摘要:
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 set 409 that 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 set 501 which 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.
摘要:
There is provided a technique for, in a medical imaging apparatus enabling imaging of an arbitrary plane in a three-dimensional space, enabling automatic calculation of a slice position and automatic calculation of an extracting slice in MPR, without prolonging examination time. Two-dimensional scout scan similar to that used for manual setting of a slice position is performed, and the obtained scout images are processed to calculate a recommended slice position. Algorithms for the processing and various image processing procedures used for the processing are stored beforehand for every type of imaging region and every type of examination.
摘要:
In order to improve image quality, a technique for obtaining information for eliminating distortions of the k-space in the readout direction and the phase encoding direction caused by the waveform distortion of the gradient magnetic field pulse is provided. A pulse sequence for the main scan is used to repeatedly measure echoes with changing the time integral value of the dephasing pulse for the readout gradient magnetic field. In the above measurement, the phase encoding pulse is not made zero, but two-dimensional data are measured in the same manner as that of the main scan. By using the measured two-dimensional data, correction information for eliminating distortions of the k-space in the readout direction and the phase encoding direction caused by the waveform distortion of the gradient magnetic field pulse is calculated in each of the readout direction and the phase encoding direction.
摘要:
In the diffusion-weighted imaging, amounts of distortion and amounts of phase offset of k-space data due to a temporally changing magnetic field error induced by eddy currents and vibrations associated with application of a diffusion-weighted gradient magnetic field pulse are corrected with good precision to improve image quality. Characteristic data for correcting distortion of k-space data are calculated for every position in the slice direction as peak shifts of projections observed between the cases of applying and not applying an MPG pulse. As the characteristic data, amounts of distortion in the read-out direction and the phase encoding direction and phase offset amounts in a slice plane are calculated.
摘要:
A technique in a medical imaging apparatus being capable of setting any plane in three-dimensional space as an imaging slice is provided, allowing an automatically-set imaging slice to be configured to suit user's preferences, and determine a position of the imaging slice being configured, with respect to an imaging target subject automatically with a high degree of accuracy. Reference information for specifying the imaging slice, set by the user for each imaging site, is associated with the anatomical feature of the imaging site, so as to generate an imaging slice parameter. Upon actual imaging, the imaging slice parameter and the anatomical feature of the imaging target subject obtained by scout imaging are used to determine the imaging slice position of the imaging target subject.
摘要:
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 set 409 that 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 set 501 which 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.
摘要:
A technique in a medical imaging apparatus being capable of setting any plane in three-dimensional space as an imaging slice is provided, allowing an automatically-set imaging slice to be configured to suit user's preferences, and determine a position of the imaging slice being configured, with respect to an imaging target subject automatically with a high degree of accuracy. Reference information for specifying the imaging slice, set by the user for each imaging site, is associated with the anatomical feature of the imaging site, so as to generate an imaging slice parameter. Upon actual imaging, the imaging slice parameter and the anatomical feature of the imaging target subject obtained by scout imaging are used to determine the imaging slice position of the imaging target subject.
摘要:
There is provided a technique for, in a medical imaging apparatus enabling imaging of an arbitrary plane in a three-dimensional space, enabling automatic calculation of a slice position and automatic calculation of an extracting slice in MPR, without prolonging examination time. Two-dimensional scout scan similar to that used for manual setting of a slice position is performed, and the obtained scout images are processed to calculate a recommended slice position. Algorithms for the processing and various image processing procedures used for the processing are stored beforehand for every type of imaging region and every type of examination.
摘要:
In order to improve image quality, a technique for obtaining information for eliminating distortions of the k-space in the readout direction and the phase encoding direction caused by the waveform distortion of the gradient magnetic field pulse is provided. A pulse sequence for the main scan is used to repeatedly measure echoes with changing the time integral value of the dephasing pulse for the readout gradient magnetic field. In the above measurement, the phase encoding pulse is not made zero, but two-dimensional data are measured in the same manner as that of the main scan. By using the measured two-dimensional data, correction information for eliminating distortions of the k-space in the readout direction and the phase encoding direction caused by the waveform distortion of the gradient magnetic field pulse is calculated in each of the readout direction and the phase encoding direction.
摘要:
In the continuous moving table imaging, an image is reconstructed with suppressed artifacts even in imaging under inhomogeneity of static magnetic field.In a magnetic resonance imaging apparatus, signals are measured with moving a table to obtain multiple data sets, and inverse Fourier transform of each data set is carried out in the read-out direction to obtain hybrid data. One-dimensional data are extracted from each hybrid data at a border with respect to the adjacent hybrid data, and correction values for corrections of discontinuity of signal intensity and phase at a border of hybrid data are obtained by using the one-dimensional data. Data obtained by inverse Fourier transform of each hybrid data are corrected by using the correction values, and an image showing continuity for signal intensity and phase is eventually obtained.