Abstract: The invention relates to a system for verifying geographical descriptiveness of a media file, such as a picture. The system comprises storage means adapted to store a media file, communication means adapted to send said media file to a plurality of user terminals, and to receive, from the user terminals, data indicating a guessed geographical position with which the user of each user terminal associates the media file. The system also comprises calculation means adapted to determine whether the media file is indicative of a geographical position based on the guessed geographical positions received from the plurality of user terminal.

Abstract: The invention relates to a system for verifying geographical descriptiveness of a media file, such as a picture. The system comprises storage means adapted to store a media file, communication means adapted to send said media file to a plurality of user terminals, and to receive, from the user terminals, data indicating a guessed geographical position with which the user of each user terminal associates the media file. The system also comprises calculation means adapted to determine whether the media file is indicative of a geographical position based on the guessed geographical positions received from the plurality of user terminal.

Abstract: Through modification of the phase-encoding gradient, a method and apparatus increases the effectiveness of a Magnetic Resonance Imaging (MRI) device by decreasing scan time without noticeably decreasing the signal-to-noise ratio. In an MRI device, a patient is subjected to a constant magnetic field, and then radio frequency (RF) pulses are used to excite the nuclei in the patient's body. The nuclei release a corresponding RF signal as the nuclei relax, which can be measured and mapped into a visual display. The RF pulses used to excite the nuclei in the body cooperate with a slice select gradient and a phase-encoding gradient. When the phase-encoding gradient is indexed and prioritized according to contribution to image quality, then phase-encoding values with little or no contribution to image quality need not be acquired but may be replaced with randomized system noise, thereby decreasing total scan time without reducing the signal-to-noise ratio.

Abstract: According to a method of detecting and compensating for MRI scan errors, MRI scan data are received. At least one statistical boundaries is determined for the generated data. The data are observed in K-space. The observed K-space data are compared to the determined statistical boundary. Data that are likely undesirable, based on the comparison, are removed. The removed data are replaced with substitute data to modify the data set. Images are generated from the modified data set.

Abstract: Through modification of the phase-encoding gradient, a method and apparatus increases the effectiveness of a Magnetic Resonance Imaging (MRI) device by decreasing scan time without noticeably decreasing the signal-to-noise ratio. In an MRI device, a patient is subjected to a constant magnetic field, and then radio frequency (RF) pulses are used to excite the nuclei in the patient's body. The nuclei release a corresponding RF signal as the nuclei relax, which can be measured and mapped into a visual display. The RF pulses used to excite the nuclei in the body cooperate with a slice select gradient and a phase-encoding gradient. When the phase-encoding gradient is indexed and prioritized according to contribution to image quality, then phase-encoding values with little or no contribution to image quality need not be acquired but may be replaced with randomized system noise, thereby decreasing total scan time without reducing the signal-to-noise ratio.

Abstract: A configurable matrix receiver comprises a plurality of antennas that detect one or more signals. The antennas are coupled to a configurable matrix comprising a plurality of amplifiers, one or more switches that selectively couple the amplifiers in series fashion, and one or more analog-to-digital converters (ADCs) that convert the output signals generated by the amplifiers to digital form. For example, in one embodiment, a matrix comprises a first amplifier having a first input and a first output, and a second amplifier having a second input and a second output, a switch to couple the first output of the first amplifier to a the second input of the second amplifier, a first ADC coupled to the first output of the first amplifier, and a second ADC coupled to the second output of the second amplifier. In one embodiment, the signals detected by the antennas include magnetic resonance (MR) signals.

Abstract: A receiver for a resonance signal of a magnetic resonance imaging system generates a baseband signal for image processing by dividing a raw resonance signal among multiple parallel channels, each amplified at a respective gain. A digital channel selector determines, at any given moment, a lowest-distortion channel to be further processed. Amplitude and phase error compensation are handled digitally using complex multipliers, which are derived by a calibration, based on a simple Larmor oscillator, which can be done without the need for a sample and without repeating when measurement conditions are changed. One of the important benefits of the invention is that it provides for gain selection without repeated calibration steps. This is particularly important in systems that employ fast imaging techniques such as fast spin echo, where the invention can speed imaging substantially.

Abstract: Through modification of the phase-encoding gradient, a method and apparatus increases the effectiveness of a Magnetic Resonance Imaging (MRI) device by decreasing scan time without noticeably decreasing the signal-to-noise ratio. In an MRI device, a patient is subjected to a constant magnetic field, and then radio frequency (RF) pulses are used to excite the nuclei in the patient's body. The nuclei release a corresponding RF signal as the nuclei relax, which can be measured and mapped into a visual display. The RF pulses used to excite the nuclei in the body cooperate with a slice select gradient and a phase-encoding gradient. When the phase-encoding gradient is indexed and prioritized according to contribution to image quality, then phase-encoding values with little or no contribution to image quality need not be acquired but may be replaced with randomized system noise, thereby decreasing total scan time without reducing the signal-to-noise ratio.

Abstract: A configurable matrix receiver comprises a plurality of antennas that detect one or more signals. The antennas are coupled to a configurable matrix comprising a plurality of amplifiers, one or more switches that selectively couple the amplifiers in series fashion, and one or more analog-to-digital converters (ADCs) that convert the output signals generated by the amplifiers to digital form. For example, in one embodiment, a matrix comprises a first amplifier having a first input and a first output, and a second amplifier having a second input and a second output, a switch to couple the first output of the first amplifier to a the second input of the second amplifier, a first ADC coupled to the first output of the first amplifier, and a second ADC coupled to the second output of the second amplifier. In one embodiment, the signals detected by the antennas include magnetic resonance (MR) signals.

Abstract: A receiver for a resonance signal of a magnetic resonance imaging system generates a baseband signal for image processing by dividing a raw resonance signal among multiple parallel channels, each amplified at a respective gain. A digital channel selector determines, at any given moment, a lowest-distortion channel to be further processed. Amplitude and phase error compensation are handled digitally using complex multipliers, which are derived by a calibration, based on a simple Larmor oscillator, which can be done without the need for a sample and without repeating when measurement conditions are changed. One of the important benefits of the invention is that it provides for gain selection without repeated calibration steps. This is particularly important in systems that employ fast imaging techniques such as fast spin echo, where the invention can speed imaging substantially.

Abstract: A method of performing a FFT of a sequence of N=Bn numbers, where B is a power of 2 and n is a positive integer. A pattern of storage locations for the Bn numbers in M in-place memories is selected recursively, where M is a power of 2 that is less than B, wherein, if n=1, each in-place memory has storage locations for a different B/M of the B numbers, and wherein, if n is greater than 1, the pattern for storing Bn numbers is a concatenation of B patterns for storing Bn−1 numbers, there being B/M successive sets of the patterns for storing Bn−1 numbers in the pattern for storing Bn numbers when n is greater than 1, the patterns, for storing Bn−1 numbers, within each of the B/M successive sets, is mutually identical and is different from the patterns, for storing B numbers, of any other the set. The numbers are stored in the storage locations. An in-place radix-B DFT is performed on each of N/B groups of values stored in the storage locations.

Abstract: A receiver for a resonance signal of a magnetic resonance imaging system generates a baseband signal for image processing by dividing a raw resonance signal among multiple parallel channels, each amplified at a respective gain. A digital channel selector determines, at any given moment, a lowest-distortion channel to be further processed. Amplitude and phase error compensation are handled digitally using complex multipliers, which are derived by a calibration, based on a simple Larmor oscillator, which can be done without the need for a sample and without repeating when measurement conditions are changed. One of the important benefits of the invention is that it provides for gain selection without repeated calibration steps. This is particularly important in systems that employ fast imaging techniques such as fast spin echo, where the invention can speed imaging substantially.

Abstract: A magnetic resonance imaging (“MRI”) simulator for evaluating an MRI device comprises sections for being selectively coupled to the corresponding portions of the MRI device. Data representative of a previously imaged object is provided to the portions of the MRI device, for processing. The results of the processing are evaluated to determine whether portions of the MRI device are operating properly. Methods of evaluating an MRI device and an MRI device incorporating such a simulator are also disclosed.

Abstract: A method of stabilizing the static magnetic field in a magnetic resonance imaging (MRI) system applies a radio frequency pulse to a test sample within the static magnetic field and an NMR signal is acquired from the test sample. A characteristic of a signal indicative of the NMR signal, such as the area, phase or the sum of the differences of sampled values is ascertained. In addition, the number of recurring features, such as zero-crossings, of the signal indicative of the NMR signal can be determined and a correction signal is generated to adjust the static magnetic field via a set of correction coils driven by a signal derived from the number of recurring features and the value of the characteristic. Apparatus for stabilizing the static magnetic field is also disclosed.

Abstract: A magnetic resonance imaging ("MRI") simulator for evaluating an MRI device comprises sections for being selectively coupled to the corresponding portions of the MRI device. Data representative of a previously imaged object is provided to the portions of the MRI device, for processing. The results of the processing are evaluated to determine whether portions of the MRI device are operating properly. Methods of evaluating an MRI device and an MRI device incorporating such a simulator are also disclosed.

Abstract: Method and apparatus for optimally decoding messages from CDMA signal sent by a plurality of users and received asynchronously at one receiver, using a minimal number of computations and minimal memory and processing resources. It is based on a novel approach to signal correlation, as well as to subsequent decoding by decorrelation, that requires a correlation period of only one symbol length, by providing for each user a pair of partial signatures sequences, with which the signal is correlated, deccorelating the results with the inverse of the cross-correlation matrix of all partial sequences, and combining the resultant partial symbol estimates--to obtain final estimated symbol values. The partial sequences are formed by separating each original sequence at a point corresponding to the estimated symbol boundary time, relative to an arbitrary correlation window, of one symbol length.

Abstract: An apparatus for obtaining, in the course of a single scan, NMR image data for a plurality of selected planes in an object, oriented at different angles, utilizes a slice pointer for outputting a signal indicating a particular plane to a multiplier and offset parameter RAM which provides multiplier and offset terms corresponding to the angle of the plane. A generator provides a generic gradient waveform to an arithmetic unit which combines this waveform with the multiplier and offset parameters from the RAM to create waveforms, which when applied to the gradient coils of an NMR apparatus, rotate the slice selector and the readout gradients, thereby permitting image data to be obtained in planes having different angles. A method in accordance with the apparatus of the present invention is also disclosed.

Abstract: A system (1000) for estimating the frequency of a tone input utilizes sample rate reduction in successive stages and processing by digital cyclotomic filters at each stage. The tone input (2001) is first transformed in network (1100) to yield two quadrature tones. Digitizer (1200) converts the two tones into data words.Buffer (1300) comprises two essentially identical storage arrangements wherein data words are stored and then supplied to succeeding stages. Frequency-shifting unit (1400) effects modulus-one multiplication by processing appropriately selected data words. Word pairs and frequency-shifted versions thereof are processed by cyclotomic filters (1500). Sequential decimation in this system effects a successively refined estimate to the tonal frequency. During each stage of decimation, the filters are configured to provide symmetric coverage of the subband containing the estimate.

Abstract: A system (1000) for estimating the frequency of a tone input utilizes sample rate reduction in successive stages and processing by digital cyclotomic filters at each stage. The tone input (2001) is first transformed in network (1100) to yield two quadrature tones. Digitizer (1200) converts the two tones into data words. Buffer (1300) comprises two essentially identical storage arrangments wherein data words are stored and then supplied to succeeding stages. Frequency-shifting unit (1400) effects modulus-one multiplication by processing appropriately selected data words. Word pairs and frequency-shifted versions thereof are processed by cyclotomic filters (1500). Sequential decimation in the system effects a successively refined estimate to the tonal frequency. During each stage of decimation, the filters are configured to provide symmetric coverage of the subband containing the estimate.