Picker International, Inc.

Technicare Corporation

Koninklijke Philips Electronics N.v.

Robert C Gauss

Gordon D DeMeester

Michael Burl

Zhiyong Zhai

Douglas M Blakeley

Waldo S Hinshaw

David C Flugan

Michael A Morich

A magnetic imaging apparatus includes an RF coil (F) in electrical communication with an RF signal generator (C) and a receiver (G) through an interface circuit (E). The signal generator transmits resonance excitation signals at one of at least two resonance frequencies, e.g. the resonance frequencies of hydrogen helium 3, fluorine, phosphorous, carbon, or xenon. During the transmit cycle, PIN diode (,) is forward biased forming a filter at a first resonance frequency, electrically isolating the receiver from first frequency excitation signals. Simultaneously during the transmit cycle, PIN diode (,) is forward biased forming a filter at a second resonance frequency electrically isolating the receiver from second frequency excitation signals. During a receive cycle, the diodes are reverse biased turning both filters into low impedance circuits around the first and second resonance frequencies allowing a received magnetic resonance signal to pass unimpeded from the RF coil to the receiver.

High power, multiple-frequency transmit-receive switch in magnetic resonance imaging

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

Apparatus for generating and detecting magnetic field components oscillating at a radio frequency in a direction transverse to a static magnetic field in a nuclear-magnetic-resonance (NMR) system. The apparatus has a plurality of conductive elements spaced from one another and from the axis along which the static magnetic field is directed. The relative amplitudes of alternating currents in the conductive elements are controlled to generate a spatially uniform field. A preferred embodiment uses a standing wave in a coil assembly to control relative current amplitudes, which takes advantage of the current-phase characteristics of such waves. Detection of RF magnetic fields results from an EMF generated in the coil assembly in response to the time-varying magnetic field; the high Q of the coil assembly enhances detection properties.

Distributed phase RF coil

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Aurora, OH, United States of America

Robert C Gauss