CN106125029A - Multi-channel magnetic resonance radio-frequency coil performance estimating method and device thereof - Google Patents
Multi-channel magnetic resonance radio-frequency coil performance estimating method and device thereof Download PDFInfo
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Abstract
The present invention provides a kind of multi-channel magnetic resonance radio-frequency coil performance estimating method and device thereof, and the method includes: obtain the signal pattern in the district to be measured that each channel radio frequency coil is gathered in a multi-channel magnetic resonance radio-frequency coil and corresponding noise image；Each described noise image is utilized to be calculated the noise coupling matrix of described multi-channel magnetic resonance radio-frequency coil；Utilize described signal pattern and described noise coupling matrix, calculated the signal-to-noise ratio image of described multi-channel magnetic resonance radio-frequency coil by quadratic sum method and covariance-weighted and method respectively, obtain the first signal-to-noise ratio image and the second signal-to-noise ratio image；The performance of described multi-channel magnetic resonance radio-frequency coil is assessed by relatively described first signal-to-noise ratio image and described second signal-to-noise ratio image.The present invention can assess the performance of multi-channel magnetic resonance radio-frequency coil simply and effectively.
Description
Technical field
The present invention relates to mr imaging technique field, particularly relate to a kind of multi-channel magnetic resonance radio-frequency coil Performance Evaluation
Method and device thereof.
Background technology
Nuclear magnetic resonance (Magnetic Resonance Imaging, MRI) technology has become as modern medicine clinic and examines
Important means in Duan.RF receiving coil, as receiving chain foremost, plays vital effect to image quality.Penetrate
Frequently the performance of coil directly influences the signal to noise ratio of final gained image.Image taking speed and signal to noise ratio are that magnetic resonance applications is paid close attention to
Important indicator.Multi-channel radio frequency receiving coil can provide the bigger visual field (Field of View, FOV) and relatively high s/n ratio
(Signal to Noise Ratio, SNR).Multi-channel radio frequency receiving coil make mainly comprise tuning, mate, decouple and
The basic processes such as off resonance.Multi-channel radio frequency receiving coil performance is had a direct impact by different interchannel magnetic couplings.General by weight
Fold the magnetic coupling reducing between adjacent coil units, utilize the preamplifier of low input impedance to reduce non-adjacent coil list
Magnetic coupling between unit.Between multi-channel coil unit, decoupling can utilize vector network analyzer to carry out actual measurement.But,
In the application process of actual radio frequency receiving coil, directly measure inconvenient and loaded down with trivial details.And, meet to design and make performance
The RF receiving coil of actual demand, needs the performance of signal to noise ratio the most directly perceived and accurate distribution assessment radio-frequency coil.But,
Currently for the assessment of magnetic resonance Multi-channel radio-frequency coil performance, the only description of signal to noise ratio definition, it is impossible to assessment is penetrated well
Frequently the performance of coil.
Summary of the invention
The present invention provides a kind of multi-channel magnetic resonance radio-frequency coil performance estimating method and device thereof, to solve prior art
In one or more disappearance.
The present invention provides a kind of multi-channel magnetic resonance radio-frequency coil performance estimating method, including: obtain a multi-channel magnetic altogether
The signal pattern in the district to be measured that each channel radio frequency coil in radio-frequency coil that shakes is gathered and corresponding noise image；Utilize each described
Noise image is calculated the noise coupling matrix of described multi-channel magnetic resonance radio-frequency coil；Utilize described signal pattern and described
Noise coupling matrix, calculates described multi-channel magnetic resonance radio-frequency coil by quadratic sum method respectively with covariance-weighted and method
Signal-to-noise ratio image, obtain the first signal-to-noise ratio image and the second signal-to-noise ratio image；By relatively described first signal-to-noise ratio image and
Described second signal-to-noise ratio image assesses the performance of described multi-channel magnetic resonance radio-frequency coil.
In one embodiment, the method also includes: utilize described signal pattern, is calculated described by quadratic sum method
The first reconstruction image in district to be measured；Utilize described signal pattern and described noise coupling matrix, by covariance-weighted and method
It is calculated the second reconstruction image in described district to be measured；Rebuild image according to described first and described second reconstruction image is further
Assess the performance of described multi-channel magnetic resonance radio-frequency coil.
In one embodiment, obtain the district to be measured that in a multi-channel magnetic resonance radio-frequency coil, each channel radio frequency coil is gathered
Signal pattern and corresponding noise image, including: obtain each channel radio frequency coil of described multi-channel magnetic resonance radio-frequency coil
The K spacing wave in the district described to be measured gathered and corresponding K spatial noise；Respectively to described K spacing wave and described K space
Noise makees inverse Fourier transform, generates corresponding to the signal pattern corresponding to each channel radio frequency coil and each channel radio frequency coil
Noise image.
In one embodiment, respectively described K spacing wave and described K spatial noise are made inverse Fourier transform, including: point
Other described K spacing wave and described K spatial noise are made inverse fast fourier transform.
In one embodiment, described noise coupling matrix is:
Φij=< Ni(x,y,z),Nj(x, y, z) >,
Wherein, ΦijRepresenting the numerical value of the i-th row jth row of noise coupling matrix Φ, 1≤i, j≤n, in<,>represents vector
Long-pending operator, Ni(x, y z) represent the noise image corresponding to the i-th channel radio frequency coil, Nj(x, y z) represent jth channel radio frequency
Noise image corresponding to coil, x, y, z represent the coordinate position in district to be measured.
In one embodiment, described first signal-to-noise ratio image is:
Described second signal-to-noise ratio image is:
Wherein, SNRSoSAnd SNRcov-rSoSRepresent described first signal-to-noise ratio image and described second signal-to-noise ratio image, S respectively
Represent all signal pattern Si(i represents the sequence number of radio-frequency coil for x, y, matrix z) constituted, and i is positive integer, SHRepresenting matrix S
Associate matrix, Φ-1Represent that noise coupling matrix Φ's is inverse.
In one embodiment, described first rebuilds image is:
Described second rebuilds image is:
Wherein, ISoSAnd Icov-rSoSRepresenting that described first rebuilds image and described second reconstruction image respectively, S represents all
Signal pattern Si(i represents the sequence number of radio-frequency coil for x, y, matrix z) constituted, and i is positive integer, SHThe conjugation of representing matrix S turns
Put matrix, Φ-1Represent that noise coupling matrix Φ's is inverse.
The present invention also provides for a kind of multi-channel magnetic resonance radio-frequency coil capability evaluating device, including: signal and noise image
Acquiring unit, for obtaining the signal graph in the district to be measured that each channel radio frequency coil is gathered in a multi-channel magnetic resonance radio-frequency coil
Picture and corresponding noise image；Noise coupling matrix acquiring unit, is used for utilizing each described noise image to be calculated described many
The noise coupling matrix of multi-channel magnetic resonance radio-frequency coil；Signal-to-noise ratio image acquiring unit, is used for utilizing described signal pattern and institute
State noise coupling matrix, calculate described multi-channel magnetic resonance radio frequency line by quadratic sum method respectively with covariance-weighted and method
The signal-to-noise ratio image of circle, obtains the first signal-to-noise ratio image and the second signal-to-noise ratio image；First coil Performance Evaluation unit, is used for leading to
Cross more described first signal-to-noise ratio image and the property of the described second signal-to-noise ratio image described multi-channel magnetic resonance radio-frequency coil of assessment
Energy.
In one embodiment, this device also includes: the first image reconstruction unit, is used for utilizing described signal pattern, passes through
Quadratic sum method is calculated the first reconstruction image in described district to be measured；Second image reconstruction unit, is used for utilizing described signal
Image and described noise coupling matrix, be calculated the second reconstruction image in described district to be measured by covariance-weighted and method；
Second coil performance assessment unit, assesses described for rebuilding image according to described first reconstruction image and described second further
The performance of multi-channel magnetic resonance radio-frequency coil.
In one embodiment, described signal and noise image acquiring unit, including: K spacing wave and noise acquisition module,
For obtaining the K spacing wave in the district described to be measured that each channel radio frequency coil of described multi-channel magnetic resonance radio-frequency coil is gathered
With corresponding K spatial noise；Signal and noise image acquisition module, for making an uproar to described K spacing wave and described K space respectively
Sound makees inverse Fourier transform, generates making an uproar corresponding to the signal pattern corresponding to each channel radio frequency coil and each channel radio frequency coil
Acoustic image.
In one embodiment, described signal and noise image acquisition module, including: inverse fast fourier transform module, use
In respectively described K spacing wave and described K spatial noise being made inverse fast fourier transform.
The multi-channel magnetic resonance radio-frequency coil performance estimating method of the embodiment of the present invention and device, obtaining signal-to-noise ratio image
Time, it is contemplated that the noise coupling matrix of noise coupling factor between each radio-frequency coil can be reflected, it is possible to obtain accurate
Signal-to-noise ratio image.Be calculated signal-to-noise ratio image by two kinds of distinct methods further, and find two kinds of signal-to-noise ratio images it
Between difference and multi-channel magnetic resonance radio-frequency coil property relationship on the basis of, by comparing two kinds of image evaluation multi-channel magnetics altogether
Shake the performance of radio-frequency coil, there is simplicity, directly perceived and accurate advantage.Further by comprising noise coupling factor and not comprising
The performance rebuilding image evaluation multi-channel magnetic resonance radio-frequency coil of noise coupling factor, the assessment knot of comprehensive signal-to-noise ratio image
Really, it is possible to consider design requirement and the noise factor of multi-channel magnetic resonance radio-frequency coil, contribute to weighing multi-channel magnetic altogether
The performance of radio-frequency coil of shaking and manufacturing cost.
Accompanying drawing explanation
In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
In having technology to describe, the required accompanying drawing used is briefly described, it should be apparent that, the accompanying drawing in describing below is only this
Some embodiments of invention, for those of ordinary skill in the art, on the premise of not paying creative work, it is also possible to
Other accompanying drawing is obtained according to these accompanying drawings.In the accompanying drawings:
Fig. 1 is the schematic flow sheet of the multi-channel magnetic resonance radio-frequency coil performance estimating method of one embodiment of the invention；
Fig. 2 is the schematic flow sheet of the multi-channel magnetic resonance radio-frequency coil performance estimating method of another embodiment of the present invention；
Fig. 3 is to obtain signal pattern and the method flow schematic diagram of noise image in one embodiment of the invention；
Fig. 4 is the structural representation of the multi-channel magnetic resonance radio-frequency coil capability evaluating device of one embodiment of the invention；
Fig. 5 is the structural representation of the multi-channel magnetic resonance radio-frequency coil capability evaluating device of another embodiment of the present invention；
Fig. 6 is signal and the structural representation of noise image acquiring unit in one embodiment of the invention.
Detailed description of the invention
For making the purpose of the embodiment of the present invention, technical scheme and advantage clearer, below in conjunction with the accompanying drawings to this
Bright embodiment is described in further details.Here, the schematic description and description of the present invention is used for explaining the present invention, but also
Not as a limitation of the invention.
Asking of multi-channel magnetic resonance radio-frequency coil performance cannot be assessed intuitively, accurately and easily to solve prior art
Topic, inventor designs a kind of multi-channel magnetic resonance radio-frequency coil performance estimating method through creative work.
Fig. 1 is the schematic flow sheet of the multi-channel magnetic resonance radio-frequency coil performance estimating method of one embodiment of the invention.As
Shown in Fig. 1, the multi-channel magnetic resonance radio-frequency coil performance estimating method of the embodiment of the present invention, it may include step:
S110: obtain the signal graph in the district to be measured that each channel radio frequency coil is gathered in a multi-channel magnetic resonance radio-frequency coil
Picture and corresponding noise image；
S120: utilize each above-mentioned noise image to be calculated the noise coupling square of above-mentioned multi-channel magnetic resonance radio-frequency coil
Battle array；
S130: utilize above-mentioned signal pattern and above-mentioned noise coupling matrix, by quadratic sum method and covariance-weighted and
Method calculates the signal-to-noise ratio image of above-mentioned multi-channel magnetic resonance radio-frequency coil respectively, obtains the first signal-to-noise ratio image and the second noise
Compare image；
S140: assess above-mentioned multi-channel magnetic altogether by relatively above-mentioned first signal-to-noise ratio image and above-mentioned second signal-to-noise ratio image
Shake the performance of radio-frequency coil.
In above-mentioned steps S110, this district to be measured can be the region of interest of object to be imaged.This noise image can be
The noise that radio-frequency coil produces when gathering the signal in this district to be measured.
In above-mentioned steps S120, the matrix element of this noise coupling matrix can be by making an uproar corresponding to each channel radio frequency coil
Acoustic image is made inner product between any two and is generated.
In above-mentioned steps S130, this noise coupling matrix can represent that the coupling between each passage coil is to signal to noise ratio
Impact, so utilizing signal pattern and noise coupling matrix can obtain more accurate signal-to-noise ratio image.
In above-mentioned steps S140, inventor finds the multi-channel magnetic resonance radio-frequency coil different for performance, by flat
Side and the first signal-to-noise ratio image of obtaining of method and the second signal-to-noise ratio image of being obtained by covariance-weighted and method are the most not
With, so inventor's consideration assesses this multi-channel magnetic altogether by comparing this first signal-to-noise ratio image and this second signal-to-noise ratio image
Shake the performance of radio-frequency coil.Specifically, can comment according to the concordance of this first signal-to-noise ratio image and the second signal-to-noise ratio image
Estimating the performance of this multi-channel magnetic resonance radio-frequency coil, such as, this first signal-to-noise ratio image and the second signal-to-noise ratio image are the most consistent, should
Multi-channel magnetic resonance radio-frequency coil interchannel coupling more weak, coil decoupling performance is the best, on the contrary this first signal-to-noise ratio image and
Second signal-to-noise ratio image is the most inconsistent, and the performance of this multi-channel magnetic resonance radio-frequency coil is the poorest.Consequently, it is possible to can comment well
Estimate the signal-to-noise performance of multi-channel magnetic resonance radio-frequency coil.
The multi-channel magnetic resonance radio-frequency coil performance estimating method of the embodiment of the present invention, when obtaining signal-to-noise ratio image, examines
Consider the noise coupling matrix that can reflect noise coupling factor between each radio-frequency coil, it is possible to obtain accurate signal to noise ratio
Image.It is calculated signal-to-noise ratio image further by two kinds of distinct methods, and in the difference found between two kinds of signal-to-noise ratio images
Different with multi-channel magnetic resonance radio-frequency coil property relationship on the basis of, by comparing two kinds of image evaluation multi-channel magnetic resonance radio frequencies
The performance of coil, has simplicity, directly perceived and accurate advantage.
In one embodiment, above-mentioned noise coupling matrix can be:
Φij=< Ni(x,y,z),Nj(x, y, z) >,
Wherein, ΦijRepresenting the numerical value of the i-th row jth row of noise coupling matrix Φ, 1≤i, j≤n, in<,>represents vector
Long-pending operator, Ni(x, y z) represent the noise image corresponding to the i-th channel radio frequency coil, Nj(x, y z) represent jth channel radio frequency
Noise image corresponding to coil, x, y, z represent the coordinate position in district to be measured.Noise corresponding to i-th channel radio frequency coil
Image Ni(x, y, noise image N z) and corresponding to jth channel radio frequency coilj(x, y z) obtain i-th row of matrix Φ as inner product
The numerical value of jth row.This noise coupling matrix computational approach is simple, it is possible to effectively reflect coupling between each channel radio frequency coil because of
Element.
In one embodiment,
Above-mentioned first signal-to-noise ratio image is:
Above-mentioned second signal-to-noise ratio image is:
Wherein, SNRSoSAnd SNRcov-rSoSRepresent above-mentioned first signal-to-noise ratio image and above-mentioned second signal-to-noise ratio image, S respectively
Represent all signal pattern Si(i represents the sequence number of radio-frequency coil for x, y, matrix z) constituted, and i is positive integer, SHRepresenting matrix S
Associate matrix, Φ-1Represent that noise coupling matrix Φ's is inverse.
In the present embodiment, it is possible to considering that between each channel radio frequency coil, coupling factor is to signal to noise ratio shadow by distinct methods
The calculating of signal-to-noise ratio image is effectively realized on the basis of sound.
Fig. 2 is the schematic flow sheet of the multi-channel magnetic resonance radio-frequency coil performance estimating method of another embodiment of the present invention.
As in figure 2 it is shown, the multi-channel magnetic resonance radio-frequency coil performance estimating method of the embodiment of the present invention, may further comprise the step of:
S150: utilize above-mentioned signal pattern, is calculated the first reconstruction image in above-mentioned district to be measured by quadratic sum method；
S160: utilize above-mentioned signal pattern and above-mentioned noise coupling matrix, be calculated by covariance-weighted and method
The second reconstruction image in above-mentioned district to be measured；
S170: rebuild image according to above-mentioned first and above-mentioned second reconstruction image assesses above-mentioned multi-channel magnetic resonance further
The performance of radio-frequency coil.
Above-mentioned steps S150 rebuilds image by quadratic sum method calculated first and does not accounts for noise coupling
Impact, rebuilds image by covariance-weighted and method calculated second in above-mentioned steps S160 and considers noise coupling
Impact, consequently, it is possible to the performance of radio-frequency coil can be assessed from different perspectives.
In above-mentioned steps S170, can be by comparing this first reconstruction image and this second reconstruction above-mentioned step of image inspection
The assessment result of rapid S140.Can be assessed this further by this first resolution rebuild in image and this second reconstruction image
The definition case of Multi-channel radio-frequency coil.Such as, when learning that the resolution of radio-frequency coil enough uses by reconstruction image,
Can lower the requirement to signal to noise ratio, such that it is able to reduce radio frequency line as far as possible on the basis of radio frequency coil designs requires ensureing
Circle manufacturing cost and the requirement to manufacturing process.
The multi-channel magnetic resonance radio-frequency coil performance estimating method of the embodiment of the present invention, further by comprising noise coupling
Factor and do not comprise noise coupling factor rebuild image evaluation multi-channel magnetic resonance radio-frequency coil performance, comprehensive signal to noise ratio figure
The assessment result of picture, it is possible to consider design requirement and the noise factor of multi-channel magnetic resonance radio-frequency coil, contributes to balance
The performance of multi-channel magnetic resonance radio-frequency coil and manufacturing cost.
In one embodiment, utilize above-mentioned signal pattern, be calculated the first of above-mentioned district to be measured by quadratic sum method
Rebuilding image can be:
Utilize above-mentioned signal pattern and above-mentioned noise coupling matrix, be calculated above-mentioned treating by covariance-weighted and method
The the second reconstruction image surveying district can be:
Wherein, ISoSAnd Icov-rSoSRepresenting that above-mentioned first rebuilds image and above-mentioned second reconstruction image respectively, S represents all
Signal pattern Si(i represents the sequence number of radio-frequency coil for x, y, matrix z) constituted, and i is positive integer, SHThe conjugation of representing matrix S turns
Put matrix, Φ-1Represent that noise coupling matrix Φ's is inverse.
In the present embodiment, can effectively be calculated reconstruction image by quadratic sum method and covariance-weighted and method.
In one embodiment, the difference comparing the first signal-to-noise ratio image and the second signal-to-noise ratio image is represented by: ratio=
(Icov-rSoS-ISoS)/ISoS* 100%.When image difference ratio is less than or equal to 10%, coupling ratio between coil channel can be described
More weak, coil decoupling performance is relatively good；When ratio is more than 10%, can illustrate to couple between coil channel stronger.
Fig. 3 is to obtain signal pattern and the method flow schematic diagram of noise image in one embodiment of the invention.Such as Fig. 3 institute
Show, in above-mentioned steps S110, obtain the district to be measured that in a multi-channel magnetic resonance radio-frequency coil, each channel radio frequency coil is gathered
Signal pattern and the method for corresponding noise image, it may include step:
S111: obtain the district above-mentioned to be measured that each channel radio frequency coil of above-mentioned multi-channel magnetic resonance radio-frequency coil gathered
K spacing wave and corresponding K spatial noise；
S112: respectively above-mentioned K spacing wave and above-mentioned K spatial noise are made inverse Fourier transform, generate each channel radio frequency
Signal pattern corresponding to coil and the noise image corresponding to each channel radio frequency coil.
In the present embodiment, the data of image space can be readily obtained according to the K space data collected.
In one embodiment, in above-mentioned steps S112, respectively above-mentioned K spacing wave and above-mentioned K spatial noise are made inverse
The method of Fourier transformation, it may include step:
S1121: respectively above-mentioned K spacing wave and above-mentioned K spatial noise are made inverse fast fourier transform.
Original K spatial noise according to each channel radio frequency coil collected obtains noise image, specifically calculates public affairs
Formula can be:
Ni(x, y, z)=IFFT (KNi(x, y, z)),
Wherein, Ni(x, y, z) represent the noise image corresponding to the i-th channel radio frequency coil, and x, y, z represent in district to be measured
Coordinate position, IFFT () represents inverse fast fourier transform, KNi(x, y z) represent the K space corresponding to i-th radio-frequency coil
Noise.
Original K spacing wave according to each channel radio frequency coil collected obtains signal pattern, specifically calculates public affairs
Formula can be:
Si(x, y, z)=IFFT (KSi(x, y, z)),
Wherein, Si(x, y, z) represent the signal pattern corresponding to i-th radio-frequency coil, and x, y, z represent the seat in district to be measured
Cursor position, IFFT () represents inverse fast fourier transform, KSi(x, y z) represent the K spacing wave that i-th radio-frequency coil gathers.
In the present embodiment, utilize inverse fast fourier transform to obtain view data, calculate speed faster.
The multi-channel magnetic resonance radio-frequency coil performance estimating method of the embodiment of the present invention, when obtaining signal-to-noise ratio image, examines
Consider the noise coupling matrix that can reflect noise coupling factor between each radio-frequency coil, it is possible to obtain accurate signal to noise ratio
Image.It is calculated signal-to-noise ratio image further by two kinds of distinct methods, and in the difference found between two kinds of signal-to-noise ratio images
Different with multi-channel magnetic resonance radio-frequency coil property relationship on the basis of, by comparing two kinds of image evaluation multi-channel magnetic resonance radio frequencies
The performance of coil, has simplicity, directly perceived and accurate advantage.Further by comprising noise coupling factor and not comprising noise coupling
The performance rebuilding image evaluation multi-channel magnetic resonance radio-frequency coil of conjunction factor, the assessment result of comprehensive signal-to-noise ratio image, it is possible to
Consider design requirement and the noise factor of multi-channel magnetic resonance radio-frequency coil, contribute to weighing multi-channel magnetic resonance radio frequency line
The performance of circle and manufacturing cost.
Based on the inventive concept identical with the multi-channel magnetic resonance radio-frequency coil performance estimating method shown in Fig. 1, the application
Embodiment additionally provides a kind of multi-channel magnetic resonance radio-frequency coil capability evaluating device, as described in example below.Owing to these are many
Multi-channel magnetic resonance radio-frequency coil capability evaluating device solves principle and the multi-channel magnetic resonance radio-frequency coil Performance Evaluation side of problem
Method is similar, and therefore the enforcement of this multi-channel magnetic resonance radio-frequency coil capability evaluating device may refer to multi-channel magnetic resonance radio frequency line
The enforcement of circle performance estimating method, repeats no more in place of repetition.
Fig. 4 is the structural representation of the multi-channel magnetic resonance radio-frequency coil capability evaluating device of one embodiment of the invention.As
Shown in Fig. 4, the multi-channel magnetic resonance radio-frequency coil capability evaluating device of the embodiment of the present invention, it may include: signal and noise image
Acquiring unit 210, noise coupling matrix acquiring unit 220, signal-to-noise ratio image acquiring unit 230 and first coil Performance Evaluation list
Unit 240, above-mentioned each unit is linked in sequence.
Signal and noise image acquiring unit 210 are for obtaining each channel radio frequency line in a multi-channel magnetic resonance radio-frequency coil
The signal pattern in the district to be measured that circle is gathered and corresponding noise image.
Noise coupling matrix acquiring unit 220 is used for utilizing each above-mentioned noise image to be calculated above-mentioned multi-channel magnetic resonance
The noise coupling matrix of radio-frequency coil.
Signal-to-noise ratio image acquiring unit 230 is used for utilizing above-mentioned signal pattern and above-mentioned noise coupling matrix, by square
Signal-to-noise ratio image with method and covariance-weighted and method calculate above-mentioned multi-channel magnetic resonance radio-frequency coil respectively, obtains first
Signal-to-noise ratio image and the second signal-to-noise ratio image.
First coil Performance Evaluation unit 240 is for by relatively above-mentioned first signal-to-noise ratio image and above-mentioned second signal to noise ratio
The performance of image evaluation above-mentioned multi-channel magnetic resonance radio-frequency coil.
The multi-channel magnetic resonance radio-frequency coil capability evaluating device of the embodiment of the present invention, by signal-to-noise ratio image acquiring unit
When obtaining signal-to-noise ratio image, it is contemplated that the noise coupling matrix of noise coupling factor between each radio-frequency coil can be reflected, so energy
Access accurate signal-to-noise ratio image.Signal-to-noise ratio image acquiring unit is calculated noise by two kinds of distinct methods further
Ratio image, and on the basis of the difference considered between two kinds of signal-to-noise ratio images with multi-channel magnetic resonance radio-frequency coil property relationship
On, by comparing the performance of two kinds of image evaluation multi-channel magnetic resonance radio-frequency coils, there is simplicity, directly perceived and accurate advantage.
In one embodiment, above-mentioned noise coupling matrix is:
Φij=< Ni(x,y,z),Nj(x, y, z) >,
Wherein, ΦijRepresenting the numerical value of the i-th row jth row of noise coupling matrix Φ, 1≤i, j≤n, in<,>represents vector
Long-pending operator, Ni(x, y, z) with the noise image represented corresponding to i-th radio-frequency coil, Nj(x, y z) represent jth radio frequency line
Noise image corresponding to circle, x, y, z represent the coordinate position in district to be measured.Noise pattern corresponding to i-th channel radio frequency coil
As Ni(x, y, noise image N z) and corresponding to jth channel radio frequency coilj(x, y z) obtain i-th row of matrix Φ as inner product
The numerical value of j row.This noise coupling matrix computational approach is simple, it is possible to effectively reflect coupling between each channel radio frequency coil because of
Element.
In one embodiment,
Above-mentioned first signal-to-noise ratio image can be:
Above-mentioned second signal-to-noise ratio image can be:
Wherein, SNRSoSAnd SNRcov-rSoSRepresent above-mentioned first signal-to-noise ratio image and above-mentioned second signal-to-noise ratio image, S respectively
Represent all signal pattern Si(i represents the sequence number of radio-frequency coil for x, y, matrix z) constituted, and i is positive integer, SHRepresenting matrix S
Associate matrix, Φ-1Represent that noise coupling matrix Φ's is inverse.
In the present embodiment, it is possible to considering that between each channel radio frequency coil, coupling factor is to signal to noise ratio shadow by distinct methods
The calculating of signal-to-noise ratio image is effectively realized on the basis of sound.
Fig. 5 is the structural representation of the multi-channel magnetic resonance radio-frequency coil capability evaluating device of another embodiment of the present invention.
As it is shown in figure 5, the multi-channel magnetic resonance radio-frequency coil capability evaluating device shown in Fig. 4, may also include that the first image reconstruction unit
250, the second image reconstruction unit 260 and the second coil performance assessment unit 270, above-mentioned each sequence of modules connects, the first image
Reconstruction unit 250 is connected with first coil Performance Evaluation unit 240.
First image reconstruction unit 250 is used for utilizing above-mentioned signal pattern, is calculated above-mentioned treating by quadratic sum method
Survey the first reconstruction image in district.
Second image reconstruction unit 260 is used for utilizing above-mentioned signal pattern and above-mentioned noise coupling matrix, passes through covariance
Weighted sum method is calculated the second reconstruction image in above-mentioned district to be measured.
Second coil performance assessment unit 270 enters one for rebuilding image according to above-mentioned first reconstruction image and above-mentioned second
Step assesses the performance of above-mentioned multi-channel magnetic resonance radio-frequency coil.
The multi-channel magnetic resonance radio-frequency coil capability evaluating device of the embodiment of the present invention, further by comprising noise coupling
Factor and do not comprise noise coupling factor rebuild image evaluation multi-channel magnetic resonance radio-frequency coil performance, comprehensive signal to noise ratio figure
The assessment result of picture, it is possible to consider design requirement and the noise factor of multi-channel magnetic resonance radio-frequency coil, contributes to balance
The performance of multi-channel magnetic resonance radio-frequency coil and manufacturing cost.
In one embodiment,
Above-mentioned first rebuilds image can be:
Above-mentioned second rebuilds image can be:
Wherein, ISoSAnd Icov-rSoSRepresenting that above-mentioned first rebuilds image and above-mentioned second reconstruction image respectively, S represents all
Signal pattern Si(i represents the sequence number of radio-frequency coil for x, y, matrix z) constituted, and i is positive integer, SHThe conjugation of representing matrix S turns
Put matrix, Φ-1Represent that noise coupling matrix Φ's is inverse.
In the present embodiment, can effectively be calculated reconstruction by the first image reconstruction unit and the second image reconstruction unit
Image.
Fig. 6 is signal and the structural representation of noise image acquiring unit in one embodiment of the invention.As shown in Figure 6, letter
Number and noise image acquiring unit 210, it may include: K spacing wave and noise acquisition module 211 and signal and noise image obtain
Module 212, the two is connected with each other.
K spacing wave and noise acquisition module 211 are penetrated for each passage obtaining above-mentioned multi-channel magnetic resonance radio-frequency coil
Frequently the K spacing wave in the district above-mentioned to be measured that coil is gathered and corresponding K spatial noise.
Signal and noise image acquisition module 212 are for making inverse Fu to above-mentioned K spacing wave and above-mentioned K spatial noise respectively
In leaf transformation, generate the signal pattern corresponding to each channel radio frequency coil and the noise image corresponding to each channel radio frequency coil.
In the present embodiment, signal and noise image acquisition module can readily obtain according to the K space data collected
The data of image space.
In one embodiment, signal and noise image acquisition module 212, it may include inverse fast fourier transform module
2121。
Inverse fast fourier transform module 2121 is inverse fast for making above-mentioned K spacing wave and above-mentioned K spatial noise respectively
Speed Fourier transformation.
Inverse fast fourier transform module 2121 is according to the original K spatial noise of each channel radio frequency coil collected
Obtaining noise image, specific formula for calculation can be:
Ni(x, y, z)=IFFT (KNi(x, y, z)),
Wherein, Ni(x, y, z) represent the noise image corresponding to i-th radio-frequency coil, and x, y, z represent the seat in district to be measured
Cursor position, IFFT () represents inverse fast fourier transform, KNi(x, y z) represent to make an uproar in the K space corresponding to i-th radio-frequency coil
Sound.
Inverse fast fourier transform module 2121 is according to the original K spacing wave of each channel radio frequency coil collected
Obtaining signal pattern, specific formula for calculation can be:
Si(x, y, z)=IFFT (KSi(x, y, z)),
Wherein, Si(x, y, z) represent the signal pattern corresponding to i-th radio-frequency coil, and x, y, z represent the seat in district to be measured
Cursor position, IFFT () represents inverse fast fourier transform, KSi(x, y z) represent the K spacing wave that i-th radio-frequency coil gathers.
In the present embodiment, inverse fast fourier transform module 2121 utilizes inverse fast fourier transform to obtain view data,
Calculate speed faster.
The multi-channel magnetic resonance radio-frequency coil capability evaluating device of the embodiment of the present invention, signal-to-noise ratio image acquiring unit is obtaining
When obtaining signal-to-noise ratio image, it is contemplated that the noise coupling matrix of noise coupling factor between each radio-frequency coil can be reflected, it is possible to
Obtain accurate signal-to-noise ratio image.Signal-to-noise ratio image acquiring unit is calculated signal to noise ratio by two kinds of distinct methods further
Image, and by first coil Performance Evaluation unit difference between two kinds of signal-to-noise ratio images and multi-channel magnetic resonance radio frequency line
On the basis of circle property relationship, by comparing the performance of two kinds of image evaluation multi-channel magnetic resonance radio-frequency coils, there is simplicity, straight
See and accurate advantage.Further by the performance of the second coil performance assessment unit evaluation multi-channel magnetic resonance radio-frequency coil,
The assessment result of comprehensive signal-to-noise ratio image, it is possible to consider the design requirement of multi-channel magnetic resonance radio-frequency coil and noise because of
Element, contributes to weighing performance and the manufacturing cost of multi-channel magnetic resonance radio-frequency coil.
In the description of this specification, reference term " embodiment ", " specific embodiment ", " some enforcements
Example ", " such as ", " example ", the description of " concrete example " or " some examples " etc. mean to combine this embodiment or example describes
Specific features, structure, material or feature are contained at least one embodiment or the example of the present invention.In this manual,
The schematic representation of above-mentioned term is not necessarily referring to identical embodiment or example.And, the specific features of description, knot
Structure, material or feature can combine in any one or more embodiments or example in an appropriate manner.
Those skilled in the art are it should be appreciated that embodiments of the invention can be provided as method, system or computer program
Product.Therefore, the reality in terms of the present invention can use complete hardware embodiment, complete software implementation or combine software and hardware
Execute the form of example.And, the present invention can use at one or more computers wherein including computer usable program code
The upper computer program product implemented of usable storage medium (including but not limited to disk memory, CD-ROM, optical memory etc.)
The form of product.
The present invention is with reference to method, equipment (system) and the flow process of computer program according to embodiments of the present invention
Figure and/or block diagram describe.It should be understood that can the most first-class by computer program instructions flowchart and/or block diagram
Flow process in journey and/or square frame and flow chart and/or block diagram and/or the combination of square frame.These computer programs can be provided
Instruction arrives the processor of general purpose computer, special-purpose computer, Embedded Processor or other programmable data processing device to produce
A raw machine so that the instruction performed by the processor of computer or other programmable data processing device is produced for real
The device of the function specified in one flow process of flow chart or multiple flow process and/or one square frame of block diagram or multiple square frame now.
These computer program instructions may be alternatively stored in and computer or other programmable data processing device can be guided with spy
Determine in the computer-readable memory that mode works so that the instruction being stored in this computer-readable memory produces and includes referring to
Make the manufacture of device, this command device realize at one flow process of flow chart or multiple flow process and/or one square frame of block diagram or
The function specified in multiple square frames.
These computer program instructions also can be loaded in computer or other programmable data processing device so that at meter
Perform sequence of operations step on calculation machine or other programmable devices to produce computer implemented process, thus at computer or
The instruction performed on other programmable devices provides for realizing at one flow process of flow chart or multiple flow process and/or block diagram one
The step of the function specified in individual square frame or multiple square frame.
Particular embodiments described above, has been carried out the purpose of the present invention, technical scheme and beneficial effect the most in detail
Describe in detail bright, be it should be understood that the specific embodiment that the foregoing is only the present invention, the guarantor being not intended to limit the present invention
Protect scope, all within the spirit and principles in the present invention, any modification, equivalent substitution and improvement etc. done, should be included in this
Within the protection domain of invention.
Claims (11)
1. a multi-channel magnetic resonance radio-frequency coil performance estimating method, it is characterised in that including:
Obtain in a multi-channel magnetic resonance radio-frequency coil signal pattern in the district to be measured that each channel radio frequency coil is gathered and corresponding
Noise image；
Each described noise image is utilized to be calculated the noise coupling matrix of described multi-channel magnetic resonance radio-frequency coil；
Utilize described signal pattern and described noise coupling matrix, counted respectively with covariance-weighted and method by quadratic sum method
Calculate the signal-to-noise ratio image of described multi-channel magnetic resonance radio-frequency coil, obtain the first signal-to-noise ratio image and the second signal-to-noise ratio image；
Described multi-channel magnetic resonance radio frequency line is assessed by relatively described first signal-to-noise ratio image and described second signal-to-noise ratio image
The performance of circle.
2. multi-channel magnetic resonance radio-frequency coil performance estimating method as claimed in claim 1, it is characterised in that also include:
Utilize described signal pattern, be calculated the first reconstruction image in described district to be measured by quadratic sum method；
Utilize described signal pattern and described noise coupling matrix, be calculated described district to be measured by covariance-weighted and method
Second reconstruction image；
Rebuild image according to described first and described second reconstruction image assesses described multi-channel magnetic resonance radio-frequency coil further
Performance.
3. multi-channel magnetic resonance radio-frequency coil performance estimating method as claimed in claim 1, it is characterised in that obtain a manifold
The signal pattern in the district to be measured that each channel radio frequency coil is gathered and corresponding noise image in road magnetic resonance radio frequency coil, bag
Include:
Obtain the K spacing wave in the district described to be measured that each channel radio frequency coil of described multi-channel magnetic resonance radio-frequency coil is gathered
With corresponding K spatial noise；
Respectively described K spacing wave and described K spatial noise are made inverse Fourier transform, generate corresponding to each channel radio frequency coil
Signal pattern and each channel radio frequency coil corresponding to noise image.
4. multi-channel magnetic resonance radio-frequency coil performance estimating method as claimed in claim 3, it is characterised in that respectively to described
K spacing wave and described K spatial noise make inverse Fourier transform, including:
Respectively described K spacing wave and described K spatial noise are made inverse fast fourier transform.
5. multi-channel magnetic resonance radio-frequency coil performance estimating method as claimed in claim 1, it is characterised in that described noise coupling
Conjunction matrix is:
Φij=< Ni(x,y,z),Nj(x, y, z) >,
Wherein, ΦijRepresenting the numerical value of the i-th row jth row of noise coupling matrix Φ, 1≤i, j≤n,<,>represents inner product of vectors fortune
Operator, Ni(x, y z) represent the noise image corresponding to the i-th channel radio frequency coil, Nj(x, y z) represent jth channel radio frequency coil
Corresponding noise image, x, y, z represent the coordinate position in district to be measured.
6. multi-channel magnetic resonance radio-frequency coil performance estimating method as claimed in claim 1, it is characterised in that
Described first signal-to-noise ratio image is:
Described second signal-to-noise ratio image is:
Wherein, SNRSoSAnd SNRcov-rSoSRepresenting described first signal-to-noise ratio image and described second signal-to-noise ratio image respectively, S represents
All signal pattern Si(i represents the sequence number of radio-frequency coil for x, y, matrix z) constituted, and i is positive integer, SHRepresenting matrix S is total to
Yoke transposed matrix, Φ-1Represent that noise coupling matrix Φ's is inverse.
7. multi-channel magnetic resonance radio-frequency coil performance estimating method as claimed in claim 2, it is characterised in that
Described first rebuilds image is:
Described second rebuilds image is:
Wherein, ISoSAnd Icov-rSoSRepresenting that described first rebuilds image and described second reconstruction image respectively, S represents all signals
Image Si(i represents the sequence number of radio-frequency coil for x, y, matrix z) constituted, and i is positive integer, SHThe conjugate transpose square of representing matrix S
Battle array, Φ-1Represent that noise coupling matrix Φ's is inverse.
8. a multi-channel magnetic resonance radio-frequency coil capability evaluating device, it is characterised in that including:
Signal and noise image acquiring unit, adopted for obtaining each channel radio frequency coil in a multi-channel magnetic resonance radio-frequency coil
The signal pattern in the district to be measured of collection and corresponding noise image；
Noise coupling matrix acquiring unit, is used for utilizing each described noise image to be calculated described multi-channel magnetic resonance radio frequency line
The noise coupling matrix of circle；
Signal-to-noise ratio image acquiring unit, is used for utilizing described signal pattern and described noise coupling matrix, by quadratic sum method
Signal-to-noise ratio image with covariance-weighted and method calculate described multi-channel magnetic resonance radio-frequency coil respectively, obtains the first signal to noise ratio
Image and the second signal-to-noise ratio image；
First coil Performance Evaluation unit, for commenting by relatively described first signal-to-noise ratio image and described second signal-to-noise ratio image
Estimate the performance of described multi-channel magnetic resonance radio-frequency coil.
9. multi-channel magnetic resonance radio-frequency coil capability evaluating device as claimed in claim 8, it is characterised in that also include:
First image reconstruction unit, is used for utilizing described signal pattern, is calculated described district to be measured by quadratic sum method
First rebuilds image；
Second image reconstruction unit, is used for utilizing described signal pattern and described noise coupling matrix, by covariance-weighted and
Method is calculated the second reconstruction image in described district to be measured；
Second coil performance assessment unit, assesses further for rebuilding image according to described first reconstruction image and described second
The performance of described multi-channel magnetic resonance radio-frequency coil.
10. multi-channel magnetic resonance radio-frequency coil capability evaluating device as claimed in claim 8, it is characterised in that described signal
And noise image acquiring unit, including:
K spacing wave and noise acquisition module, for obtaining each channel radio frequency coil of described multi-channel magnetic resonance radio-frequency coil
The K spacing wave in the district described to be measured gathered and corresponding K spatial noise；
Signal and noise image acquisition module, become for respectively described K spacing wave and described K spatial noise being made inverse Fourier
Change, generate the signal pattern corresponding to each channel radio frequency coil and the noise image corresponding to each channel radio frequency coil.
11. multi-channel magnetic resonance radio-frequency coil capability evaluating device as claimed in claim 10, it is characterised in that described signal
And noise image acquisition module, including:
Inverse fast fourier transform module, for making inverse fast Fourier to described K spacing wave and described K spatial noise respectively
Conversion.
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