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5311136 Gradient power source apparatus for magnetic resonance imaging system
XXVIII
New Patents
posite image is then constructed using only the unblurred regions from each base image. Focusing criterion can include minimization of the imaginary part of the complex MRI after removal of constant and low frequency phase information.
5311134 MAGNETIC RESONANCE IMAGING SYSTEM Hitoshi Yamagata, Masafumi Kondo, Fumikaz Takahashi, Otawara, Japan assigned to Kabushiki Kaisha Toshiba An MR imaging system comprises a first gradient coil unit(first G coil unit) for providing magnetic gradients superimposed in a static magnetic field, a first RF coil unit for transmitting an RF pulse to a patient and receiving a MR signal from the patient, a second gradient coil unit(second G coil unit) and a second RF coil unit. The second G coil unit is located between the patient and the first G coil unit. In a first operating mode(for example, spin echo scan mode), the second G and RF coil units are moved out the first G coil unit and the first RF coil unit is moved into the first G coil unit by guiding these units along a rail or the second G and RF coil units are drawn out from the first G coil unit and the first RF coil unit is inserted into the first G coil unit so that these units are located in predetermined position. A connection of a gradient power source to the first and second G coil unit and a connection of a duplexer to the first and second RF coil unit are switched so that the gradient power source is connected to the first G coil unit and the duplexer is connected to the first RF coil assembly. In a second operating mode (for example, echo planar scan mode), these units are located inversely and the connections are switched inversely. In one preferred embodiment, the second G coil unit and the first RF coil unit are integrated into an inner unit and these units are moved together by moving the inner unit.
An NMR imaging system includes an apparatus for producing a magnetic field gradient within an imaging volume into which the object being imaged is placed. The relatively linear region of the magnetic field gradient is adjusted depending upon the size of the object. The apparatus comprises a source of a gradient signal and four saddle coils positioned in quadrant of a sheet that is wrapped around a cylindrical form. Each saddle coil has a spiral shaped conductive pattern on which are located a primary termination point and a pair of secondary termination points. A switch mechanism connects the four saddle coils in series with the source of a gradient signal, so that voltage from the gradient signal is applied between the primary termination point and a selected secondary termination point of each saddle coil. A control signal applied to the switch mechanism indicates selected secondary termination point and the signal varies according to the size of the object.
5311136 GRADIENT APPARATUS RESONANCE
POWER SOURCE FOR MAGNETIC IMAGING SYSTEM
Fumikaz Takahashi, Tochigi, Japan assigned to Kabushiki Kaisha Toshiba A capacitor is connected in parallel with a gradient coil to form a parallel resonance circuit with the gradient coil. A gradient coil current is reversed utilizing parallel resonance of the gradient coil and the capacitor. The gradient coil current is detected by a shunt resistor connected in series to a power source. A voltage across the shunt resistor is compared with a reference voltage to control a power-source voltage, thereby controlling a gradient-coil current waveform. This arrangement allows imaging sequences to be performed in a short time without involving gradient field waveform distortion and increasing power consumption. A gradient power source apparatus suited for ultra high-speed MRI apparatus is provided.
5311135 5312617 MULTIPLE TAP GRADIENT FIELD COIL FOR MAGNETIC RESONANCE IMAGING Robert M Vavrek, Christopher C Myers assigned to General Electric Company
LIPOSOLUBLE COMPOUNDS USEFUL AS MAGNETIC RESONANCE IMAGING AGENTS Evan Unger, DeKang
Shen
New Patents
posite image is then constructed using only the unblurred regions from each base image. Focusing criterion can include minimization of the imaginary part of the complex MRI after removal of constant and low frequency phase information.
5311134 MAGNETIC RESONANCE IMAGING SYSTEM Hitoshi Yamagata, Masafumi Kondo, Fumikaz Takahashi, Otawara, Japan assigned to Kabushiki Kaisha Toshiba An MR imaging system comprises a first gradient coil unit(first G coil unit) for providing magnetic gradients superimposed in a static magnetic field, a first RF coil unit for transmitting an RF pulse to a patient and receiving a MR signal from the patient, a second gradient coil unit(second G coil unit) and a second RF coil unit. The second G coil unit is located between the patient and the first G coil unit. In a first operating mode(for example, spin echo scan mode), the second G and RF coil units are moved out the first G coil unit and the first RF coil unit is moved into the first G coil unit by guiding these units along a rail or the second G and RF coil units are drawn out from the first G coil unit and the first RF coil unit is inserted into the first G coil unit so that these units are located in predetermined position. A connection of a gradient power source to the first and second G coil unit and a connection of a duplexer to the first and second RF coil unit are switched so that the gradient power source is connected to the first G coil unit and the duplexer is connected to the first RF coil assembly. In a second operating mode (for example, echo planar scan mode), these units are located inversely and the connections are switched inversely. In one preferred embodiment, the second G coil unit and the first RF coil unit are integrated into an inner unit and these units are moved together by moving the inner unit.
An NMR imaging system includes an apparatus for producing a magnetic field gradient within an imaging volume into which the object being imaged is placed. The relatively linear region of the magnetic field gradient is adjusted depending upon the size of the object. The apparatus comprises a source of a gradient signal and four saddle coils positioned in quadrant of a sheet that is wrapped around a cylindrical form. Each saddle coil has a spiral shaped conductive pattern on which are located a primary termination point and a pair of secondary termination points. A switch mechanism connects the four saddle coils in series with the source of a gradient signal, so that voltage from the gradient signal is applied between the primary termination point and a selected secondary termination point of each saddle coil. A control signal applied to the switch mechanism indicates selected secondary termination point and the signal varies according to the size of the object.
5311136 GRADIENT APPARATUS RESONANCE
POWER SOURCE FOR MAGNETIC IMAGING SYSTEM
Fumikaz Takahashi, Tochigi, Japan assigned to Kabushiki Kaisha Toshiba A capacitor is connected in parallel with a gradient coil to form a parallel resonance circuit with the gradient coil. A gradient coil current is reversed utilizing parallel resonance of the gradient coil and the capacitor. The gradient coil current is detected by a shunt resistor connected in series to a power source. A voltage across the shunt resistor is compared with a reference voltage to control a power-source voltage, thereby controlling a gradient-coil current waveform. This arrangement allows imaging sequences to be performed in a short time without involving gradient field waveform distortion and increasing power consumption. A gradient power source apparatus suited for ultra high-speed MRI apparatus is provided.
5311135 5312617 MULTIPLE TAP GRADIENT FIELD COIL FOR MAGNETIC RESONANCE IMAGING Robert M Vavrek, Christopher C Myers assigned to General Electric Company
LIPOSOLUBLE COMPOUNDS USEFUL AS MAGNETIC RESONANCE IMAGING AGENTS Evan Unger, DeKang
Shen