Kabushiki Kaisha Toshiba

Toshiba Medical Systems Corporation

Tokyo Shibaura Denki Kabushiki Kaisha

Kabushiki Kaishi Toshiba

Masatoshi Hanawa

Kazuto Nakabayashi

Kazuya Okamoto

Kohei Adachi

Hiroshi Hayakawa

Mitsue Miyazaki

Yoshimori Kassai

Masao Yui

Yoshio Machida

Hitoshi Kanazawa

Yoshitomo Sakakura

Hiromitsu Takamori

Seiji Nozaki

Masaaki Yamanaka

Ayumi Katsunuma

Takeshiro Suzuki

A magnetic resonance imaging apparatus includes an imaging condition acquisition unit and an imaging unit. The imaging condition acquisition unit acquires at least one of optimum amplitude and optimum phase of a radio frequency transmission signal so as to reduce a deviation of data in at least one region of interest set in an object. The imaging unit acquires image data by imaging according to an imaging condition including at least one of optimum amplitude and optimum phase.

Magnetic resonance imaging apparatus and magnetic resonance imaging method

A magnetic resonance apparatus in which magnetic metal pieces are accommodated in an accommodation section so as to correct uniformity in a main magnetic field, includes an acquisition unit which acquires temperature information related to at least one of a temperature of the magnetic metal pieces accommodated in the accommodation section, a temperature of the accommodation section, and a temperature of a position in the vicinity of the accommodation section, and a temperature adjustment unit which adjusts the temperature of the magnetic metal pieces to a target temperature by preheating the magnetic metal pieces on the basis of the temperature information acquired by the acquisition unit.

Magnetic resonance apparatus with temperature controlled magnet shim pieces

A magnetic resonance imaging apparatus includes a static magnetic field magnet which generates a static magnetic field, a gradient coil unit which generates a gradient magnetic field for overlapping with the static magnetic field, a shim unit which is disposed between the static magnetic field magnet and the gradient coil unit to control the static magnetic field, and a heat shielding member which is disposed between the gradient coil unit and the shim unit to shield a radiant heat of the gradient coil unit.

Magnetic resonance imaging apparatus

A magnetic resonance imaging apparatus which applies RF pulses to a subject placed on a top board which is moving in an imaging field in which a static magnetic field and gradient magnetic fields are formed, acquiring magnetic resonance signals emitted from the subject as a result of application of the RF pulses, producing image data based on the acquired magnetic resonance signals, and stopping the generation of a drive signal to move the top board during a magnetic resonance signal acquisition interval.

A magnetic resonance imaging apparatus generates an MR signal from an object by applying a gradient field pulse generated by a gradient field coil and a high-frequency magnetic field pulse generated by a high-frequency coil to the object in a static field, and reconstructs an image on the basis of the MR signal. The gradient field coil is housed in a sealed vessel. The internal air in the sealed vessel is exhausted by the pump to prevent noise. By controlling the operation of the pump using a control circuit, noise in imaging operation can be reduced more effectively.

An inversion pulse is applied to the subject in a static magnetic field. An excitation pulse is applied after a delay time depending on the time constant of the longitudinal relaxation of the spins of proton contained in fat molecule from this inversion pulse. As a result, the spins of proton contained in the fat molecule can be suppressed at high precision. On the basis of the MR signal collected after this suppression, the resonance frequency data of the spins of proton contained in water molecule which is not suppressed or the data corresponding to this resonance frequency, or the magnetic field distribution data of the static magnetic field or the data corresponding to this magnetic field distribution can be determined at high precision.

Magnetic reasonance diagnosis apparatus

In addition to the known MT (magnetization transfer) effect, an RMT (reverse MT) is newly found, which increases a detected MR signal strength. Both the MT and RMT effects can be explained with mutual interaction, such as phenomena of chemical exchange and/or cross relaxation, acted between a pool of water proton spins and another pool of macromolecule proton spins, for example, within an object. In order to enhance the MT or RMT effect, the frequency bandwidths of RF pulses, such as a 90.degree. RF exciting pulse in a SE or FSE method, an inversion pulse in a FLAIR or fast FLAIR method, and others, are controlled. To enhance the MT effect, the bandwidth is controlled into a wider value (approx. more than 1250 Hz) than the normally (conventionally) used bandwidth, while to obtain the RMT effect, the bandwidth is controlled into a narrower value (approx. less than 1000 Hz) than the normally used bandwidth. Actively controlling the MT or RMT effect permits changed image contrast in MR imaging.

MR imaging using mutual interaction between different kinds of pools of

A magnetic resonance imaging system includes a static magnetic field generating section, a gradient magnetic field applying section, an RF pulse applying section, a sequence control section, a receiving section, and an imaging processing section. The sequence control section causes an RF pulse to excite magnetic resonance, causes at least one of the RF pulse and the gradient field to produce an initial magnetic resonance echo, applies a read gradient field to the imaging volume upon reception of the magnetic resonance echo, and inverts the read gradient field at least once to produce at least one magnetic resonance echo in addition to the initial magnetic resonance echo. The receiving section adds and averages data of a plurality of such magnetic resonance echoes or performs an addition or subtraction of the magnetic resonance echoes.

Magnetic resonance imaging system

A magnetic resonance imaging system includes a static field generating section, a gradient field applying section, high-frequency pulse applying section, a sequence control section, a receiving section and an imaging processing section. The sequence control section generates a 180.degree. pulse at a timing at which a center of the 180.degree. pulse appears at time t=TE'/2 when a center of a 90.degree. pulse appears at time t=0 under the condition TE'=TE-N.tau.c (where TE is an echo time with respect to a proton, .tau.c is a period in which phases of spins of the proton and fat match with each other and which is obtained on the basis of a chemical shift of protons of water and the fat, and n is an integer not less than 1), and generates a read gradient field Gr such that its intensity is set to allow an echo peak to appear at time t=TE=TE'+n.tau.c.

Magnetic resonance imaging system and method

A method and an apparatus for nuclear magnetic resonance imaging, using a shim coil which adjusts a static magnetic field to improve the homogeneity of the static magnetic field, capable of determining an appropriate amount of current to flow through the shim coil in accordance with a nuclear magnetic resonance signal due to water, in order to achieve an accurate adjustment of the homogeneity of the static magnetic field. The determination of the amount of current may be made by selecting current parameters for which a half-width of the nuclear magnetic resonance signal spectrum due to water is the smallest. The determination of the amount of current may be made by selecting current parameters for which a peak value of the nuclear magnetic resonance signal spectrum due to water is the largest.

Method and apparatus for determining shim coil current in nuclear

A magnetic resonance spectroscopy system repeatedly performs operations of selectively exciting, using a 90.degree. pulse, first two regions which sandwich a local region therebetween in the direction of one of the X axis and y axis for a slice portion, subsequently erasing transverse magnetization components in the first two regions, selectively exciting, using a 90.degree. pulse, second two regions which sandwich the local region therebetween in the direction of the other of the x axis and y axis, subsequently erasing transverse magnetization components in the second two regions, exciting a region having one local region in the z-axis direction to acquire magnetic resonance data therefor, and exciting a region including another local region in the z-axis direction to acquire magnetic resonance data therefor within a repetition time.

Magnetic resonance spectroscopy system

The magnetic resonance imaging system applies a uniform static magnetic field and a gradient magnetic field to an object and further applies an excitation rotating magnetic field to cause magnetic resonance phenomena in the object to detect the induced magnetic resonance signals and then to obtain image data by processing the magnetic resonance signals. The system has a power controller for controlling the transmission power in a transmitter for transmitting the excitation rotating field. The system further has a transmission controller for controlling the power controller in response to the magnetic resonance signal which is received by the receiver from the object. The transmission controller controls the power controller to sequentially change the transmission power and detects the transmission power at which the maximum magnetic resonance signal is obtained in response to the reception signal by the receiver when the excitation rotating field is applied to the object, thereby controlling the power controller in accordance with the detected data. A fraction of the detected maximum power is utilized to generate the excitation field to thereby rotate the spin angle of the nuclei by an amount less than 90.degree., and preferably 45.degree., so as to reduce data collection time.

A magnetic resonance imaging system erases magnetization components of at least a pair of adjacent regions sandwiching a region to be examined including a predetermined portion of interest of an object to be examined, and then selectively excites the region to be examined to obtain image information based on magnetic resonance data of the region to be examined. The magnetic resonance imaging system includes a controller for changing the polarity of a gradient field, which is applied simultaneously with a .pi./2 pulse, in units of the pair of adjacent regions when the magnetization components are to be erased.

A coil system for magnetic resonance imaging in a magnetic resonance imaging system, used to transmit the excitation pulse and to receive the magnetic resonance signals, includes a first coil for transmitting a predetermined high-frequency pulse, second and third coils, arranged on a propagation path of the magnetic resonance signal at a position closer to the object to be examined than the first coil in directions orthogonal to each other, for receiving the magnetic resonance signals, and a pair of tuning elements, respectively provided in association with the second and third coils, for tuning the second and third coils to predetermined magnetic resonance signals. The tuning elements tune the second and third coils slightly offset from accurate tuning points so that voltage phases of the magnetic resonance signals received through the second and third coils coincide with each other.

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Otawara, Japan

Masatoshi Hanawa