Inspection apparatus using magnetic resonance
First Claim
1. An inspection apparatus using magnetic resonance, comprising:
- magnetic field generation means for generating a static magnetic field, a gradient magnetic field and a radio frequency (RF) magnetic field, respectively;
signal detection means for detecting magnetic resonance signals from an inspected object;
a computer for executing arithmetic operations for detection signals from said signal detection means; and
output means for outputting the result of the operations by said computer;
wherein said gradient magnetic field generation means comprises a first set of gradient coils and a second set of gradient coils;
said first set of gradient coils is fixed to a magnet directly or indirectly for generating said static magnetic field;
said second set of gradient coils is movable; and
the magnetic field generated by said second set of gradient coils at a conducting portion of said magnet is offset by the magnetic field generated by said first set of gradient coils.
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Accused Products
Abstract
An inspection apparatus using magnetic resonance includes magnetic field generators for generating a static magnetic field, a gradient magnetic field and a radio frequency magnetic field, respectively, a signal detector for detecting magnetic resonance signals from an inspected object, a computer for executing arithmetic operations for detection signals from the signal detector and an output device of the result of the arithmetic operations by the computer. The gradient magnetic field generator includes first and second gradient coils, the first gradient coil is a coil fixed to a magnet for generating a static magnetic field, the second gradient coil is a movable coil, and the magnetic field generated by the second gradient coil at a conducting portion of the magnet is offset by the magnetic field generated by the first gradient coil. According to this construction, an eddy current that occurs with the time change of the gradient magnetic field can be reduced.
66 Citations
33 Claims
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1. An inspection apparatus using magnetic resonance, comprising:
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magnetic field generation means for generating a static magnetic field, a gradient magnetic field and a radio frequency (RF) magnetic field, respectively; signal detection means for detecting magnetic resonance signals from an inspected object; a computer for executing arithmetic operations for detection signals from said signal detection means; and output means for outputting the result of the operations by said computer; wherein said gradient magnetic field generation means comprises a first set of gradient coils and a second set of gradient coils; said first set of gradient coils is fixed to a magnet directly or indirectly for generating said static magnetic field; said second set of gradient coils is movable; and the magnetic field generated by said second set of gradient coils at a conducting portion of said magnet is offset by the magnetic field generated by said first set of gradient coils. - View Dependent Claims (2, 3, 4, 5)
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6. An inspection apparatus using magnetic resonance, comprising:
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magnetic field generation means for generating a static magnetic field, a gradient magnetic field and a radio frequency (RF) magnetic field, respectively; signal detection means for detecting magnetic resonance signals from an inspected object; a computer for executing arithmetic operations for detection signals from said signal detection means; and output means for outputting the result of the operations by said computer; wherein said gradient magnetic field generation means comprises a first set of gradient coils and a second set of gradient coils; said first set of gradient coils is fixed to a magnet for generating said static magnetic field; said second set of gradient coils is movable; the gradient magnetic field generated by said first set of gradient coils in the proximity of the center of said magnet is smaller than the gradient magnetic field generated by said second set of gradient coils; and the magnetic field generated by said second set of gradient coils at a conducting portion of said magnet is offset by the magnetic field generated by said first set of gradient coils. - View Dependent Claims (7, 8)
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9. An inspection apparatus using magnetic resonance, comprising:
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magnetic field generation means for generating a static magnetic field, a gradient magnetic field and a radio frequency (RF) magnetic field, respectively; signal detection means for detecting magnetic resonance signal from an inspected object; a computer for executing arithmetic operations for detection signals from said signal detection means; and output means for outputting the result of the operations of said computer; wherein said gradient magnetic field generation means comprises a first set of gradient coils and a second set of gradient coils; said first set of gradient coils is fixed to a magnet for generating said static magnetic field; said second set of gradient coils is movable; the center of the gradient magnetic field generated by said first set of gradient coils is in conformity with the center of the magnetic field generated by said second set of gradient coils; the gradient magnetic field generated by said first set of gradient coils in the proximity of the center of said magnet is smaller than the gradient magnetic field generated by said second set of gradient coils; and the magnetic field generated by said second set of gradient coils at a conducting portion of said magnet is offset by the magnetic field generated by said first set of gradient coils. - View Dependent Claims (10, 11)
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12. An inspection apparatus using magnetic resonance, comprising:
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magnetic field generation means for generating a static magnetic field, a gradient magnetic field and a radio frequency (RF) magnetic field, respectively; signal detection means for detecting magnetic resonance signals from an inspected object; a computer for executing arithmetic operations for detection signals from said signal detection means; and output means for outputting the result of the operations by said computer; wherein said gradient magnetic field generation means comprises a first set of gradient coils, a second set of gradient coils and a third set of gradient coils; said first set of gradient coils and third set of gradient coils are fixed to a magnet for generating said static magnetic field; said second set of gradient coils is movable; and the magnetic field generated by said second set of gradient coils at a conducting portion of said magnet is offset by the magnetic field generated by said first set of gradient coils. - View Dependent Claims (13, 14, 15, 16, 17)
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18. An inspection apparatus using nuclear magnetic resonance, comprising:
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a magnet for generating a static magnetic field; a cylindrical inside space disposed inside said magnet and accommodating an inspected object; a gradient coil disposed inside said magnet and comprising a plurality of coils for generating a gradient magnetic field in said inside space; a radio frequency (RF) probe for transmitting and receiving an RF magnetic field to and from said inspected object; and a local gradient coil for imaging a local part of said inspected object, disposed in the proximity of said local part, generating a local gradient magnetic field, and smaller than said gradient coil; said magnet generating said static magnetic field in an axial direction of said cylindrical inside space; wherein, among a plurality of said coils constituting said local gradient coil, at least one of a plurality of said coils generating said local gradient magnetic field in a direction other than the direction of said static magnetic field is disposed in such a fashion that the direction of the magnetic field generated by said coil at the center thereof has an angle other than 90°
with respect to the direction of said static magnetic field. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26)
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27. A nuclear magnetic resonance imaging (MRI) apparatus comprising:
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a magnet for generating a static magnetic field; a cylindrical inside space disposed inside said magnet and accommodating an inspected object; a gradient coil disposed inside said magnet and comprising a plurality of coils for generating a gradient magnetic field in said inside space; a radio frequency (RF) probe for transmitting and receiving a radio frequency magnetic field to and from said inspected object; and a local gradient coil for imaging a local part of said inspected object, disposed in the proximity of said local part, generating a local gradient magnetic field, and smaller than said gradient coil; said magnet generating said static magnetic field in an axial direction of said cylindrical inside space; wherein said RF probe is fixed to a bobbin for supporting said local gradient coil; and among a plurality of said coils constituting said local gradient coil, at least one of a plurality of coils for generating said local gradient magnetic field in a direction other than the direction of said static magnetic field is disposed in such a fashion that the direction of the magnetic field generated by said coil at the center thereof has an angle other than 90°
with respect to the direction of said static magnetic field. - View Dependent Claims (28, 29, 30)
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31. A nuclear magnetic resonance imaging (MRI) apparatus comprising:
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a magnet for generating a static magnetic field; a cylindrical inside space disposed in said magnet and accommodating an inspected object; a gradient coil disposed in said magnet and comprising a plurality of coils for generating a gradient magnetic field in said inside space; and a radio frequency (RF) probe for transmitting and receiving a radio frequency magnetic field to and from said inspected object; said magnet generating said static magnetic field in the axial direction of said cylindrical inside space; wherein, among a plurality of said coils constituting said gradient coil, at least one of a plurality of coils generating said gradient magnetic field in a direction other than the direction of said static magnetic field is disposed in such a fashion that the direction of the magnetic field generated by said coil at the center thereof has an angle other than 90°
with respect to the direction of said static magnetic field.
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32. A nuclear magnetic resonance inspection (MRI) apparatus comprising:
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a magnet for generating a static magnetic field; a cylindrical inside space disposed inside said magnet and accommodating an inspected object; a gradient coil disposed inside said magnet and comprising a plurality of coils for generating a gradient magnetic field in said inside space; and a radio frequency (RF) probe for transmitting and receiving a radio frequency magnetic field to and from said inspected object; said magnet generating said static magnetic field in an axial direction of said cylindrical inside space; wherein, among a plurality of said coils constituting said gradient coil, at least one of a plurality of said coils for generating said gradient magnetic field in a direction other than the direction of said static magnetic field is disposed in such a fashion that the direction of the magnetic field generated by said coil at the center thereof is substantially in parallel with the direction of said static magnetic field.
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33. An inspection apparatus using magnetic resonance, comprising magnetic field generation means for generating a static magnetic field, a gradient magnetic field and a radio frequency (RF) magnetic field, respectively, said gradient magnetic field generation means including a plurality of gradient coils, wherein said plurality of gradient coils include at least one of (a) a first set of gradient coils fixed to a magnet directly or indirectly for generating said static magnetic field, and a second set of gradient coils which is movable, the magnetic field generated by said second set of gradient coils at a conducting portion of said magnet being offset by the magnetic field generated by said first set of gradient coils, and (b) at least one set of gradient coils generating a local gradient magnetic field in a direction other than a direction of said static magnetic field and being disposed so that the direction of the local gradient magnetic field generated by said at least one set of gradient coils at a center thereof has an angle other than 90°
- with respect to the direction of said static magnetic field.
Specification