摘要:
The present invention provides an image processing technique which enables 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.
摘要:
A magnetic resonance imaging system capable of conducting spectroscopic imaging with an improved SNR without degrading the spatial resolution includes edge-preserving filter processing means for spectroscopic imaging. The edge-preserving filter processing means executes processing including the steps of calculating spectral similarity in spatial neighborhoods (spatially neighboring voxels) at each voxel in spectroscopic imaging data, calculating a spectral weight according to the spectral similarity, and conducting weighted smoothing for compounding spectra of spatial neighborhoods (spatially neighboring voxels) according to the spectral weight.
摘要:
A magnetic resonance imaging (MRI) apparatus for high-speed and high-accuracy detection of cell positions labeled with magnetic nanoparticles. A transmitter coil is controlled to generate amplitude-modulated burst RF pulses as excitation RF pulses whose amplitude is modulated by a function that repeatedly inverts the polarity of multiple high-frequency magnetic field sub-pulses separated time-wise and changes the amplitude at each polarity inversion, moreover the time interval of the amplitude-modulated burst RF pulse is set to effectively 1/(2×a first frequency), and the transmitter coil controlled so the carrier frequency of the amplitude-modulated burst RF pulse is set to a second frequency shifted substantially from the first frequency of the magnetic resonance frequency of the proton at the magnetic field strength in the MRI apparatus. The first frequency is here determined based on magnetic nanoparticle information loaded from the magnetic nanoparticle information storage unit and the magnetic resonance frequency of the proton in the static magnetic field. The MRI apparatus can in this way detect the position of cells labeled with magnetic nanoparticles, with high-speed and high accuracy.
摘要:
Images of two or more kinds of substances showing different chemical shifts, such as water image and metabolite image, are obtained without extending measurement time. For example, images of two or more kinds of desired substances showing different chemical shifts, such as water image and metabolite image, are obtained by one time of execution of an imaging sequence. In this execution, a pre-pulse is applied so that signals of the substances to be separated shift on the image, and magnetic resonance signals are received with receiver RF coils in a number not smaller than the number of types of the substances to be separated. An image reconstructed from the magnetic resonance signals is separated into images of the individual substances using sensitivity maps of the receiver RF coils. Then, correction is performed for returning the shifted image to the original position. Further, residual signals induced by errors generated in the measurement and the separation processing are eliminated by using spectroscopic images obtained after the separation.
摘要:
A method for obtaining the most appropriate amplitude of signal suppression pulse, which suppresses unnecessary signals from the substance not subjected to measurement, highly accurately, swiftly and stably, and an MRI apparatus that enables the optimization are provided.A pulse amplitude adjusting means equipped in the MRI apparatus acquires signals while changing the amplitude of signal suppression pulse and calculates signal absolute values and phase values, and computes reference signals, which are polarized signal absolute values, based on the changes in signal phase values. This reference signals are subjected to polynomial fitting. A value which makes this fitting curve is 0 or closes to 0 is set as the optimal pulse amplitude.
摘要:
A magnetic resonance measurement technique is provided which shortens the measurement time while suppressing artifacts caused by body movement of a measuring object and enables high-speed imaging. An excitation pulse which excites a plurality of slice planes and an excitation pulse which excites slice planes perpendicular to the slice planes are applied and a plurality of substantially parallel linear crossing areas are simultaneously measured. Spatial information of a linear direction of the crossing areas is acquired by modulating a magnetic resonance signal from the crossing areas by a gradient magnetic field. A spatial information of a direction perpendicular to the linear direction is acquired by changing the position of the plane and an image is reconstructed.
摘要:
With minimizing extension of imaging time, the B1 non-uniformity reducing effect of RF shimming is maximized for an imaging section of an arbitrary axis direction and an arbitrary position. B1 distributions are measured for only several sections of one predetermined direction, and a radio frequency magnetic field condition that maximizes the B1 non-uniformity reducing effect for an imaging section of an arbitrary direction and an arbitrary position is calculated from the B1 distribution data. For example, after B1 distributions of only several sections of the AX direction are measured, the optimal radio frequency magnetic field condition for an imaging section of an arbitrary position for the AX direction is obtained by interpolation with optimal radio frequency magnetic field conditions calculated from B1 distributions of two sections near the imaging section, and the optimal radio frequency magnetic field condition for an imaging section of an arbitrary position for the SAG or COR direction is obtained by using only B1 values of a crossing region with the imaging section extracted from the B1 distributions.
摘要:
There is provided a high-frequency coil of an MRI device, which can easily and highly reproducibly reduce electromagnetic coupling between adjacent surface coils among a plurality of surface coils disposed with intervals. An electromagnetic decoupling coil that can generate a magnetic flux for canceling a magnetic flux generated by one of the adjacent surface coils and interlinking with the other surface coil is disposed between the adjacent surface coils. The electromagnetic decoupling coil is provided with a capacitor, and is tuned by means of the capacitor so that the electromagnetic coupling should be minimized in such a range that the resonance frequency thereof should be lower than the resonance frequency of the surface coils.
摘要:
There is a provided a technology of receiving a magnetic resonance signal highly sensitively and with a uniform sensitivity distribution in an RF coil of an MRI device which is an RF coil including a switch circuit of switching a circuit configuration. The RF coil of the MRI device of the present invention includes a switch circuit of switching a circuit configuration. Also, the switch circuit switches the circuit configuration by being driven by a control signal received by wireless. For that purpose, the switch circuit includes an antenna of receiving the control signal and a conversion circuit of converting an alternating current voltage received into a direct current voltage.
摘要:
There is provided a technique for securing a comfortable examination space in a tunnel type MRI apparatus without increasing the manufacturing cost of the MRI apparatus and sacrificing performance thereof. In an RF coil provided with a hollow-shaped outer conductive element and a strip-shaped conductive element disposed along the outer conductive element in the axial direction, meander lines constituting the strip-shaped conductive element are disposed at uneven distances from the outer conductive element to secure an internal space. In order to obtain uniform sensitivity at the center of the RF coil, the strip-shaped conductive element is constituted with N of connected meander lines, and length of the strip-shaped conductive element is adjusted so that, in the strip-shaped conductive element resonating at resonance frequency of the antenna, nodes are formed in a number of (M+1)×N−1, wherein M is 0 or a natural number of 1 or larger.