Abstract: Temperature in frozen tissue can be measured from magnetic resonance signals from the frozen tissue based on spin-spin relaxation time (T2) or based on relative intensity of the magnetic resonance signals. Short echo times are required, and use of tailored RF pulses, non-Cartesian readouts, and multi-slice and 3D k-space acquisitions are preferably employed.
Type:
Grant
Filed:
February 19, 1998
Date of Patent:
February 29, 2000
Assignee:
The Board of Trustees of the Leland Stanford Junior University
Abstract: An antenna system for a magnetic resonance imaging apparatus has an active coil connected between a transmitter or receiver and ground and also has an isolated loop coil which is not conductively connected to ground. The isolated loop coil preferably overlies the electrically conductive pole surface of the field magnet. The isolated loop coil is inductively coupled to the active coil. The assembly has relatively low parasitic capacitance to ground and hence can be tuned to the resonant frequencies required for high field strength imaging.
Type:
Grant
Filed:
July 17, 1997
Date of Patent:
February 22, 2000
Assignee:
Fonar Corporation
Inventors:
Charles Green, Jan Votruba, Gregory Eydelman, Raymond V. Damadian
Abstract: Fast spin echo pulse sequences are adjusted to reduce, or eliminate image artifacts caused by Maxwell terms arising from the linear imaging gradients. The waveforms of the slice selection, phase encoding and readout gradients are adjusted in shape, size or position to eliminate or reduce the phase error caused by the spatially quadratic Maxwell terms.
Type:
Grant
Filed:
January 12, 1998
Date of Patent:
January 4, 2000
Assignee:
General Electric Company
Inventors:
Xiaohong Zhou, Matthew A. Bernstein, Gousheng Tan
Abstract: This invention relates to a method of electron spin resonance enhanced magnetic resonance imaging which relies on ex vivo dynamic nuclear polarisation of an MR imaging agent.
Type:
Grant
Filed:
July 3, 1997
Date of Patent:
December 28, 1999
Assignees:
Picker Nordstar OY, Nycomed Imaging AS
Inventors:
Ib Leunbach, Ian Young, Gosta Ehnholm, Georg Hansson, Stefan Petersson, Lars-Goran Wistrand, Klaes Golman
Abstract: A gradient coil (1) to generate switched magnetic field gradients in an nuclear spin resonance (NMR) device consisting of one or several current paths (a, b) following windings and being arranged on the surface of a geometric body is characterized in that at least two electrical current paths (a, b) are provided for, running geometrically essentially parallel to each other and being electrically connected in parallel, which current paths cross n times per winding, wherein n is an integer with n.ltoreq.8, preferably n=1 or n=2. In this way, eddy current generation by current re-distributions on the gradient coil conductor strips and thereby a time-dependent distortion of the generated magnetic field gradient inside the volume of interest of the NMR apparatus is considerably reduced.
Abstract: In an apparatus for treatment of a subject with acoustic waves, a spatial allocation, required for the treatment of the patient and a source of acoustic waves relative to each other is effected by a surgical work station using a three-dimensional navigation system on the basis of a number of images of a region to be treated, which are obtained independently of the treatment apparatus, in different coordinate systems, and are displayed on a display screen of the work station.
Abstract: A bipolar, phase-encoding, pre-phaser pulse is employed in each shot of a multi-shot EPI pulse sequence to smooth the phase-encoding gradient first moment throughout the scan. The first moment of the pre-phaser pulse is calculated for each shot in the scan and is played out at the beginning of each shot after the RF excitation.
Type:
Grant
Filed:
April 9, 1997
Date of Patent:
July 20, 1999
Assignee:
Mayo Foundation For Medical Education and Research
Abstract: A magnetic resonance imaging apparatus capable of measuring a temperature increase due to an application of RF magnetic fields for data acquisition purpose, and notifying an information on the measured temperature increase regularly to an operator, so as to secure the safety of a body to be examined. In this magnetic resonance imaging apparatus, the image data acquisition operation is controlled to acquire a phase information associated with a temperature change in an interior of the body to be examined, by displacing either an observation start timing or a radio frequency magnetic field application timing for a prescribed magnetic resonance signal in the magnetic resonance signal sequence from a normal timing for acquiring image data.
Abstract: A device for invasive temperature measurements during surface and deep hyperthermia treatments. The device includes a needle-pin element and a catheter of a biocompatible material semi-rigid sheath surrounding the needle-pin element. The needle-pin element and the sheath are coupled such that the needle-pin element can be drawn out. At least one thermocouple is provided on an outer circumference of the semi-rigid sheath of the catheter. The thermocouple has an end to affect the temperature reading and is provided close to a surface of the sheath which is in contact with tissue of a human body. Positioning means are provided at the bottom of the catheter to position the catheter adjacent to a human body and for maintaining the catheter in position.