Insertable biplanar gradient coils for magnetic resonance imaging

ABSTRACT:In this work a superposition technique for designing gradient coils for the purpose of magnetic resonance imaging is outlined, which uses an optimized weight function superimposed upon an initial winding similar to that obtained from the target field method to generate the final wire winding. This work builds on the preliminary work performed in Part I on designing planar insertable gradient coils for high resolution imaging. The proposed superposition method for designing gradient coils results in coil patterns with relatively low inductances and the gradient coils can be used as inserts into existing magnetic resonance imaging hardware. The new scheme has the capacity to obtain images faster with more detail due to the deliver of greater magnetic field gradients. The proposed method for designing gradient coils is compared with a variant of the state-of-the-art target field method for planar gradient coils designs, and it is shown that the weighted superposition approach outperforms the well-known the classical method.

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“…I and V and in Equation [7] are the current and voltage produced by the power supply driving the gradient coils.…”

Section: The Weighted Superposition Methodsmentioning

confidence: 99%

The design of planar gradient coils. Part II: A weighted superposition method

Vegh

Zhao

Doddrell

et al. 2005

Concepts Magn. Reson.

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“…These eddy currents generate magnetic fields, which cause problems in imaging (6,9,50,(73)(74)(75)(76)(77)(78)(79)(80)(81)(82)(83). One solution was proposed by Martens et al (84) and Van Vaals et al (85). The idea is to adjust the current waveform applied to the gradient coils so as to produce a field variation which when combined with the eddy current-induced fields produces the desired field variation with time.…”

Section: Shielded Gradient Coilsmentioning

confidence: 99%

“…Planar gradient coils provide an interest to researchers due to their ability to be separated and also because the DSV contained between the plates is more accessible (87)(88)(89)(90)(91)(92)(93)(94)(95)(96). The DSV is the region in which a quality image can be obtained and it should be as large as possible for a given plate size.…”

Section: Planar Gradient Coilsmentioning

confidence: 99%

Theory of gradient coil design methods for magnetic resonance imaging

Hidalgo-Tobón

2010

Concepts Magnetic Resonance

129

104

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The process to produce an MR image includes nuclear alignment, RF excitation, spatial encoding, and image formation. In simple terms, an magnetic resonance imaging (MRI) system consists of five major components: a magnet, gradient systems, an RF coil system, a receiver, and a computer system. To form an image, it is necessary to perform spatial localization of the MR signals, which is achieved using gradient coils. In modern MRI, gradient coils able to generate high gradient strengths and slew rates are required to produce high imaging speeds and improved image quality. MRI also requires the use of gradient coils that generate magnetic fields, which vary linearly with position over the imaging volume. Gradient coils for MRI must therefore have high current efficiency (defined as the ratio of gradient generated to current drawn), short switching time (i.e., low inductance), gradient linearity over a large volume, low power consumption, and minimal interaction with any other equipment, which would otherwise result in eddy currents. Over the last two decades new methods of gradient coil design have been developed, and a combination of these methods can be a mixture of them trying to avoid discomforts to patients that at the end is the center of all the technological efforts in the art of MRI.

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“…The TF method for planar geometries, first introduced by Yoda (8), was applied to design gradient coils with minimum inductance for axial magnets (10,11), but due to limitations on coil size the uniformity region is restricted.…”

Section: Introductionmentioning

confidence: 99%