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Accurate Measurement of Magnetic Resonance Imaging Gradient Characteristics
Center for Imaging of Neurodegenerative Diseases, Veterans Affairs Medical Center, San Francisco, CA 94121, USA
Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143, USA
* Author to whom correspondence should be addressed.
Received: 3 November 2013; in revised form: 13 December 2013 / Accepted: 16 December 2013 / Published: 19 December 2013
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
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Cite This Article
MDPI and ACS Style
Liu, H.; Matson, G.B. Accurate Measurement of Magnetic Resonance Imaging Gradient Characteristics. Materials 2014, 7, 1-15.
Liu H, Matson GB. Accurate Measurement of Magnetic Resonance Imaging Gradient Characteristics. Materials. 2014; 7(1):1-15.
Liu, Hui; Matson, Gerald B. 2014. "Accurate Measurement of Magnetic Resonance Imaging Gradient Characteristics." Materials 7, no. 1: 1-15.