Hitachi Medical Corporation

Hitachi, Ltd.

Hiroyuki Itagaki

Takashi Nishihara

Etsuji Yamamoto

Yo Taniguchi

Tetsuhiko Takahashi

Tomohiro Goto

Kenji Takiguchi

Hisaaki Ochi

Hidemi Shiono

Yukari Onodera

Yoshitaka Bito

Kenji Nakanishi

Hiroyuki Takeuchi

Masahiro Takizawa

Toru Shirai

Shinichiro Umemura

Yoshihisa Soutome

Suguru Yokosawa

Yoshikuni Matsunaga

Satoshi Hirata

Kenichi Okajima

Hisako Nagao

Yumiko Yatsui

Kosuke Hirai

Nobuyuki Yoshizawa

Binrong Wu

Norimasa Nakai

Provided is a technique in MRI to efficiently suppress downstream blood in a specific region in a blood vessel having a slow flow velocity, such as the portal vein. For this purpose, a plurality of Beam Sat pulses are applied so as to equally suppress signals of blood flowing into a desired imaging region from a desired blood vessel during the period from applying an IR pulse to starting main imaging. Downstream blood in a specific region in a blood vessel having a slow flow velocity, such as the portal vein, can be suppressed efficiently by determining application conditions of the plurality of Beam Sat pulses that achieve the above based on a flow velocity of blood in a desired blood vessel and Tof the said blood.

Magnetic resonance imaging apparatus and magnetic resonance imaging method

In order to provide a technique for improving image quality by selectively exciting only a target region with high precision in either of a two-dimensional spatial selective excitation method or a three-dimensional spatial selective excitation method, selecting a k-space trajectory restraining excitation in a non-target region by side lobes is received. At this time, an excitation region of the selected k-space trajectory is presented to an operator, and the operator can adjust the excitation region through the display. After the adjustment of the excitation region by the operator is reflected, a multi-dimensional spatial selective excitation pulse is stabilized.

Magnetic resonance imaging apparatus and magnetic resonance imaging method, configured to adjust multi-dimensional selective excitation pulse

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

To acquire a more accurate tissue contrast image such as a water-fat separation image in time-series imaging by an MRI apparatus, a static magnetic field non-uniformity map is created from a plurality of echo signals having different TEs obtained in time series, and a water-fat separation image is obtained using the static magnetic field non-uniformity map. Processing (spatial direction discontinuity correction processing) for correcting discontinuity of a phase or a frequency in a spatial direction and processing (time-series direction discontinuity correction processing) for correcting discontinuity in a time-series direction are performed for the static magnetic field non-uniformity map.

Magnetic resonance imaging apparatus, time-series image generation method, and program

In order to reduce image quality deterioration due to static magnetic field inhomogeneity according to imaging conditions without increasing an operator workload, shimming current where static magnetic field inhomogeneity of a selected region is reduced is calculated, shimming is performed for the selected region using the calculated local Bo shimming current, and then an increment (RF-Phase) in an irradiation phase of an RF pulse that excites the selected region in a state where static magnetic field inhomogeneity of the selected region is reduced or a post-adjustment excitation frequency (f0') that is an excitation frequency is calculated. These increments (RF-Phase) in an irradiation phase and post-adjustment excitation frequency (f0&#x2032;) that is an excitation frequency correspond with each other in amount.

Method for increment of RF-phase based on static magnetic field inhomogeneity in MRI apparatus

A high-quality image is obtained using a two-dimensional selective excitation method even if the static magnetic field is not uniform. Therefore, non-uniformity of a static magnetic field of a region to be focused in particular in a selective excitation region excited by 2DRF is measured, and a result of the measurement is reflected in an imaging sequence using the 2DRF. For example, a resonance frequency of magnetization obtained from the measurement result is set as an irradiation frequency of the 2DRF. In addition, a shim gradient magnetic field is applied so as to correct the non-uniformity of the magnetization obtained from the measurement result. These are applied only in the imaging sequence using the 2DRF, and an irradiation frequency and a shim gradient magnetic field set in a conventional method are used in other imaging sequences.

Magnetic resonance imaging apparatus and irradiation frequency adjusting method

Disclosed are a magnetic resonance imaging apparatus and an RF pulse control method wherein an RF pulse sequence in a start-up sequence is set as a monotonically increasing flip angle with offset, in order to reduce ghosts, blurring, and other artifacts during measurement in a transient state. For example, the sum of two adjacent consecutive terms in a monotonically increasing sequence is set as the flip angle. Specifically, the number of RF pulses in the RF pulse sequence and the flip angle for the RF pulses in an SSFP sequence are set, and the monotonically increasing flip angle with offset is found, based on the set number of RF pulses in the RF pulse sequence and the flip angle for the RF pulses in the SSFP sequence, and used as the RF pulse sequence.

Magnetic resonance imaging apparatus and RF pulse control method

In imaging using 2-dimensional selective excitation pulses, regardless of applications thereof, a technique for obtaining a high quality image is provided. In the technique, a 2-dimensional selective excitation sequence is carried out while changing a coefficient for determining the cylinder diameter of a region excited by the 2-dimensional selective excitation sequence and a time difference for determining an offset position. The obtained excitation region and a desired region are compared with each other, and the coefficient and time difference with which the obtained excitation region and the desired region match each other are determined to be the optimum ones. The determination processing may be performed as an initial adjustment, may be performed according to need in each imaging, or may be performed on a per-application basis.

Magnetic resonance imaging apparatus and method for adjusting excitation region

In imaging for labeling only the fluid of a specific region, a high-quality image is acquired in a short time. In order to achieve this, the optimal number of segments N is determined from the flow velocity V and the size &#x3c6; of a specific region to be labeled when performing imaging by labeling only the fluid of the specific region using a two-dimensional selective excitation pulse as a pre-pulse. In addition, the k-space ordering is determined according to the arrival timing of the fluid to the imaging region. In addition, the optimal flip angle (FA) is determined depending on the type of pre-pulse.

Magnetic resonance imaging apparatus and fluid imaging method

An image in which an area of interest on an image is optimally susceptibility-emphasized is obtained in susceptibility-emphasized imaging. A measuring order of plural echo signals is controlled in accordance with the size of a desired area of interest of an examinee. Preferably, a target frequency in a K space is determined in accordance with the size of the area of interest, and the measuring order of plural echo signals is controlled so that an echo signal corresponding to the target frequency is measured at a target echo signal or in the neighborhood of the target echo time.

There is provided an MRI apparatus and a blood vessel image capturing method capable of improving the separability of an artery and a vein. In order to do so, using an imaging sequence obtained by combining a first sequence portion for measuring a first echo signal used for acquisition of a blood vessel image of a desired region of an object with a second sequence portion for measuring a second echo signal used for acquisition of blood flow information of the object, the object is imaged by one examination scan. In addition, blood flow information is acquired using the second echo signal, and at least one of an artery and a vein is extracted in an image, which is reconstructed using the first echo signal, using the acquired blood flow information.

Magnetic resonance imaging apparatus and blood vessel image capturing method

An MRI apparatus and a two-dimensional excitation adjustment method capable of performing appropriately two-dimensional excitation of a region, in which materials with different resonance frequencies are present, according to imaging conditions are provided. In order to do so, when performing the two-dimensional excitation of a two-dimensional excitation region of an object formed by a first material with a first resonance frequency and a second material with a second resonance frequency, an irradiation frequency of a high-frequency magnetic field for the two-dimensional excitation is set on the basis of the imaging conditions related to the two-dimensional excitation and the first and second resonance frequencies so that desired regions of the first and second materials are excited in a two-dimensional manner.

Magnetic resonance imaging apparatus and two-dimensional excitation adjustment method

An object is to enhance usability of parameter check when an imaging parameter is changed in multistation imaging, and easily obtain a desired image with high quality. In the multistation imaging, it is determined in a lump before imaging whether an image having desired quality is obtained by using the changed value of the imaging parameter, and the result is presented to an operator. The determination is executed in the order of 'possible or impossible' determination of execution of imaging itself and 'possible or impossible' determination of combination of obtained images. When it is determined that it is impossible to execute the imaging itself, the determination processing is finished. At this time, a recommended value may be presented.

Magnetic resonance imaging apparatus and method of assisting setting of imaging parameter

In order to provide a technique for accurately realizing an examination, which is for acquiring a plurality of images of the same examination section, without a complicated operation and an extension of an examination time, body movement information of a subject is acquired immediately before each imaging in an examination, and it is determined whether or not there is a change in the position of the subject by comparing it with body movement information immediately before reference imaging. Only when there is a change in the position of the subject, an imaging slice setting image is acquired again. Then, a recommended imaging slice is calculated using the newest imaging slice setting image.

Magnetic resonance imaging apparatus and imaging slice determination method

A magnetic resonance imaging apparatus is provided, which is capable of reducing SAR while maintaining S/N ratio and image contrast in a GrE-type pulse sequence, regardless of whether a synchronous imaging is performed or not. The present invention controls a flip angle as to each measurement setthat is obtained by division according to the size of phase encoding and a body motion cycle of a subject in the GrE-type pulse sequence. In a setwhich measures echoes with phase encoding having a minimum absolute value, the flip angle is maximized as to the RF pulse having a minimum phase encoding amount and at least one RF pulse irradiated immediately before. As for the other RF pulses, the flip angle varies within a range less than the maximum, irrespective of the non-imaging mode, the imaging mode, or the size of phase encoding.

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Tokyo, Japan

Hiroyuki Itagaki