Identification of common cardiovascular magnetic resonance (CMR) artifacts is important to optimal image acquisition quality and the avoidance of mistaken clinical diagnosis. We describe an off-frequency tuning error artifact observed during rapid steady-state free precession acquisitions in three patients and resulting in a dramatic appearance within the right and left ventricles. These artifa...

Resistive or hybrid magnets can achieve substantially higher fields than those available in superconducting magnets, but their spatial homogeneity and temporal stability are unacceptable for high-resolution NMR. We show that modern stabilization and shimming technology, combined with detection of intermolecular zero-quantum coherences (iZQCs), can remove almost all of the effects of inhomogenei...

In Cs frequency standards a zone of highly uniform magnetic flus density, lower in value of 0.1 T, is required The magnetic homogeneity value is tied to the overall accuracy of the standard and, for an accuracy of a design value 1 p.p.m. is required. For this purpose a resistive solenoid 700 mm long with a bore radius of 32.5 mm has been designed and built. This paper reports the design process...

Background Image quality of cine imaging using steady state free precession (SSFP) sequences at 3T is insufficient due to increased RF-inhomogeneity (B1 field) and the high sensitivity of SSFP sequences to off-resonance artefacts. Recently, the introduction of a dual source RF transmission system with patient-adaptive local RF-shimming has led to a significant improvement of image quality of SS...

A significant problem in the concurrent application of transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) is the image artefact caused by the effect of the TMS-coil on the homogeneity of the static magnetic field (B0). The resulting field inhomogeneity can lead to spatial distortions and local signal loss in echo-planar (EP) images. Here we demonstrate that...

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...