Abstract: In the present invention, a current plane which is virtually disposed and surrounds a measurement position is assumed from magnetic field measurement values, and a current distribution (or magnetic moment distribution) which mimics a measured magnetic field is reproduced with current potentials. This is used to perform shimming calculation by a truncated singular value decomposition method with discrete shim trays that are actually used and ideal virtual continuous shim trays to carry out shimming under conditions for shimming having a uniformity that is close to ideal shimming.

Abstract: A magnetic moment arrangement calculation method for magnetic field adjustment by combining correction of a component of a low-order mode with correction of a component of a high-order mode among the eigenmodes so as to calculate arrangement of the magnetic moment for approximately correcting the error magnetic field distribution, in which the low-order mode is an eigenmode group from the first of eigenmode numbers assigned to respective eigenmodes in the magnitude order of singular values to an eigenmode number specified by a first threshold value, in which the high-order mode is an eigenmode group with an eigenmode number more than the first threshold value, and in which a correction amount of the component of the high-order mode is smaller than a correction amount of the component of the low-order mode.

Abstract: In order to provide a static magnetic field homogeneity adjustment method capable of reducing an arrangement amount of magnetic pieces and achieving desired magnetic field homogeneity with high accuracy in magnetic field homogeneity adjustment, there is provided a static magnetic field homogeneity adjustment method in an imaging space of computing positions of a plurality of magnetic pieces separated from the imaging space through shimming computation with respect to a static magnetic field in the imaging space generated by a magnetic field generation device, and disposing the plurality of magnetic pieces at the positions obtained through the shimming computation, the method including an adjustment step of imposing restriction that a polarity of a magnetic field distribution generated in the imaging space by the magnetic pieces disposed at the positions is either positive or negative during the shimming computation, and adjusting the static magnetic field homogeneity.

Abstract: In order to reduce errors in assessment of a structure caused by noise and remove the noise superimposed in an image without causing artificiality in the result image after the removal while retaining significant information, a similarity is calculated by comparing a reference image generated from a plurality of original images with each original image and set as an index of noise determination. The respective original images are smoothed and synthesized using the said index to acquire a final image after the noise removal.

Abstract: In order to obtain a highly reliable image with no image distortion or no artifacts, such as ghosting, by compensating for the distortion of an output gradient magnetic field waveform caused by various factors with high accuracy, an input gradient magnetic field waveform and an output gradient magnetic field waveform corresponding to the input gradient magnetic field waveform are calculated, a response function that is a sum of response functions of a plurality of elements affecting the output gradient magnetic field waveform is calculated using the input gradient magnetic field waveform and the output gradient magnetic field waveform, an output gradient magnetic field waveform is calculated from an input gradient magnetic field waveform of a gradient magnetic field pulse set in the imaging sequence using the response function, and various kinds of correction are performed using the calculated value of the calculated output gradient magnetic field waveform.

Abstract: In order to obtain a high-quality image even in multi-slice imaging in a UTE sequence that uses a half RF pulse, a refocusing pulse of the slice gradient magnetic field is adjusted and applied so that the excitation profiles of positive polarity data and negative polarity data have phase distributions that are 180 [deg] inverted with respect to each other in side lobe portions. In addition, the irradiation frequency of the half RF pulse is adjusted so as to eliminate a position shift between the intensity distributions of the positive polarity data and the negative polarity data.

Abstract: 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.

Abstract: In order to obtain highly accurate images with a high SNR without extending measurement time or increasing hardware costs and software processing costs, the present invention narrows a dynamic range (amplitude) of an NMR signal to be received by a reception coil (reception NMR signal) in an MRI apparatus. In order to narrow the amplitude of the reception NMR signal, according to the position of an imaging region, a peak position of the reception NMR signal is shifted from the said position in the present embodiment. The shift is achieved by applying frequency encoding gradient magnetic field pulses whose application amount in the time direction is different according to the position. This is realized by a plurality of gradient magnetic field generating systems that can be driven independently.

Abstract: The present invention obtains high-quality images even in a case of measurement with a radial sampling method. For this purpose, pre-measurement is performed to extract only a component different for each blade from among shift amounts from among echo signals, and a shift amount in k-space of an echo signal by the said component is reflected to a reconstruction process. In the pre-measurement, echo signals are obtained respectively by applying readout gradient magnetic field pulses that change the polarity to the positive and negative and that have the same pulse shape as readout gradient magnetic field pulses to be used in an image acquisition sequence. A shift amount is obtained for each axis of X, Y, and Z of an MRI apparatus as a variation amount of a phase difference between both the echo signals.

Abstract: It is an object of the present invention to provide a technique for reducing the degradation of the image quality due to the phase difference between scanning trajectories (blades) in measurement using a non-orthogonal sampling method. Therefore, in the present invention, correction for reducing the phase difference between a plurality of scanning trajectories (blades) measured by using a non-orthogonal sampling method is performed at the time of image reconstruction. For example, the reduction of the phase difference is performed using a method of matching the phases at the intersections between blades, matching the phases of all blades at positions determined by considering the shift amount in the frequency direction, or canceling out the phase change amount of each blade obtained by calculation.

Abstract: In order to reduce errors in assessment of a structure caused by noise and remove the noise superimposed in an image without causing artificiality in the result image after the removal while retaining significant information, a similarity is calculated by comparing a reference image generated from a plurality of original images with each original image and set as an index of noise determination. The respective original images are smoothed and synthesized using the said index to acquire a final image after the noise removal.

Abstract: 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.

Abstract: In order to obtain a high-quality image even in multi-slice imaging in a UTE sequence that uses a half RF pulse, a refocusing pulse of the slice gradient magnetic field is adjusted and applied so that the excitation profiles of positive polarity data and negative polarity data have phase distributions that are 180 [deg] inverted with respect to each other in side lobe portions. In addition, the irradiation frequency of the half RF pulse is adjusted so as to eliminate a position shift between the intensity distributions of the positive polarity data and the negative polarity data.

Abstract: In order to obtain a highly reliable image with no image distortion or no artifacts, such as ghosting, by compensating for the distortion of an output gradient magnetic field waveform caused by various factors with high accuracy, an input gradient magnetic field waveform and an output gradient magnetic field waveform corresponding to the input gradient magnetic field waveform are calculated, a response function that is a sum of response functions of a plurality of elements affecting the output gradient magnetic field waveform is calculated using the input gradient magnetic field waveform and the output gradient magnetic field waveform, an output gradient magnetic field waveform is calculated from an input gradient magnetic field waveform of a gradient magnetic field pulse set in the imaging sequence using the response function, and various kinds of correction are performed using the calculated value of the calculated output gradient magnetic field waveform.