Introduction: RF field non-uniformities caused by shortened RF wavelengths in human tissue significantly affect the image quality, especially for high-field MRI [1]. Spiral coils [2, 3] have been put forth to improve field homogeneity. In addition, RF shimming based on a TEM coil [4] or an RF transmit array [5] is an efficient method to address such non-uniformities. In this work, we combine th...

High magnetic fields increase the sensitivity and spectral dispersion in MR spectroscopy. However, 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. In our current 7T MR system, the shim requirements exceeded the dynamic range of the...

conclusions by a simple check of the water peak characteristics, lots of information can be obtained, one of which is the status of shimming that has a considerable effect on the accuracy of the spectrum. thus, performing an automatic or manual shimming is not a criterion of the spectrum accuracy, and performing a periodic quality control using a test phantom by a specialist is necessary. brief...

Introduction: Proton magnetic resonance spectroscopy (MRS) is a well-known device for analyzing the biological fluids metabolically. Obtaining accurate and reliable information via MRS needs a homogeneous magnetic field in order to provide well-defined peaks and uniform water suppression. There are lots of reasons which can disturb the magnetic field homogeneity which can be corrected by a proc...

Purpose: Previous studies have shown a substantial reduction in local SAR when introducing dielectric pads in a quadrature driven body coil. One concern is that, when using dual-transmit B1 + shimming, the SAR estimate provided by the scanner could be incorrect since it is typically based on models that do not include the presence of dielectric pads [1]. This work explores the implications of u...

This is the companion to the shimming simulation module contained in the NUTS NMR data processing software.

INTRODUCTION With the advent of high field 3T and ultrahigh field 7T MR systems, significant improvements in a variety of brain imaging modalities were anticipated. Although improvements in SNR have been demonstrated at 3T and 7T [1, 2], limitations due to increased static field (B0) inhomogeneity have also been noted. One modality particularly affected by poor B0 homogeneity is magnetic resona...