Abstract: An MRI system is employed to produce an image of an ultrasonic wave propagating through tissue or the like. An imaging pulse sequence used to acquire the image data is performed in synchronism with the operation of an ultrasonic transducer, and reconstructed phase images measure the motion of excited spins. Physical parameters of the acoustic field such as acoustic pressure, acoustic intensity and wave number may be calculated and imaged. Non-linear propagation characteristics of the acoustic field are also measured and imaged.

Abstract: Two incomplete k-space data sets are acquired with an MRI system using two surface coils. The data from the two surface coils is combined in a Sense process to reduce aliasing artifacts in the reconstructed image. The incomplete k-space data is filled out using a modified Homodyne reconstruction method which preserves phase information for the Sense process.

Abstract: A field-frequency lock system for an MRI system includes a microcoil and resonant sample located to sense changes in the polarizing magnetic field. Changes are detected as a shift in frequency of the NMR signal produced by the resonant sample, and the frequency shift is used to compensate the MRI system. Compensation is achieved by adjusting the RF reference signal employed in the MRI system transceiver.

Abstract: A method and apparatus for simultaneously acquiring imaging data at two different resolutions, a high resolution data set using for forming a diagnostic image and a plurality of low resolution data sets used for various purposes including high resolution data correction for patient movement and data errors and for observing dynamic physiological occurrences.

Abstract: A method for correcting the temporal relationships between event detection pulses generated by a PET scanner system, the method including, for each pulse, identifying the impact point of an associated photon on a scanner surface area and based on the impact point, selecting a compensation delay for the pulse and delaying the pulse by the compensation delay. The invention also includes an apparatus for practicing the method.

Abstract: An RF coil assembly for an NMR instrument includes a cylindrical shield disposed concentrically about a central axis and a set of linear conductors disposed concentrically about the central axis and radially inward from the shield. Assembly further includes an annular member positioned to span the gap between the shield and linear conductors. The annular member includes an insulating substrate, a conductive layer over the substrate, and a series of non-conducting gaps through the conductive layer. One or more lumped element capacitors are connected across one or more of the gaps to tune to resonance.

Abstract: A computed tomography x-ray imaging system acquires a three-dimensional array of x-ray attenuation values using a cone beam x-ray source and a curved two-dimensional array of detector elements. Two-dimensional image slices are reconstructed using a filtered back projection method, and corrections are made to the images to account for incomplete data due to the cone beam geometry.

Abstract: A method and apparatus for compressing an initial imaging data stream, the method dividing the data stream into acquired data nibbles, comparing the acquired nibbles to initial nibble values and where an acquired nibble value and an associated initial nibble value are equal, discarding the acquired nibble and indicating so in a bit map and where the acquired nibble value and the initial value are different, placing the acquired value in an intermediate data stream and indicating retention in the bit map.

Abstract: An MRI system automatically performs a calibration procedure to calculate optimal compensation parameter values for all three gradient pre-emphasis filters. A single fixture is employed to measure the errors caused by gradient pulses produced by each of the three gradient systems. The measured errors are used to calculate a gradient error function and the optimal compensation parameter values are calculated for each pre-emphasis filter by finding the minimum in the gradient error function.

Abstract: An imaging system for generating SPECT images wherein first and second cameras are mounted to a gantry for rotation about an imaging axis, the cameras are positionible in an L configuration wherein their camera axis intersect at an intersection point, the cameras are mounted such that when in the L position the intersection point is further away from each of the cameras than is the rotation axis allowing the cameras to be moved radially inward with respect to the rotation axis thus reducing the degree of table movement within the imaging area required to position an object to be imaged adjacent the cameras.