Abstract: In the axial direction, a collimator is a fan-beam collimator. In the transverse direction, the collimator has a set of central magnifying fan beams located between two sets of peripheral magnifying fan beams.

Abstract: A paramagnetic gas such as oxygen is administered twice at different concentrations to a living patient, as by causing the patient to breathe air and causing the patient to breathe pure oxygen. Two T1-weighted MR images are then acquired of a region in which the gas is present; advantageously, the region includes the patient's lungs. Because the paramagnetic gas shortens the T1 relaxation time of e.g. the patient's lung tissue, a comparison of the T1-weighted MR images shows where the gas has reached the patient's lung tissue and where the gas has been prevented from reaching the patient's lung tissue. This permits the radiologist to carry out e.g. a ventilation study without administering a radioactive material to the patient.

Abstract: A three-dimensional gadolinium-enhanced MR study of e.g. the patient's thoracic vasculature is carried out while the patient holds his or her breath. Acquisition of all data in each three-dimensional partition takes place during one and only one heartbeat. By synchronizing the MR pulse sequence to the patient's cardiac cycle, and advantageously by acquiring the MR data during the diastolic phase of the cardiac cycle, image artifacts caused by cardiac motion and pulsatile flow are eliminated or minimized.

Abstract: A plurality of non-overlapping bands is established in k-space. Each band includes a set of lines to be read out between a maximum phase-encoding gradient and a minimum phase-encoding gradient. Similarly, an identical plurality of temporally sequential and non-overlapping subsequences of pulses are established in the MR pulse sequence. Each subsequence corresponds to one and only one of the bands and reads out lines of MR data at phase-encoding gradients that are between the maximum and minimum phase-encoding gradients for that corresponding one. Lines of MR data are read out using the MR pulse sequence and the k-space bands are filled with lines of MR data. Advantageously, the first subsequence is used to fill up the center band in k-space.

Abstract: A two-dimensional radiation emitter has a plurality of line sources, advantageously of Gd-153. The line sources are removeably retained in the emitter, and form an array. The most active line sources are located in the center region of the array, and the activity of the sources progressively diminishes from the center of the array to the ends of the array (where the least active line sources are located). As the line sources undergo radioactive decay, they are moved towards the ends.

Abstract: An MR pulse sequence for conducting fat- or water-suppressed multislice MR studies. Saturation prepulses are used less frequently than is conventional practice. Each time at least one saturation prepulse is used to saturate all slices in a group of slices, one line of MR data is acquired from each slice in the group without using any other saturation prepulse.

Abstract: A patient pallet has two sides, a proximal end and a distal end. The patient pallet is horizontally elongated and is positioned to support a human patient with the patient's body axis horizontal. The pallet is supported by a pedestal. The pedestal is vertically moveable so that the patient may be raised and lowered with respect to the floor. The pedestal receives the patient pallet so that the pallet can slide horizontally, parallel to the floor. A pallet support is horizontally spaced from the pedestal and is so located that the distal end of the patient pallet can be supported by the pallet support when the patient pallet is slid horizontally. In this way, the patient pallet is either supported by the pedestal alone or by the pedestal and the pallet support. In the latter instance, the patient pallet bridges between the pedestal and pallet support. Left and right horizontally elongated arm rests are provided.

Abstract: A three-dimensional GRASE-type MR pulse sequence varies phase-encoding along the Z-axis identically in all signals between each two adjacent RF refocussing pulses in the MR pulse sequence. The phase error modulation caused by magnetic field inhomogeniety and the T2 amplitude modulation are separated onto two different spatial axes. This permits complete elimination of periodicity in both modulations and thereby improves image quality.

Abstract: A hybrid BTE and CIC hearing aid has a BTE component which is worn behind the patient's ear and a CIC component which is worn in the bony portion of the patient's ear canal. The BTE and CIC components are connected together with a wire cable. Electroacoustic feedback is reduced or eliminated, allowing gain to be increased. The patient is not disturbed by the occlusion effect.

Abstract: In a system which corrects for attenuation artifacts in a SPECT study, a line source is parallel to the axis of rotation of the scintillation camera detector(s) and is scanned in a plane which is parallel to the detector. Advantageously, the line source is initially scanned at high speed across the detector to acquire preliminary transmission CT data and is subsequently scanned across the detector at lower speed to acquire additional transmission CT data. During rescanning, the shuttering of the line source, and/or the speed of the line source, is varied. This acquires transmission CT data which is more reliable and from which the attenuation of the patient may be more accurately calculated.

Abstract: The gradient read time is varied during the course of a single pulse sequence in which both proton density weighted image data and T.sub.2 -weighted image data are collected. The number of gradient refocussings after each RF refocussing pulse in a gradient spin echo pulse sequence is changed during the course of the pulse sequence.

Abstract: A Platz-Heinzelmann collimator is produced by introducing strips of material between the dies of a die press, heating the material to below its extrusion temperature, applying pressure, removing the strips and adhesively securing them together.The collimator may be of the focussing type.

Abstract: Echo signals from the same multiple echo pulse train sequence which are taken at the same phase-encoding gradient are averaged to prevent spin-spin relaxation from degrading an MR medical diagnostic image. Echo signals from two different pulse sequences taken at the same phase-encoding gradient and occupying different temporal positions within each pulse sequence are likewise averaged.

Abstract: Two conjugate views of a patient are acquired during a SPECT nuclear medicine study. A common anatomical feature is identified in the views. Based on the differences in location of the common feature in the views, the center of rotation ("COR") of the detector during the study can be calculated after the study has been concluded. This COR can then be used during image reconstruction to determine the location at which each filtered view is backprojected. The resulting SPECT data is of higher quality because COR artifacts in the reconstructed image are reduced or eliminated.

Abstract: First and second scintillation camera detectors are provided and are mounted, respectively, to first and second yoke assemblies. The first yoke assembly is mounted to a ring gear which is rotatable within a vertical plane about a horizontal axis. The second yoke assembly is mounted to an annulus which is located within the ring gear and which is rotatable within the plane and about the axis. A rotating device is provided for rotating the ring gear in the plane and about the axis and a locking device is also provided for locking the first and second yoke assemblies together, whereby the first and second yoke assemblies rotate together when they are locked together and the first yoke assembly is being rotated by the rotating device. Advantageously, each detector is pivotally secured to its corresponding yoke assembly and each of the detectors is radially movable towards and away from the axis of the gantry. Further advantageously, the entire gantry is laterally moveable.

Abstract: An automatic blood pressure monitor has a dual-speed control circuit which is used to control the speed of a DC motor that powers the inflation cuff. The control circuit limits the motor current, permitting operation from a limited power source (such as a battery). The control circuit also includes structure for electrically braking the motor; the motor is braked after a time delay which commences after motor power is cut off.

Abstract: When a PMT "views" a scintillation event in the scintillation crystal of a scintillation camera system, the PMT produces an output signal. Based on the output signal, the event can be localized to a circular locus of points ("PMT locus"). Further localization can be accomplished on the basis of straight lines which are unambigously determined by intersections between such PMT loci.

Abstract: The present invention relates to the use of diffusion weighted magnetic resonance imaging procedures for the diagnosis of conditions in which blood circulation or similar molecular displacements within biological tissues are measured. Pulse sequences are used in accordance with the invention which suppress the contribution of non-moving tissue or bulk motion.

Abstract: A photomultiplier uses an avalanche photodiode as a position-sensitive anode. The envelope of the photomultiplier has a flat input end. Electrically conductive regions mounted to the input end are configured to produce at the input end a potential distribution characteristic of a photomultiplier with a spherical-type input end as measured in a transverse plane immediately adjacent the spherical-type input end. A photocathode is located inside the photomultiplier and is electrically connected to the electrically conductivew regions. Advantageously, the envelope has flat sides and a square cross-section; in this instance, conductors are run along the sides to produce within the envelope a potential distribution characteristic of a photomultiplier which is cylindrical in cross-section, as measured at flat surfaces having the same shape as the envelope.

Abstract: MR angiography method and apparatus either moves the saturation slab or eliminates it during a predetermined portion of the patient's cardiac cycle. This permits an MR image of a slice of interest to contain information relating to arterial bloodflow without becoming degraded by regurgitated bloodflow and information relating to venous bloodflow.