Picker International, Inc.

Koninklijke Philips Corporation N.V.

Douglas M Blakeley

Daniel Gagnon

Michael Andrew Morich

G Neil Holland

David A Molyneaux

Raymond E Gangarosa

David C Flugan

Michael Burl

Kenneth S Denison

Kevin Nieman

Robert C Gauss

Theodore J Reisker

John R Stauber

Denis W Vanek

Robert L Zahn

Carolyn A Kershaw

Steven D Pace

James J Rogers

Kevin M Nieman

A hybrid imaging system includes a magnetic resonance scanner and a second modality imaging system disposed in the same radio frequency isolation space. The second modality imaging system includes radiation detectors configured to detect at least one of high energy particles and high energy photons. In some embodiments a retractable radio frequency screen is selectively extendible into a gap between the magnetic resonance scanner and the second modality imaging system. In some embodiments shim coils are disposed with the magnetic resonance scanner and are configured to compensate for distortion of the static magnetic field of the magnetic resonance scanner produced by proximity of the second modality imaging system.

Hybrid PET/MR imaging systems

A hybrid imaging system and a patient bed for same are disclosed. The hybrid imaging system includes a magnetic resonance scanner and a second modality imaging system spaced apart from the magnetic resonance scanner by a gap. In some embodiments, the gap is less than seven meters. The patient bed is disposed at least partially in the gap between the magnetic resonance scanner and the second modality imaging system, and includes a linearly translatable patient support pallet aligned to be selectively moved into an examination region of the magnetic resonance scanner for magnetic resonance imaging and into an examination region of the second modality imaging system for second modality imaging. In some embodiments, a linear translation range of the linearly translatable pallet is less than five times a length of the patient support pallet along the direction of linear translation.

Patient bed for PET/MR imaging systems

A magnetic resonance imaging system includes a main magnetic field generator ( ) which produces a temporally constant magnetic field through an examination region ( ). A gradient coil assembly ( ) powered by a gradient field amplifier ( ) produces gradient fields orthogonal to the main magnetic field. The gradient field amplifier ( ) includes a heat sink ( ) for dissipating the thermal energy of at least one power semiconductor device ( ) having a first surface opposite a thermally conductive surface ( ). The thermally conductive surface ( ) is in contact with the heat sink ( ) for transferring the thermal energy. A rigid plate clamp assembly ( ) is affixed to the heat sink ( ) and the semiconductor device ( ) is disposed therebetween. A resiliently deformable spring ( ) is positioned between a first surface of the semiconductor package ( ) and the plate clamp ( ) maintaining positive pressure between the thermally conductive surface ( ) and the heat sink ( ). The resilient deformable spring ( ) has an inner ring ( ) in contact with the rigid plate assembly ( ) and an outer ring ( ) angled from the inner ring in contact with the first surface of the semiconductor package ( ). Preferably, a plurality of semiconductor devices are provided each utilizing a deformable spring to ensure thermal contact between each semiconductor power device and the heat sink.

Apparatus for effecting heat transfer from power semiconductors

A gradient amplifier (,), for driving a gradient coil (,) of an MRI scanner, includes a plurality of first modules (,). The first modules (,) provide unipolar PWM control of an input supplied thereto to generate a unipolar waveform. A high voltage DC power supply (,) electrically connected to the first modules (,) supplies the input to the first modules (,). At least one second module (,) is electrically connected to the first modules (,). The second module (,) selectively provides polarity switching of the unipolar waveform output from the first modules (,) to generate a bipolar waveform which drives the gradient coil (,).

Modular MRI gradient amplifier using unipolar PWM drive

A movable patient supporting portion (10) of a patient couch (A) includes a socket (26) for receiving a mating plug (24) on a localized coil (B). The patient couch selectively inserts the localized coil and a supported patient into a bore (14) of a cryogenic magnet system (C). The localized coil includes a resistor (86) whose magnitude identifies the coil. A coil identification interrogator (84) interrogates the coil identification resistor and derives a corresponding binary coil identification. The coil identification addresses a look-up table (90) to retrieve diagnostic test information, an identification of a coil for a human-readable display, and, preferably, an identification of an isocenter of the coil. A diagnostic test unit (92) electrically tests the coil through the plug and socket connection with the diagnostic tests prescribed by the look-up table. A display interface (94) converts error messages from the diagnostic test unit and the coil identification from the look-up table into appropriate format for a display (40). A couch computer (18) controls a motor (20) in accordance with the isocenter of the coil from the look-up table to control positioning of the patient and the localized coil.

RF coil identification and testing interface for NMR systems

Magnetic resonance imaging hardware (A) defines a patient receiving region (20) that is surrounded by a bore liner (22). A socket (50) is mounted in the bore liner with an appropriate receptacle for receiving a standard plug (52) of a conventional pulse oximetry system. Conventional pulse oximetry systems include a sensor unit (54) connected with a cable (56) having the plug (52) at one end thereof. A notch filter (62) attenuates currents near the resonance frequency of the imager. A preamplifier (60) amplifies signals from the sensor unit. Within the shielding (66) of the preamplifier, a low pass filter (68) is provided to remove induced radio frequency components from the preamplified sensor unit signal. A radio frequency filter (70) mounted at the shield of the shielded room (B) prevents radio frequency signals from reaching an exterior processing and display unit (E) and prevents radio frequency signals from a clock (72) of the processing and display unit from being conveyed into the shielded room (B). The processing and display unit processes the signal received from the preamplifier to generate a pulse rate display (78) and a blood oxygen concentration display (80).

MRI compatible pulse oximetry system

A cardiac electrode (40) has a plug (48) which is frictionally received in a socket (50) of an electrical lead (56). An impedance (54) is connected in series between the electrical lead and the socket to pass ECG signals substantially unattenuated and for blocking radio frequency signals induced in the lead from reaching the socket and the electrode and heating the electrode to a sufficient temperature to burn the patient. The impedance includes an LC circuit (66, 68) which freely passes low frequency signals, such as cardiac signals, but which is tuned to resonance at radio frequencies, particularly at the frequency of resonance excitation and manipulation pulses of a magnetic resonance imager (A). Alternately, the impedance may include a resistive element for blocking the induced currents. A temperature sensor (60) is mounted in intimate contact with an electrically and thermally conductive socket portion (52) to sense the temperature of the electrode, indirectly. A temperature sensor lead (62), the cardiac lead (56), and a respiratory or other anatomical condition sensor are connected with a multiplexing means (140) which cyclically connects the output signals thereof with an analog to digital converter (142). The digital signals are converted to digital optical signals (102) to be conveyed along a light path (104) out of the examination region. The bits of the received digital signal are sorted (144) between an R-wave detector (120), a temperature limit check (122) which checks whether the temperature of the electrode exceeds preselected limits, and a respiratory detector (132).

Temperature sensing and control system for cardiac monitoring electrodes

A magnetic resonance imaging apparatus includes one or more digital transmitters (B), one or more digital receivers (C), and digital data processing circuitry (D) which are all clocked and controlled by a single clock (F). Each digital transmitter includes a numerically controlled modulated oscillator (20) which processes digital phase and frequency signals to produce an output which addresses a wave-form map stored in a PROM (22). Each wave-form output of the PROM is multiplied (24) by a digital amplitude profile signal to generate a phase, frequency, and amplitude modulated digital RF signals. A clock gate (30) controls clocking of the digital modulation to create RF pulses. A digital-to-analog converter (28) converts the digital information to an analog RF pulse which is applied to a subject in an image region. The receivers each include an analog-to-digital converter (60) which digitizes the magnetic resonance signal emanating from the subject in the image region with four fold oversampling. A pair of FIR filters (62a, 62b) multiply the digital resonance signal by digital sine and cosine filter coefficients to create in-phase and out-of-phase digital magnetic resonance signal components. After additional digital filtering (64a, 64b), the digital in-phase and quadrature components are Fourier transformed (70) and accumulated in an image memory (72) to form an image representation.

Magnetic resonance imager with digital transmitter/receiver

A magnetic resonance imaging apparatus (A) generates a uniform magnetic field, causes gradient fields transversely thereacross, excites resonance in nuclei within the image region, receives radio frequency signals from resonating nuclei, and reconstructs images representative thereof. Electrodes (30) monitor the cardiac cycle of a patient (B) being imaged and an expansion belt (32) monitors the respiratory cycle. During a magnetic resonance imaging scan, noise signal wave forms or spikes are superimposed on the cardiac cycle signal. A noise spike detector detects noise spikes. Specifically, a comparator (48) compares each wave form received from the electrodes with properties of a cardiac signal, such as the slope. When the comparator determines that a noise wave form is being received, it gates a track and hold circuit (52). The track and hold circuit passes the received signal except when gated by the comparator. When gated by the comparator, the track and hold circuit continues to supply the same output amplitude as it had in the beginning of the gating period. A filter (54) smooths the plateaus in the cardiac signal formed as the noise signal wave forms are removed.

Cardiac and respiratory monitor with magnetic gradient noise elimination

A patient (B) is disposed in a region of interest of a magnetic resonance apparatus (A). During an imaging sequence, changing magnetic field gradients and radio frequency pulses are applied to the region of interest. The changing magnetic field gradients induce a corresponding electrical response in the patient. Electrodes (40) of a cardiac monitor (C) sense the electrocardiographic signal of the patient as well as the electrical response to the magnetic field gradient changes and produces an output signal having a cardiac component and a noise component. The bandwidth of the noise component varies in accordance with the changes of the magnetic field gradients. An adaptive filter (80) filters the output signal to remove the changing magnetic field gradient induced noise. The bandwidth of the filter function with which the output signal is filtered is varied or adjusted in accordance with the magnetic field gradient changes. The magnetic field gradient changes are monitored (84), their rate of change determined (88), and the bandwidth of the filter function is adjusted (92) in accordance with the rate of change. Alternately, the magnetic field gradient changes are determined a priori from a knowledge of the imaging sequence. As the imaging sequence progresses, a look-up table (150) is addressed to retrieve preprogrammed filter function information for various views or stages of the imaging sequence.

Adaptive filtering of physiological signals in physiologically gated

A magnetic resonance imaging apparatus (A) generates a uniform main magnetic field, gradient fields transversely thereacross, excites resonance in nuclei within an image region, receives radio frequency signals from the resonating nuclei, and reconstructs images representative thereof. Electrodes (30) monitor the cardiac cycle of a patient (B) being imaged and an expansible belt (32) monitors the respiratory cycle. A carrier signal from a generator (52) is modulated with the respiratory signals. The modulated carrier signals are combined (60) with the cardiac signals and converted to a light signal by a light source (62). A fiber optic cable (36) conducts the light signals to a light receiver (70). Band pass filters (72, 100) separate the received cardiac and respiratory encoded carrier signals. A zero detector (80) provides a scan initiation signal in response to a preselected portion of the cardiac cycle. The respiratory encoded carrier signal is demodulated by demodulator (102) and a comparator (116) blocks or enables the processing of image data during a selected window of the respiratory cycle. A window adjustment means (118) adjusts the respiratory window as a function of phase encoding of the resonating nuclei.

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Euclid, OH, United States of America

Douglas M Blakeley