Abstract: A turret system providing access to the interior of a vacuum vessel integral to a cryostat used for super conducting magnets in MRI systems. The system enabling the movable connection of a neck tube that provides access to the interior of the vacuum vessel when that tube is fixedly attached to the liquified gas container of the cryostat and moves with the liquified gas container, said moveable connection being affected by a supple member attaching said neck tube to said vacuum member, so that relative movement between said liquified gas container and said vacuum vessel does not over-stress said neck tube.

Abstract: A slice orientation selection arrangement for magnetic resonance imaging in planes oblique to the normal cartesian coordinates. The coordinates are rotated to applying gradient signals using Euler computations.

Abstract: An NMR imaging system includes apparatus for producing a uniform magnetic field in a predetermined volume. Such apparatus includes a ring assembly having an axial extent L defined by a plurality of nonmagnetic rings, each having an axis and positioned side-by-side so that the axes of the rings are colinear and define the axis of the ring assembly. A plurality of discrete permanent magnet segments are angularly mounted within each ring for defining a central coaxial aperture. Each segment in a ring has a easy axis of magnetization whose orientation is functionally related to the angular position of the segment in the ring. Each segment has inner and outer edges that are nominally located at distances r.sub.1 and r.sub.2, respectively, from the axis of the ring from which it is mounted. The inner free ends of the segments of all of the rings define a central aperture of length L within the ring assembly. Finally, an adjustment is provided for moving the segments in each ring such that the distance r.sub.

Abstract: A patient intercom arrangement for magnetic resonance imaging systems wherein the gradient noises are recorded and substracted from the voice plus noise signals received from the patient during scan procedures to provide clear and audible voice signals.

Abstract: A line locking system for use with X-ray video imaging equipment comprising: a system oscillator, a divider for frequency dividing the output of the system oscillator to obtain a signal having a frequency that is an integer multiple of the line frequency, a comparator for comparing the phase of the integer multiple signal to the phase of the line signal and means for controlling the oscillator frequency responsive to the output of the comparator.

Abstract: A method of quantitatively determining the stenosis of the blood vessel using a digital subtraction angiographic image of the blood vessel. The method includes obtaining numbers proportional to the cross sectional areas of the blood vessel at stenosis portions and normal portions by obtaining density profiles less residual background from the images at those portions.

Abstract: A radio frequency surface probe for data acquisition in magnetic resonance systems. The probe is comprised of a plurality of inductors connected together with tuning capacitors in a balanced configuration. The configuration enables the probe to be impedance matched and to resonate at two separate frequencies without having to be tuned between frequency settings and without being effected by the impedance variations that are caused by the different samples or patients.

Abstract: Image enhancement accomplished by filtering using filters optimally adjusted to system parameters to enhance long edges, attenuate noise and "points" so that the long-edge data normally buried in noise is available and to further enable using low-frequency data.

Abstract: An X-ray tube with an adjustable focal spot is provided wherein the focal-spot position can be moved along the anode and the focal-spot width can be changed by applying a small voltage to the cathode-bias cup. The cathode includes means integral with the cathode for deflecting the flow of electrons to selectable focal-spot areas on the anode in response to an external drive circuit. The cathode includes a filament for emitting electrons to impinge on the anode, and a cathode cup having first and second parts electrically insulated from each other. The filament is electrically insulated from at least one of the parts of the cathode cup. The electrical insulation between the first and second parts of the cathode cup can be provided by a gap therebetween. The device includes biasing means for applying a voltage between the filament and the cathode to control the size and position of the region of impingement of the electron beam on the anode. The anode can be rotatable with respect to the cathode.

Abstract: An improved NMR imaging system that minimizes truncated time function generated artifacts on a real time basis by selecting sampling points on the FID generated signals either as a function of a varying magnetic field gradient or at varying sampling intervals.

Abstract: A method and system for determining the movement of an object between different images of the same object; where the movement is defined by a vector value and the vector value is used to correct for misregistration between the different images.

Abstract: Equipment and methods improving the quality of a tomograph are presented for rearranging divergent beam derived data into parallel data. The equipment and method perform uniform noise distribution interpolation either in the reordering phase or in the rebinning phase or in both phases. When the uniform noise distribution interpolation is employed noise streak artifacts, normally present in images, virtually disappear.

Abstract: An antenna system for nuclear magnetic resonance (NMR) imaging or spectroscopy devices which produce a uniform magnetic field in an object under examination includes transmit and receive antenna arrays each comprising a group of loop antennas. A signal generating circuit produces a set of input antenna signals which are applied to the loop antennas of the transmit array which transmits RF signals of a frequency that perturbs the magnetic moment of nuclei in a volume of the object. The receiving antenna array is responsive to NMR signals produced by the relaxation of perturbed nuclei in said volume for producing a set of output antenna that are applied to a signal processing circuit. A control circuit selectively controls the relative phases and amplitudes of at least one set of antenna signals to control the size and location of the region of the volume in which excitation of nuclei occurs, or from which NMR signals are processed.

Abstract: A method for the correction of ring artifacts in images obtained by rotate-rotate computerized tomography (CT) scanners includes the step of reconstructing an original image, which comprises a real image and a ring artifact image. The ring artifact image is determined by edge enhancing the original image and dividing the edge enhanced original image into rings or annuli with the annuli being concentric around the axis of rotation. The average intensity is determined for each concentric annulus. This average value of each annulus is substracted from pixels of the original image belonging to that annulus to provide a ring artifact free image.

Abstract: A CT scanner has an X-ray source for producing a fan beam that is rotatable relative to the axis of the scanner in a plane perpendicular to the axis, and a plurality of X-ray detectors mounted in a non-rotatable helical detector ring whose axis is colinear with the scannner axis for reeiving X-rays from the fan beam, the detectors extending 360.degree. around the axis. The detector ring has an inner surface facing the axis of the helix, and the detectors are mounted on the inner surface so that their photosensitive areas face the axis of the helix. At any given axial position of the detector ring, a given group of detectors will have an unobstructed view of certain of the X-ray sources through the space between adjacent leaves of the helix.

Abstract: An image optimizing method for reducing statistical noise in medical diagnostic images constructed from data obtained by the interaction of radiation and detectors. The radiation occurs in a random manner such that the data obtained at specific locations on the detectors are only estimates of "true" values of the data at the locations. The method includes the steps of fitting a surface to each of the locations; the surface is defined by the measured values of the location and neighboring locations. The fitted surface is used to determine new values for each of the locations. It has been found that the new values are closer to the "true" values of the data at the locations than were the measured values.

Abstract: A data compression system for use in processing diagnostic image data which combines delta modulation with coding the most prevelant difference by a code other than a least bit code but coding the most prevalent number of strings with a least bit code and also coding the next most common differences with a least bit code and subsequent most common differences with sequentrial least bit codes to provide compression ratios of over 3:1.

Abstract: An improved body probe for use in high field Mr data acquisition systems having a two feed balanced inductor circuit using series capacitors to control the effect of stray capacitance and coupling resistors connected across the coil approximately mid-way between the two feed points. This arrangement is superior to prior art body probes operating in whole body high field MR imagers.

Abstract: An imaging system that acquires and stores every other line to be used in a display image and interpolates the stored lines to obtain the lines between the stored lines for display purposes.

Abstract: A slice selection arrangement for MRI systems uses a psuedo-spin echo procedure by applying a 90 degree RF pulse in the presence of gradient pulse, applied in the direction of the encoding pulses; applying the 180 degree RF pulse in the presence of a gradient in another orthogonal direction and reading out the echo in the presence of the third orthogonal gradient pulse. Aliasing artifacts are avoided even though the section imaged is smaller than the object size, allowing zooming and/or a reduced number of encoding cycles for single slice imaging.