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Magnetic resonance imaging device and method for determining flip angle

A technology of magnetic resonance imaging and flip angle, which can be used in magnetic resonance measurement, measurement using nuclear magnetic resonance imaging system, measurement device, etc., and can solve problems such as optimal SNR

Active Publication Date: 2015-09-23
HITACHI HEALTHCARE MFG LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In the technique disclosed in Patent Document 1, the aim is to keep the signal intensity constant, so the SNR of the obtained image is not necessarily optimal.

Method used

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  • Magnetic resonance imaging device and method for determining flip angle
  • Magnetic resonance imaging device and method for determining flip angle
  • Magnetic resonance imaging device and method for determining flip angle

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no. 1 approach

[0081] A first embodiment to which the present invention is applied will be described. Hereinafter, in all the drawings for describing the embodiments of the present invention, parts having the same functions are given the same symbols, and overlapping descriptions thereof will be omitted.

[0082] Initially, according to figure 1 The outline of the MRI apparatus 100 of this embodiment will be described. figure 1It is a block diagram showing the overall configuration of the MRI apparatus 100 of the present embodiment. The MRI apparatus 100 of this embodiment obtains a tomographic image of a subject by utilizing the NMR phenomenon, and includes a static magnetic field generating system 20, a gradient magnetic field generating system 30, a sequence generator 40, a high-frequency magnetic field transmitting system (transmitting system) 50, and a signal receiving system. (receiving system) 60, control system (sequence generator 40 and signal processing system 70).

[0083] If t...

no. 2 approach

[0152] Next, a second embodiment to which the present invention is applied will be described. In the first embodiment, the FA of all the reconvergent RF pulses is changed within a possible range, and the FA change shape that maximizes the SNR (minimizes the noise amplification factor NA) is searched for. That is, the number of parameters explored (explored parameters) is the total number of reconvergent RF pulses (the number of echoes) N applied during one TR. For example, the signal strength SS, which is mutually convertible with the FA, may also be used as a search parameter. In this case, the number of search parameters is N. In this embodiment, the number of search parameters is made smaller than N.

[0153] The configurations of the MRI apparatus 100 and the sequence generator 300 of this embodiment are basically the same as those of the first embodiment. In addition, the flow of imaging processing by the signal processing system 70 of this embodiment is also the same a...

no. 3 approach

[0177] Next, a third embodiment to which the present invention is applied will be described. In each of the above-described embodiments, as a specific example, the parameters directly related to the FA variation shape are controlled to minimize the noise amplification factor.

[0178] In the present embodiment, the signal strength change shape is changed to determine a signal strength change shape that minimizes the noise amplification factor, and the FA shape that realizes the signal strength change shape is used as the FA shape used for imaging. That is, information specifying the shape of the signal strength change is used as the search parameter in the second embodiment.

[0179] The MRI apparatus 100 and the sequence generator 300 of this embodiment have basically the same configuration as those of the second embodiment. In addition, the flow of imaging processing by the signal processing system 70 of this embodiment is also the same as that of the second embodiment. Th...

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Abstract

In order to maximize the SNR of the image in consideration of signal correction in the multi-echo sequence, the flip angles of the multiple reconvergent high-frequency magnetic field pulses in the multi-echo imaging sequence are determined, and the signal correction reflecting the acquired multiple echo signals is used The index of the SNR of the final image is changed according to a predetermined optimization method by changing the information for determining the flip angle of each reconvergent RF pulse, and the index is repeatedly calculated to determine the flip angle at which the SNR of the image is the largest.

Description

technical field [0001] The present invention relates to nuclear magnetic resonance imaging (hereinafter referred to as "NMR") that measures nuclear magnetic resonance (hereinafter referred to as "NMR") signals from a subject to image nuclear density distribution, delay time distribution, etc. MRI") technology, in particular an imaging technique using VRFA (Variable Refocus Flip Angle) using multi-echo photography. Background technique [0002] The MRI device is used to measure the NMR signal (echo signal) generated by the spin of the atomic nucleus that constitutes the subject, especially the tissue of the human body, and image the shape or function of the head, abdomen, limbs, etc. in two or three dimensions ( camera) device. In imaging, NMR signals are given different phase codes and frequency codes depending on the gradient magnetic field, and are measured as time-series data. Perform two-dimensional or three-dimensional Fourier transform on the measured echo signal to ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): A61B5/055G01R33/48
CPCG01R33/5617G01R33/583G01R33/543G01R33/56
Inventor 黑川真次
Owner HITACHI HEALTHCARE MFG LTD