News Column

Patent Issued for Gradient Coil Device, Magnetic Resonance Imaging Device, and Method of Designing Coil Pattern

February 7, 2014



By a News Reporter-Staff News Editor at Health & Medicine Week -- From Alexandria, Virginia, NewsRx journalists report that a patent by the inventors Abe, Mitsushi (Hitachinaka, JP); Imamura, Yukinobu (Hitachi, JP); Kurome, Akira (Kashiwa, JP), filed on December 22, 2009, was published online on January 21, 2014 (see also Hitachi Medical Corporation).

The patent's assignee for patent number 8633698 is Hitachi Medical Corporation (Tokyo, JP).

News editors obtained the following quote from the background information supplied by the inventors: "The present invention relates to a magnetic resonance imaging (hereinafter, 'MRI') device, a gradient coil device used in the MRI device, and a method of designing a coil pattern of a coil used in the gradient coil device.

"MRI devices obtains a cross-sectional image of an object under test indicating physical and chemical characteristics thereof by utilizing nuclear magnetic resonance phenomena which occurs when the object under test arranged in a uniform static magnetic field is irradiated with high-frequency pulses, and such devices are used for, in particular, medical purposes. MRI devices generally include static-magnetic-field coil devices which generate a uniform static magnetic field in an imaging region where the object under test is put in, gradient coil devices which generate a pulsed gradient magnetic field having magnetic field intensity spatially inclined in order to add positional information to the imaging region, RF coils emitting high-frequency pulses to the object under test, a reception coil which receives a magnetic resonance signal from the object under test, and a computer system which processes the received magnetic resonance signal to display the cross-sectional image.

"JP2001-353137A discloses a gradient coil device which generates a gradient magnetic field having magnetic field intensity linearly inclined in order to improve the performances of the MRI devices (see FIG. 1)."

As a supplement to the background information on this patent, NewsRx correspondents also obtained the inventors' summary information for this patent: "Conventional gradient coil has a coil with a complex coil pattern. In such a coil pattern, a plurality of looped main lines each having an opened part are multiply arranged on one plane in such a way that one main line is arranged inwardly of another adjacent main line, and a connecting line for connecting adjacent main lines and a return line running from an inward main line to an outward main line are provided so as to partially overlap with each other.

"As the plurality of main lines each formed in a loop shape with an opened part are multiply arranged and adjacent main lines are connected together by the connecting line, a spiral coil pattern having multiple main lines connected together is formed. Providing the return line allows a current to flow through the plurality of main lines. According to the conventional gradient coils, however, it is designed to generate a linear gradient magnetic field when a current flows through only the plurality of main lines. Therefore, when a current flows through the connecting line and the return line, this causes generation of an error magnetic field. Such an error magnetic field generates an eddy current at the static-magnetic-field coil devices, and such an eddy current may generate a magnetic field which disturbs the cross-sectional image in the imaging region.

"Therefore, it is an object of the present invention to provide a gradient coil device, an MRI device, and a coil pattern designing method which can suppress any generation of an error magnetic field and thus an eddy current, and which can improve the image quality of a cross-sectional image.

"In order to achieve the above object, the present invention provides a gradient coil device including: a first coil which generates a linear magnetic field distribution at an imaging region of a magnetic resonance imaging device; and a second coil which suppresses any leakage of a magnetic field from the first coil to a static-magnetic-field coil that generates a uniform magnetic field distribution at the imaging region, in which a connecting line part of at least either one of the first coil and the second coil which intersects with a return line from a spiral coil pattern meanders.

"Also, the present invention provides a gradient coil device including: a first coil which generates a linear magnetic field distribution at an imaging region of a magnetic resonance imaging device; and a second coil which suppresses any leakage of a magnetic field from the first coil to a static-magnetic-field coil that generates a uniform magnetic field distribution at the imaging region, in which a width of a connecting line part of at least either one of the first coil and the second coil which intersects with a return line from a spiral coil pattern is greater than or equal to four times and less than or equal to ten times than a width of the return line.

"Also, the present invention provides a gradient coil device including: a first coil which generates a linear magnetic field distribution at an imaging region of a magnetic resonance imaging device; and a second coil which suppresses any leakage of a magnetic field from the first coil to a static-magnetic-field coil that generates a uniform magnetic field distribution at the imaging region, in which at least either one of the first coil and the second coil includes a coil pattern having an bypassed interval which intersects with a feeder line to a spiral coil pattern and a return line from the coil pattern.

"Also, the present invention provides a coil pattern designing method for at least either one of a first coil which generates a linear magnetic field distribution at an imaging region of a magnetic resonance imaging device and a second coil which suppresses any leakage of a magnetic field to a static-magnetic-field coil device that generates a uniform magnetic field distribution at the imaging region, the method including the steps of: calculating an error magnetic field at the static-magnetic-field coil device based on an initial coil pattern prepared beforehand; calculating a correction current component to cancel the error magnetic field; and deforming the initial coil pattern based on the correction current component. Further, the present invention provides a gradient coil device or a magnetic resonance imaging device including at least either one of a first coil and a second coil, which are designed and manufactured by the coil pattern designing method

"According to the present invention, there are provided a gradient coil device, an MRI device, and a coil pattern designing method which can suppress any generation of an error magnetic field and thus an eddy current, and which can improve the image quality of a cross-sectional image."

For additional information on this patent, see: Abe, Mitsushi; Imamura, Yukinobu; Kurome, Akira. Gradient Coil Device, Magnetic Resonance Imaging Device, and Method of Designing Coil Pattern. U.S. Patent Number 8633698, filed December 22, 2009, and published online on January 21, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=50&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=2479&f=G&l=50&co1=AND&d=PTXT&s1=20140121.PD.&OS=ISD/20140121&RS=ISD/20140121

Keywords for this news article include: Magnetic Resonance, Hitachi Medical Corporation.

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


For more stories covering the world of technology, please see HispanicBusiness' Tech Channel



Source: Health & Medicine Week


Story Tools