Hitachi, Ltd.

Fujifilm Healthcare Corporation

Hitachi Medical Corporation

Hitachi Software Engineering Company, Ltd.

Yasuhiro Kamada

Masahiro Takizawa

Toru Shirai

Ryota Satoh

Nobuo Kawamura

Hisaaki Ochi

Tetsuhiko Takahashi

Yoshitaka Sato

Shinji Kurokawa

Kota Yamaguchi

Hikaru Hanada

Takenori Murase

Yoshihisa Sotome

Keisuke Toda

Hiroki Shoji

Junko Katsumata

Keisuke Nishio

To calculate a high-resolution coil sensitivity distribution that does not depend on a shape or a structure of a subject with high accuracy. An MRI apparatus of the invention includes: a measurement unit that includes a reception coil including a plurality of channels, a measurement unit that measures a nuclear magnetic resonance signal of a subject for every channel of the reception coil; and an image computation unit that creates an image of the subject by using a sensitivity distribution for every channel of the reception coil, and a channel image obtained from the nuclear magnetic resonance signal measured by the measurement unit for every channel. The image computation unit includes a sensitivity distribution calculation unit that calculates a sensitivity distribution on a k-space for every channel by using the channel images and a composite image obtained by combining the channel images.

Magnetic resonance imaging apparatus, sensitivity distribution calculation method, and sensitivity distribution calculation program

During obtaining a sensitivity distribution in a k-space, data based on which the sensitivity distribution is obtained is expanded with a mirror image to create an expanded image to prevent spectrum leakage, and the sensitivity distribution is stably calculated. During obtaining the sensitivity distribution in the k-space, image data based on which the sensitivity distribution is obtained is inverted as a mirror image to be made into the expanded image, the expanded image is transformed into k-space data, and a frequency component (frequency space data) of the sensitivity distribution is calculated. A region corresponding to the original image data is clipped from the calculated frequency space data, and the sensitivity distribution is obtained.

Magnetic resonance imaging device and sensitivity distribution calculation program

To provide a technique in which, in imaging using an EPI method, an occurrence of an artifact when phase correction is performed for each channel is avoided and the phase correction is accurately performed. A common phase correction value to be applied to data of all channels is calculated using pre-scan data of each channel. The common phase correction value is obtained by combining a difference phase obtained for each of the channels. The difference phase is obtained by complex integration, while an absolute value of each channel is maintained as it is. The combination is performed by complex average, and averaging processing according to a weight of the absolute value is performed. The occurrence of an artifact can be prevented by using the common phase correction value, and robust phase correction can be performed by including the weight of the absolute value.

Magnetic resonance imaging apparatus, image processing apparatus, and phase correcting method

In an image acquired by a plurality of receiver coils with the use of MRI, separated images are obtained by separating spatially overlapping signals according to PI method, and noise in the separated images is eliminated with a high degree of precision. A complex image spatially overlapping is measured from nuclear magnetic resonance signals received by a plurality of receiver coils, and spatially overlapping signals are separated and a plurality of separated images are calculated, by using sensitivity information of the plurality of receiver coils. Then, noise is eliminated based on a correlation of noise mixed between the separated images.

Magnetic resonance imaging apparatus and noise elimination method

In order to improve contrast in non-orthogonal measurement without sacrificing speed, in imaging which combines a fast imaging sequence for acquiring a plurality of echo signals in one shot with non-orthogonal system measurement, the shape of a blade in which an echo train of each shot is arranged is a fan shape having the radius and the arc of a circle centered on the origin of a k space. At this time, echo signal arrangement is controlled such that an echo signal for desired TE of each fan-shaped blade is arranged in a low spatial frequency region of the k space.

Magnetic resonance imaging apparatus and echo signal measurement method

In the non-Cartesian measurement, image quality is improved while the advantages of non-Cartesian measurement are maintained. To realize the aforementioned, in the non-Cartesian measurement, artifacts caused by non-uniform data density in k-space are reduced. Therefore, each unit k-space is imaged by an inverse Fourier transform, the field of view of the image is enlarged in a direction in which data density is to be increased, and the image after the enlargement of the field of view is Fourier transformed and gridded as unit k-space that has a small k-space pitch in the direction in which the field of view has been enlarged and has an increased amount of data. This processing is repeated for all blades.

Magnetic resonance imaging apparatus and magnetic resonance imaging method

In order to improve contrast and image quality in non-orthogonal measurement without sacrificing speed, in imaging which combines a fast imaging sequence for acquiring a plurality of echo signals in one shot with non-orthogonal system measurement, the shape of a blade in which an echo train of each shot is arranged includes a fan-shaped region having the radius and the arc of a circle centered on the origin of the k space, and a region overlapping an adjacent blade. During measurement, control is performed such that an echo signal for desired TE of each blade is arranged in a low spatial frequency region of a k space, and during image reconstruction, body motion between the blades is corrected using data of the overlapping regions.

Magnetic resonance imaging apparatus and reconstructed image acquisition method

In order to make it possible to set the optimal breath-holding imaging conditions according to the subject without extension of an imaging time or the sacrifice of image quality, one scan is divided into one or more breath-holding measurements and free-breathing measurements on the basis of the imaging conditions of a breath-holding measurement, which are input and set according to the subject, and a region of the k space measured in the breath-holding measurement is controlled. Preferably, in the breath-holding measurement, low-frequency data of the k space is measured. Moreover, preferably, imaging conditions of the breath-holding measurement include the number of times of breath holding or a breath-holding time, and the operator can set any of these values.

Magnetic resonance imaging apparatus and breath-holding imaging method

Magnetic resonance imaging apparatus, and breath-holding imaging method

An MRI apparatus capable of performing a high-speed operation for removing aliasing from the data measured by non-Cartesian imaging in a real space with a small amount of operation is provided. Non-Cartesian data sampling is performed by thinning the number of data by using multiple receiver coils having different sensitivity distribution from each other. Image reconstruction means creates orthogonal data by gridding non-orthogonal data obtained by each receiver coil on a grid having an equal spatial resolution to and a narrower field of view than a target image, subjects it to Fourier transform and creates the first image data containing aliasing components. The second image data is created by using the first image data created for each receiver coil and a sensitivity distribution of each receiver coil.

Parallel imaging in non-cartesian magnetic resonance imaging (MRI) and MRI apparatus realizing the same

If relocation of a table with a high reference frequency is made possible, the database management method and system are arranged to improve performance according to the number of increased nodes and accumulate a reference frequency of each external storage unit allocated to each database management node. A data storage area for storing the table with a high reference frequency, located in the external storage unit, is specified as a shared data area to be referenced by plural nodes. The system is controlled to cause the nodes to refer to the shared table stored in the shared data area on any timing in parallel. This prevents load from being concentrated onto the node allocated to the data area.

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Tokyo, Japan

Yasuhiro Kamada