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4721911 Nuclear magnetic resonance tomography apparatus
XII
New Patents
distortion correction circuit (106) selectively interpolates values in the real and imaginary images in accordance with the field map to correct the image for geometric distortion.
4721911 NUCLEAR MAGNETIC RESONANCE TOMOGRAPHY APPARATUS Helmu Neumann, Erlangen, Federal Republic Of Germany assigned to Siemens Aktiengesellschaft A nuclear magnetic resonance tomography apparatus, and a method for operating such an apparatus, generate a tomographic image by projecting acquired signals corresponding to the nuclear spins on a frequency axis as a Fourier line, and the image of the examined slice is calculated by Fourier transformation of the Fourier lines. In the method and apparatus, a number of echo sequences are acquired after excitation of the nuclear spins in the axamination subject by a high frequency pulse. Each echo sequence consists of a selected number of individual echoes occurring in succession within each sequence. In the method and apparatus, entry of these individual echoes into a matrix having a central zero line is controlled such that the first-occuring echoes from each sequence are entered in the matrix on alternating sides of the zero line, i.e., above and below the zero line, at increasing distances from the zero line. After all of the firstoccurring echoes have been entered, the same alternating entry format is undertaken for the second-occurring echoes in each sequence, and so on until all echoes from all sequences have been entered in the matrix.
4721912 APPARATUS AND METHOD FOR INITIALLY CAPTURING MOST SIGNIFICANT LOW SPATIAL FREQUENCY NMR IMAGING DATA Leon Kaufman, Lawrence Crooks, Douglas A Ortendahl assigned to The Reagents of the University of California NMR imaging apparatus and method is arranged so as elicit NMR image response data in a predetermined order which provides the more
significant lower spatial frequency image data during an initial portion of a relatively long complete image data acquisition cycle. The remaining higher spatial frequency image data is captured during subsequent portions of the overall image data acquisition cycle. In this manner, apparent motion artifact in the resulting image is reduced. Furthermore, such a special data acquisition sequence permits image reconstruction processes to produce a recognizable image at an earlier time in the complete data gathering cycle thus permitting a more timely image display for the apparatus operator to use in monitoring and/or controlling the NMR imaging procedure.
4721913 NMR LOCAL COIL NETWORK James S Hyde, Wojciech Froncisz, Andrzej Jesmanowicz, Thomas M Grist assigned to MCW Research Foundation Inc Counter Rotating Current (CRC) pairs of loopgap resonators are combined with planar pairs of loop-gap resonators to form networks of NMR local coils. A first embodiment is a quadrature probe in which a planar pair is sandwiched between the loop-gap resonators of the CRC pair. In a plurality of other embodiments, CRC pairs, planar pairs, and other types of local coils are arranged adjacent to one another to form networks of NMR local coils with an enlarged net region of sensitivity.
4721914 APPARATUS FOR UNILATERAL GENERATION OF A HOMOGENEOUS MAGNETIC FIELD Eiichi Fukushima, Alan R Rath, Stephen B W Roeder assigned to The United States of America as represented by the United States Department of Energy An apparatus for unilaterally producing a substantially homogeneous magnetic field. The apparatus includes two circular electromagnet coils, a small coil and a large coil, which are coaxial with one another and which are separated by a distance equal to one-half the difference in the radius of the two coils. By appropriate selection of electrical currents, which are passed through the coil in opposite direc-
New Patents
distortion correction circuit (106) selectively interpolates values in the real and imaginary images in accordance with the field map to correct the image for geometric distortion.
4721911 NUCLEAR MAGNETIC RESONANCE TOMOGRAPHY APPARATUS Helmu Neumann, Erlangen, Federal Republic Of Germany assigned to Siemens Aktiengesellschaft A nuclear magnetic resonance tomography apparatus, and a method for operating such an apparatus, generate a tomographic image by projecting acquired signals corresponding to the nuclear spins on a frequency axis as a Fourier line, and the image of the examined slice is calculated by Fourier transformation of the Fourier lines. In the method and apparatus, a number of echo sequences are acquired after excitation of the nuclear spins in the axamination subject by a high frequency pulse. Each echo sequence consists of a selected number of individual echoes occurring in succession within each sequence. In the method and apparatus, entry of these individual echoes into a matrix having a central zero line is controlled such that the first-occuring echoes from each sequence are entered in the matrix on alternating sides of the zero line, i.e., above and below the zero line, at increasing distances from the zero line. After all of the firstoccurring echoes have been entered, the same alternating entry format is undertaken for the second-occurring echoes in each sequence, and so on until all echoes from all sequences have been entered in the matrix.
4721912 APPARATUS AND METHOD FOR INITIALLY CAPTURING MOST SIGNIFICANT LOW SPATIAL FREQUENCY NMR IMAGING DATA Leon Kaufman, Lawrence Crooks, Douglas A Ortendahl assigned to The Reagents of the University of California NMR imaging apparatus and method is arranged so as elicit NMR image response data in a predetermined order which provides the more
significant lower spatial frequency image data during an initial portion of a relatively long complete image data acquisition cycle. The remaining higher spatial frequency image data is captured during subsequent portions of the overall image data acquisition cycle. In this manner, apparent motion artifact in the resulting image is reduced. Furthermore, such a special data acquisition sequence permits image reconstruction processes to produce a recognizable image at an earlier time in the complete data gathering cycle thus permitting a more timely image display for the apparatus operator to use in monitoring and/or controlling the NMR imaging procedure.
4721913 NMR LOCAL COIL NETWORK James S Hyde, Wojciech Froncisz, Andrzej Jesmanowicz, Thomas M Grist assigned to MCW Research Foundation Inc Counter Rotating Current (CRC) pairs of loopgap resonators are combined with planar pairs of loop-gap resonators to form networks of NMR local coils. A first embodiment is a quadrature probe in which a planar pair is sandwiched between the loop-gap resonators of the CRC pair. In a plurality of other embodiments, CRC pairs, planar pairs, and other types of local coils are arranged adjacent to one another to form networks of NMR local coils with an enlarged net region of sensitivity.
4721914 APPARATUS FOR UNILATERAL GENERATION OF A HOMOGENEOUS MAGNETIC FIELD Eiichi Fukushima, Alan R Rath, Stephen B W Roeder assigned to The United States of America as represented by the United States Department of Energy An apparatus for unilaterally producing a substantially homogeneous magnetic field. The apparatus includes two circular electromagnet coils, a small coil and a large coil, which are coaxial with one another and which are separated by a distance equal to one-half the difference in the radius of the two coils. By appropriate selection of electrical currents, which are passed through the coil in opposite direc-