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5278501 Method and apparatus for measuring fluid transport properties through porous media by NMR imaging
New Patents
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coherent component of the magnetic resonance signal is then determined by projection reconstruction of the standard deviation projection data sets.
linear magnetic field gradients along x, y, and zdirections which have a region of primary linearity offset from their geometric center.
5278505 5278501 METHOD AND APPARATUS FOR MEASURING FLUID TRANSPORT PROPERTIES THROUGH POROUS MEDIA BY NMR IMAGING David N Guilfoyle, West Bridgford, United Kingdom assigned to British Technology Group Limited The fluid transport properties of a porous media are determined by NMR imaging showing the fluid transport properties such as fluid velocity, fluid acceleration, fluid jerk, translational self diffusion, sample permeability to fluid transport, etc.
5278504 GRADIENT COIL WITH OFF CENTER SWEET SPOT FOR MAGNETIC RESONANCE IMAGING John L Patrick, Michael Morich, Labros Petropoulos, J V Hajnal, A S Hall assigned to Picker International Inc An examination region (12) is defined along a zaxis offset from a geometric center (30) of a gradient coil assembly (20). Cylinders of a nonconductive, non-magnetic material support x, y, and z-gradient coils (24, 26, 22) for causing orthogonal magnetic field gradients through the offset examination region. The z-gradient coil (FIG. 2 ) includes a plurality of distributed loop arrays with a winding pattern selected to cause a region of linear magnetic field gradients in the zdirection in a region offset toward a cylinder first end (32). The x and y-gradient coils each include two pairs of oppositely disposed windings (FIG. 3 ) which include a pair of inner spirals (96, 98) offset towards the first end of the cylinder and an outer spiral (90) extending therearound. The outer spiral bows in (92) toward the cylinder first end and fans out (94) toward the second end. In this manner, the x, y, and z-gradient coils create
SELF-CANCELLING RF RECEIVE COIL USED TO DECOUPLE MRI TRANSMIT/RECEIVE RF COILS Mitsuaki Arakawa assigned to The Regents of the University of California In addition to the usual winding of an MRI RF receive coil, a second, opposite sense, winding is connected to the same pair of RF output terminals and linked to at least part of the same space as the first winding. One or more serially connected RF switches in the second winding selectively connect it in circuit only during transmission of NMR RF nutation pulses. Under these conditions, any transmitted RF fields linked to the first winding are also linked to the second winding. Accordingly, any induced RF currents flowing in the receive coil windings produce self-cancelling effects in the tissue being imaged (thereby reducing possible distortion of the desired transmit fields being used for NMR nutation purposes).
5278506 METHOD AND CIRCUIT FOR OPERATING A MAGNETIC RESONANCE IMAGING APPARATUS FOR PRODUCING TOMOGRAMS IN AN ARBITRARY POSITION Franz Schmitt, Erlangen, Federal Republic Of Germany assigned to Siemens Aktiengesellschaft A method and circuit for operating a magnetic resonance imaging apparatus to produce tomograms in an arbitrary position (plane) generate logic gradients which are arbitrarily spatially oriented by a combination of a number of physical magnetic field gradients. At least one gradient coil is operated in a resonant circuit. The logic gradients do not chronologically overlap. A logic read-out gradient can have gaps (non-signal regions) in the region of its zero-axis crossings, at which time a logic phase-coding gradient can be activated.
VI
coherent component of the magnetic resonance signal is then determined by projection reconstruction of the standard deviation projection data sets.
linear magnetic field gradients along x, y, and zdirections which have a region of primary linearity offset from their geometric center.
5278505 5278501 METHOD AND APPARATUS FOR MEASURING FLUID TRANSPORT PROPERTIES THROUGH POROUS MEDIA BY NMR IMAGING David N Guilfoyle, West Bridgford, United Kingdom assigned to British Technology Group Limited The fluid transport properties of a porous media are determined by NMR imaging showing the fluid transport properties such as fluid velocity, fluid acceleration, fluid jerk, translational self diffusion, sample permeability to fluid transport, etc.
5278504 GRADIENT COIL WITH OFF CENTER SWEET SPOT FOR MAGNETIC RESONANCE IMAGING John L Patrick, Michael Morich, Labros Petropoulos, J V Hajnal, A S Hall assigned to Picker International Inc An examination region (12) is defined along a zaxis offset from a geometric center (30) of a gradient coil assembly (20). Cylinders of a nonconductive, non-magnetic material support x, y, and z-gradient coils (24, 26, 22) for causing orthogonal magnetic field gradients through the offset examination region. The z-gradient coil (FIG. 2 ) includes a plurality of distributed loop arrays with a winding pattern selected to cause a region of linear magnetic field gradients in the zdirection in a region offset toward a cylinder first end (32). The x and y-gradient coils each include two pairs of oppositely disposed windings (FIG. 3 ) which include a pair of inner spirals (96, 98) offset towards the first end of the cylinder and an outer spiral (90) extending therearound. The outer spiral bows in (92) toward the cylinder first end and fans out (94) toward the second end. In this manner, the x, y, and z-gradient coils create
SELF-CANCELLING RF RECEIVE COIL USED TO DECOUPLE MRI TRANSMIT/RECEIVE RF COILS Mitsuaki Arakawa assigned to The Regents of the University of California In addition to the usual winding of an MRI RF receive coil, a second, opposite sense, winding is connected to the same pair of RF output terminals and linked to at least part of the same space as the first winding. One or more serially connected RF switches in the second winding selectively connect it in circuit only during transmission of NMR RF nutation pulses. Under these conditions, any transmitted RF fields linked to the first winding are also linked to the second winding. Accordingly, any induced RF currents flowing in the receive coil windings produce self-cancelling effects in the tissue being imaged (thereby reducing possible distortion of the desired transmit fields being used for NMR nutation purposes).
5278506 METHOD AND CIRCUIT FOR OPERATING A MAGNETIC RESONANCE IMAGING APPARATUS FOR PRODUCING TOMOGRAMS IN AN ARBITRARY POSITION Franz Schmitt, Erlangen, Federal Republic Of Germany assigned to Siemens Aktiengesellschaft A method and circuit for operating a magnetic resonance imaging apparatus to produce tomograms in an arbitrary position (plane) generate logic gradients which are arbitrarily spatially oriented by a combination of a number of physical magnetic field gradients. At least one gradient coil is operated in a resonant circuit. The logic gradients do not chronologically overlap. A logic read-out gradient can have gaps (non-signal regions) in the region of its zero-axis crossings, at which time a logic phase-coding gradient can be activated.