Abstract: A magnetic resonance system employs a sequence of radio frequency pulses and magnetic field gradients to generate a flow-compensated image of a selected portion of a sample. Flow-compensation is performed with an oscillating readout gradient waveform which is comprised of two components. The first component is a constant amplitude gradient waveform whose amplitude is determined by the desired field-of-view and the bandwidth of the imaging system. The second component is an oscillating waveform whose amplitude, frequency and phase are chosen to obtain the desired degree of flow-compensation. The frequency of the oscillating waveform is typically chosen to match the sampling frequency of the imaging system. In effect, each acquired data point is preceded by the application of a bi-polar magnetic field gradient pulse which causes a phase shift in the acquired signal which is proportional to nuclear spin velocity.

Abstract: A system for testing the integrity of critical circuitry, lines and wires employs a differential amplifier having an input resistance R.sub.in and a feedback loop with a resistance R.sub.fb. The critical wires being tested must be a signal wire series connected to a resistance R.sub.s, which is in turn series connected to a return wire. A test voltage source is connected to the noninverting input of the differential amplifier. The signal wire is connected to the inverting input of the differential amplifier. The test voltage source is activated by a test control unit. When activated, the test voltage source provides two distinct outputs allowing computation of a test gain in the presence of other functional signals. The test control unit measures the output V.sub.out of the differential amplifier and computes the value of the test gain. A break in either the signal wire or the return wire will result in a test gain of 1. If the signal and return wires are shorted, the test gain will be 1+R.sub.fb /R.sub.in.

Abstract: An automatically positioned focussed energy transducer system facilitates medical procedures by allowing a physician to interactively view the position the focal point of a focussed energy transducer superimposed upon a medical image and computer generated model of internal structures of a patient. A tracking device tracks the position and orientation of the ultrasound transducer. A medical imaging system creates an image of internal structures of the patient near the location of the energy transducer. A general purpose computer either receives a model of internal structures constructed in advance, or employs a medical imaging device to create the model. The general purpose computer displays selected surfaces of the model in an orientation and view which coincides with the medical image acquired.

Abstract: An interactive display system superimposes images of internal structures on a semi-transparent screen through which a surgeon views a patient during a medical procedure. The superimposed image is derived from image data obtained with an imaging system. An invasive device is also tracked and displayed on the semi-transparent screen. A ray extending through the invasive device can also be displayed which shows the intended path of the invasive device. The image is registered with the surgeon's view of the patient and displayed in real-time during a medical procedure. This allows the surgeon to view internal and external structures, the relation between them, the proposed path of the invasive device, and adjust the procedure accordingly. A second embodiment employs stereoscopic viewing methods to provide three-dimensional representations of the radiological images superimposed on the semi-transparent screen through which the surgeon views the patient.

Abstract: A real-time data processing system employs a control computer which defines a pre-processing arrangement of data channels to speed processing, and an arrangement of output data channels to provide a desired output format. The data channels are samples and arranged into a data packet which is passed to an array of digital signal processors (DSPs) arranged in a series of stages, with at least one DSP per stage. A front-end DSP receives the data packet and appends a control field having commands addressed to specific DSPs to the data packet along with adding a monitor field. The DSPs monitor the control field for commands addressed to it and then executes those. The status of the operation is written in the monitor field and the data packet is passed to DSPs of the next stage for `pipelined` processing. DSPs of the last stage collect the process portions of the data packet, assemble them according to the desired output format and pass on the completed data packet.

Abstract: An elasticity imaging method uses magnetic resonance to detect the distribution of eternally induced velocities within a subject. Distributions am measured responsive to at least two different field-of-views. Differences of the velocity distribution obtained with one field-of-view and the second field-of-view are computed to give a component of stress. The method can be used to obtain velocity measurements in any of three mutually orthogonal directions responsive to field-of-view shifts in as many as three mutually orthogonal directions to give a total of nine stress components. Data for each component can be acquired independently or data acquisition can be multiplexed to reduce data acquisition requirements.

Abstract: A set of phases defining an `address` and a `spreading key` is selected. These are employed in determining a preamble waveform and a traffic waveform. The preamble carrier waveform is a sum of a set of tones each offset by its phase, whereas the traffic carrier waveform is the product of these same offset tones. The tones have frequencies which are geometrically increasing multiples of a fundamental frequency. The phases and magnitudes of the preamble and traffic carrier waveforms are determined and prestored in a transmit and receive unit storage device. An inverse discrete Fourier Transform unit (IDFT) in the transmit unit receives the phase preamble offsets and magnitudes from the storage unit and creates a preamble carrier signal transmitted to the receive unit which determines if the phases match those which it is to listen to. If not, the following message is ignored; if they are, the following message is despread and decoded.

Abstract: The present invention provides a novel Geometric Harmonic Modulation (GHM) system. The GHM system operates in two modes, a preamble mode and a traffic mode. During the preamble mode, n+1 frequencies are each offset by a predetermined phase offset in a transmit unit and passed through a channel to a receive unit. The set of phase offsets is used as the spreading code in the transmit unit, and also acts as an `address` of receive units to transmit to. The receive unit monitors preamble signals to determine the phase offsets. When it recognizes a set of phase offsets, or `address`, which pertains to itself, the receive unit stores the phase offsets and uses these phase offsets to despread and decode the appended message. After the preamble mode is finished, the transmit unit enters the traffic mode and requests the message to be transmitted from the message source. A traffic carrier waveform is created by multiplying tones, each having its specific phase offset.

Abstract: A method of simultaneously imaging multiple components of velocity of moving materials within a subject employs magnetic resonance. Velocity 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: Three-dimensional (3D) image data is acquired from a subject with a medical imaging device and stored. The stored 3D image data is processed by a model workstation to segment the model into discrete structures and produce a segmented computer graphic model. An operator interacts with the model workstation to cause it to display desired structures of the the segmented model in a desired view and orientation. The operator also selects a position and orientation of a cutting plane passing through the segmented model. Once selected, the position and orientation information is provided to a pulse sequencer of a magnetic resonance (MR) imaging system. The pulse sequencer controls an RF transmitter and gradient amplifiers to cause an MR image of the subject at an imaging plane, corresponding to the cutting plane of the model workstation, to be acquired.

Abstract: A 3D model of a subject is acquired. Sensors spatially located on the subject are displayed on the 3D model in their appropriate locations. An operator selects the proper viewing angle and sensors to monitor via input devices. A 3D modeler in a display processor provides an image viewed from the proper angle and identifies the selected sensors. The 3D modeler identifies the data channels which correspond to the selected sensors and provides these to a system control computer which then provides the samples for these data channels. The 3D modeler also identifies a screen location which pertains to the locations of the selected sensors on the model. A postage stamp trace unit receives the samples for the selected data channels and the screen locations pertaining to the selected sensor locations of the image of the model and produces a video signal representing a window having a number of real-time traces each pertaining to a sensor.

Abstract: A newly acquired MR image of an imaging subject is displayed on a display device. An operator interactively manipulates the imaging plane during imaging, by using a button, a rocker switch, a knob, and a trackball. The button enables or disables interactive scan-plane control. The rocker switch chooses between "translate", and "rotate" modes. In "translate" mode, the knob pushes the imaging plane deeper or shallower relative to the most recently displayed image, while the trackball slides the plane sideways and/or up and down. In "rotate" mode, the knob spins the imaging plane about the center of the most recently displayed image without changing the tilt of the plane, while the trackball tumbles or tilts the imaging plane. Colored icons displayed over the image change location, size, and/or shape to indicate the direction and extent of the translation or rotation.

Abstract: An MR image of a subject is displayed on a display device. Scan-control icons are displayed over this image. An operator interacts with an interface device to select imaging plane parameters during imaging. This is performed by selecting one of the icons with a pointing device, and dragging. Interface device then provides a display which indicates the motion of the imaging plane as well as the extent of the motion. Once selected, the location and orientation information transformed to global coordinates and is provided to a pulse sequencer of a magnetic resonance (MR) imaging system. The pulse sequencer controls an RF transmitter and gradient amplifiers to cause an MR image of the subject at an imaging plane to be acquired. This allows fast, accurate imaging plane selection, which may be selected by an operator who is searching for structures within the subject, or who is simultaneously performing a medical procedure on the subject.

Abstract: An improved method of assaying local metabolite concentrations the chemical entity (CE) of interest, of a living subject by non-invasive means using magnetic resonance (MR) spectroscopy employs acquiring an MR response signal for a naturally occurring, abundant marker material of known concentration, such as water (H.sub.2 O) from the subject. An MR response signal is also acquired from the CE being assayed, e.g., adenosine triphosphate (ATP) with phosphorus (.sup.31 P) nuclei producing the MR response signal. The subject is replaced with a test phantom having a known concentration of the marker material and a reference concentration standard (e.g., phosphate) having the same resonant nuclei as the CE. Both sets of MR response signals are again acquired. The volume of tissue contributing to the CE MR response signal in the subject is deduced from the ratios of marker material MR response signals from the subject and phantom and the known concentration of the test phantom.

Abstract: Data words are transmitted over a radio channel with a novel modulation scheme which transmits data in parallel. An entire data word is modulated by separating a carrier frequency band into a number of discrete `tones`. Tone T.sub.1 is set to a zero phase shift in order to provide timing in synchronization of the signal. The remaining tones are phase shifted according to a predetermined convention, thereby encoding the bits of the data word. The phase shifts for all tones comprises a spectrum which is transmitted to a receiver simultaneously. A receiver monitors tone T.sub.1 for zero phase shifts to provide synchronization of the signal. The remaining tones are analyzed for their phase shift to provide bits which are assembled into a transmitted data word. Since the bits are transmitted in parallel as the data word, as opposed to conventional modulation schemes, the throughput is increased.

Abstract: Thermal drug treatment of tumor tissue is obtained by attaching a thermally active drug to carrier molecules which have an affinity to tumor tissue. Localized heating is performed on the tumor tissue, thereby activating the drug in the tumor tissue. The end result may be concentrated delivery of a drug to a chosen tissue, or, in the case where the drug creates a toxin when heated, selective tissue destruction of a selected locations heated. The localized heat may be applied by focused ultrasound heating.

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 complexity is reduced by tracking a reduced number of estimated reference symbol constellation points and taking advantage of the geometry to estimate the remaining symbol constellation points. Branch metrics are also determined with a reduced number of computations.

Abstract: An in-situ method of extracting contaminants from a soil volume comprises applying a radiofrequency (RF) excitation signal to heat the soil with an array of electrodes. The electrodes are inserted into the contaminated volume or inserted into a matrix of holes drilled into the volume. A first row of electrodes is electrically coupled to a shield of a coaxial cable, with a second row electrically coupled to the central conductor of the coaxial cable. RF energy is applied to pairs of electrode rows through the coaxial cable and a matching network is installed in front of the electrode-row pair to maximize power flow into the electrode-row pair. This results in very evenly distributed voltages which results in even heating. A balanced-to-unbalanced transformer (balun) is installed at the input to the matching network to prevent the deposition of RF energy outside the target volume and creation of voltages that could be hazardous to personnel.

Abstract: A highly fault tolerant method of radio communication of information in the form of a message packet employs a distributed network of transmitter/receivers `transceivers` each having a unique identification ("ID") number. An initiating transceiver creates a message packet having the ID of a transceiver intended to receive the message packet. It then broadcasts the message packet to transceivers within its transmission range. Each transceiver which receives the message packet checks to see if there are errors and sends an acknowledgement if no errors. The transceivers 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. The transceiver also determines if the transceiver ID in the message packet match its own transceiver ID, and if it does, is the message has been successfully transmitted to its intended transceiver.

Abstract: A highly fault tolerant system for datagram communication of information in the form of a message packet employs a distributed network of transmitter/receivers `transceivers`, which interact with `bridge transceivers` which are transceivers connected to a wired network, and wired nodes each having a unique identification ("ID") number. An initiating unit, which may be a transceiver, bridge transceiver or wired node, creates a message packet having an ID of an intended destination unit. If initiated from a transceiver, the message packet finds its way to a wired network by broadcasting the message packet to local transceivers. The transceivers determine valid message packets which have not expired, not been received before and were transmitted without errors. If the message packet is valid and the transceiver ID does not match its internal ID, the transceiver broadcasts the valid message packet to other local transceivers. The transceivers which receive the message packet repeat the process.