Introduction: Small animal MR imaging and spectroscopy, where spatial resolution is a limiting factor, requires the use of distinct transmit and receive coils [1]. This approach makes easier the optimization of the RF field homogeneity for transmit-only coils and signal-to-noise ratio (SNR) for receive-only coils. It also requires that RF coils should be electrically decoupled, commonly using P...

INTRODUCTION: Transmit arrays hold growing promise for MRI by enabling improved safety, RF homogeneity, selectivity, and pulse acceleration. Yet achieving good performance with complex Transmit-SENSE pulses [1] requires Tx array channels to be characterized, closely calibrated, and decoupled. To address these needs, we propose Vector Iterative Pre-distortion (VIP), a multichannel iterative corr...

Background Spin lock or T1rho MRI methods may be very useful for assessing myocardial disease. Recently, we reported that there is significant low field relaxation dispersion in myocardial and fibrotic scar tissue during in vivo T1rho MRI, contributing to contrast enhancement compared to spin echo (T2) MRI. However, we also observed that differences in magnetic field susceptibility between the ...

Introduction Parallel transmission allows compensating for transmit field inhomogeneities in high field MRI by means of RF shimming, i.e. by the optimization of the amplitudes and phases of a multi-element RF array [1]. Moreover, the RF transmit power can be simultaneously reduced by regularization techniques. This allows for a reduction of the specific absorption rate (SAR) and hence reduces t...

Wave propagation effects diminish the quality of MR images at main fields of 3T or above. Parallel RF transmission has the potential of compensating for these effects through RF shimming. RF shimming can be performed in two different ways. The basic way of RF shimming is to adjust the global amplitude and phase of the currents in each transmit element, aiming at a constant B1 in the region of i...

INTRODUCTION Currently with 7 tesla (T) and other ultra-high-field magnetic resonance imaging (MRI), the B1 magnetic fields have a high degree of inhomogeneity with stock MRI configuration. B1 inhomogeneity can lead to the creation of artifacts in the medical image and result in misdiagnosis of medical ailments [1]. Along with artifacts, distortions of both the geometry and intensity of the res...

Deep Brain Stimulation (DBS) is increasingly used to treat a variety of brain diseases by sending electrical impulses to deep brain nuclei through long, electrically conductive leads. Magnetic resonance imaging (MRI) of patients pre- and post-implantation is desirable to target and position the implant, to evaluate possible side-effects and to examine DBS patients who have other health conditio...

Thick NiTi shape memory alloy coatings (300–500 µm) were produced on graphite and AISI 304 substrates by radio frequency inductively-coupled plasma spray technology (RF-ICP) from feedstock powders. Their microstructure as well chemical phase composition characterized a methodology for the characterization of functional properties thick was developed. The exhibited cubic to monoclinic martensiti...

Purpose: To study the possibilities and limitations of RF phase and amplitude shimming with a standard 2 channel head coil at 7T. Introduction One of the main problems in high field MRI is the reduced SNR and loss in contrast due to inhomogeneous B1 RF transmit fields. Spatial homogeneity is of primary importance for diagnostic imaging. At 3T the homogeneity problem is mainly limited to regions...