we reconstruct the 3-D MR spectroscopic data acquired using an echo-planar spectroscopic imaging (EPSI) sequence. We propose to compensate for 0 B inhomogeneity artifact by using the 0 B field map and * 2 T decay estimated from a higher resolution, multi-slice proton imaging data scanned with similar shimming to the EPSI one. We employ total variation (TV) regularization to obtain...

Improvements in Bo mapping and shimming were achieved by measuring the static field information in multiple subsequent echoes generated by an asymmetric echo-planar readout gradient train. With careful compensation, eddy current effects were shown to affect the adjustment of the shim coils minimally. In addition to reducing the time required for field mapping by two-fold, the sensitivity was si...

Resistive and resistive-superconducting hybrid magnets can generate dc magnetic fields much higher than conventional superconducting NMR magnets but the field spatial homogeneity and temporal stability are usually not sufficient for high-resolution NMR experiments. Hardware and technique development addressing these issues are presented for high-resolution NMR at magnetic fields up to 40T. Pass...

Introduction FDTD is widely used for EM analyses in MRI applications, due to its simplicity and efficiency in wave modelling and its ability to handle field-tissue interactions. However, contemporary MRI problems, such as high field-tissue interaction modelling requires high performance computing. Conventional CPU-based FDTD calculations offer compromised computing performance without expensive...

We present a method of 3D automated shimming in high-resolution applications. This does not heavily rely on Pulsed Field Gradient (PFG) modules and can be used with any spectrometer equipped with shims and homospoil facilities at least. The method exploits Fourier imaging technique for mapping of static magnetic field inhomogeneity and field shapes generated by shim coils, which are used as inp...

Introduction. Several studies showing the feasibility of high-field (7T and above) cardiac imaging have been demonstrated within the past year [1-5]. Many used sophisticated, custom-built transmit arrays with B1-shimming capabilities [1-3], but the use of relatively simple surface coils has also been shown to be practical [4,5]. To date, no quantitative analysis of high field cardiac images has...

Background 3T MRI is advantageous to CMR as it offers higher SNR and better T1 contrast. Its slow clinical adoption is partly due to the lack of robustness in SSFP cine imaging [1]. Banding artifact in SSFP caused by main field inhomogeneity is common at 3T. Wideband SSFP [2] or prescans (shimming, frequency scout, etc.) are needed to avoid/ reduce the artifact, increasing patient scan time. We...

Background Quantification of myocardial iron overload is critical for the management of patients with hemochromatosis. T2* relaxation time or its inverse R2*, are currently the noninvasive gold standard at 1.5T, as they strongly correlate with myocardial iron concentration, and are obtained using a fast single breath-hold ECG-gated multi-echo GRE sequence. However, due to high sensitivity to B0...

High magnetic fields increase the sensitivity and spectral dispersion in magnetic resonance spectroscopy (MRS). In contrast, spectral peaks are broadened in vivo at higher field strength due to stronger susceptibility-induced effects. Strategies to minimize the spectral linewidth by optimal shimming are therefore of critical importance. The problem of shim requirements exceeding the active shim...

Background Cardiac MR (CMR) at ultrahigh fields (≥7.0 T) is challenged by B1+ inhomogeneities and signal voids which bear the potential to spoil the signal-to-noise (SNR) benefits at 7.0 T. There is a trend towards an ever larger number of transmit and receive channels, to support multidimensional B1+ shimming and parallel imaging. Therefore this work proposes a modular, two dimensional 32-chan...