Hitachi, Ltd.

Hitachi Medical Corporation

Fujifilm Healthcare Corporation

Takenori Murase

Yoshitaka Bito

Toru Shirai

Hisaaki Ochi

Yo Taniguchi

Ryota Satoh

Tetsuhiko Takahashi

Shinji Kurokawa

Masahiro Ogino

Yoshimi Noguchi

Yasuhiro Kamada

Yoshihisa Sotome

Hiroki Shoji

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

A magnetic resonance imaging apparatus includes: a static magnetic field generating magnet configured to generate a static magnetic field in a space where a subject is arranged; a transmission unit configured to transmit a high frequency magnetic field to the subject; a reception unit configured to receive a nuclear magnetic resonance signal generated in the subject due to transmission of the high-frequency magnetic field thereto; a gradient magnetic field application unit configured to apply a gradient magnetic field which adds positional information to the nuclear magnetic resonance signal; a computer configured to control the transmission unit, the reception unit, and the gradient magnetic field application unit, and configured to process the nuclear magnetic resonance signal; and a display unit configured to display an image processed by the computer; and the computer performs a predetermined calculation processing.

Magnetic resonance imaging apparatus

Provided is a technique for calculating an oxygen extraction fraction by using MRI where the oxygen extraction fraction in a brain including brain parenchyma is calculated via a simple processing without an impact on an examinee, such as administration of caffeine. For this purpose, an MRI apparatus of the present invention measures a complex image of nuclear magnetic resonance signals, and calculates from thus measured complex image, a physical property distribution for obtaining a physical property image reflecting the oxygen extraction fraction. Then, thus calculated physical property distribution is separated into tissue-specific physical property distributions for at least two tissues (separated tissue images). After converting any of the separated tissue images into the oxygen extraction fraction, a distribution of the oxygen extraction fraction is estimated based on the condition that a value of any selected pixel is substantially equal to a mean value of pixels surrounding the selected pixel.

Magnetic resonance imaging device and method for calculating oxygen extraction fractions

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

In calculating a local magnetic field distribution caused by a magnetic susceptibility difference between living tissues, using MRI, a local frequency distribution with a high SNR is calculated in a short computation time. Multi-echo complex images obtained by measurement of at least two different echo times using the MRI are converted into low-resolution images. A global frequency distribution caused by global magnetic field changes and an offset phase distribution including a reception phase and a transmission phase are separated from a phase distribution of the low-resolution multi-echo complex images. Thus calculated global frequency distribution and the offset phase distribution are enhanced in resolution. A local frequency distribution of each echo is calculated from the measured multi-echo complex images, the high-resolution global frequency distribution, and the high-resolution offset phase distribution. The local frequency distributions of respective echoes are subjected to weighted averaging, whereby a final local frequency distribution is calculated.

Magnetic resonance imaging apparatus and image processing method

Provided is a technique in calculating a magnetic susceptibility distribution by using an MRI, for reducing artifacts and noise and improving precision in the magnetic susceptibility distribution being calculated. According to this technique, a magnetic field distribution is obtained via a phase image from a complex image acquired through MRI. Under the constraint based on a relational expression between the magnetic field and the magnetic susceptibility, smoothing process is performed iteratively on the magnetic susceptibility distribution calculated from the magnetic field distribution. Specifically, a minimization process for minimizing through the iterative operation, an error function defined by a predetermined initial magnetic susceptibility distribution and the magnetic field distribution is performed, thereby calculating the magnetic susceptibility distribution. At this time, an updated magnetic susceptibility distribution calculated based on the error function during the minimization process is smoothed, every time the updated magnetic susceptibility distribution is calculated.

Magnetic resonance imaging apparatus and quantitative magnetic susceptibility mapping method

In order to eliminate a global phase change caused by static magnetic field inhomogeneity included in a nuclear magnetic resonance signal, focusing on that phase components generated in a nuclear magnetic resonance signal caused by the static magnetic field inhomogeneity is in a predetermined frequency band (low-frequency band), phase components in the frequency band caused by the static magnetic field inhomogeneity is eliminated from an image generated from the nuclear magnetic resonance signal in main imaging. The predetermined frequency band of the phase components caused by the static magnetic field inhomogeneity is calculated from the nuclear magnetic resonance signal obtained in preliminary imaging.

Magnetic resonance imaging apparatus and magnetic resonance imaging method

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.

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Tokyo, Japan

Takenori Murase