Hitachi Medical Corporation

Hitachi, Ltd.

Ricoh Company, Ltd.

Kyushu University

Tetsuhiko Takahashi

Masahiro Takizawa

Hiroyuki Takeuchi

Takayuki Abe

Hisaaki Ochi

Yoshikuni Matsunaga

Yo Taniguchi

Etsuji Yamamoto

Yoshitaka Bito

Yoshihisa Soutome

Hideta Habara

Yumiko Yatsui

Kenichi Okajima

Minoru Yoshida

Hiroyuki Itagaki

Hiroshi Takeuchi

Yoshiki Murakami

Toshikazu Shimada

Shigeru Watanabe

Satoshi Hirata

Tomohiro Goto

Hisako Nagao

Masayoshi Dohata

Hideji Fujii

Manabu Nakagawa

Kenji Maio

Ryuichi Suzuki

Kenji Takiguchi

Haruo Itoh

Takenori Murase

Hideki Kumai

Koji Kajiyama

Hiromichi Shimizu

Kazumi Komura

Toshihiko Shimizu

Kageyoshi Katakura

Toru Shirai

Hideaki Yamamoto

Tadaaki Hirai

Hirotaka Takeshima

Fumio Kawaguchi

Yukio Kaneko

Ken Ueda

Takayuki Nabeshima

Takahiro Yoshida

Hisatake Yokouchi

Masahiro Ogino

Yosuke Otake

Ryuji Ishii

Masatoshi Takihiro

Hiroshi Nishimura

Yoshimi Noguchi

Yasuhiro Kamada

Saburo Ataka

Shinji Kawasaki

Masaharu Ono

Shin-ichi Muramatsu

Takayuki Hayakawa

Hideo Utsumi

Miyuki Kawamura

Tsuyoshi Kano

Kazuhiro Ichikawa

Yu Mitsui

Kenji Umetani

Ken'ichi Okajima

Haruo Itho

Hirosh Takeuch

Tomohiro c/o Hitachi Medical Corporation Goto

To avoid the complication of an MRI apparatus and avoid the overestimation of a calculated value of SAR without extending a processing time and to perform accurate SAR management. To this end, the MRI apparatus is equipped with a high frequency antenna which has a plurality of channels and resonates at a predetermined frequency, and a measuring instrument which measures the amplitudes of a forward traveling and reflected waves of each high frequency signal supplied to the high frequency antenna. In the MRI apparatus, a reflection matrix S is determined based on the measured amplitudes. Diagonal terms of the determined reflection matrix S are used to calculate Q values for each of the channels. Each non-diagonal term of the reflection matrix S is used to correct the calculated Q value. The corrected Q value is used to calculate irradiation power consumed in a subject among irradiation power from the high frequency signals supplied to the high frequency antenna when imaging to thereby manage a specific absorption rate.

Magnetic resonance imaging apparatus, Q-value calculation method, and specific absorption rate management method

In a diagnostic imaging device, such as an MRI device, correction processing improves an image to be a high-quality image and an imaging time is shortened. In the diagnostic imaging device, a noise reduction unitreduces a noise in observation data acquired with an observation unitand converted into an image, and the image correction unitcorrects the noise reduced data by correction processing that uses visual characteristics of human. The image correction unitseparates the noise reduced data into a broad luminance component and a local variation component, and generates a correction level map using the broad luminance component. Correcting the noise reduced data using this correction level map and the local variation component acquires a high-quality image that is competent in the clinical field.

Diagnostic imaging device and image acquisition method

There is provided a technique for obtaining temperature information for inside of a living body and accuracy information thereof in short time with low burden imposed on a subject. It is realized with a spectrum calculator configured to perform MRS or MRSI measurement for two kinds of substances showing difference of resonant frequencies and calculating spectra of magnetic resonance signals of the two kinds of substances, a temperature information calculator configured to calculate temperature information for inside of the subject on the basis of peaks of the calculated spectra, a temperature accuracy information calculator configured to calculate temperature accuracy information indicating accuracy of the temperature information on the basis of peaks of the calculated spectra, and a display information generator configured to generate display information to be displayed on a display device on the basis of the temperature information and the temperature accuracy information.

Magnetic resonance imaging apparatus

Systems and methods for magnetic resonance imaging, including adjusting spatial distribution of a rotating magnetic field. By minimizing imaging time, the Bnonuniformity reducing effect of RF shimming is maximized for an imaging section of an arbitrary axis direction and an arbitrary position. Bdistributions are measured for only several sections of one predetermined direction, and a radio frequency magnetic field condition that maximizes the Bnon-uniformity reducing effect for an imaging section of an arbitrary direction and an arbitrary position is calculated from the Bdistribution data.

Magnetic resonance imaging equipment, high frequency magnetic field irradiation method and program

In order to approximate the gradient magnetic field pulse waveform shape with high accuracy and improve the image quality at the time of imaging cross-section change or oblique imaging, an MRI apparatus of the present invention divides the waveform shape of the gradient magnetic field pulse into a plurality of sections, defines an approximation function for each section, and corrects the k-space coordinates at which the echo signal is arranged using the parameter of the approximation function. In addition, an optimal parameter of the approximation function of the waveform shape of the gradient magnetic field pulse is searched for using the measured signal.

Magnetic resonance imaging apparatus, and method for correcting measurement-space coordinates

A technique is provided to reserve large examination space in the tunnel type MRI apparatus, without increasing production cost nor reducing significantly irradiation efficiency and homogeneity in an irradiation distribution within an imaging region. The present invention provides an RF coil unit in which four partial cylindrical coils are placed with a gap therebetween in the circumferential direction inside a cylindrical RF shield, in such a manner that two pairs of the partial cylindrical coils are opposed to each other, and magnetic fields produced by the individual partial cylindrical coils are combined, thereby producing a circularly polarized wave field or an elliptically polarized wave field. The partial cylindrical coil is provided with a partial cylindrical conductor, multiple first conductors substantially parallel with the central axis of the RF shield, multiple capacitors connecting both ends of the first conductors with the partial cylindrical conductor, and a second conductor adjacent to at least one of the ends of the first conductor. The partial cylindrical coils are respectively provided with high frequency signals having a desired amplitude ratio and phase difference, while a reference frequency thereof being identical.

High-frequency coil and magnetic resonance imaging device employing same

There is provided a technique for suppressing increase of SAR without sacrificing sensitivity in RF coils used in MRI apparatuses. The present invention provides an antenna device comprising a sheet-shaped conductor and a ribbon-shaped conductor disposed on the subject side with respect to the sheet-shaped conductor with a predetermined distance from the sheet-shaped conductor. The ribbon-shaped conductor has a meandering shape, and is adjusted so as to resonate at transmission and reception frequencies, and it is constituted so that distance to the sheet-shaped conductor becomes smaller at both end part thereof along the static magnetic field direction compared with the distance to the sheet-shaped conductor at the center thereof. Moreover, the ribbon-shaped conductor is constituted so as to have a smaller width, as the distance to the sheet-shaped conductor becomes smaller.

Antenna device and magnetic resonance imaging device for suppressing absorption rate of irradiated waves

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.

High-frequency coil unit and magnetic resonance imaging device

Image processing techniques which enable various contrast control, by quantitatively handling a degree of phase enhancement in a contrast control as a post-processing of the image reconstruction. A complex operation is performed on each pixel value of a complex image obtained by an MRI, thereby generating an image with desired contrast. Intensity is controlled by increasing or decreasing the argument of the pixel value of each pixel by a constant amount, and the degree of phase enhancement is controlled by multiplying the phase (argument) of each pixel by a constant.

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)&#xd7;N&#x2212;1, wherein M is 0 or a natural number of 1 or larger.

Magnetic resonance examination apparatus and antenna device

A measuring instrument and a measurement method which measures, using magnetic resonance, images such as a functional image, a morphologic image of an object to be measured eliminate the influences of the moving speed of the object to be measured during moving, thereby obtaining a precise measured image. The instrument comprises: the first and second external magnetic field generation devices which generate magnetic fields for exciting the magnetic resonance of a mouse (M) as a living body to be measured; a turntable which rotates and moves the mouse (M) as an object to be measured, thereby moving the mouse (M) in the magnetic fields of the first and second external magnetic field generation devices; an OMRI measurement processing unit and an MRI measurement processing unit which obtain measured image signals within the mouse (M) by phase encoding while applying a gradient magnetic field in the moving direction (y) of the mouse (M) without stopping during the movement by the turntable; and a measured signal correction unit which corrects the measured image signal (S (k., ky)), thereby obtaining a corrected image signal (S' (k., ky)) wherein influence of movement in y-direction is corrected.

Measurement device and measurement method

An image with a desired contrast is obtained while suppressing body motion artifacts caused by both random motion and periodic motion of an object. In order to do so, an imaging sequence using a non-Cartesian sampling method is executed so as to synchronize with a biological signal only at the start time and a repetition time (TR), which is an execution interval between shots within the imaging sequence, is maintained. In addition, a time difference between a delay time and a start time of each shot is calculated, and a shot with a predetermined time difference or more is executed again after the TR time.

Magnetic resonance imaging apparatus and synchronous measurement method

An RF coil is provided with a hollow-shaped outer conductive element and strip-shaped conductive elements disposed along the outer conductive element in the axial direction. The strip-shaped conductive elements are disposed with uneven intervals to secure an internal space at a position where the strip-shaped conductive elements are not disposed. In order to obtain uniform sensitivity at the center section of the RF coil, the strip-shaped conductive elements and the outer conductive element are electrically connected via capacitors of which capacitances are adjusted so that a magnetic field component perpendicular to the center axis should be generated at a desired resonance frequency, and the strip-shaped conductive elements are axisymmetrically disposed with respect to the center axis of the outer conductive element. As a result, a comfortable examination space in a tunnel type MRI apparatus is achieved without increasing the manufacturing cost of the MRI apparatus.

Antenna system and magnetic resonance imaging apparatus

When multiple types of imaging are performed while moving a table on which a subject to be examined is placed, an imaging efficiency is improved and a high-quality image is obtained within a short time. Therefore, within a predetermined time interval such as an identical period of a periodic living body motion, a predetermined number of echo signals from each of the multiple types of imaging sequences are acquired and the table on which the subject to be examined is placed is moved. Along with the movement of the table, data items within the same range in the Ky-direction as to each of the imaging sequences are acquired, the moving speed of the table is controlled in such a manner that the acquired data items become continuous in the x-direction, and images are reconstructed based on the data items obtained respectively from the imaging sequences.

Magnetic resonance imaging apparatus and magnetic resonance imaging method

In the continuous moving table imaging, high-speed imaging such as the echo planar method is implemented without deteriorating image quality, realizing a high-speed table movement, namely, high-speed imaging. In the magnetic resonance imaging apparatus, an imaging control means for controlling a magnetic field generation means, a transfer means, and a signal processing means executes an imaging sequence for applying multiple readout gradient magnetic fields to measure multiple nuclear magnetic resonance signals, after one-time application of an exciting RF pulse, while moving the transfer means. On this occasion, a positional deviation of the readout gradient magnetic fields given to the multiple nuclear magnetic resonance signals, caused by the movement of the transfer means, is calculated in advance as correction data, so that the measured nuclear magnetic resonance signals are corrected by the correction data.

Magnetic resonance imaging apparatus and method

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Tokyo, Japan

Tetsuhiko Takahashi