Abstract: A highly fault tolerant method of radio communication piggybacked upon time division multiple access (TDMA) digital cellular radio telephone systems transmits message packet through a distributed network of transmitter/receivers, (tranceivers) mobile units, each having a unique identification (ID) number. An initiating mobile unit creates a message packet having the ID of a mobile unit intended to receive the message packet. It then broadcasts the message packet in a non-interfering fashion to local mobile units within its transmission range, at a time period which does not overlap a time slot in which it communicates with a cellular base unit. Each mobile unit which receives the message packet checks to see if there are errors and sends an acknowledgement if no errors. The mobile units determine valid message packets by determining if the message has not expired, if it has not been seen before and there were no errors in the received message packet.

Abstract: A magnetic resonance (MR) active invasive device system employs a small, high-field polarizing magnet, and a large low-field magnetic resonance (MR) imaging magnet for the purpose of generating MR angiograms of selected blood vessels. A subject is positioned in a large low-field MR imaging magnet. A catheter in inserted into the patient at or near the root of a vessel tree desired to be imaged. A fluid, intended to be used as a contrast agent is first passed through the small high-field polarizing magnet, causing a great deal of net longitudinal magnetization to be produced in the fluid. The fluid is then introduced into the subject through the catheter. Radiofrequency (RF) pulses and magnetic field gradients are then applied to the patient as in conventional MR imaging. Since the fluid has a larger longitudinal magnetization, before the MR imaging sequence, the fluid produces a much larger MR response signal than other tissue resulting in the vessel tree being imaged with excellent contrast.

Abstract: A motion imaging method uses magnetic resonance to detect acceleration, and an velocity distribution within moving materials in a subject. Acceleration encoding is performed by computing differences of data obtained with modulated motion-encoding magnetic field gradient pulses. Distributions of velocity are measured responsive to a motion sensitive phase-encoding gradient pulse.

Abstract: A low complexity adaptive equalizer for use in U.S. digital cellular radios demodulates .pi./4-shifted differentially encoded quadrature phase shift keyed (DQPSK) encoding in the presence of intersymbol interference (ISI) with reduced decoding complexity by employing an estimated received constellation which takes into account channel changes over time and ISI. The decoding complexity is reduced by tracking a reduced number of estimated reference constellation points and taking advantage of the geometry to estimate the remaining symbol constellation points. A slot of symbols is decoded, employing unique filtering, in segments from the beginning in a forward direction and from the end in a reverse direction meeting at a fade point. This isolates a fade and allows the equalizer to perform more reliably.

Abstract: A digital radio communications system employs a digital information source for providing digital information such as message bits, a transmitter for transmitting encoded digital information into data symbols in a radio-frequency (RF) signal to a plurality of antennae which sense the transmitted RF signal. A post detection measure of signal quality, the signal-to-impairment ratio, (SIR), is utilized by the receiver to perform post detection combining of signals received by a plurality of antennae. The antennae are coupled to a receiver which for each received signal: digitizes the signal, determines phase angles of the digitized signal, converts the signal to unit vectors, determines a signal-to-impairment ratio (SIR) estimates .gamma..sup.j of the digitized signals. The SIR estimate .gamma..sup.j is weighted by combining weight computation element and multiplied by each unit vector to provide an in-phase is component and a quadrature component for each signal.

Abstract: A graphic technique, implemented on a graphics computer, for visualizing 3-D vector data uses a stream tube which is a tube-like structure having a cross section of an n-sided polygon. The stream tube follows the path of a streamline in the 3-D vector data. Data can be visualized by varying the shape and size of the polygon along the streamline to represent changes in normal and shear strain, rotation and velocity. Additional scalar functions are represented by coloring the sides of the stream tube.

Abstract: A non-invasive imaging device obtains a four dimensional (4D) image data set of a living subject representing three dimensions and time in relation to the subject's cardiac cycle. In order to determine various vascular parameters, it is useful to segment the image data set into internal structures defined as having the same tissue types contiguous locations. To accomplish this, a gradient calculation unit constructs a gradient data set from the image data set indicating the magnitude of spatial changes in the image data set. A plurality of locations are selected by an operator with a pointing device during `training` along with corresponding data values in the image and gradient data sets. These data values are plotted by a scatter generator against each other to construct a scatter plot then processed to determine a bivariate statistical probability distribution. The remaining data values are then assigned a tissue type based upon their plot on the bivariate statistical probability distribution.

Abstract: A system for communicating data between an aircraft and ground unit over conventional amplitude modulated (AM) voice radio channels employs a data collection unit for collecting data desired to be transmitted, such as global positioning system (GPS) data, altitude, or aircraft identification information which is encoded by a data encoder. A gating means senses when the microphone of the AM transmitter is keyed, and passes the encoded data and the voice signals to the existing AM modulator of the AM voice transceiver. This results in a transmitted signal received by a receiving unit, such as a ground unit, which separates the received signal into an AM modulated voice signal and a AM data signal. The AM voice signal is demodulated by normal means into an audible signal, with the AM data signal being decoded by a data decoder into data.

Abstract: A magnetic resonance (MR) active invasive device system employs a radio-frequency (RF) coil embedded in an invasive device for the purpose of generating MR angiograms of a selected blood vessels. A subject is first placed in a polarizing magnetic field. The invasive device is then placed into a selected blood vessel of the subject such that the RF coil of the invasive device is located at or near the root of a vessel tree desired to be imaged. The RF coil is then used to alter the nuclear spin magnetization of blood flowing within the vessel. This is done by employing an RF excitation signal to the coil at the Larmor frequency of the blood. The nutation of spin magnetization can change the amount of longitudinal spin magnetization or the Amount of magnetization in the transverse plane. Because the size of the radio-frequency coil in the invasive device is small, the change in spin magnetization is limited to blood flowing by the invasive device.

Abstract: An invasive imaging system employs a self-contained RF transmitter attached to an invasive device which allows tracking of the invasive device within a subject without physical connections to a tracking/display system and without the use of ionizing rays. An imaging system obtains a medical diagnostic image of the subject. The self-contained RF transmitter is comprised of a power generator, a power conversion means such as an oscillator which converts the generated power to a radiofrequency (RF) signal, and a broadcasting means such as a tuned transmit coil for radiating the RF signal. The radiated RF signal is received by receive coils of a tracking/display means which calculates the location of the RF transmitter. The tracking/display means displays the medical diagnostic image on a monitor and superimposes a symbol on the image at a position corresponding to the calculated location of the RF transmitter.

Abstract: A method of magnetic resonance (MR) fluid flow measurement within a subject employs an invasive device with an RF transmit/receive coil and an RF transmit coil spaced a known distance apart. The subject is positioned in a static magnetic field. The invasive device is positioned in a vessel of a subject in which fluid flow is desired to be determined. A regular pattern of RF transmission pulses are radiated through the RF transmit/receive coil causing it to cause a steady-state MR response signal. Intermittently a second RF signal is transmitted from the RF coil positioned upstream which causes a change in the steady-state MR response signal sensed by the downstream transmit/receive coil. This is detected a short delay time later at the RF receive coil. The time delay and the distance between the RF coils leads directly to a fluid velocity. By exchanging the position of the RF transmit and transmit/receive coils, retrograde velocity may be measured. In another embodiment, more RF coils are employed.

Abstract: Magnetic resonance images of selected chemical species are generated by the application of a multi-band radio-frequency excitation pulse. The radio-frequency pulse excites an arbitrary number of spectral bands. As the imaging phase encoding gradient pulse is advanced, the phase of each excitation band is advanced by a unique amount. This causes the signals from the spins in a particular band to appear at a position in the phase encoding direction which is the stem of the spin position and an offset arising from the phase increment given to that excitation band. Additional selectivity of selected chemical species can be accomplished by combining the multi-band excitation with chemical shift selective saturation radio-frequency pulses and echo-time modulation.

Abstract: A positioner for a magnetic resonance (MR) surgery system which positions a focal point of an ultrasound transducer to selectively destroys tissue in a region within a patient. The positioning means moves an ultrasound transducer under the control of an operator. Mechanical threaded shafts and slides act as screw drives causing several connected slides to move the ultrasound transducer in three dimensions. Expanding shafts are connected between a fixed point on a housing and the actuating point of the threaded shafts. Two of the expanding shafts employ universal joints allowing the shafts to rotate as they follow the slides. The third expanding shaft need only expand but the relative angle between its attachment points does not change, thereby eliminating the need for universal joints.

Abstract: An invasive imaging system employs a self-contained RF transmitter attached to an invasive device which allows tracking of the invasive device within a subject without physical connections to a tracking/display system and without the use of ionizing rays. An imaging system obtains a medical diagnostic image of the subject. The self-contained RF transmitter is comprised of a power generator means, a power conversion means such as an oscillator which converts the generated power to a radiofrequency (RF) signal, and a broadcasting means such as a tuned transmit coil for radiating the RF signal. The radiated RF signal is received by receive coils of a tracing/display means which calculates the location of the RF transmitter. The tracking/display means displays the medical diagnostic image on a monitor and superimposes a symbol on the image at a position corresponding to the calculated location of the RF transmitter.

Abstract: An integrated full duplex radio data link for aircraft capable of a sustained 4 to 8 Mb/sec raw data transfer rate communicates on newly proposed dedicated digital channels (DDC) for radio communications between the existing analog VHF amplitude modulated (AM) voice channels, and causes no perceptible interference to the remaining AM voice channels. While the present invention is intended primarily for terminal areas and airport surface applications, it may be employed with enroute applications. The present invention transmits AM encoded digital aircraft identification information appended to AM voice transmissions. An ground unit strips off the aircraft identification and assigns a DDC frequency to that aircraft unit over a control uplink channel (CUC) for further data communication. Downlink information, such as acknowledgement of the DDC assigned is transmitted over a digital control downlink channel (CDC). Data communication then proceeds on the DDC.

Abstract: RF tracking system employs a RF invasive device coupled to surgical tracking equipment for tracking the invasive device. An inductive coupling permits the device to be quickly coupled to, and decoupled from, the equipment. The coupling comprises an inducting coil which transmits a signal from the surgical tracking equipment to a communicating coil in the invasive device. The signal received by the communicating coil passes along leads to a tracked coil in a distal end of the invasive device. The tracked coil transmits the signal as RF energy which is received by the surgical tracking equipment which superimposes the position of the distal end of the invasive device on an X-ray image and displays it on a monitor A sterile shield is employed as a sterile barrier between the inducting coil and the equipment end of the invasive device to prevent contamination of the invasive device by the inducting coil.

Abstract: A motion imaging method uses magnetic resonance to detect the two or more components of motion such as velocity, acceleration or jerk within a subject. One component of motion is detected by computing differences of data obtained with modulated motion-encoding magnetic field gradient pulses. Distributions of at least one component of motion are measured responsive to a motion sensitive phase-encoding gradient pulse. The method can be used to obtain velocity and acceleration measurements in any of three mutually orthogonal directions.

Abstract: An interactive system for producing X-ray fluoroscopic images determines X-ray tube photon count and voltage for producing acceptable quality images while minimizing X-ray radiation dosage to a subject. An image is created and a signal to noise (S/N) ratio is estimated from the image by a unitary transform method. The S/N ratio is determined by solving several simultaneous equations and the photon count is estimated to produce an image with a desired S/N ratio. Subsequent X-ray fluoroscopy images are produced with the optimum photon count Q, thereby reducing X-ray dosage. The optimization is repeated periodically to readjust the system.

Abstract: A 4D image data set of a living subject is obtained by non-invasive imaging means representing three dimensions and time in relation to the subject's cardiac cycle. In order to determine various vascular parameters, it is useful to segment the image data set into internal structures defined as having the same tissue types contiguous locations. To accomplish this, a gradient data set is constructed from the image data set indicating the magnitude of spatial changes in the image data set. A plurality of locations are selected in `training` along with corresponding data values in the image and gradient data sets. These data values are plotted against each other to construct a scatter plot then processed to determine a bivariate statistical probability distribution. The remaining data values are then assigned a tissue type based upon their plot on the bivariate statistical probability distribution. Contiguous locations having the same tissue type assignment are identified as a solid structure.

Abstract: A magnetic resonance (MR) angiography system employs a Faraday catheter for generating MR angiograms of selected blood vessels. A subject is first placed in a polarizing magnetic field. The Faraday catheter is then inserted into a selected blood vessel of the subject at or near the root of a vessel tree desired to be imaged. An MR imaging pulse sequence is then applied to the subject to obtain image information from the region containing the desired vessel tree. Fluid inside the Faraday catheter is shielded from the RF pulses of the MR imaging sequence allowing the fluid to be in a relaxed state, while tissue outside the Faraday catheter is on a steady-state. As the fluid exits the catheter, and before it reaches steady-state, it produces an increased MR response signal causing the desired vessel tree to be imaged.