Magnetic resonance imaging apparatus and RF coil employed therein
AssigneeHitachi, Ltd.
InventorsTetsuhiko Takahashi, Etsuji Yamamoto, Yoshiki Murakami, Yoshikuni Matsunaga
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Abstract
In a bird cage resonator, the axial length of rungs is changed between orthogonal elements. By doing this, the real view fields of orthogonal ports A and B in the sagittal direction are changed and the sensitivity difference between both view fields is reduced. For an object with an elliptical section to be inspected such as the human body, a remarkable difference in detection sensitivity between each orthogonal ports is eliminated and the receiving sensitivity of MRI apparatus employing the QD method is improved.
Claims15
A magnetic resonance imaging apparatus for irradiating a rotating high-frequency magnetic field on the xy plane which is created by combining linear high-frequency magnetic fields in the x and y directions to an object to be inspected which is placed in a space defined by the x, y, and z coordinate axes crossing at right angles with each other wherein a static magnetic field exists in the z direction, said apparatus comprising:
- means for generating magnetic resonance signals in the x direction and in the y direction, in combination with a magnetic field generation coil, from said object to be inspected;
- and
- means for detecting said magnetic resonance signals in the x and y directions;
- said magnetic field generation coil generating a magnetic field for generation of said magnetic resonance signals and comprising a pair of electrically conductive loop elements connected through a plurality of axial electrically conductive segments;
- each of the x and y direction magnetic resonance signals generating means generating respectively a magnetic field strength in the x and y directions in a z direction distribution range, wherein the z direction distribution range of the x direction field strength differs from the z direction distribution of the y direction field strength.
A magnetic resonance imaging apparatus for irradiating a high-frequency magnetic field to an object to be inspected which is placed in a space defined by the x, y, and z coordinate axes crossing at right angles with each other wherein a static magnetic field exists in the z direction, for generating magnetic resonance signals from said object to be inspected, said apparatus comprising:
- means for detecting the generated magnetic resonance signals in the x direction and in the y direction, in combination with a magnetic field detecting coil;
- said magnetic field detecting coil detecting said magnetic resonance signals and comprising a pair of electrically conductive loop elements connected through a plurality of axial electrically conductive segments;
- each of the x and y direction magnetic resonance signals detecting means detecting respectively a magnetic field strength in the x and y directions in a range in the z direction, wherein the range in the x direction differs from the range in the y direction.
A magnetic resonance imaging apparatus for irradiating a rotating high-frequency magnetic field on the xy plane which is created by combining linear high-frequency magnetic fields in the x and y directions to an object to be inspected which is placed in a space defined by the x, y, and z coordinate axes crossing at right angles with each other wherein a static magnetic field exists in the z direction, said apparatus comprising:
- means for generating a magnetic resonance signal through a magnetic field coil, from said object to be inspected;
- means for detecting a rotating high-frequency magnetic field on the xy plane through said magnetic field coil, in the x and y directions;
- and
- means for changing operations of said magnetic field coil to and from the generating means and the detecting means;
- said magnetic field coil comprising a pair of electrically conductive loop elements connected through a plurality of axial electrically conductive segments;
- each of the x and y direction magnetic field generating and detecting means respectively generating and detecting a magnetic field strength in the x and y directions in a range in the z direction, wherein the range in the x direction differs from the range in the y direction.
An RF probe comprising a pair of conductive loop elements which are apart from each other along a common vertical axial line, a plurality of axial conductive segments for connecting said conductive loop elements electrically to each other, and a plurality of capacitive elements which are arranged in said loops, wherein a first group of segments among said plurality of axial conductive segments which are practically opposite to each other on both sides of a first plane containing said vertical axial line has a first length and a second group of segments which are practically opposite to each other on both sides of a second plane which contains said common vertical axial line and intersects said first plane orthogonally has a second length which is different from the first length.
A magnetic resonance imaging apparatus for irradiating a high-frequency magnetic field to an object to be inspected which is placed in a space defined by the x, y, and z coordinate axes crossing at right angles with each other wherein a static magnetic field exists in the z direction, for generating magnetic resonance signals from said object to be inspected, said apparatus comprising:
- means for detecting the generating magnetic resonance signals in the x direction and in the y direction, in combination with a magnetic field detecting coil;
- said magnetic field detecting coil detecting said magnetic resonance signals and comprising a pair of electrically conductive loop elements connected through a plurality of axial electrically conductive segments;
- each of the x and y direction magnetic resonance signals detecting means respectively detecting a magnetic field strength in the x and y directions in a range in the z direction, wherein the range in the x direction differs from the range in the y direction;
- converting means for converting the generated magnetic resonance signals in the x and y directions from analog to digital;
- weighting means for weighting each converted signal by a specific weighting function;
- and combining means for combining outputs of said weighting means.
A magnetic resonance imaging apparatus for irradiating a rotating high-frequency magnetic field on the xy plane which is created by combining linear high-frequency magnetic fields in the x and y directions to an object to be inspected which is placed in a space defined by the x, y, and z coordinate axes crossing at right angles with each other wherein a static magnetic field exists in the z direction and for generating and detecting a magnetic resonance signal from said object to be inspected, wherein the magnetic field generation ranges of the linear high-frequency magnetic fields in said x and y directions are different from each other in the z direction, and further comprising a RF probe including a pair of conductive loop elements which are apart from each other along a common vertical axis line, a plurality of axial conductive segments for connecting said conductive loop elements electrically to each other, and a plurality of capacitive elements which are arranged in said loops or said segments, wherein a first group of segments among said plurality of axial conductive segments which are practically opposite to each other on both sides of a first plane containing said vertical axial line has a first length and a second group of segments which are practically opposite to each other on both sides of a second plane which contains said common vertical axial line and intersects said first plane orthogonally has a second length which is different from the first length.
A magnetic resonance imaging apparatus irradiating a high-frequency magnetic field to an object to be inspected which is placed in a space defined by the x, y, and z coordinate axes crossing at right angles with each other wherein a static magnetic field exists in the z direction, for generating a magnetic resonance signal from said object to be inspected, and for detecting a rotating high-frequency magnetic field on the xy plane by combining linear high-frequency magnetic field detection coils in the x and y directions, comprising amplifying means for amplifying received signals of the linear high-frequency magnetic field detection coils in said x and y directions respectively, converting means for converting outputs of said amplifying means in the x and y directions from analog to digital, weighting means for weighting each signal by an optional weighting function, and combining means for combining outputs of said weighting means, and further comprising a RF probe including a pair of conductive loop elements which are apart from each other along a common vertical axis line, a plurality of axial conductive segments for connecting said conductive loop elements electrically to each other, and a plurality of capacitive elements which are arranged in said loops or said segments, wherein a first group of segments among said plurality of axial conductive segments which are practically opposite to each other on both sides of a first plane containing said vertical axial line has a first length and a second group of segments which are practically opposite to each other on both sides of a second plane which contains said common vertical axial line and intersects said first plane orthogonally has a second length which is different from the first length.
An RF probe comprising a pair of conductive loop elements which are apart from each other along a common vertical axis line, a plurality of axial conductive segments for connecting said conductive loop elements electrically to each other, and a plurality of capacitive elements which are arranged in said segments, wherein a first group of segments among said plurality of axial conductive segments which are practically opposite to each other on both sides of a first plane containing said vertical axial line has a first length and a second group of segments which are practically opposite to each other on both sides of a second plane which contains some common vertical axial line and intersects said first plane orthogonally has a second length which is different from the first length.
Dependencies are inferred from the claim text.