Abstract: A quadrature coil combiner for phase shifting the pulses and signals of a quadrature coil system used in magnetic resonance (MR) systems to selectively combine or cancel the pulses and signals transmitted and received. The combiner comprises a first and a second conductor for coupling a first and a second coil respectively of the quadrature coil system to a transmit-receive circuit of the MR system. The first conductor comprises an insertable .pi./2 radian delay. The second conductor includes a fixed .pi./2 radian delay. At least one of either the fixed delay or the insertable delay is a quarter wavelength cable whereby active elements are minimized.

Abstract: A method of acquiring in-vivo magnetic resonance spectroscopic data for multiple regions in substantially the time required to obtain such data from a single region. The method includes applying a basic sequence to obtain data from a selected one of said multiple regions, waiting a definite time period before reapplying the basic sequence and reapplying modified basic sequences during said definite time period but with parameters for selecting and acquiring data from other selected regions during said definite time period.

Abstract: Improved T2 values and signal to noise ratio obtained by magnetic resonance image synthesization. Each measured echo signal intensity is divided by a correcting factor that is a function of the echo number to obtain corrected echo signal intensity. A characteristic curve is best fitted to the corrected intensity values and the intensity values of the curve are used.

Abstract: An X-ray mammographic biopsy needle holder positioning system wherein the X-ray source is tilted to provide parallax views of the needle holder inserted in the breast. The tilting occurs independently of the breast compressor which remains untilted.

Abstract: A data compression system for use in processing diagnostic image data which uses a predictor to predict future data. The actual data is subtracted from the predicted value to obtain data related difference values. The difference values are coded by coding the most prevalent difference by a code other than the least bit code but further coding the most prevalent number by string length coding, with the most common being the coded with a least bit code, and also coding the next most common difference with a least bit code and the subsequent most prevalent differences with sequential least bit codes to provide compression ratios of over 3:1. A procedure for finding the best predictor in noisy data is provided.

Abstract: A continuous phase magnetic field map is provided by dividing the field map of elements into regions; determining discontinuities in the regions and adding a constant modulo 2.pi. to the phase values of each element of the region which results in a minimum difference between adjacent elements of the region. Then similarly joining the continuous regions to form continuous sections and the continuous sections to form continuous zones until substantially continuous phase magnetic field maps are obtained.

Abstract: A radio frequency RF balanced coil for magnetic resonance operations. The coil is tuned to a plurality of frequencies for use in acquiring data of different elements at various frequencies without having to remove and/or return the coil. The coil has a single terminal pair and is coupled to the MR system with a single shielded cable.

Abstract: A magnetic resonance (MR) system and method for determing absolute image intensities (MR numbers) comparable to "CT" numbers by removing the dependence of the intensity measurement on system dependent parameters. The dependence of the intensity measurement on system parameters is removed by determining the absolute gain of the receiver portion of the MR system. The absolute gain is a function of the loaded gain and the unloaded gain of the receiver system, the loaded gain is divided by the unloaded gain to provide a normalization factor which is multiplied by output data to provide the absolute values of intensity of absolute MR numbers.

Abstract: An RF probe for acquiring MR data comprising four loop means. There are first and second loop means that are substantially round, centered about a longitudinal axis of said probe and spaced apart substantially the length of said probe to define a cylindrical shape therebetween. There are third and fourth loop means being substantially saddle shaped spaced apart, oppositely disposed and extending between said first and second loop means. Conductors attached to said first and second loop means at points on said first and second loop means spaced apart by 180 degrees couple said third and fourth loop means to said first and second loop means to form a point of psuedo-saddle coils providing extremely homogenous signals.

Abstract: A method of obtaining spatially localized spectroscopic signals by using RF pulse sequences in the presence or gradient fields to generate stimulated echoes.

Abstract: A data compression-expansion (decrease-increase) method for improving the signal-to-noise ratio of compressed-expanded data while retaining the fidelity of the original data comprises the steps of using a filter that can be separated into a smoothing portion and an enhancing portion. The selected filter is separated into the two portions: a first portion for smoothing prior to decreasing the data, and a second portion for enhancing after increasing the data whereby the filter has the maximal effect of decreasing noise while having a minimal effect on the data.

Abstract: A circularly polarized radio frequency probe for use in magnetic resonance systems, the probe comprises four effective "saddle coils" arranged to define a single cylinder. The saddle coils each comprise a pair of 120 degree arcuate conductor sectors separated by longitudinal conductors. RF power is coupled to each of said "saddle coils" so that first and second pairs of said saddle coils generate first and second fields normal to each other.

Abstract: A windowing system for use when using data to form video display images. The digital data is operated on by a transfer function delineated by predefined parameters or by newly generated parameters determined by the image being displayed.

Abstract: An automatic shimming system for correcting inhomogeneties in magnetic resonance magnetic fields. The static magnetic field is mapped using three dimensional phantoms that comprise a plurality of samples including at least an element having non-zero nuclear magnetic moments spatially distributed to enable uniquely locating each sample with only two locating gradients.

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 method of obtaining a separate data contribution from first and second spectral components during a single magnetic resonance scan. The method uses a scan sequence causing the data from the first and second spectral components to be 90 degrees out of phase. This shift of the data along with a measurement of the inhomegeneities of the field initiates two output signals which are used to provide all of the data required for imaging the two spectral components and/or correcting images for chemical shifts.

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.