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4788834 Method and system for controlling magnetic field generating unit in magnetic resonance imaging apparatus
Magndic Resonance Printed in the USA.
Imaging, Vol. 8, pp. I-11, 1990 All rights reserved.
Copyright
0730-725x/90 $3.00 + .oa 0 1990 Pergamon Press plc
NEW PATENTS This Section contains abstracts and, where appropriate, illustrations of recently issued United States patents and published patent applications filed from over 30 countries under the Patent Cooperation Treaty. This information was obtained from recent additions to the Pergamon PATSEARCH@ online database in accordance with interest profiles developed by the Editors. Further information about Pergamon PATSEARCH@ can be obtained from Pergamon Orbit InfoLine Inc., 8000 Westpark Drive, McLean, Virginia 22102 U.S.A. Copies of complete patents announced in this Section are available from Pergamon Orbit InfoLine Inc. for $8 per copy. Payment with order is required. Orders outside North America add $2 for air postage. Order by patent number for Pergamon Orbit InfoLine only.
4788500
In magnetic resonance imaging apparatus in which bird-cage coils are used in combination with other coils, a capacitance is bridged by means of an inductive element. Substantial detuning and hence adequate uncoupling of the bird-cage coil from the other (receiving) coil is achieved. Use can be made of the already present coaxial transmission line via which the RF energy is applied to the bird-cage coil. Connecting the core and the jacket of the coaxial transmission line there is arranged a diode switch so that the bird-cage coil circuit can be electronically detuned, thus enabling fast switching on and off of the bird-cage coil.
MEASUREMENT OF CAPILLARY FLOW USING NUCLEAR MAGNETIC RESONANCE H Samuel
Brigham
Patz,
Robert
& Women’s
C Hawkes Hospital
assigned
to
An improved method for measuring very slow flow rates using nuclear magnetic resonance techniques is disclosed. The basic technique is that of steady state free precession, in which a sequence of radio frequency pulses are applied to nuclei in a magnetic field having a substantial gradient, so that a driven equilibrium state is obtained and which is characterized by a spatial periodicity in the magnetization response of the nuclei. Two images are generated. The two images may be generated using different time intervals between the application of the radio frequency pulses. Alternatively, the two images may be generated using different effective gradients. The spatial periodicity, and the NMR response of flowing nuclei to the spatial periodicity, is thus different during the two image formations. One image is subtracted from the other, which cancels signals from static nuclei in the signal, while relatively fast flowing nuclei, namely in the larger blood vessels or the like, never reach the equilibrium state. The subtraction difference is therefore proportional only to nuclei which are part of relatively slowly flowing liquids, such as in capillary blood flow in organs.
4788834 METHOD AND SYSTEM FOR CONTROLLING MAGNETIC FIELD GENERATING UNIT IN MAGNETIC RESONANCE IMAGING APPARATUS Yoshiyuki Usui, Koji Kitamura, Kuroiso, assigned to Kabushiki Kaisha Toshiba
Japan
To reduce the running cost of an MRI apparatus, power supplied to a normal conductive coil from a pre-regulator is reduced in an idling mode. This reduction in power also reduces the heat generated in the normal conductive coil and a shunt resistor. A computer controls a cooling unit according to the amount of the heat reduced in order to reduce to flow rate of a cooling medium. In this manner, the temperatures of the normal conductive coil and shunt resistor can be maintained at constant levels. Further, if a current value is set to maintain the temperatures of the normal conductive coil and shunt resistor at the constant levels only by natural heat radiating, circulation of the cooling medium can be stopped.
4788503 MAGNETIC RESONANCE IMAGING APPARATUS HAVING A DETUNED RF COIL Teunis R Van Heelsbergen, Eindhoven, Netherlands assigned to U S Philips Corporation I
Imaging, Vol. 8, pp. I-11, 1990 All rights reserved.
Copyright
0730-725x/90 $3.00 + .oa 0 1990 Pergamon Press plc
NEW PATENTS This Section contains abstracts and, where appropriate, illustrations of recently issued United States patents and published patent applications filed from over 30 countries under the Patent Cooperation Treaty. This information was obtained from recent additions to the Pergamon PATSEARCH@ online database in accordance with interest profiles developed by the Editors. Further information about Pergamon PATSEARCH@ can be obtained from Pergamon Orbit InfoLine Inc., 8000 Westpark Drive, McLean, Virginia 22102 U.S.A. Copies of complete patents announced in this Section are available from Pergamon Orbit InfoLine Inc. for $8 per copy. Payment with order is required. Orders outside North America add $2 for air postage. Order by patent number for Pergamon Orbit InfoLine only.
4788500
In magnetic resonance imaging apparatus in which bird-cage coils are used in combination with other coils, a capacitance is bridged by means of an inductive element. Substantial detuning and hence adequate uncoupling of the bird-cage coil from the other (receiving) coil is achieved. Use can be made of the already present coaxial transmission line via which the RF energy is applied to the bird-cage coil. Connecting the core and the jacket of the coaxial transmission line there is arranged a diode switch so that the bird-cage coil circuit can be electronically detuned, thus enabling fast switching on and off of the bird-cage coil.
MEASUREMENT OF CAPILLARY FLOW USING NUCLEAR MAGNETIC RESONANCE H Samuel
Brigham
Patz,
Robert
& Women’s
C Hawkes Hospital
assigned
to
An improved method for measuring very slow flow rates using nuclear magnetic resonance techniques is disclosed. The basic technique is that of steady state free precession, in which a sequence of radio frequency pulses are applied to nuclei in a magnetic field having a substantial gradient, so that a driven equilibrium state is obtained and which is characterized by a spatial periodicity in the magnetization response of the nuclei. Two images are generated. The two images may be generated using different time intervals between the application of the radio frequency pulses. Alternatively, the two images may be generated using different effective gradients. The spatial periodicity, and the NMR response of flowing nuclei to the spatial periodicity, is thus different during the two image formations. One image is subtracted from the other, which cancels signals from static nuclei in the signal, while relatively fast flowing nuclei, namely in the larger blood vessels or the like, never reach the equilibrium state. The subtraction difference is therefore proportional only to nuclei which are part of relatively slowly flowing liquids, such as in capillary blood flow in organs.
4788834 METHOD AND SYSTEM FOR CONTROLLING MAGNETIC FIELD GENERATING UNIT IN MAGNETIC RESONANCE IMAGING APPARATUS Yoshiyuki Usui, Koji Kitamura, Kuroiso, assigned to Kabushiki Kaisha Toshiba
Japan
To reduce the running cost of an MRI apparatus, power supplied to a normal conductive coil from a pre-regulator is reduced in an idling mode. This reduction in power also reduces the heat generated in the normal conductive coil and a shunt resistor. A computer controls a cooling unit according to the amount of the heat reduced in order to reduce to flow rate of a cooling medium. In this manner, the temperatures of the normal conductive coil and shunt resistor can be maintained at constant levels. Further, if a current value is set to maintain the temperatures of the normal conductive coil and shunt resistor at the constant levels only by natural heat radiating, circulation of the cooling medium can be stopped.
4788503 MAGNETIC RESONANCE IMAGING APPARATUS HAVING A DETUNED RF COIL Teunis R Van Heelsbergen, Eindhoven, Netherlands assigned to U S Philips Corporation I