MRI gradient coil assembly with reduced acoustic noise

Abstract

The invention relates to a magnetic resonance imaging system which comprises means for generating a static magnetic field and a gradient coils system for generating a time varying magnetic gradient field by use of a first electrical current and a second electrical current. The gradient coils system is located in the magnetic field and the gradient coils system has a plurality of vibrational modes. Lorentz forces are generated due to the interaction of the first and / or second electrical currents with the superposition of the static magnetic field and the magnetic gradient field. The gradient coils system and / or the first electrical current are adapted so that the integral of the in-products of said Lorentz forces and a vibrational mode of said plurality of vibrational modes is at a value close to zero, wherein said in-products are determined for all points of the gradient coils system, and wherein the integral is determined by summing the in-products determined for all the points. As the above mentioned integral is close to zero or preferably zero, the Lorentz forces are not able to excite the vibrational mode (for example the lowest order bending mode) of the gradient coils system. Thus acoustical noise that is generated by a vibrating gradient coils system is reduced and the comfort for a patient that is examined by the magnetic resonance imaging system is therefore enhanced.

Description

technical field [0001] The present invention relates generally to a magnetic resonance imaging system and a gradient coil system for said magnetic resonance imaging system, and to a magnetic resonance imaging system comprising a gradient coil system which, by adjustment and operation thereof, will cause the Acoustic noise generated by the gradient coil system described above is minimized. Among other aspects, the invention relates to a method of reducing acoustic noise generated by a magnetic resonance imaging system and a computer program product adapted to perform the steps of the method according to the invention. Background technique [0002] Magnetic gradient coils are a prerequisite for NMR imaging (P. Mansfield P. and P.G. Morris, NMR Imaging in Biomedicine, Academic Press, New York, 1982) and are also used in a range of applications including diffusion studies and flow in NMR applications. In MRI, the acoustic noise associated with rapid gradient switching combined...

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Problems solved by technology

[0005] A disadvantage of the method and system proposed in US 5,990,680 is that said first current supply means and said at least second current supply means are rather complex electronic systems, since they have to provide said first and at least second current, thus The two must be adjusted relative to each other in magnitude and relative phase

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