Abstract: A device for delivering radiation to at least one preselected site in a vascular system of a patient, includes an elongated flexible catheter tube of a diameter for insertion into the patient's vascular system, and a flexible guide wire within the catheter tube and movable along its length. The guide wire includes a proximal end to be located externally of the patient's vascular system for moving the guide wire within the catheter tube, and a rounded distal tip at the opposite end to facilitate movement of the guide wire through the catheter tube. At least one radiation-producing element is fixed to the guide wire at an intermediate location spaced from the rounded distal tip.

Abstract: A system for decoupling the body coil of the magnetic resonance imaging system when surface coils are used, and especially when the surface coils are used only for receiving. Semi-conductor switches; i.e., diodes are used in the body coil to decouple the body coils. However, gradient generated transients often erroneously switch off the diodes which are then destroyed by a subsequent transmitted RF signal. The invention provides fail safe circuitry for preventing RF transmission when the diode switches are in the non-conducting condition.

Abstract: A quadrature surface coil array comprising a plurality of single loop surface coils interspersed with a plurality of adjacent double loop surface coils, at least some of said surface coils overlapping the ends of adjacent surface coils and said double loop surface coils having the two loops in series to support only a single current mode thereby inhibiting cross coupling including next nearest neighbor cross coupling.

Abstract: Receiver circuitry for a surface coil array used in magnetic resonance diagnostic systems, said circuitry minimizes reflections and thus relaxes the prior art necessity for balancing the individual receiver channel for each array by obtaining quadrature signals from the acquired signals in processing circuitry located as close as possible process-wise to the display equipment.

Abstract: A miniaturized surface probe for use with magnetic resonance (MR) systems. The probe comprises a conductor loop for use juxtaposed to a patient. A tuning and matching section connects the probe to the receiver. The section tunes the loop to the desired Larmor frequency and matches the loop to the MR system. A N.lambda./2 length of shielded cable is used to couple the loop to the spatially removed tuning and matching section.

Abstract: A system for providing hyperthermic treatment of tumerous tissue using a phased array antenna for focusing radio frequency (RF) energy on the tumorous tissue. A magnetic resonance system generating free induction decay (FID) signals from the tumorous tissue. The FID signals are used to determine the relative phase and amplitude of RF excitations which are to be transmitted by each element of the phase array antenna.

Abstract: A surface coil for use in MRI data acquisition systems wherein the surface coil has the capability of operating as a quadrature coil and of supporting two independent current moles enabling tuning to two separate frequencies.

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 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: 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 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 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 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: 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: 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: An Rf coil arrangement for MRI systems wherein the electrical length is reduced to improve the S/N ratio and the Rf power efficiency.

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.