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Correction: Koush, Y.; Elliott, M.A. and Mathiak, K. Single Voxel Proton Spectroscopy for Neurofeedback at 7 Tesla. Materials 2011, 4, 1548–1563
Materials 2014, 7(1), 1-15; doi:10.3390/ma7010001
Article

Accurate Measurement of Magnetic Resonance Imaging Gradient Characteristics

1
 and
1,2,*
1 Center for Imaging of Neurodegenerative Diseases, Veterans Affairs Medical Center, San Francisco, CA 94121, USA 2 Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143, USA
* Author to whom correspondence should be addressed.
Received: 3 November 2013 / Revised: 13 December 2013 / Accepted: 16 December 2013 / Published: 19 December 2013
(This article belongs to the Special Issue High Field Magnetic Resonance Methods and Materials)
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Abstract

Recently, gradient performance and fidelity has become of increasing interest, as the fidelity of the magnetic resonance (MR) image is somewhat dependent on the fidelity of the gradient system. In particular, for high fidelity non-Cartesian imaging, due to non-fidelity of the gradient system, it becomes necessary to know the actual k-space trajectory as opposed to the requested trajectory. In this work we show that, by considering the gradient system as a linear time-invariant system, the gradient impulse response function (GIRF) can be reliably measured to a relatively high degree of accuracy with a simple setup, using a small phantom and a series of simple experiments. It is shown experimentally that the resulting GIRF is able to predict actual gradient performance with a high degree of accuracy. The method captures not only the frequency response but also gradient timing errors and artifacts due to mechanical vibrations of the gradient system. Some discussion is provided comparing the method presented here with other analogous methods, along with limitations of these methods.
Keywords: magnetic resonance imaging (MRI); gradients; impulse response function magnetic resonance imaging (MRI); gradients; impulse response function
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Liu, H.; Matson, G.B. Accurate Measurement of Magnetic Resonance Imaging Gradient Characteristics. Materials 2014, 7, 1-15.

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