Yoshitaka Bito has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
Abstract: In the continuous moving table imaging, an image is reconstructed with suppressed artifacts even in imaging under inhomogeneity of static magnetic field. In a magnetic resonance imaging apparatus, signals are measured with moving a table to obtain multiple data sets, and inverse Fourier transform of each data set is carried out in the read-out direction to obtain hybrid data. One-dimensional data are extracted from each hybrid data at a border with respect to the adjacent hybrid data, and correction values for corrections of discontinuity of signal intensity and phase at a border of hybrid data are obtained by using the one-dimensional data. Data obtained by inverse Fourier transform of each hybrid data are corrected by using the correction values, and an image showing continuity for signal intensity and phase is eventually obtained.
April 28, 2008
Date of Patent:
December 25, 2012
Hitachi Medical Corporation
Yo Taniguchi, Shinji Kurokawa, Suguru Yokosawa, Yoshitaka Bito
Abstract: There is provided a technique for improving quality of images obtained with an MRI apparatus by using the geometric structures of the conventional RF transmission coil and RF reception coil and without increasing burden on patients or MRI technicians. A conductor loop of an RF reception coil disposed between a subject and an RF transmission coil is used also as a loop for magnetic field adjustment in order to shield or enhance a rotating magnetic field B1 generated by the RF transmission coil. Further, the conductor loop operated as a conductor loop for magnetic field adjustment among the conductor loops constituting the RF reception coil is driven so that inhomogeneity of the rotating magnetic field B1 is reduced.
Abstract: There is provided a technique for securing a comfortable examination space in a tunnel type MRI apparatus without increasing the manufacturing cost of the MRI apparatus and sacrificing performance thereof. In an RF coil provided with a hollow-shaped outer conductive element and a strip-shaped conductive element disposed along the outer conductive element in the axial direction, meander lines constituting the strip-shaped conductive element are disposed at uneven distances from the outer conductive element to secure an internal space. In order to obtain uniform sensitivity at the center of the RF coil, the strip-shaped conductive element is constituted with N of connected meander lines, and length of the strip-shaped conductive element is adjusted so that, in the strip-shaped conductive element resonating at resonance frequency of the antenna, nodes are formed in a number of (M+1)×N?1, wherein M is 0 or a natural number of 1 or larger.
Abstract: Water/fat separation imaging is performed by an MRI device, even if the measurement is not performed with such echo times that the phases of water and fat signals become in-phase or out-of-phase. A determination is made as to which of two obtained separation images is a water image or a fat image. Two water/fat ratio maps are calculated from two original images obtained with such two echo times that phase differences of water and fat signals do not become positive and negative values, and do not becomes integral multiples of ?. Two phase maps are calculated from the two water/fat ratio maps and are combined to calculate two minimum phase difference maps showing minimum spatial phase difference. From dispersion in differential maps obtained by spatially differentiating the minimum phase difference maps, a correct minimum phase difference map is determined, and is used to perform phase correction of the original image.
Abstract: There is provided a technique for securing a large examination space in a tunnel type MRI device without inviting increase of manufacturing cost and without significantly reducing irradiation efficiency or uniformity of the irradiation intensity distribution in an imaging region. Between rungs of a partially cylindrical RF coil, which coil corresponds to a cylindrical RF coil of which part is removed, there are disposed half-loops generating magnetic fields, which are synthesized with magnetic fields generated by loops constituted by adjacent rungs of the partially cylindrical RF coil and rings connecting the rungs to generate a circularly polarized or elliptically polarized magnetic field. Further, high-frequency signals of the same reference frequency having a desired amplitude ratio and phase difference are supplied to the partially cylindrical RF coils and half-loops.
Abstract: An object of the invention is to obtain a magnetic resonance spectroscopic image to which the MAC summation is applied with high accuracy and in short time, even though a phase characteristic distribution of the MAC has a spatial non-uniformity, in the MRSI measurement using a magnetic resonance imaging apparatus provided with a MAC. Using a non-water-suppressed image signal with high SNR, obtained in the non-water-suppressed measurement (a reference measurement) without water suppression, a correction value for correcting the phase distortion for the MAC summation is calculated on each pixel in each coil. After correcting a phase on each pixel in each coil of a main-scan image signal measured under suppressing water (water-suppressed image signal) using the corrective value, signal adding operation (summation) is performed. Then, a phase correction in a spectrum-axis is to be performed on the summed spectrum signal.
Abstract: A coil unit comprises a gradient coil which is disposed along a static magnetic field generating source, and a radio frequency coil which is disposed along the gradient coil in a test region at a position closer to the center of the test region compared with the gradient coil, and a conductor part which is disposed between the gradient coil and the radio frequency coil, and covers periphery of the radio frequency coil. The radio frequency coil comprises a first loop coil and a second loop coil locating in planes substantially perpendicular to direction of the static magnetic field, a plurality of linear conductors connecting the first loop coil and the second loop coil and substantially parallel to the direction of the static magnetic field, and a plurality of first capacitors disposed in the first loop coil and the second loop coil.
December 13, 2007
Date of Patent:
June 19, 2012
Hitachi, Ltd., Hitachi Medical Corporation
Abstract: An RF coil for MR Imaging that can change a resonance frequency easily and instantaneously in response to a nuclide to be imaged without exchange and adjustment and that also causes only small lowering of sensitivity. The RF coil has a sub coil for changing a resonance frequency of the transmitting/receiving RF coil for transmitting and receiving an MR signal between itself and a nuclide that is an object to be imaged. The sub coil is equipped with a switch, and at the time of switching-on, shifts the resonance frequency of the RF coil by changing an inductance value of the RF coil in a noncontact manner using inductance coupling.
Abstract: An RF coil having at least three different resonance frequencies, wherein one of the resonance frequencies is adjusted to be a frequency fA of a magnetic resonance signal generated by a test subject, and the coil is adjusted so that ratio of difference between the frequency fA and a first frequency fB lower than fA and nearest to fA among the resonance frequencies (fA?fB), and difference between the frequency fA and a second resonance frequency fC higher than fA and nearest to the frequency fA among the resonance frequencies (fC?fA), should be from 0.5 to 2.0. There is provided a technique for receiving magnetic resonance signals always with high detection efficiency by an RF coil of an MRI apparatus even if significant loss is caused in the RF coil, or test subject is changed.
November 19, 2008
Date of Patent:
June 5, 2012
Yosuke Otake, Yoshihisa Soutome, Koji Hirata, Yoshitaka Bito
Abstract: A method for obtaining the most appropriate amplitude of signal suppression pulse, which suppresses unnecessary signals from the substance not subjected to measurement, highly accurately, swiftly and stably, and an MRI apparatus that enables the optimization are provided. A pulse amplitude adjusting means equipped in the MRI apparatus acquires signals while changing the amplitude of signal suppression pulse and calculates signal absolute values and phase values, and computes reference signals, which are polarized signal absolute values, based on the changes in signal phase values. This reference signals are subjected to polynomial fitting. A value which makes this fitting curve is 0 or closes to 0 is set as the optimal pulse amplitude.
June 29, 2007
Date of Patent:
May 29, 2012
Hitachi Medical Corporation
Toru Shirai, Yoshitaka Bito, Yo Taniguchi, Satoshi Hirata
Abstract: There is provided a technique for, in a medical imaging apparatus enabling imaging of an arbitrary plane in a three-dimensional space, enabling automatic calculation of a slice position and automatic calculation of an extracting slice in MPR, without prolonging examination time. Two-dimensional scout scan similar to that used for manual setting of a slice position is performed, and the obtained scout images are processed to calculate a recommended slice position. Algorithms for the processing and various image processing procedures used for the processing are stored beforehand for every type of imaging region and every type of examination.
June 22, 2010
April 19, 2012
Suguru Yokosawa, Yo Taniguchi, Yoshitaka Bito
Abstract: In the diffusion spectroscopic imaging, in which intensity of molecular diffusion is imaged with separating chemical substances, with suppressing artifacts resulting from object motion of an object, spatial resolution, spectral band and SNR are maintained, and measurement accuracy is enhanced. A measurement for acquiring diffusion SI data is repeated a plurality of times with changing acquisition timing, phase variation of each measurement result is corrected, and a diffusion SI image is reconstructed from the corrected measurement results. In addition, the phase variation is calculated for every point in the space from the diffusion SI data acquired by each measurement or navigation data obtained by each measurement. The phase correction is independently performed for every point in the space.
Abstract: An MRI apparatus comprises a waveform controlling means for calculating a radio frequency pulse and applying the pulse to an irradiating means, and the waveform controlling means reads out a radio frequency pulse waveform vector from a first memory means which memorizes multiple radio frequency pulse waveform vectors, calculates a simulated irradiation pattern, and calculates a radio frequency pulse waveform which gives the minimum value of weighted sum of squares of differences of absolute values and squares of differences of phases for an ideal irradiation pattern and the simulated irradiation pattern. An RF pulse waveform showing superior ideal irradiation pattern reproducibility and providing reduced power of the RF waveform is formed, and safety of MRI subject is improved by performing imaging using such an RF pulse.
Abstract: The present invention provides a technique for maintaining a function for effectively blocking common mode noise with a simple configuration, even in the case where unbalance occurs in characteristic impedance of a coaxial cable in an MRI apparatus, and improving the performance of an RF coil. In a circuit where a balun is established by parallel connection with the coaxial cable, multiple serial resonance circuits having different resonance frequencies are connected in parallel. A value of each constitutional element of each of the serial resonance circuits is adjusted in such a manner that the frequency for blocking the common mode noise of the entire balun falls into a range between the resonance frequencies of these serial resonance circuits.
Abstract: An information memory device using an electromagnetic-wave resonance phenomenon is provided to achieve both high density and long-period storage of stored data. Memory cells are three-dimensionally arranged in the inside of a solid-like medium which is not contacted with a surface of the medium, and the memory cell has resonance characteristics to electromagnetic waves depending on the space coordinates of the memory cell. For the medium, a material is selected so that an electromagnetic wave having the resonance frequency of the memory cell. By observing absorption spectra of the irradiated electromagnetic wave or emission spectra after the absorption, three-dimensional space coordinates of the memory cell are calculated.
Abstract: A magnetic resonance imaging system capable of conducting spectroscopic imaging with an improved SNR without degrading the spatial resolution includes edge-preserving filter processing means for spectroscopic imaging. The edge-preserving filter processing means executes processing including the steps of calculating spectral similarity in spatial neighborhoods (spatially neighboring voxels) at each voxel in spectroscopic imaging data, calculating a spectral weight according to the spectral similarity, and conducting weighted smoothing for compounding spectra of spatial neighborhoods (spatially neighboring voxels) according to the spectral weight.
Abstract: Manufacture cost and maintenance cost of RF coils of MRI devices are reduced without any limitation concerning size of the coils. By constituting an antenna device for magnetic resonance imaging devices with a cylindrical outer conductor, a looped ribbon-shaped conductor disposed inside the cylindrical outer conductor along the cylindrical surface, and a feed point for transmission and/or reception between the cylindrical conductor and the ribbon-shaped conductor, and disposing the ribbon-shaped conductor so that length thereof can be readily adjusted, there is provided an antenna device for magnetic resonance imaging devices that generates a magnetic field component perpendicular to the central axis of the cylinder at a desired resonance frequency and shows sensitivity without using capacitors and without being imposed any limitation concerning size in the diametral direction of the cylinder.
Abstract: In the MRS measurement using magnetic resonance for performing measurement of two regions in the same section, highly precise results are efficiently obtained with coincidence of axes with axes in positioning image. In measurement according to the PRESS method for a plurality of regions each localized (specified) with a set of perpendicularly intersecting three slices, wherein one or two slices are common to the sets of three slices localizing the regions, and slices not common do not intersect, a slice not common to those of a region to be selectively excited is excited with a radio frequency magnetic field of which phase is different by 180 degrees from that of a radio frequency magnetic field used for exciting the region to be selectively excited a number of times equal to the number of common slices, and during the measurement of the region to be selectively excited, a group of regions other than the region to be selectively excited are thermally equilibrated.
Abstract: There is provided a coil unit having a large region of homogeneous sensitivity for the axial direction even with a shortened rung length of birdcage type RF coil. The coil unit comprises a gradient coil which is disposed along a static magnetic field generating source, and a radio frequency coil which is disposed along the gradient coil in a test region at a position closer to the center of the test region compared with the gradient coil, and a conductor part which is disposed between the gradient coil and the radio frequency coil, and covers periphery of the radio frequency coil. The radio frequency coil comprises a first loop coil and a second loop coil locating in planes substantially perpendicular to direction of the static magnetic field, a plurality of linear conductors connecting the first loop coil and the second loop coil and substantially parallel to the direction of the static magnetic field, and a plurality of first capacitors disposed in the first loop coil and the second loop coil.
Abstract: An association rule is extracted by processing a database partitioned into record units in which the same attribute is missing, from a database including missing values. The association rule is extracted from the database including the missing by means for partitioning a database so that a database including a missing analysis object becomes record blocks in which the same attribute is missing, and means for estimating an upper threshold of a support value in the entire database from local support counts in partitioned databases and thereby limiting records for which the support count is counted.