Receiving coil device and magnetic resonance imaging apparatus including the same
The receiving coil device includes one or a plurality of receiving coils configured to cover a head of a subject, a base portion on which the head of the subject is to be placed, a holder portion supported by the base portion, one of the receiving coils being fixed to the holder portion, a mechanism portion configured to bring the receiving coil fixed to the holder portion into close contact with a part of the head, and further, a detection unit configured to detect a physical quantity related to a displacement of the holder portion on the holder portion or the base portion. The physical quantity detected by the detection unit is sent to an MRI apparatus including the receiving coil device.
1. A receiving coil device for a magnetic resonance imaging apparatus, the receiving coil device comprising:
one or more receiving coils configured to cover a head of a subject;
a base portion on which the head of the subject is to be placed;
a holder portion supported by the base portion, a receiving coil of the one or more receiving coils being fixed to the holder portion;
a holder support portion configured to support the holder portion with respect to the base portion;
two guide portions provided on the base portion to guide movement of the holder portion, the holder portion being supported by (i) one point fixed to the holder support portion and (ii) respective contact points of the two guide portions in contact with respective end portions of the holder portion;
a mechanism portion configured to bring the receiving coil fixed to the holder portion into close contact with a part of the head; and
a detection unit disposed on the base portion and configured to detect a body movement of the subject, the detection unit detecting a physical quantity related to a displacement of the holder portion corresponding to the body movement, the detection unit including a distance meter configured to determine a distance between an end portion of the holder portion and the base portion,
wherein the detection unit detects a change in the distance between the end portion of the holder portion and the base portion, that exceeds a threshold value and necessitates re-acquisition of a nuclear magnetic resonance signal.
2. The receiving coil device according to claim 1 , wherein
the holder portion has a curved shape along both side surfaces from a front surface of the head when a surface of the head to be placed on the base portion is defined as a back surface and a surface on an opposite side of the head is defined as the front surface.
3. The receiving coil device according to claim 1 , wherein
the holder portion has a curved shape along both side surfaces of the head when a surface of the head to be placed on the base portion is defined as a back surface and a surface on an opposite side of the head is defined as a front surface, and
the detection unit is an accelerometer that detects a movement of an end portion of the holder portion as the physical quantity.
4. The receiving coil device according to claim 1 , wherein
the detection unit includes a pressure gauge that is disposed between an end portion of the holder portion and a guide portion of the two guide portions, to detect a pressure change between the end portion of the holder portion and the guide portion as the physical quantity.
5. The receiving coil device according to claim 1 , wherein
the holder portion has a left side end portion and a right side end portion corresponding to left and right sides of the subject, and
the left side end portion and the right side end portion of the holder portion are provided with the detection unit.
6. The receiving coil device according to claim 1 , wherein
the mechanism portion includes a movable portion that is fixed to the holder portion and to move the holder portion between a wearing position and a retreat position, and a support portion that supports the movable portion in a stepped manner with respect to the base portion.
7. The receiving coil device according to claim 6 , wherein
the movable portion is a mechanism that slides the holder portion along a shape of the head.
8. A magnetic resonance imaging apparatus comprising:
a transmission unit including a transmitting coil that applies a high-frequency magnetic field to a subject placed in a static magnetic field;
a reception unit including:
one or more receiving coils configured to cover a head of the subject, each receiving coil receiving a nuclear magnetic resonance signal generated from the subject;
a base portion on which the head of the subject is to be placed;
a holder portion supported by the base portion, a receiving coil of the one or more receiving coils being fixed to the holder portion;
a holder support portion configured to support the holder portion with respect to the base portion;
two guide portions provided on the base portion to guide movement of the holder portion, the holder portion being supported by (i) one point fixed to the holder support portion and (ii) respective contact points of the two guide portions in contact with respective end portions of the holder portion;
a mechanism portion configured to bring the receiving coil fixed to the holder portion into close contact with a part of the head; and
a detection unit disposed on the base portion and configured to detect a body movement of the subject, the detection unit detecting a physical quantity related to a displacement of the holder portion corresponding to the body movement, the detection unit including a distance meter configured to determine a distance between an end portion of the holder portion and the base portion;
a gradient magnetic field generation unit configured to generate a gradient magnetic field that gives position information to the nuclear magnetic resonance signal;
a control unit configured to control the transmission unit, the gradient magnetic field generation unit, and the reception unit; and
a calculation unit configured to create an image of the subject based on the nuclear magnetic resonance signal acquired under different gradient magnetic field conditions, wherein
the detection unit detects a change in the distance between the end portion of the holder portion and the base portion, that exceeds a threshold value and necessitates re-acquisition of the nuclear magnetic resonance signal, and when the control unit determines based on the distance determined by the distance meter that re-acquisition is necessary, the control unit performs control to re-acquire the nuclear magnetic resonance signal.
9. The magnetic resonance imaging apparatus according to claim 8 , wherein
the calculation unit calculates a correction amount of the nuclear magnetic resonance signal based on the physical quantity detected by the detection unit, and corrects the nuclear magnetic resonance signal to reconstruct the image.
10. The magnetic resonance imaging apparatus according to claim 8 , wherein
the holder portion has a left side end portion and a right side end portion corresponding to left and right sides of the subject, and
the calculation unit calculates a movement amount of the holder portion with a detection result of the detection unit provided on both the left side end portion and the right side end portion of the holder portion.
11. The magnetic resonance imaging apparatus according to claim 8 , wherein
the holder portion is provided with a marker,
the reception unit further includes a camera disposed at a position where at least a part of the holder portion including the marker is in an image captured by the camera, and
the calculation unit calculates the physical quantity related to the displacement of the holder portion based on an image of the camera.
12. The magnetic resonance imaging apparatus according to claim 8 , wherein at least one of the one or more receiving coils also serves as a transmitting coil.