نتایج جستجو برای: pulse sequence
تعداد نتایج: 491602 فیلتر نتایج به سال:
We propose a set of simplified terms to describe applied Cardiovascular Magnetic Resonance (CMR) pulse sequence techniques in clinical reports, scientific articles and societal guidelines or recommendations. Rather than using various technical details in clinical reports, the description of the technical approach should be based on the purpose of the pulse sequence. In scientific papers or othe...
The abdomen and pelvis present an ensemble of problems for MR imaging. 1. There is a problem of contrast; there are an almost infinite variety of disease processes that can occur in the abdomen/pelvis, and no one sequence is ideal for all. 2. There is the problem of signal-to-noise and coverage; evaluation of the abdomen/pelvis often requires a large field-of-view 3. There are problems with com...
The design of a new pulse programmer is presented. It is based on an application-specific integrated circuit (ASIC) and designed to fulfill the requirements of pulse electron paramagnetic resonance (EPR). The pulse EPR ASIC provides a high time resolution (2 ns) and a high channel density (8 channels per chip). The pulse sequences are controlled by a digital signal processor (DSP). The sequence...
Composite pulse sequences, which produce arbitrary predefined rotations of a qubit on the Bloch sphere, are presented. The composite sequences contain up to 17 pulses and can compensate 8 orders experimental errors in amplitude duration. for three basic quantum gates, X (not), Hadamard rotation, derived. Three classes presented: one symmetric two asymmetric. They as their lowest members well-kn...
The use of genetic algorithms for the optimisation of magic angle spinning NMR pulse sequences is discussed. The discussion uses as an example the optimisation of the C7(2)(1) dipolar recoupling pulse sequence, aiming to achieve improved efficiency for spin systems characterised by large chemical shielding anisotropies and/or small dipolar coupling interactions. The optimised pulse sequence is ...
The development of software for the simulation of NMR experiments has increased at an enormous pace in the last decade. Its usefulness has spread far beyond the analysis of lineshapes and spectra. Today, search-and-optimize strategies are used to develop new pulse sequences while other programs measure the performance of pulse sequences on spin systems of interest [1, 2]. Up to now, most of the...
Methods: The mixed turbo spin echo pulse (mixed-TSE) sequence was implemented with second order binomial water-selective spatial-spectral excitation pulses (1), hereafter SSE-mixed-TSE (Figure 1). Mixed-TSE is a four time point pulse sequence that incorporates the principles of differential T1and T2-weighting in a single acquisition. By substituting the standard spatially-selective excitation p...
We implemented a dual sequence version of the mixed-TSE sequence, termed here as tandem-mixed-TSE with the following parameters: pulse sequence 1, dual-echo RARE: TE1=14ms, TE2=27ms, TR=4000; pulse sequence 2, dual-echo RARE with inversion recovery pulse: TE1=14ms, TE2=27ms, TI=400ms, TR=4400ms (Figure 1) (1). Images acquired with these two sequences were used to calculate parametric PD, T1, an...
polarization for au/pb(zr ti )o /yba cu o ferroelectric capacitor has been studied and measured by pulse method. a sequence of pulses with amplitudes varying from 0 to 10 volts in 2 volt steps is applied and a conventional polarization curve is obtained by integrating the charge flow from the polarization switching induced by the voltage ramp. a value of 25?c/cm2 is measured for the saturated p...
In magnetic resonance electrical impedance tomography (MREIT), we measure induced magnetic flux densities subject to multiple injection currents to reconstruct crosssectional conductivity images. Spin echo pulse sequence has been widely used in MREIT and produce postmortem and in vivo conductivity images of animal and human subjects. The image quality depends on the SNR of the measured magnetic...
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