Method for synthesis and reconstruction of output signal of quadrature coil of MRI (magnetic resonance imaging) system

A technology of output signals and quadrature coils, which is applied in the field of synthesis and reconstruction of quadrature coil output signals in MRI systems, can solve problems such as inflexibility and inability to obtain synthesis effects, and achieve ideal image effects

Active Publication Date: 2011-05-25

鑫高益医疗设备股份有限公司

5 Cites 0 Cited by

AI-Extracted Technical Summary

Problems solved by technology

This method is relatively rigid. When the actual phase difference between the two sign...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine

Abstract

The present invention relates to a method for synthesis and reconstruction of output signals of a quadrature coil of an MRI (magnetic resonance imaging) system, which is characterized by comprising the following steps: 1, collecting two paths of output signals of the quadrature coil of the MRI system; 2, screening the original output signals S1 and S2 of the path I and the path Q of the quadrature coil and eliminating gain overflow layers; 2, analyzing first signals and finding out the position of maximum signal data in the first signals; 4, finding out the range of full width at half maximum of signal data with a maximum magnitude in the first signals; 5, respectively calculating phase differences of the signal data of the first signals and second signals at each point within the range of the full width at half maximum obtained in the further step, and averaging the phase differences to obtain a final phase difference; and 6, obtaining a final image through synthesizing and reconstructing the original output signals of the path I and the original output signals of the path Q by adopting the final phase difference obtained in the fifth step. Compared with the prior art, the image synthesized and reconstructed in the method has ideal quality.

Application Domain

Measurements using NMR imaging systems

Technology Topic

PhysicsQuadrature filter +4

Image

Examples

Experimental program(1)

Example Embodiment

[0034] The present invention will be described in further detail below in conjunction with the embodiments of the drawings.

[0035] See figure 1 The method for synthesizing and reconstructing output signals of quadrature coils in the MRI system includes the following six steps:

[0036] Step 1. Collect the two output signals of the quadrature coil in the MRI system:

[0037] The orthogonal coils in the MRI system are marked as I and Q respectively, and the magnetic resonance signals induced by the I and Q of the orthogonal coils are amplified and collected by their respective receivers to obtain the I circuits of the orthogonal coils. The original output signal S 1 And the original output signal S of the quadrature coil Q 2;

[0038] I original output signal S 1 And Q original output signal S 2 Both are a two-dimensional data set. If the magnetic resonance signal obtained by the respective receiver contains n layers, then the original output signal S 1 It is a two-dimensional signal data set containing n layers, and each layer contains multiple signal data representing different positions; Q original output signals S 2 also the same;

[0039] Step 2: To the original output signal S of the quadrature coil I and Q 1 , S 2 Carry out a screening to remove the layers of gain overflow:

[0040] First, set a threshold for signal gain overflow in advance. This threshold can be set to different values according to different MRI systems. At present, the threshold of conventional MRI systems is generally 31000, because the original signal after digital-to-analog conversion in ordinary MRI systems is The maximum value is 32767. When the value is greater than this value, the signal will be truncated, and when it is greater than 32000, it is the non-linear region of the signal. Therefore, the threshold value of 31000 in this embodiment can ensure the accuracy of the processed signal. Of course, this value is Adjustable

[0041] Then, to the original output signal S 1 Analyze the data of each layer in the original output signal S1. If it is found that the value of the real part or the imaginary part of any data in a certain layer of the original output signal S1 of the I path is greater than the threshold, then the original output signal S 1 This layer is the gain overflow layer, and the original output signal S 1 All data related to the gain overflow layer are eliminated, and Q original output signal S 2 All the data in the same layer corresponding to the gain overflow layer in the same layer is also eliminated; I route the original output signal S 1 All signals of the layer where the gain does not overflow are recorded as the first signal;

[0042] Finally, the Q original output signal S 2 Analyze the data in each layer, if it is found that Q original output signal S 2 If the value of the real or imaginary part of any one of the data in a certain layer is greater than the threshold, then it is determined that the Q original output signal S 2 This layer in is the gain overflow layer, and the Q original output signal S 2 All data related to the gain overflow layer are eliminated, and the original output signal S 1 All data in the same layer corresponding to the gain overflow layer in the same layer is also eliminated; Q original output signal S 2 All signals of the layer where the mid gain does not overflow are recorded as the second signal;

[0043] Step 3: Analyze the first signal to find the location of the largest signal data in the first signal:

[0044] Analyze the first signal, find out the layer number of the signal data with the largest modulus value in the first signal and the specific position of the signal data in the layer number, and set the first signal with the largest modulus value The signal data is denoted as |S 1 | max , The specific process is as follows:

[0045] 3-1. Start

[0046] 3-2. The number of layers is assigned as 1, and the maximum value of the modulus is assigned as 0;

[0047] 3-3. Judge whether the current layer exceeds the total number of layers, if yes, go to 3-8; if not, go to 3-4;

[0048] 3-4. Determine whether the current layer is a gain overflow layer. If yes, add 1 to the number of layers and return to 3-3; if not, enter 3-5;

[0049] 3-5. Find the signal data with the maximum modulus value in the signal of this layer;

[0050] 3-6. Determine whether the above-mentioned modulus value is greater than the maximum value of the previous signal modulus, if yes, enter 3-7; if not, add 1 to the number of layers and return to 3-3;

[0051] 3-7. Record the maximum value of the signal modulus and the position of the signal. At the same time, add 1 to the number of layers and return to 3-3;

[0052] 3-8, end

[0053] Step 4: Find the half-height range of the signal data whose modulus value is the maximum in the first signal:

[0054] Since the signal noise at positions smaller than the half-height width is larger, the phase fluctuation is larger, and the accuracy of the processing result is lower, the signal in the half-height range is used for analysis in this embodiment;

[0055] In the first signal, the signal data with the maximum modulus value in the first signal |S 1 | max As the center, the phase encoding line where the signal data is located is detected point by point to both sides, first to the starting direction, if a certain signal data S 1 The modulus of (j) is greater than And the last signal data S of the signal data 1 The modulus of (j-1) is less than which is

[0056] | S 1 ( j ) | | S 1 | max 2 , And | S 1 ( j - 1 ) | | S 1 | max 2

[0057] Then set the position of point j as the starting position of the FWHM of the signal data with the maximum modulus value in the first signal;

[0058] Then, to the end direction detection, if a certain signal data S 1 The modulus of (k) is greater than And the signal data next signal data S 1 The modulus of (k+1) is less than which is

[0059] | S 1 ( k ) | | S 1 | max 2 , And | S 1 ( k + 1 ) | | S 1 | max 2

[0060] Then set the position of the k point as the end position of the FWHM of the signal data with the maximum modulus value in the first signal, thereby determining that the FWHM range of the signal data with the maximum modulus value in the first signal is S 1 (j) to S 1 (k);

[0061] Step 5: Calculate the phase difference of the signal data at each point within the half-height range found in step 4 for the first signal and the second signal, and get the final phase difference after averaging:

[0062] In the first signal and the second signal, the signal data at the same position within the half-height range found in step 4 are respectively marked as S 1 (x)=a+bi; S 2 (x)=c+di, where j≤x≤k

[0063] Then the phase difference between the signal data at the x-th position in the first signal and the second signal is arctan ( bc - ad ac + bd ) ;

[0064] Calculate the phase difference of each point corresponding to the same position in the first signal and the second signal in the half-width range found in step 4, and then take the average value, and use the average value as the original output signal of I channel and Q The final phase difference θ of the original output signal;

[0065] Step 6. Use the final phase difference obtained in step 5 to synthesize and reconstruct the original output signals of I and Q to obtain the final image:

[0066] The signal after the synthesis of I original output signal and Q original output signal is S=S 1 +S 2 ×e iθ , And then do a two-dimensional Fourier transform on S to get the final image.

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine

Login to view more

PUM

Description & Claims & Application Information

We can also present the details of the Description, Claims and Application information to help users get a comprehensive understanding of the technical details of the patent, such as background art, summary of invention, brief description of drawings, description of embodiments, and other original content. On the other hand, users can also determine the specific scope of protection of the technology through the list of claims; as well as understand the changes in the life cycle of the technology with the presentation of the patent timeline. Login to view more.

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine

Login to view more

Magnetic core material for electrophotographic developer, carrier for electrophotographic developer, developer, method for producing magnetic core material for electrophotographic developer, method for producing carrier for electrophotographic developer, and method for producing developer

ActiveUS20210080847A1Small environmental dependenceGood imageDevelopersNitrite ionMagnetic core

Owner:POWDERTECH

Curve determination method, device and equipment

PendingCN114245002AGood imageUnsmoothTelevision system detailsColor television detailsOphthalmologyZoom lens

Owner:HANGZHOU HIKVISION DIGITAL TECH

Classification and recommendation of technical efficacy words

Good image

People also interested in

Phase difference

Method for synthesis and reconstruction of output signal of quadrature coil of MRI (magnetic resonance imaging) system

A technology of output signals and quadrature coils, which is applied in the field of synthesis and reconstruction of quadrature coil output signals in MRI systems, can solve problems such as inflexibility and inability to obtain synthesis effects, and achieve ideal image effects

AI-Extracted Technical Summary

Problems solved by technology

Abstract

Image

Examples

Example Embodiment

PUM

Description & Claims & Application Information

Similar technology patents

Image sensor and forming method thereof

Peripheral device of gaming machine, server, and game system

Ultrasonic imaging system and imaging method

Magnetic core material for electrophotographic developer, carrier for electrophotographic developer, developer, method for producing magnetic core material for electrophotographic developer, method for producing carrier for electrophotographic developer, and method for producing developer

Curve determination method, device and equipment

Classification and recommendation of technical efficacy words

Method for Aiding Valve Annuloplasty

Catheter device with a position sensor system for treating a vessel blockage using image monitoring

Image forming device, image forming method and storage medium

Double-camera white balance synchronization method, double-camera white balance synchronization device and terminal

Image capturing apparatus

People also interested in