Hitachi, Ltd.

Hitachi Medical Corporation

Fujifilm Healthcare Corporation

Yukinobu Imamura

Mitsushi Abe

Akira Kurome

Hiroyuki Takeuchi

Takeshi Yatsuo

Masanao Terada

Manabu Aoki

Takeshi Kawamura

Taisuke Takayanagi

Ryuya Ando

Takuya Fujikawa

Akihisa Miyazoe

Chishin Hori

Shin Hoshino

Tatsuhiko Kawakami

Takuro Honda

Kengo Goto

Takeshi Nakayama

An MRI apparatus equipped with a magnetic shield structure to reduce flux leakage. The MRI apparatus includes: a pair of static magnetic magnets that are disposed on opposite sides of an imaging space; and a pair of gradient coils that are disposed on opposite sides of the imaging space. Each static magnetic magnet has a disk-shaped magnetic material poleand a ring-shaped magnetic material pole. Each gradient coil has a first coilthat applies a magnetic field gradient in a Z axis direction in an imaging region, and a laminatethat shields the disk-shaped magnetic material pole from magnetic flux produced in the first coil. The laminate has a smaller thickness in the Z axis direction on the ring-shaped magnetic material pole side than that in a center portion of the imaging space. A vertical lowest portion of a laminate end portion on the ring-shaped magnetic material pole side of the laminate is in a higher position than a position of a lowest portion of a laminate central portion on the imaging region side of the laminate.

Magnetic resonance imaging apparatus

An open-type MRI apparatus includes a pair of static magnetic field magnets and a pair of gradient magnetic field coils. Each static magnetic field magnet includes a discoid magnetic pole configured to generate a static magnetic field in a Z axis direction in which the pair of static magnetic field magnets are opposed each other, and an annular magnetic pole configured to generate a static magnetic field on an X-Y plane perpendicular to the Z axis direction. Each gradient magnetic field coil includes a Z coil configured to provide a magnetic field being gradient in the Z axis direction in the imaging region, a magnetic material block configured to shield the discoid magnetic pole from a magnetic flux generated from the Z coil, and a correction coil configured to shield the annular magnetic pole from the magnetic flux generated from the Z coil.

Open-type magnetic resonance imaging apparatus

Provided are a magnetic resonance imaging device and a superconducting magnet capable of preventing generation of eddy currents accompanying vibration of a radiation shield and of reducing image quality deterioration. The superconducting magnet for a magnetic resonance imaging device includes a substantially cylindrical vacuum vessel, a substantially cylindrical radiation shield that is provided inside the vacuum vessel, and a superconducting coil that is provided inside the radiation shield. The radiation shield has an inner cylinder located radially inward of the superconducting coil. The inner cylinder of the radiation shield is provided with an annular rib formed in a circumferential direction about the central axis of the inner cylinder.

Magnetic resonance imaging device and superconducting magnet

According to one embodiment, a magnetic resonance imaging apparatus includes: a cylindrical magnetic pole for generating a static magnetic field in an imaging region; a cylindrical gradient magnetic field coil arranged on a radially inner side of the magnetic pole, coaxially with the magnetic pole to generate a dynamic magnetic field having a linear magnetic field strength in the imaging region; a cylindrical high frequency coil arranged on a radially inner side of the gradient magnetic field coil, coaxially with the magnetic pole and the gradient magnetic field coil to generate a high frequency magnetic field in the imaging region; and a computer system for processing signals to obtain images. The magnetic resonance imaging apparatus further includes at least two loop-shaped additional coils arranged on the radially outer side of the gradient magnetic field coil and having different electric current circulating direction.

Vibration reduction for a magnetic resonance imaging apparatus

A superconducting magnet in which efficiency of conduction cooling is improved is described as well as a magnetic resonance imaging apparatus that includes the superconducting magnet and requires no liquid helium. The magnet resonance imaging apparatus includes: a coil portion including a winding core, a winding portion formed by winding a wire around the winding core, a first flange provided on one side of the winding core, and a second flange provided on the other side of the winding core; a cooling device for cooling the coil portion; and a heat conducting member for thermally connecting the coil portion and the cooling device, in which at least one of the first flange, the second flange, and the winding core has a region made of a material whose thermal contraction rate is larger than a thermal contraction rate of the winding portion.

Superconducting magnet and magnetic resonance imaging apparatus

The present invention addresses a challenge of providing a superconducting magnet device that enables it to realize an operation of opening and closing a permanent current switch of the superconducting magnet device at high speed with small electric heater capacity, avoiding an increase in the amount of heat incursion into the superconducting coil by not providing a driving mechanism from outside while enabling it to reduce refrigerant consumption or electric power consumed by a refrigerator, or an MRI apparatus using it having means for obtaining good image quality. The superconducting magnet device including a superconducting coil and a permanent current switch to enable it to realize permanent current flowing with the permanent current switch operated by an electric heater or an MRI apparatus using it has a heat transfer member to cool the permanent current switch from a cooling stage with solid conductivity and a thermal switch, and the thermal switch generates a gap in a heat transfer path including the heat transfer member for cooling and a refrigerator by thermal expansion when an electric heater is electrified.

Superconducting magnet device or magnetic resonance imaging apparatus including a support member having a coefficient of thermal expansion highter than that of a columnar member

A gradient magnetic field coil device is provided in which an eddy current magnetic field of an even-ordered component can be reduced. The gradient magnetic field coil device includes a forward coil and a reverse coil which faces the forward coil so as to sandwich a middle surface and through which flows an electric current directed opposite to the forward coil. The forward coil and the reverse coil have a middle region approaching the middle surface and an outside-the-middle region where the distance from the middle surface is greater than the middle region. A line width of coil lines in the middle region is narrower than a line width of coil lines in the outside-the-middle region.

Gradient magnetic field coil device and magnetic resonance imaging device

An alternating current loss measuring apparatus for superconductors includes a superconductor specimen, a magnetic field applying coil, a radiation shield, a vacuum vessel, first cooling means, and second cooling means. The first cooling means or the second cooling means is provided with a temperature regulating mechanism. The magnetic field applying means and the radiation shield are set to be a first cooling part, whereas the superconductor specimen is set to be a second cooling part, and the first cooling part and the second cooling part are cooled by first and second cooling means, respectively. A high thermal resistance member is disposed between the superconductor specimen and the second cooling means, and temperature measuring means are disposed at at least two positions on the high thermal resistance member. The alternating current loss of a superconductor under an external magnetic field can be measured at each of different temperatures.

Alternating current loss measuring apparatus

In a gradient magnetic field coil device including: a plurality of main coils generating in an imaging region of a magnetic field resonance imaging device a magnetic field distribution in which an intensity linearly inclines; and a plurality of shield coils, arranged on an opposite side of the imaging region across the main coils, suppressing residual magnetic field generated by the main coils on the opposite side. The plurality of main coils and the plurality of shield coils are connected in series. The device further includes a plurality of current adjusting devices, connected to the shield coils in parallel, independently adjusting currents flowing through the shield coils, respectively, to enhance symmetry of the residual magnetic field. The gradient magnetic field coil device is provided which can suppress generation of eddy current magnetic field even if there is a relative position deviation between the main coils and shield coils.

Gradient magnetic field coil device, adjustment method therefor, and magnetic resonance imaging apparatus

A device includes: a static magnetic field generating device including static magnetic field generating sources generating a homogeneous magnetic field in a space; gradient magnetic field generating sources superimposing a gradient magnetic field on the homogeneous magnetic field, and conductor rings arranged between the static magnetic field generating sources and the gradient magnetic field generating sources in a pair of arranging regions on both sides in a direction of the homogeneous magnetic field in a region where the homogeneous magnetic field is generated (imaging region), respectively, the conductor rings being separated from each other and making a pair. The conductor rings are mechanically connected to the gradient magnetic field generating device or the static magnetic field generating device. This provides an MRI device 1 capable of reduction in vibration with suppression of the image quality deterioration of the tomographic images.

Magnetic resonance imaging device with vibration suppression

A gradient coil device includes a major axis gradient coil, having an ellipse in a cross section generating a gradient magnetic field inclined in a major axis direction of the ellipse at a magnetic field space; and a minor axis gradient coil, having an ellipse in a cross section generating a gradient magnetic field inclined in a minor axis direction of the ellipse at the magnetic field space. A length of the minor axis field coil in the center axis direction is shorter than a length of the major axis gradient coil in the center axis direction. A maximum value of a residual magnetic field generated by the minor axis gradient coil at a space outside the magnetic field space is equal to or smaller than a maximum value of a residual magnetic field generated by the major axis gradient coil at a space outside the magnetic field space.

Gradient coil device and magnetic resonance imaging device

In the magnetic resonance imaging device, the distance between the first and second coils is different in the circumferential direction and has a first region (A) (&#x3b8;=0, &#x3c0;) and a second region (A) (&#x3b8;=&#x3c0;/2) narrower than the first region (A). In the first coil, wiring patterns () on the side of a zero-plane (F) passing through the center of the first coil and perpendicular to the axis direction (z-axis direction) meander in the circumferential direction such that the wiring patterns () depart from the zero-plane (F) in the first region (A) and approach the zero-plane (F) in the second region (A). This provides a gradient magnetic field coil capable of configuring wiring patterns without using a loop coil that does not pass through the z-axis.

Gradient magnetic field coil and magnetic resonance imaging device

There is provided a gradient coil device 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. An MRI device includes a first coil generating a linear magnetic field distribution at an imaging region of the MRI device, and a second coil which suppresses any leakage of a magnetic field from the first coil to a static-magnetic-field coil device that generates a uniform magnetic field distribution at the imaging region.

Gradient coil device, magnetic resonance imaging device, and method of designing coil pattern

When the gradient magnetic fieldis generated, a low magnetic field regionand a high magnetic field regionare generated where a magnetic field crossing at least one of the first forward coil, a second forward coil, first revere coil, and a second reverse coilhas different intensities between the low and high magnetic field regions and the intensity in the high magnetic region is higher than the intensity in the low magnetic field region. A line width Dlh of the coil line in the high magnetic field regionis narrower than the line width Dll of the coil linein the low magnetic field region. There is provided a gradient magnetic field coil can suppress in a usable range heat generations due to eddy current and due to a pulse large current which steeply varies.

Gradient magnetic field coil device and magnetic resonance imaging apparatus

The gradient coil for a magnetic resonance imaging apparatus is adapted to encode information on a spatial position of a subject to be inspected into a nuclear magnetic resonance signal. The gradient coil includes a primary gradient coil and a shielded gradient coil. The primary gradient coil generates a gradient magnetic field in the imaging area. The shielded gradient coil is located on the side opposite to the imaging area relative to the primary gradient coil and cancels the gradient magnetic field generated by the primary magnetic field. The shielded gradient coil has a first area including a central axis perpendicularly extending through the central portion of the imaging area and a second area located on the side of the outer circumference of the first area. The second area is more inclined toward the imaging area than the first area.

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Tokyo, Japan

Yukinobu Imamura