ITFA excitations made it possible to reduce the T1-effects on B1 mapping of the human-brain-mimicking phantom and the human brain at 3T. The authors expect the ITFA method can be used for B1 shimming once the optimal flip angles have been predetermined for the target imaging region and for the preferred TR.
Magnetic steering of an untethered ferromagnetic device in a living body has many advantages in the clinical fields. In this paper, the positioning and tracking methods of a ferromagnetic sphere have been compared with magnetic resonance phantom images obtained with three different imaging sequences, spin echo, gradient echo, and selected positive contrast sequences. The position of the ferromagnetic sphere has been calculated from the MRI images which have susceptibility artifacts caused by the magnetic sphere. We have compared the positioning errors among the magnetic sphere images.
Based on the current situation of large volume and single detection function of the underwater acoustic beacon detection device, combined with the requirements of multi-parameter detection of underwater acoustic beacon function and performance, an embedded underwater acoustic beacon multi-parameter detection device is developed. The detection device uses ARM as the core processor, carries Linux embedded system, and establishes QT graphical user interface. The detection device can realize the acoustic signal of underwater acoustic beacon Frequency, pulse width, period, sound source level, spectrum, and other multi-parameter detection and graphical display of the test results.
We propose a whole-body transmit coil structure for two-channel B 1 shimming at 3T. The transmit coil consists of four identical vertical-loop-coils placed on a cylindrical former by equiangular basis. A vertical loop coil consists of an inner-conductor plane and an outer-conductor plane both of which constitute a vertical loop when the two planes are connected by tuning capacitors at both ends. To improve the B 1 homogeneity of the transmit coil, we split the inner-and outer-conductor planes into two rungs. We made the transmit coil with the length of 500 mm on a frame that had the inner and outer diameters of 550mm and 600mm, respectively. In the B 1 shimming experiment with the transmit coil, we drove the coil with two RF power amplifiers of 18kWp each through two quadrature hybrids. Before the B 1 shimming, we performed B 1 mapping for each driving channel, and then, we determined the optimal magnitude and phase of the input signals to the RF power amplifiers. In the B 1 shimming experiment on a human-bodymimicking phantom, the optimized transmission improved the image uniformity by 24.7% as compared to the conventional quadrature transmission. V C 2013 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 43B: 59-68, 2013
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