Abstract: Means and methods for correcting the loss of contrast caused by modulation transfer function (MTF) effects in imaging. Images of small objects are enhanced without adversely affecting large object images. A homogeneous background is provided and image contrast is obtained with total MTF effects. The scale of the determined image contrast is manipulated to cause the contrast to approximate an ideal contrast not affected by the MTF contrast reduction.

Abstract: A surface coil arrangement for magnetic resonance data acquisition comprising a first coil designed to generate a circular magnetic field and a second coil designed to generate a linear magnetic field in quadrature to said circular magnetic field with said first and second coils positioned relative to one another to provide circular polarization.

Abstract: Separation of spectral components is achieved by acquiring radio frequency (RF) signals using a two dimensional scan sequence wherein the bandwidth of at least one of the RF pulses is less than or equal to the Larmor frequency difference of the spectral components. The slice select gradient pulse applied during the application of the RF pulse of limited frequency is smaller than the slice select gradient pulses applied during application of the other Rf pulses.

Abstract: A broadband matching and decoupling network for matching RF coils to an MR system at more than one Larmor frequency using coaxial cable that is equal to 1/4.lambda. at the lower Larmor frequency and an odd multiple of 1/4.lambda. at the higher Larmor frequency.

Abstract: A process and system for constructing three dimensional images by acquiring two dimensional image data maps of two spaced apart planes and using binary interpolation to provide image data on planes between the two spaced apart planes. The acquired image data is first converted to "bit" data maps denoting whether an organ of interest, for example, occupies the elements of the spaced apart planes. The bit maps are used to obtain distance maps denoting where there is transition of values in each element of the bit maps. The distance maps and at least one of the bit maps are used to obtain bit values of interpolated planes between the spaced apart acquired planes for use in constructing three dimensional images.

Abstract: Divergent X-ray beams of a computerized tomographic system are used for reconstruction with parallel reconstruction algorithms by determining "sets" of the divergent X-ray beams after passage through the patient at a number of angularly spaced positions within the angle subtended by the divergent beams. The determined sets are reordered, filtered and rebinned to obtain laterally spaced parallel filtered data that are backprojected to form the tomographic image. Corrections are made on the detected divergent beams to prevent "cupping" and to assure that the image has correct CT numbers.

Abstract: A Magnetic Resonance (MR) data acquisition system using driven equilibrium in a spin echo scan sequence wherein the dephased spins in the transverse plane are accurately refocused prior to being driven to the Z axis and the encoding gradient pulses are distributed and adjusted to keep the encoding gradient pulses from affecting the refocused magnetization.

Abstract: A method of using a stimulated echo sequence for acquiring imaging data of spatially localized volumes with a magnetic resonance system.

Abstract: A method of acquiring data for use in providing magnetic resonance images (MRI) wherein prior to stabilization of the system, data is acquired using phase encoding gradient pulses far removed from zero. Immediately after system stabilization data proximate and equal to the zero value phase encoding gradient pulse is acquired.

Abstract: Methods and Apparatus using frequency modulated RF pulses for spatially localizing spectroscopic data. Three different pairs of 90 degree RF pulses are applied during the application of three different gradient pulses to excite and dephase unwanted volumes. A selected volume of interest (VOI) now contains unexcited and non-dephased spins. A 90 degree RF pulse is applied to excite the spins in the selected VOI and signals are acquired from the selected VOI.

Abstract: A method and system for using magnetic resonance imaging (MRI) to acquire separate data contributions from first and second spectral components by causing a 90 degree phase difference between the data of said components in a first of at least two echoes and using the two echoes to determine the approximate .DELTA..phi. delay due to inhomogeneity, determining linear phase delay .beta. and using .DELTA..phi. and .beta. in the calculation of the separated data contributions of each of the spectral components.

Abstract: A split screen imaging display system including interactive controls operating on random access memories for designating subdisplay images on a split screen basis. The interactive controls in conjunction with random access memories individually control each of the split screen subdisplay images with an independant set of parameters which are variable even during the imaging process.

Abstract: In-vivo bone density measuring system using a modified emission computed tomographic gamma camera arrangement for detecting radiation from two separate sources located outside of the body of the patient and oppositely disposed to the gamma camera during rotation of the gamma camera and sources means about the patient for obtaining tomographic data. The two separate sources emitting at least two energy levels. The system includes processing means for the detected radiation to provide a bone mineral density map.

Abstract: Method and apparatus for improving the signal-to-noise ratio in magnetic resonance imaging systems using echo acquisition modes. The bandwidth of the received signals are reduced along with the amplitude of the view gradient and the sampling time. Since the signal-to-noise ratio is proportional to one over the square root of the bandwidth, this results in an increased signal-to-noise ratio.

Abstract: A balun circuit arrangement for radio frequency (RF) coils in magnetic resonance (MR) systems. The balun circuit arrangement comprises a conductor having a length equal to a quarter wavelength at the tuned resonance frequency of the (RF) coil.

Abstract: Apparatus for spatial localization in magnetic resonance (MR) systems applicable to both imaging and spectroscopy. Spatial localization provides data from a volume of interest (VOI) by means of selective inversion followed by the application of a modified spin-echo sequence having a second slice selection gradient used with the 180.degree. pulse being orthogonal to a first slice selection gradient used with the 90.degree. pulse. The selective inversion 180.degree. pulse is applied in the presence of a third selection gradient which is orthogonal to the other two selection gradient pulses. This basic sequence is applied twice with the preinversion pulse absent in the second application. The resulting signals are substracted from one another to obtain a net localized signal from the VOI.

Abstract: Time gain compensation is provided on an automatic basis by storing an amplification gain function for an amplifier operating on the received signals and automatically varying the function until the intensity versus time functions of the received signal is substantially flat.

Abstract: A superconducting magnet arrangement for magnetic resonance systems including a cryomagnetic dewar containing magnetic coils in a helium vessel surrounded by a nitrogen vessel. A separate support structure is used to support the vessels in the dewar.

Abstract: Spatial separation of first and second spectral components in magnetic resonance imaging systems is accomplished by causing the first and second spectral components to generate first and second signals of different frequencies which are spatially separated and converting the spatially separated signals to image data for first and second images of said first and second spectral components respectively.

Abstract: A pattern generator and controller arrangement operats for controlling the component parts of an MRI system. The arrangement comprises a plurality of channels including a main control channel and output channels. The arrangement receiver instructions from the system CPU which then leaves the control and outputting to the arrangement, thereby avoiding the necessity of a large expensive CPU to operate the system with versatility and speed.