Magnetic resonance scan sequencer
First Claim
1. A magnetic resonance imaging system comprising:
- a magnetic field means for generating a temporally constant magnetic field through an examination region;
gradient field coils for generating gradient magnetic fields across the examination region;
a radio frequency coil disposed adjacent the magnetic field region for transmitting radio frequency signals into and receiving radio frequency signals from the examination region;
a display means for displaying human-readable images reconstructed from magnetic resonance data collected from the examination region;
a central processor means for providing waveform information and timing programs;
a scan sequencer means including;
a master sequencer means into which the timing programs from the central processor are loaded,a plurality of waveform channel means each having channel memory means for holding at least the waveform information, the channel means are controlled by the master sequencer means to generate a series of radio frequency control signals and a series of gradient control signals in accordance with the waveform information in the channel memory means and the timing program loaded in the master sequencer device,a gradient digital-to-analog converter means for converting the gradient control signals into current pulses which are supplied to the gradient field coils,a radio frequency synthesizer for converting the radio frequency control signals into radio frequency signals.
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Accused Products
Abstract
A magnetic resonance imaging magnet, gradient coil, and RF coil assembly is controlled by a workstation (40). The workstation (40) includes an operator input (46, 48) and a display system (58) including a video monitor (44) for displaying human-readable images reconstructed from magnetic resonance data. A scan/reconstruction rack (50) includes a scan processor (60) which controls scan parameters and a reconstruction processor (64) and associated hardware for reconstructing received magnetic resonance signals into the image representation. A scan sequencer (52) includes a master microcode board (90) which controls the scan sequencer in accordance with instructions received from the scan processor (60). The scan processor loads a series of codes describing gradient and RF waveform profiles into memories (130) of each of a plurality of profile channels (100, 102, 104, 106, 110, 112, 114). Associated state machines (126) of each channel under control of a clock (138) step the pulse information from the memory (130) to respective output registers. The outputs from four of the channels for controlling the magnetic field gradients are connected to an obliquer (94) which processes the four outputs with a matrix to generate x, y, and z gradient components. The gradient components are connected through digitally controlled pre-emphasis circuits (150) to the gradient coils. The rest of the channels are connected to a frequency synthesizer (116) which provides frequency information for driving the radio frequency coil.
62 Citations
26 Claims
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1. A magnetic resonance imaging system comprising:
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a magnetic field means for generating a temporally constant magnetic field through an examination region; gradient field coils for generating gradient magnetic fields across the examination region; a radio frequency coil disposed adjacent the magnetic field region for transmitting radio frequency signals into and receiving radio frequency signals from the examination region; a display means for displaying human-readable images reconstructed from magnetic resonance data collected from the examination region; a central processor means for providing waveform information and timing programs; a scan sequencer means including; a master sequencer means into which the timing programs from the central processor are loaded, a plurality of waveform channel means each having channel memory means for holding at least the waveform information, the channel means are controlled by the master sequencer means to generate a series of radio frequency control signals and a series of gradient control signals in accordance with the waveform information in the channel memory means and the timing program loaded in the master sequencer device, a gradient digital-to-analog converter means for converting the gradient control signals into current pulses which are supplied to the gradient field coils, a radio frequency synthesizer for converting the radio frequency control signals into radio frequency signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of controlling scan sequences in a magnetic resonance imaging apparatus that includes a means for generating a temporally constant magnetic field through an examination region, gradient field coils for generating gradient magnetic fields across the examination region, a radio frequency coil for transmitting radio frequency signals into and receiving radio frequency signals from the examination region, and a central processor for providing waveform information and timing programs, the method comprising:
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loading waveform information into each of a plurality of waveform channels; with each waveform channel, under the control of one of the timing programs, generating a series of radio frequency control signals and a series of gradient control signals; converting the gradient control signals into current pulses and applying the current pulses to the gradient field coil; frequency synthesizing radio signals from the radio frequency control signals and applying the radio signals to the radio frequency coil. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification