1H MRS in the human spinal cord at 7T using a combined RF shimming and travelling wave transmit approach
نویسندگان
چکیده
Anke Henning, Wouter Koning, Alexander Fuchs, Alexander Raaijmakers, Johanna J. Bluemink, Erin L. MacMillan, Cornelius A.T. van den Berg, Peter Luijten, Peter Boesiger, and Dennis W.J. Klomp Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland, University Medical Center Utrecht, Utrecht, Netherlands, Department for Clinical Research, University of Bern, Bern, Switzerland
منابع مشابه
Gain of Imaging Fidelity by Employing a Higher Number of Independent Transmit Channels Together with Slice-Selective Radio-Frequency (RF) Shimming at 7T
Dielectric resonance effects and radio-frequency (RF) power deposition have become challenging issues for magnetic resonance imaging at ultrahigh-field (UHF) strengths. The use of transmit (Tx) coil arrays with independently-driven RF sources using a parallel transmission system is a promising method for alleviating the resulting RF inhomogeneities. In this study, the effect on homogeneity and ...
متن کاملTravelling-wave MRI: Initial results of in-vivo head imaging at 7T
Introduction: MRI in humans at ultra-high field strengths of 7T and beyond offers superior sensitivity and intriguing contrast options, especially for neurological applications. However, at such high fields the restricted axial coverage of transmit resonators [1] is a main hindrance to studies of lower brain regions, such as the cerebellum, the brain stem and the upper spinal cord, as well as t...
متن کاملBasic and Tailored RF Shimming in a Multi-transmit Whole Body MR System
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...
متن کاملNuts & Bolts of Advanced Imaging: Theory and Demonstration for Coils, RF Shimming and SAR
Highlights: At high frequency MRI operation and electrically large (≥ 7T head, ≥ 3T body), asymmetrical, inhomogeneous, and/or irregularly-shaped loading, integer multiples of phase-shifts and uniform amplitudes are not necessarily the ideal characteristics to impose on the voltages driving the transmit array/coil in order to obtain a homogeneous transmit (with safe electric field) and/or rec...
متن کاملTransmit Arrays and Circuitry
For body dimensions at 3T and head dimensions at 7T and above the RF wavelength in dielectric tissue is comparable or smaller than the dimensions of the human anatomy. This in turn leads to RF phase related traveling time differences, prominent wave behavior and the potential for a significant difference between transmit B1 + and receive B1 fields [5-10]. It is possible to correct some of the r...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2011