Hitachi Medical Corporation

Hideki Kumai

Hiroyuki Takeuchi

Tetsuhiko Takahashi

Yumiko Yatsui

Koji Kajiyama

Shouichi Miyawaki

Shinji Kawasaki

Taeko Ito

Blood streams different in direction can be selectively depicted, and a blood vessel image (MRA image) which has an excellent blood vessel contrast and in which a background signal is suppressed is obtained. Therefore, the present invention sets a pre-saturation area (pre-saturation area) in an area containing at least a part of an imaging area and performs imaging in a blood vessel imaging operation using a pre-saturation pulse for pre-exciting spins.

Magnetic resonance imaging apparatus and blood vessel imaging method

In an imaging according to the step moving method, a slice imaging condition with respect to each station is optimized, thereby enabling an efficient imaging. A controller of an MRI apparatus displays positioning framesto, and operation handlesandthereof, in order to set a slice imaging condition at every various positions (stations) of a table on which a test object is mounted. By manipulating the positioning frames and the operation handles via I/O unit, the slice imaging condition is set. According to this slice imaging condition, imaging at each station position of the table is executed.

Magnetic resonance imaging method and apparatus

A control means controls an imaging means for taking an image of a test object by a magnetic resonance, the test object being placed in an imaging space, and a transfer means that moves the test object, and on the basis of a difference (moving distance) between a position of the transfer means at the time of receiving a command of pausing the imaging and a position of the transfer means at the time of resuming the imaging, the control means controls the position of the transfer means or the position for imaging at the time of resuming, in such a manner that missing of datacaused by the difference can be compensated. With this configuration, it is possible to provide an MRI apparatus that is provided with an imaging pause function, and even when the pause function is activated, there is data consistency between the data before the pausing and the data after the resuming, thereby obtaining a high quality image.

Nuclear magnetic resonance imaging apparatus and method

In a magnetic resonance imaging apparatus, in order to suppress generation of artifacts when a linear or non-linear phase error is generated during sampling of the echo signals, a first sequence for acquiring a plurality of echo signals by radiating a radio-frequency magnetic field pulse to an object to be examined, performing phase encoding, while alternating the polarity of a readout gradient magnetic field, and a second sequence for acquiring a plurality of echo signals by repeatedly applying the readout gradient magnetic field while reversing its polarity to that in the first sequence at the same phase encoding direction are performed. Signal processing means performs complex addition of the echo signals having the same phase encoding amount respectively obtained in the first sequence and the second sequence, and reconstructs an image.

Magnetic resonance imaging apparatus and magnetic resonance imaging method

In diffusion weighted imaging, motion monitoring navigation echoes are measured at every measurement of data after applying an RF excitation pulse, and one of them is set as a reference navigation echo. The reference navigation echo and other navigation echoes are one-dimensionally Fourier-transformed, a linear phase gradient thereof is calculated from those data, a linear phase gradient of the reference navigation echo is compared with those of other navigation echoes, and it is judged whether a difference therebetween is within an acceptable value or not. An echo signal corresponding to a navigation echo having the above difference being larger than the acceptable value is judged that correction based on the navigated motion correction is not applicable therein, and the image is produced by using an echo signal measured along with a navigation echo having the difference being the acceptable value or less. In this manner, a motion component included in the echo signal used for producing the image is made uniform and motion artifacts are eliminated.

An MRI apparatus having a calibration pulse sequence, wherein a group of pulse sequences for applying test gradient magnetic fields are established from a basic pulse sequence by a gradient echo method of short TR, a group of pulse sequences not applying test gradient fields are established from the basic pulse sequence, a set of three- or four-dimensional data including a time variable is created by using echo signals collected by at least one of the groups, two data sets are created as a whole by inverting the polarity of the test gradient magnetic field, the difference between phase images thereof is determined, the magnitude and time constant of eddy current induced at the fall or rise of the gradient magnetic field are determined from the phase difference image, and the variation of the magnetic field due to eddy current induced at the rise and/or fall of the gradient magnetic field can be measured in a relatively short time with a desired time resolution even if the magnetic field variation is of a very long time constant.

Magnetic resonance imaging device

In processing of measurement data of each slab obtained by 3D-TOF multi-slab measurement, data in the overlapped portion of the slabs are weighted and added for each slice position. The weight function is calculated based on parameters set previously and is the same as the slab profile or an approximation curve thereof. The weighted and added data are normalized and reconstructed to obtain images. In the obtained image, signal difference between slabs can be suppressed.

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Kashiwa, Japan

Hideki Kumai