Electricity: measuring and testing – Particle precession resonance – Spectrometer components
Reexamination Certificate
2000-01-11
2001-07-10
Oda, Christine (Department: 2862)
Electricity: measuring and testing
Particle precession resonance
Spectrometer components
C324S309000, C324S322000
Reexamination Certificate
active
06259251
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an RF (radio frequency) coil and a magnetic resonance imaging method and apparatus, and more particularly to an RF coil for generating an RF magnetic field in a direction parallel to a loop surface of the coil, and a magnetic resonance imaging method and apparatus employing such an RF coil.
A magnetic resonance imaging apparatus with a static magnetic field direction perpendicular to the body axis of a subject, commonly referred to as a vertical magnetic field-type magnetic resonance imaging apparatus, generates an open static magnetic field space, and hence employs as an RF coil for generating the RF magnetic field an RF coil having a loop surface parallel to the pole piece surface of a static magnetic field generating unit. The RF coil of this type generates the RF magnetic field in the direction parallel to the coil loop surface to form the RF magnetic field perpendicular to the static magnetic field direction. Such an RF coil is disclosed in U.S. Pat. No. 5,760,583 of the present applicant.
On the other hand, there is another type of an RF coil referred to as a quadrature RF coil, which consists of a combination of two RF coils, and can provide an RF magnetic field having an increased strength through vector composition of respective RF magnetic fields generated by the two RF coils or can reduce a drive power per coil to generate the RF magnetic field of a desired strength.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a quadrature RF coil having a good frequency property, and a magnetic resonance imaging method and apparatus employing such an RF coil.
In accordance with a first aspect of the invention, there is provided an RF coil comprising: when three mutually orthogonal directions are represented as an x-direction, a y-direction and a z-direction, a first electric path extending in the x-direction; a second electric path parallel to the first electric path in an x-y plane; a third electric path parallel to the first electric path in an x-z plane; a fourth electric path parallel to the third electric path in a plane parallel to the x-y plane, and parallel to the second electric path in a plane parallel to the x-z plane; a fifth electric path connecting the first-fourth electric paths in series so that the first and second electric paths carry respective electric currents in the same direction, and the third and fourth electric paths carry respective electric currents in the same direction opposite to the direction of the first and second electric paths; a sixth electric path extending in the y-direction in the x-y plane; a seventh electric path parallel to the sixth electric path in the x-y plane; an eighth electric path parallel to the sixth electric path in a y-z plane; a ninth electric path parallel to the eighth electric path in a plane parallel to the x-y plane, and parallel to the seventh electric path in a plane parallel to the y-z plane; and a tenth electric path connecting the sixth-ninth electric paths in series so that the sixth and seventh electric paths carry respective electric currents in the same direction, and the eighth and ninth electric paths carry respective electric currents in the same direction opposite to the direction of the sixth and seventh electric paths; wherein the fifth electric path and the tenth electric path do not overlap each other in the z-direction.
In accordance with a second aspect, there is provided the RF coil as described regarding the first aspect, wherein one of the fifth and tenth electric paths lies inside of the other one in the x-y plane, and the other one of the fifth and tenth electric paths lies inside of the one of the fifth and tenth electric paths in the plane parallel to the x-y plane.
In accordance with a third aspect, there is provided an RF coil comprising: when three mutually orthogonal directions are represented as an x-direction, a y-direction and a z-direction, a first electric path extending in the x-direction; a second electric path parallel to the first electric path in an x-y plane; a fifth electric path connecting the first and second electric paths in series so that the first and second electric paths carry respective electric currents in the same direction; a sixth electric path extending in the y-direction in the x-y plane; a seventh electric path parallel to the sixth electric path in the x-y plane; and a tenth electric path connecting the sixth and seventh electric paths in series so that the sixth and seventh electric paths carry respective electric currents in the same direction; wherein the fifth electric path and the tenth electric path do not overlap each other in the z-direction.
In accordance with a fourth aspect, there is provided a magnetic resonance imaging method comprising the steps of: when three mutually orthogonal directions in a space in which a subject is placed are represented as an x-direction, a y-direction and a z-direction, generating a static magnetic field in the z-direction; generating gradient magnetic fields within the space; generating a high-frequency magnetic field within the space; measuring a magnetic resonance signal from the space; and producing an image based on the measured magnetic resonance signal; wherein the step of generating a high-frequency magnetic field is performed by employing an RF coil comprising: a first electric path extending in the x-direction; a second electric path parallel to the first electric path in an x-y plane; a third electric path parallel to the first electric path in an x-z plane; a fourth electric path parallel to the third electric path in a plane parallel to the x-y plane, and parallel to the second electric path in a plane parallel to the x-z plane; a fifth electric path connecting the first-fourth electric paths in series so that the first and second electric paths carry respective electric currents in the same direction, and the third and fourth electric paths carry respective electric currents in the same direction opposite to the direction of the first and second electric paths; a sixth electric path extending in the y-direction in the x-y plane; a seventh electric path parallel to the sixth electric path in the x-y plane; an eighth electric path parallel to the sixth electric path in a y-z plane; a ninth electric path parallel to the eighth electric path in a plane parallel to the x-y plane, and parallel to the seventh electric path in a plane parallel to the y-z plane; and a tenth electric path connecting the sixth-ninth electric paths in series so that the sixth and seventh electric paths carry respective electric currents in the same direction, and the eighth and ninth electric paths carry respective electric currents in the same direction opposite to the direction of the sixth and seventh electric paths; wherein the fifth electric path and the tenth electric path do not overlap each other in the z-direction.
In accordance with a fifth aspect, there is provided a magnetic resonance imaging apparatus comprising: when three mutually orthogonal directions in a space in which a subject is placed are represented as an x-direction, a y-direction and a z-direction, static magnetic field generating means for generating a static magnetic field in the z-direction; gradient magnetic field generating means for generating gradient magnetic fields within the space; high-frequency magnetic field generating means for generating a high-frequency magnetic field within the space; measuring means for measuring a magnetic resonance signal from the space; and image producing means for producing an image based on the magnetic resonance signal measured by the measuring means; wherein the high-frequency magnetic field generating means comprises an RF coil comprising: a first electric path extending in the x-direction; a second electric path parallel to the first electric path in an x-y plane; a third electric path parallel to the first electric path in an x-z plane; a fourth electric path parallel to the third electric path in a plane parallel to the x-y
Kato Yasushi
Shimo Yukitoshi
Sugiura Sunao
GE Yokogawa Medical Systems Limited
Oda Christine
Shrivastav Brij B.
LandOfFree
RF coil and magnetic resonance imaging method and apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with RF coil and magnetic resonance imaging method and apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and RF coil and magnetic resonance imaging method and apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2532717