Picker International, Inc.

Philips Medical Systems (cleveland), Inc.

John R Stauber

G Neil Holland

Michael Burl

Douglas M Blakeley

Kenneth S Denison

David C Flugan

A magnetic resonance imaging system includes a patient couch ( ) which selectively positions a patient relative to an examination region ( ). An imaging coil (B) is disposed adjacent to a region of interest for receiving magnetic resonance signals emanating from the patient. A processor ( ) both controls the imaging event and processes received signals from the imaging coil. A plug and socket assembly ( ) having a proximal component and a distal component relative to the imaging coil provides selective electrical connectivity between the imaging coil (B) and the processor ( ). A non-volatile memory device ( ), such as a 1-WIRE&trade; EEPROM, is affixed to the proximal component of the plug and socket assembly ( ) for storing a variety attributes associated with the imaging coil. The memory device is most conveniently mounted to a coaxial connector ( ).

Method and apparatus to embed and retrieve attribute information in magnetic resonance imaging coils

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

In a magnetic resonance imaging apparatus, a gradient profile generator (30) generates gradient energization profiles or current pulses (32, 34, 36) each of which has a shape that corresponds to a profile of a preselected magnetic field gradient that is to be applied across an image region (10) by gradient coils (38). The applied gradient magnetic field profile inherently causes eddy currents which generate opposing magnetic field components and distort the gradient magnetic field profile. A series of calibration circuits (62) alters the gradient energization profiles to compensate for eddy current distortion. A profile amplifier (74) is connected with a first MDAC (80) in parallel with a capacitor (82) and a second MDAC (84) in a feedback loop. By digitally controlling the internal resistance of the MDACs, the magnitude of a feedback signal and its RC time constant are digitally adjusted. A magnetic field sensor (90) measures the resultant gradient magnetic field profile. An iterative adjustment computer (92) compares the measured and preselected gradient magnetic field profiles and iteratively adjusts the MDACs to optimize the conformity therebetween. The calibration circuits are enabled only during a radio frequency transmission or receipt. Between radio frequency transmissions and reception, bypass switches (114, 116) bypass the calibration circuits to conserve electrical power.

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Fairview Park, OH, United States of America

John R Stauber