Composite MRI antenna with reduced stray capacitance
First Claim
Patent Images
1. Magnetic resonance apparatus comprising:
- (a) field applying apparatus including means for defining a subject-receiving space, and means for directing magnetic flux into said subject-receiving space, said field applying apparatus including an electrically conductive element defining a conductive surface adjacent the subject-receiving space;
(b) a composite antenna for transmission of radiofrequency ("RF") radiation into said subject-receiving space or reception of radiofrequency radiation from said subject-receiving space, said composite antenna including an active coil and an isolated loop coil which is not conductively connected to said conductive surface, at least a part of said isolated loop coil being disposed adjacent to said conductive surface, said isolated loop coil being inductively coupled to said active coil; and
(c) a transmitter or receiver connected said active coil.
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Accused Products
Abstract
An antenna system for a magnetic resonance imaging apparatus has an active coil connected between a transmitter or receiver and ground and also has an isolated loop coil which is not conductively connected to ground. The isolated loop coil preferably overlies the electrically conductive pole surface of the field magnet. The isolated loop coil is inductively coupled to the active coil. The assembly has relatively low parasitic capacitance to ground and hence can be tuned to the resonant frequencies required for high field strength imaging.
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Citations
14 Claims
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1. Magnetic resonance apparatus comprising:
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(a) field applying apparatus including means for defining a subject-receiving space, and means for directing magnetic flux into said subject-receiving space, said field applying apparatus including an electrically conductive element defining a conductive surface adjacent the subject-receiving space; (b) a composite antenna for transmission of radiofrequency ("RF") radiation into said subject-receiving space or reception of radiofrequency radiation from said subject-receiving space, said composite antenna including an active coil and an isolated loop coil which is not conductively connected to said conductive surface, at least a part of said isolated loop coil being disposed adjacent to said conductive surface, said isolated loop coil being inductively coupled to said active coil; and (c) a transmitter or receiver connected said active coil.
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2. Magnetic resonance apparatus comprising:
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(a) field applying apparatus including means for defining a subject-receiving space, and means for directing magnetic flux into said subject-receiving space, said field applying apparatus including an electrically conductive element defining a conductive surface adjacent the subject-receiving space; (b) a composite antenna for transmission of radiofrequency ("RF") radiation into said subject-receiving space or reception of radiofrequency radiation from said subject-receiving space, said composite antenna including an active coil and an isolated loop coil which is not conductively connected to said conductive surface, at least a part of said isolated loop coil being disposed adjacent, to said conductive surface, said isolated loop coil being inductively coupled to said active coil; and (c) a transmitter or receiver connected said active coil, wherein the field applying apparatus includes a structure defining an electrically conductive pole surface facing towards said subject receiving space and a source of magnetic flux associated with said structure for application of a substantially constant primary magnetic field in said subject receiving space through said pole surface and wherein at least a part of said isolated loop coil overlies said pole surface.
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3. Magnetic resonance apparatus comprising:
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(a) field applying apparatus including means for defining a subject-receiving space, and means for directing magnetic flux into said subject-receiving space, said field applying apparatus including an electrically conductive element defining a conductive surface adjacent the subject-receiving space; (b) a composite antenna for transmission of radiofrequency ("RF") radiation into said subject-receiving space or reception of radiofrequency radiation from said subject-receiving space, said composite antenna including an active coil and an isolated loop coil which is not conductively connected to said conductive surface, at least a part of said isolated loop coil being disposed adjacent to said conductive surface, said isolated loop coil being inductively coupled to said active coil; and (c) a transmitter or receiver connected said active coil, wherein said active coil is conductively connected to said conductive surface. - View Dependent Claims (4)
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5. Magnetic resonance apparatus comprising:
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(a) field applying apparatus including means for defining a subject-receiving space, and means for directing magnetic flux into said subject-receiving space, said field applying apparatus including an electrically conductive element defining a conductive surface adjacent the subject-receiving space; (b) a composite antenna for transmission of radiofrequency ("RF") radiation into said subject-receiving space or reception of radiofrequency radiation from said subject-receiving space, said composite antenna including an active coil and an isolated loop coil which is not conductively connected to said conductive surface, at least a part of said isolated loop coil being disposed adjacent to said conductive surface, said isolated loop coil being inductively coupled to said active coil; and (c) a transmitter or receiver connected said active coil, wherein said isolated loop coil includes a winding defining an isolated loop coil surface overlying said conductive surface and extending generally parallel thereto. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12)
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13. Magnetic resonance apparatus comprising:
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(a) field applying apparatus including means for defining a subject-receiving space, and means for directing magnetic flux into said subject-receiving space, said field applying apparatus including an electrically conductive element defining a conductive surface adjacent the subject-receiving space; (b) a composite antenna for transmission of radiofrequency ("RF") radiation into said subject-receiving space or reception of radiofrequency radiation from said subject-receiving space, said composite antenna including an active coil and an isolated loop coil which is not conductively connected to said conductive surface, at least a part of said isolated loop coil being disposed adjacent to said conductive surface, said isolated loop coil being inductively coupled to said active coil; and (c) a transmitter or receiver connected said active coil, the apparatus further comprising means for providing an isolated loop coil tuning capacitance connected to said isolated loop coil and means for providing an active tuning capacitance connected to said active coil.
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14. Magnetic resonance apparatus comprising:
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(a) field applying apparatus including means for defining a subject-receiving space, and means for directing magnetic flux into said subject-receiving space, said field applying apparatus including an electrically conductive element defining a conductive surface adjacent the subject-receiving space; (b) a composite antenna for transmission of radiofrequency ("RF") radiation into said subject-receiving, space or reception of radiofrequency radiation from said subject-receiving space, said composite antenna including an active coil and an isolated loop coil which is not conductively connected to said conductive surface, at least a part of said isolated loop coil being disposed adjacent to said conductive surface, said isolated loop coil being inductively coupled to said active coil; and (c) a transmitter or receiver connected said active coil, wherein said isolated loop coil is substantially in the form of a flat closed loop.
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Specification