High-frequency coil device and magnetic resonance imaging apparatus using the same
A high-frequency coil device can maintain a distance between coils at any mounting position in an RF coil including a movable coil unit and can achieve a uniform sensitivity distribution and high sensitivity. A first coil unit configured to move along a substantially circular trajectory and a second coil unit fixed within the substantially circular trajectory are provided, the first coil unit and the second coil unit are disposed at substantially point-symmetric positions, and magnetic coupling between conductor loops provided in both the coil units is maintained substantially constant in a movable range of the first coil unit.
1 . A high-frequency coil device for magnetic resonance imaging, comprising:
a first coil unit having at least one conductor loop;
a second coil unit having at least one conductor loop; and
a mechanism unit configured to move at least one of the first coil unit and the second coil unit to make a relative position thereof variable,
the first coil unit and the second coil unit being disposed, respectively, to be physically independent from each other, and one or more conductor loops of each of the first coil unit and the second coil unit being electro-magnetically coupled to each other,
wherein the mechanism unit is configured to maintain, when at least one of the first coil unit and the second coil unit is moved, electromagnetic coupling between a conductor loop of the first coil unit and an adjacent conductor loop of the second coil unit in at least a part of a movable range.
2 . The high-frequency coil device according to claim 1 ,
wherein some conductor loops of the first coil unit and of the second coil unit are disposed at substantially point-symmetric positions with respect to a point between the first coil unit and the second coil unit as a center.
3 . The high-frequency coil device according to claim 1 , wherein the mechanism unit comprises:
a fixing unit to which the first coil unit is fixed; and
a movable unit having one end fixed to the fixing unit and another end to which the second coil unit is attached, the movable unit being configured to move the second coil unit along a trajectory so as to maintain the electromagnetic coupling.
4 . The high-frequency coil device according to claim 3 ,
wherein the trajectory of the movable unit is any of a circular trajectory, an elliptical trajectory, or a polygonal trajectory.
5 . The high-frequency coil device according to claim 3 ,
wherein the first coil unit and the second coil unit are movable with a constant overlapping area between some conductor loops thereof.
6 . The high-frequency coil device according to claim 1 , which is a coil for examination by magnetic resonance imaging of an anatomical head.
7 . A magnetic resonance imaging apparatus comprising:
an RF transmission coil configured to apply a high-frequency magnetic field to a subject under examination; and
an RF reception coil configured to detect a nuclear magnetic resonance signal from the subject under examination,
wherein at least one of the RF transmission coil or the RF reception coil is a high-frequency coil device comprising:
a first coil unit having at least one conductor loop;
a second coil unit having at least one conductor loop; and
a mechanism unit configured to move at least one of the first coil unit and the second coil unit to make a relative position thereof variable,
the first coil unit and the second coil unit being disposed, respectively, to be physically independent from each other, and one or more conductor loops of each of the first coil unit and the second coil unit being electro-magnetically coupled to each other, and
wherein the mechanism unit is configured to maintain, when at least one of the first coil unit and the second coil unit is moved, electromagnetic coupling between a conductor loop of the first coil unit and an adjacent conductor loop of the second coil unit in at least a part of a movable range.
8 . The magnetic resonance imaging apparatus according to claim 7 ,
wherein a dual-purpose RF coil that serves as both the RF transmission coil and the RF reception coil is provided, and the dual-purpose RF coil is the high-frequency coil device.
9 . The magnetic resonance imaging apparatus according to claim 7 , wherein the RF reception coil is a reception coil for examination by magnetic resonance imaging of an anatomical head and is the high-frequency coil device.
10 . The magnetic resonance imaging apparatus according to claim 7 ,
wherein some conductor loops of the first coil unit and of the second coil unit are disposed at substantially point-symmetric positions with respect to a point between the first coil unit and the second coil unit as a center.
11 . The magnetic resonance imaging apparatus according to claim 7 , wherein the mechanism unit comprises:
a fixing unit to which the first coil unit is fixed; and
a movable unit having one end fixed to the fixing unit and another end to which the second coil unit is attached, the movable unit being configured to move the second coil unit along a trajectory so as to maintain the electromagnetic coupling.
12 . The magnetic resonance imaging apparatus according to claim 11 , wherein the trajectory of the movable unit is any of a circular trajectory, an elliptical trajectory, or a polygonal trajectory.
13 . The magnetic resonance imaging apparatus according to claim 11 , wherein the first coil unit and the second coil unit are movable with a constant overlapping area between some conductor loops thereof.
14 . The magnetic resonance imaging apparatus according to claim 7 , wherein the high-frequency coil device is a coil for head examination.