CN106841273A - A kind of reconstructing water fat separated method based on single sweep space-time code magnetic resonance imaging - Google Patents
A kind of reconstructing water fat separated method based on single sweep space-time code magnetic resonance imaging Download PDFInfo
- Publication number
- CN106841273A CN106841273A CN201710288050.8A CN201710288050A CN106841273A CN 106841273 A CN106841273 A CN 106841273A CN 201710288050 A CN201710288050 A CN 201710288050A CN 106841273 A CN106841273 A CN 106841273A
- Authority
- CN
- China
- Prior art keywords
- water
- fat
- time code
- space
- signal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 151
- 238000000034 method Methods 0.000 title claims abstract description 33
- 238000002595 magnetic resonance imaging Methods 0.000 title claims abstract description 19
- 238000003384 imaging method Methods 0.000 claims abstract description 42
- 238000000926 separation method Methods 0.000 claims abstract description 16
- 125000002723 alicyclic group Chemical group 0.000 claims abstract description 8
- 239000011159 matrix material Substances 0.000 claims description 16
- 238000002474 experimental method Methods 0.000 claims description 14
- 239000000523 sample Substances 0.000 claims description 10
- 230000009466 transformation Effects 0.000 claims description 10
- 238000012360 testing method Methods 0.000 claims description 9
- 238000012937 correction Methods 0.000 claims description 8
- 238000011049 filling Methods 0.000 claims description 7
- 239000006101 laboratory sample Substances 0.000 claims description 7
- 238000005259 measurement Methods 0.000 claims description 7
- 230000000007 visual effect Effects 0.000 claims description 5
- 230000000694 effects Effects 0.000 claims description 4
- 238000011478 gradient descent method Methods 0.000 claims description 4
- 239000002131 composite material Substances 0.000 claims description 3
- 230000005284 excitation Effects 0.000 abstract description 3
- 241000700159 Rattus Species 0.000 description 17
- 210000001015 abdomen Anatomy 0.000 description 11
- 238000005516 engineering process Methods 0.000 description 10
- 206010002091 Anaesthesia Diseases 0.000 description 8
- 230000037005 anaesthesia Effects 0.000 description 7
- 239000000126 substance Substances 0.000 description 6
- 238000001914 filtration Methods 0.000 description 5
- RGCLLPNLLBQHPF-HJWRWDBZSA-N phosphamidon Chemical compound CCN(CC)C(=O)C(\Cl)=C(/C)OP(=O)(OC)OC RGCLLPNLLBQHPF-HJWRWDBZSA-N 0.000 description 5
- 238000002955 isolation Methods 0.000 description 4
- PIWKPBJCKXDKJR-UHFFFAOYSA-N Isoflurane Chemical compound FC(F)OC(Cl)C(F)(F)F PIWKPBJCKXDKJR-UHFFFAOYSA-N 0.000 description 3
- 210000001367 artery Anatomy 0.000 description 3
- 238000002939 conjugate gradient method Methods 0.000 description 3
- 229960002725 isoflurane Drugs 0.000 description 3
- 238000004080 punching Methods 0.000 description 3
- 210000003462 vein Anatomy 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 2
- 238000002075 inversion recovery Methods 0.000 description 2
- 101000573451 Homo sapiens Msx2-interacting protein Proteins 0.000 description 1
- 102100026285 Msx2-interacting protein Human genes 0.000 description 1
- 238000001949 anaesthesia Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000003902 lesion Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000011017 operating method Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000012805 post-processing Methods 0.000 description 1
- 230000000284 resting effect Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 230000004936 stimulating effect Effects 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N24/00—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects
- G01N24/08—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects by using nuclear magnetic resonance
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/30—Assessment of water resources
Landscapes
- Physics & Mathematics (AREA)
- High Energy & Nuclear Physics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Magnetic Resonance Imaging Apparatus (AREA)
Abstract
A kind of reconstructing water fat separated method based on single sweep space-time code magnetic resonance imaging, it is related to MR imaging method, the method is encoded and gathered using single sweep space-time code imaging sequence to water fat signal, wherein 90 degree of linear frequency sweep pulse combination space-time code gradients impart one quadratic phase of water fat signal in excitation phase.Based on this characteristic, the data for gathering are pre-processed by choosing appropriate wave filter, the priori image of water and fat can be obtained, be used to instruct the separation and reconstruction of water fat.In water fat separation phase, by the use of priori image as initial value and weighted information, by solving, the super-resolution under water alicyclic ring border is lifted and edge removes artifact algorithm equation, can obtain the water figure and fat figure of high-resolution and high s/n ratio.The water fat that the method for proposition can effectively realize single sweep space-time code magnetic resonance imaging is separated, while improving the picture quality of separate picture, promotes clinical practice process.
Description
Technical field
The present invention relates to magnetic resonance imaging (Magnetic Resonance Imaging, MRI) method, more particularly, to one
The reconstructing water fat separated method based on single sweep space-time code magnetic resonance imaging is planted, the method can effectively improve supper-fast water fat
The image resolution ratio and signal to noise ratio of separate imaging.
Background technology
The signal that mr imaging technique is detected generally from the signal produced by the Hydrogen Proton in some molecules,
Such as water and fat.In most cases, for many practical applications it is interested come from water in produced by Hydrogen Proton
Signal.But because the T1 relaxation times of fat are extremely short, therefore it can be shown as letter high in many important imaging sequences
Number, such as fast acquisition interleaved spin echo[1], disturb phase gradient echo sequence[2,3]And steady state free precession[4].This high RST pair
It is very unfavorable in clinical magnetic resonance image, serious motion related artifacts may be caused, so as to influences facing for lesion region
Bed judges.Therefore, the water fat isolation technics of efficient stable is most important for the clinical practice of magnetic resonance imaging.
There is the more ripe water fat isolation technics of several development at present, but all had the following disadvantages：(1) chemical shift
Selection (chemical shift selective, CHESS) pressure fat imaging technique[5,6]Easily realize and simultaneous with most Number Sequence
Hold, but to B0And B1Field inhomogeneities is all very sensitive, and this can cause to press the inaccuracy of fat.(2) spatial spectrum is excited
(spatial-spectral excitation) technology[7,8]Directly alignment water is excited, and can be improved to B1Non-uniform field
Repellence, but also easily receive B0The influence of non-uniform field.(3) inversion recovery (short inversion time (TI)
Inversion recovery, STIR) technology[9]Pressure fat is carried out using shorter this property of fatty T1 relaxation times, for B0With
B1Field inhomogeneities all has stronger repellence, therefore can provide reliable pressure fat effect.Weak point be the technology not
T2 weighted imagings or proton density weighted imaging can be applied to, and have certain infringement to signal to noise ratio.(4) Dixon water fat
Isolation technics[10]Several are obtained by setting the different echo times has the water fat mixed image of particular phases, and passes through
Post-processing algorithm realizes the separation of water and fat.The advantage of the technology can be to provide two kinds of images of water and fat, and be not only
One-sided compacting to fat.But due to needing to obtain multiple images, therefore imaging time accordingly increases.While Dixon skills
Art is also easily subject to B0Phase caused by non-uniform field winds the influence of problem, and current many unwrapping algorithms have been suggested
Solve this problem[11-14]。
Above-mentioned several water fat isolation technics are all based on many scanning imagery sequences, and imaging time is all long, and this is to most
Number clinical imaging application is unfavorable.In the past few decades, supper-fast mr imaging technique is developed rapidly.Frydman groups carry
Go out space-time code (spatiotemporal encoding, SPEN) mr imaging technique of single sweep[15]Can not only provide
The time suitable with echo-planar imaging (echo planar imaging, EPI) and spatial resolution, and can effectively support
Anti- non-uniform field and the influence of chemical shift.Based on the special quadratic phase encoding mechanism of space-time code, can be by space-time
Coding dimension carries out one-dimensional Fourier transform to obtain the chemical shift information of water and fat[16,17].Have benefited from this property, during utilization
Sky encodes to realize the quick separate imaging of water and fat of single sweep.But because the number of the unknown number of equation to be solved is equation quantity
Twice, the water and the resolution ratio of the image of fat that obtain have a loss of half, therefore super-resolution rebuilding algorithm is for improving
Water fat separate picture quality it is critical that[18-23].It is one that super-resolution is lifted and removes artifact algorithm (SEED algorithms) with edge
Plant advanced space-time code super-resolution algorithms[23]。
Bibliography：
[1]Hennig J,Nauerth A,Friedburg H.RARE imaging:a fast imaging method
for clinical MR.Magn Reson Med 1986；3(6):823-833.
[2]Disler DG,Mccauley TR,Kelman CG,Fuchs MD,Ratner LM,Wirth CR,et
al.Fat-suppressed three-dimensional spoiled gradient-echo MR imaging of
hyaline cartilage defects in the knee:comparison with standard MR imaging and
arthroscopy.Am J Roentgenol 1996；167(1):127-132.
[3]Zur Y,Wood ML,Neuringer LJ.Spoiling of transverse magnetization in
steady-state sequences.Magn Reson Med 1991；21(2):251-263.
[4]Sekihara K.Steady-state magnetizations in rapid NMR imaging using
small flip angles and short repetition intervals.IEEE T Med Imaging 1987；6
(2):157-164.
[5]Haase A,Frahm J, W,Matthaei D.1H NMR chemical shift
selective(CHESS)imaging.Phys Med Biol 1985；30(4):341-344.
[6]Riederer SJ.Chemical shift selective MR imaging using a whole-body
magnet.Radiology 1985；156(2):441-444.
[7]Meyer CH,Pauly JM,Macovski A,Nishimura DG.Simultaneous spatial and
spectral selective excitation.Magn Reson Med 1990；15(2):287-304.
[8]Schick F.Simultaneous highly selective MR water and fat imaging
using a simple new type of spectral-spatial excitation.Magn Reson Med 1998；40
(2):194-202.
[9]Bydder GM,Pennock JM,Steiner RE,Khenia S,Payne JA,Young IR.The
short TI inversion recovery sequence--an approach to MR imaging of the
abdomen.Magn Reson Imaging 1985；3(3):251-254.
[10]Dixon WT.Simple proton spectroscopy imaging.Radiology 1984；153
(1):189-194.
[11]Szumowski J,Coshow WR,Li F,Quinn SF.Phase unwrapping in the
three-point Dixon method for fat suppression MR imaging.Radiology 1994；192
(2):555-561.
[12]Coombs BD,Szumowski J,Coshow W.Two-point Dixon technique for
water-fat signal decomposition with B0inhomogeneity correction.Magn Reson Med
1997；38(6):884–889.
[13]Glover GH,Schneider E.Three-point dixon technique for true water/
fat decomposition with B0inhomogeneity correction.Magn Reson Med 1991；18(2):
371-383.
[14]Xiang QS.Two-point water-fat imaging with partially-opposed-phase
(POP)acquisition:an asymmetric Dixon method.Magn Reson Med 2006；56(3):572-
584.
[15]Ben-Eliezer N,Irani M,Frydman L.Super-resolved spatially encoded
single-scan 2D MRI.Magn Reson Med 2010；63(6):1594-1600.
[16]Schmidt R,Frydman L.In vivo 3D spatial/1D spectral imaging by
spatiotemporal encoding:A new single-shot experimental and processing
approach.Magn Reson Med 2013；70(2):382-391.
[17]Chen Y,Cai CB,Zhong JH,Chen Z.Water-fat separation from a single
spatiotemporally encoded echo based on nominal k-space peaking and joint
regularized estimation.Magn Reson Med 2015；73(4):1441-1449.
[18]Cai CB,Dong JY,Cai SH,Li J,Chen Y,Bao LJ,et al.An efficient de-
convolution reconstruction method for spatiotemporal-encoding single-scan 2D
MRI.J Magn Reson 2013；228:136-147.
[19]Chen L,Bao LJ,Li J,Cai SH,Cai CB,Chen Z.An aliasing artifacts
reducing approach with random undersampling for spatiotemporally encoded
single-shot MRI.J Magn Reson 2013；237:115-124.
[20]Chen Y,Li J,Qu XB,Chen L,Cai CB,Cai SH,et al.Partial Fourier
transform reconstruction for single-shot MRI with linear frequency-swept
excitation.Magn Reson Med 2013；69(5):1326-1336.
[21]Ben-Eliezer N,Shrot Y,Frydman L,Sodickson DK.Parametric analysis
of the spatial resolution and signal-to-noise ratio in super-resolved
spatiotemporally encoded(SPEN)MRI.Magn Reson Med 2014；72(2):418-429.
[22]Schmidt R,Frydman L.New spatiotemporal approaches for fully
refocused,multislice ultrafast 2D MRI.Magn Reson Med 2014；71(2):711-722.
[23]Chen L,Li J,Zhang M,Cai SH,Zhang T,Cai CB,et al.Super-resolved
enhancing and edge deghosting(SEED)for spatiotemporally encoded single-shot
MRI.Med Image Anal 2015；23(1):1-14.
The content of the invention
It is an object of the invention to provide can solve the problem that equation present in single sweep space-time code separate imaging of water and fat owe
Problem is determined, so that the one kind for providing the water fat separate picture of higher resolution and signal to noise ratio is based on single sweep space-time code magnetic resonance
The reconstructing water fat separated method of imaging.
The present invention is comprised the following steps：
1) laboratory sample is got out, testing sample is placed on experimental bed and fixed, will be equipped with the experimental bed of sample
Send into the test chamber of magnetic resonance imager；
2) imager operation software is opened on the operating desk of magnetic resonance imager, laboratory sample is positioned first,
Then be tuned, shimming, frequency correction and capability correction；
3) with 90 degree of chirp pulse powers of measurement sequence measuring of linear frequency sweep pulse (chirp pulses) power, and record
Its performance number；
4) compiled single sweep space-time code imaging sequence in advance is imported on magnetic resonance imager, and needed for calling in
90 degree of chirp pulses；
5) be arranged to the experiment parameter of picture, by step 3) in measured performance number be assigned to corresponding 90 degree of chirp arteries and veins
In the power and variable of punching, remaining parameter of 90 degree of chirp pulses and the relevant parameter of visual field are set, checking experiment parameter sets
Whether correct put；
6) click scan performs the single sweep space-time code imaging sequence for setting, and carries out data acquisition；Data acquisition
After the completion of, preserve data；
7) the water fat signal S for collecting is pre-processed, obtains the priori of water and fat；
8) lifted with super-resolution and edge goes artifact algorithm respectively to the coarse time-domain signal S of waterwWith the coarse time domain of fat
Signal SfRebuild, obtained the priori image of waterWith the priori image of fat
9) enter the super-resolution rebuilding of water-filling fat separation to water fat signal S, obtain the water of high-quality and the final image of fat.
In step 3) in, the measurement sequence of the chirp pulse powers is an one-dimensional space-time code sequence, by one
Chirp pulses are constituted with the composite module and decoding gradient of coding gradient, wherein decoding the gradient area of gradient and coding gradient
It is equal, in the opposite direction.
In step 4) in, the single sweep space-time code imaging sequence may include：90 degree of chirp pulses, 180 degree sinc arteries and veins
Punching, phase dimension (PE directions) coding gradient Ge, layer choosing gradient Gss, phase dimensional decoding gradient GaLadder is read with frequency dimension (RO directions)
Degree Gro.90 degree of chirp pulses combine coding gradient GePE directions are spatially encoded；The 180 degree sinc pulse knots
Close layer choosing gradient GssCarry out layer choosing；And then in phase dimensional decoding gradient GaWith frequency dimension readout gradient GroCollective effect under,
Realize the collection to spin signals.
In step 7) in, the detailed process that the described couple of water fat signal S for collecting is pre-processed is as follows：A () is to S's
Space-time code dimension carries out one-dimensional Fourier transform, obtains frequency domain water fat signal S'；B () chooses appropriate wave filter to frequency-region signal
S' is split, and obtains the coarse frequency-region signal S' of water and fatwAnd S'f；C () is respectively to S'wAnd S'fSpace-time code dimension carry out
One-dimensional inversefouriertransform, obtains the coarse time-domain signal S of water and fatwAnd Sf。
In step 8) in, the edge goes the artifact algorithm can be using SEED algorithms, and the SEED algorithms are a kind of advanced
Space-time code super-resolution rebuilding algorithm, the algorithm makes full use of the relation between actual signal and aliasing artefacts, can be single
Scanning space-time code imaging reconstruction goes out high-resolution and the image without aliasing artefacts.
In step 9) in, the method for the super-resolution rebuilding for entering the separation of water-filling fat to water fat signal S is by water fat
Priori is combined with the SEED algorithms under water alicyclic ring border, and the specific formula of new method is：
WhereinIt is the merging matrix of the space-time code matrix of the water and fat being calculated by experiment parameter；It is the merging matrix of the aliasing artefacts extra phase matrix of water and fat；W is for minimizing water and fat
Final image in residual signal (i.e. minimize water images in fat signal, minimize fat image in water signal)；ψ is represented
Wavelet transformation, TV represents full variation, and the two belongs to sparse transformation；α and β are the weighting factors of sparse transformation and fidelity.Profit
The solution of the linear equation is solved with Nonlinear conjugate gradient descent method.WhereinIt is finally to solve the figure for obtaining
Picture, wherein ρwIt is the final image of water, wherein ρfIt is the final image of fat.
The present invention is mutually tied by by the distinctive chemical shift priori of space-time code and the SEED algorithms under water alicyclic ring border
Close to improve the resolution ratio and signal to noise ratio of separate picture, so as to provide more reliable high quality water fat separate picture.
The reconstructing water fat separated method based on single sweep space-time code magnetic resonance imaging that the present invention is provided is by space-time code
Distinctive chemical shift priori is combined with the SEED algorithms under water alicyclic ring border, can ensure the situation of supper-fast imaging
Under, to realize the separation of water and fat and reconstruct the MRI of high-resolution and high s/n ratio, the proposition of the method can be pushed away
Enter the process of single sweep space-time code separate imaging of water and fat technology clinical practice.
Brief description of the drawings
Fig. 1 is the single sweep space-time code imaging sequence that the present invention is used.
Fig. 2 is the flow chart of reconstructing water fat separated method of the present invention based on single sweep space-time code magnetic resonance imaging.
In Fig. 2, a is the initial profile figure of water fat sample；B is the coarse profile diagram of single sweep space-time code imaging sequence collection；C is right
Water fat signal S carries out the one-dimensional spectrogram and selected Butterworth filter that one-dimensional Fourier transform is obtained；After d is for filtering
The one-dimensional spectrogram of fat after the one-dimensional spectrogram of water and filtering；E be rebuild by Fourier inversion and SEED algorithms the water that obtains and
The priori figure of fat；F is the equation to be solved of water fat separation method of the present invention；G is that the present invention rebuilds the water figure for obtaining；
H is that the present invention rebuilds the fat figure for obtaining.
Fig. 3 illustrates the image result that the rat abdomen water fat under different sequence equivalent environments is separate.In figure 3, a is many
The water fat hybrid reference figure that scanning sequence is obtained；B is the water figure that Dixon technologies are obtained；C is the fat figure that Dixon technologies are obtained；d
It is the water figure that is obtained of traditional conjugate gradient method based on the imaging of single sweep space-time code；E be based on single sweep space-time code into
The fat figure that traditional conjugate gradient method of picture is obtained；F is obtained by the water fat novel method for separating being imaged based on single sweep space-time code
The water figure for obtaining；G is the fat figure that the water fat novel method for separating based on the imaging of single sweep space-time code is obtained.
Specific embodiment
Below in conjunction with the drawings and specific embodiments, the invention will be further described.
Referring to Fig. 2, the embodiment of the present invention is comprised the following steps：
1) laboratory sample is got out, testing sample is placed on experimental bed and fixed, will be equipped with the experimental bed of sample
Send into the test chamber of magnetic resonance imager；
2) imager operation software is opened on the operating desk of magnetic resonance imager, laboratory sample is positioned first,
Then be tuned, shimming, frequency correction and capability correction；
3) with 90 degree of chirp pulse powers of measurement sequence measuring of linear frequency sweep pulse (chirp pulses) power, and record
Its performance number；The measurement sequence of the chirp pulse powers is an one-dimensional space-time code sequence, by a chirp pulse
Composite module and decoding gradient with coding gradient are constituted, wherein decoding gradient is equal with the gradient area of coding gradient, direction
Conversely.
4) compiled single sweep space-time code imaging sequence in advance is imported on magnetic resonance imager, and needed for calling in
90 degree of chirp pulses；The single sweep space-time code imaging sequence may include：90 degree of chirp pulses, 180 degree sinc pulses, phases
Position dimension (PE directions) coding gradient Ge, layer choosing gradient Gss, phase dimensional decoding gradient Ga(RO directions) readout gradient G is tieed up with frequencyro。
90 degree of chirp pulses combine coding gradient GePE directions are spatially encoded；The 180 degree sinc pulses combination layer choosing
Gradient GssCarry out layer choosing；And then in phase dimensional decoding gradient GaWith frequency dimension readout gradient GroCollective effect under, it is right to realize
The collection of spin signals.
5) be arranged to the experiment parameter of picture, by step 3) in measured performance number be assigned to corresponding 90 degree of chirp arteries and veins
In the power and variable of punching, remaining parameter of 90 degree of chirp pulses and the relevant parameter of visual field are set, checking experiment parameter sets
Whether correct put；
6) click scan performs the single sweep space-time code imaging sequence for setting, and carries out data acquisition；Data acquisition
After the completion of, preserve data；
7) the water fat signal S for collecting is pre-processed, obtains the priori of water and fat；Described pair collects
The detailed processes that are pre-processed of water fat signal S it is as follows：A () carries out one-dimensional Fourier transform to the space-time code dimension of S, obtain
Frequency domain water fat signal S'；B () chooses appropriate wave filter and frequency-region signal S' is split, obtain the coarse frequency domain letter of water and fat
Number S'wAnd S'f；C () is respectively to S'wAnd S'fSpace-time code dimension carry out one-dimensional inversefouriertransform, obtain the coarse of water and fat
Time-domain signal SwAnd Sf。
8) lifted with super-resolution and edge goes artifact algorithm respectively to the coarse time-domain signal S of waterwWith the coarse time domain of fat
Signal SfRebuild, obtained the priori image of waterWith the priori image of fatThe edge removes artifact algorithm
SEED algorithms can be used, the SEED algorithms are a kind of advanced space-time code super-resolution rebuilding algorithms, and the algorithm is fully sharp
With the relation between actual signal and aliasing artefacts, high-resolution can be gone out and without aliasing for single sweep space-time code imaging reconstruction
The image of artifact.
9) enter the super-resolution rebuilding of water-filling fat separation to water fat signal S, obtain the water of high-quality and the final image of fat.
The method of the super-resolution rebuilding for entering the separation of water-filling fat to water fat signal S is by under the priori of water fat and water alicyclic ring border
SEED algorithms be combined, the specific formula of new method is：
WhereinIt is the merging matrix of the space-time code matrix of the water and fat being calculated by experiment parameter；It is the merging matrix of the aliasing artefacts extra phase matrix of water and fat；W is for minimizing water and fat
Residual signal (minimizing the fat signal in water images, minimize the water signal in fat image) in final image；ψ represents small
Wave conversion, TV represents full variation, and the two belongs to sparse transformation；α and β are the weighting factors of sparse transformation and fidelity.Utilize
Nonlinear conjugate gradient descent method solves the solution of the linear equation.WhereinIt is finally to solve the image for obtaining, its
Middle ρwIt is the final image of water, wherein ρfIt is the final image of fat.
In fig. 2, a is the initial profile figure of water fat sample；B is the rough wheel of single sweep space-time code imaging sequence collection
Exterior feature figure；C is that one-dimensional spectrogram and the selected Butterworth filtering that one-dimensional Fourier transform is obtained are carried out to water fat signal S
Device；D be filtering after water one-dimensional spectrogram and filtering after fat one-dimensional spectrogram；E is by Fourier inversion and SEED algorithm weights
Build the priori figure of the water and fat for obtaining；F is the equation to be solved of water fat separation method of the present invention；G is present invention weight
Build the water figure for obtaining；H is that the present invention rebuilds the fat figure for obtaining.
Specific embodiment given below：
The instrument of the present embodiment is Varian 7T imagers (Agilent a Technologies, Santa
Clara, CA, USA), laboratory sample is for about the live body SD rats of 350g.Single sweep space-time code imaging sequence used, each
Parameter name is as shown in figure 1, other operating procedures are as follows：
(1) rat one is prepared, rat is put into Anesthesia machine before experiment carries out quick-anaesthesia, treats that rat enters resting state
Rat is placed on experimental bed and is fixed afterwards, and connects the wireway of Anesthesia machine carries out maintenance anesthesia, then will be equipped with
The experimental bed of sample sends into the test chamber of magnetic resonance imager.
The Anesthesia machine is the gas that is mixed by a certain percentage using isoflurane and oxygen realizes the anesthesia to sample, soon
Speed anesthesia isoflurane concentration used is 5%, and it is 2% to maintain the isoflurane concentration used by anesthesia.
(2) imager operation software is opened on the operating desk of magnetic resonance imager, rat is positioned first, adjusted
To area-of-interest, this experimental selection is imaged experiment bed position to the cross section of rat abdomen.Carried out after the completion of positioning
Tuning, shimming (automatically and manually coordinating), frequency correction and capability correction.
(3) the measurement sequence of chirp pulse powers is called, multiple reality is carried out by setting different chirp pulse powers values
Test, find and record suitable 90 degree of chirp pulse power values, the performance number that this example is measured is 51dB.
(4) single sweep space-time code imaging sequence compiled in advance is imported on magnetic resonance imager, and is called in required
90 degree of chirp pulses.
(5) it is arranged to the experiment parameter of picture, it is specific as follows：Performance number 51dB measured in (3) is assigned to corresponding
In 90 degree of power and variables of chirp pulses, it is 32kHz, firing time T to set 90 degree of stimulating frequency width of chirp pulseseFor
4ms；Total sampling number is 64 × 64；The visual field L in RO directionsxIt is 7.0cm, the visual field L in PE directionsyIt is 7.0cm；Into
As thickness degree thk is 2mm.The run time of whole sequence is about 50ms.
(6) click scan performs the single sweep space-time code imaging sequence for setting, and carries out data acquisition；Data acquisition
After the completion of, preserve data.
(7) the rat abdomen water fat signal S for collecting is pre-processed, obtains the priori of water and fat.Specifically
Process is as follows：A () carries out one-dimensional Fourier transform to the space-time code dimension of S, obtain frequency domain water fat signal S'；B () is chosen appropriate
Wave filter frequency-region signal S' is split, obtain the coarse frequency-region signal S' of water and fatwAnd S'f；C () is respectively to S'wWith
S'fSpace-time code dimension carry out one-dimensional inversefouriertransform, obtain the coarse time-domain signal S of water and fatwAnd Sf。
(8) lifted with super-resolution and edge removes artifact algorithm (SEED algorithms) respectively to SwAnd SfRebuild, obtained rat
The priori image of belly water and fatWith
(9) enter the super-resolution rebuilding of water-filling fat separation to rat abdomen water fat signal S, obtain the water and fat of high-quality
Final image.Specific practice is that the priori of water fat is combined with the SEED algorithms under water alicyclic ring border.New method it is specific
Formula is：
WhereinIt is the space-time code matrix of the rat abdomen water and fat being calculated by experiment parameter
Merge matrix；It is the merging matrix of the aliasing artefacts extra phase matrix of rat abdomen water and fat；W
It is (to minimize the fat signal in water images, most for minimizing the residual signal in the final image of rat abdomen water and fat
Water signal in smallization fat image).ψ represents wavelet transformation, and TV represents full variation, and the two belongs to sparse transformation；α and β are dilute
Dredge the weighting factor of conversion and fidelity.The solution of the linear equation is solved using Nonlinear conjugate gradient descent method.AndIt is finally to solve the image for obtaining, wherein ρwIt is the final image (as shown in the f in Fig. 3) of rat abdomen water,
Wherein ρfIt is the final image (as shown in the g in Fig. 3) of rat abdomen fat.
In figure 3, the water fat mixed image of rat abdomen is as shown in a in Fig. 3 for the Experimental results show of the present embodiment.For
The validity of evaluation method proposed by the present invention, has carried out many scanning Dixon water fat separating experiments under identical environment, and
Using the image (respectively as shown in b and c in Fig. 3) of isolated water and fat as reference picture.It is equally based on single sweep space-time
The image of the signal that coded imaging sequence acquisition is arrived, the water tried to achieve by traditional conjugate gradient method and fat is (respectively such as the d and e in Fig. 3
It is shown) image as a comparison.From the results, it was seen that water fat separation method proposed by the present invention can not only provide high-resolution
With the water figure and fat figure (respectively as shown in f and g in Fig. 3) of high s/n ratio, and can realize that more thorough water fat is separated (such as
Shown in arrow), so as to provide more effective water fat separating resulting.
The present invention is encoded and gathered using single sweep space-time code imaging sequence to water fat signal, wherein 90 degree of lines
Property scanning frequency pulse (chirp pulses) imparts one quadratic phase of water fat signal with reference to space-time code gradient in excitation phase.Base
In this characteristic, the data for gathering are pre-processed by choosing appropriate wave filter, the priori of water and fat can be obtained
Knowledge graph picture, is used to instruct the separation and reconstruction of water fat.In water fat separation phase, by the use of priori image is as initial value and adds
Power information, by solving, the super-resolution under water alicyclic ring border is lifted and edge removes artifact algorithm equation, can obtain high-resolution
With the water figure and fat figure of high s/n ratio.The water fat that the present invention can effectively realize single sweep space-time code magnetic resonance imaging is separated,
The picture quality of separate picture is improved simultaneously, is greatly promoted the clinical practice process of the technology.
Claims (6)
1. a kind of reconstructing water fat separated method based on single sweep space-time code magnetic resonance imaging, it is characterised in that including following step
Suddenly：
1) laboratory sample is got out, testing sample is placed on experimental bed and fixed, will be equipped with the experimental bed feeding of sample
The test chamber of magnetic resonance imager；
2) imager operation software is opened on the operating desk of magnetic resonance imager, laboratory sample is positioned first, then
Be tuned, shimming, frequency correction and capability correction；
3) with 90 degree of chirp pulse powers of measurement sequence measuring of linear frequency sweep pulse power, and its performance number is recorded；
4) single sweep space-time code imaging sequence compiled in advance is imported on magnetic resonance imager, and calls in required 90 degree
Chirp pulses；
5) be arranged to the experiment parameter of picture, by step 3) in measured performance number be assigned to corresponding 90 degree of chirp pulses
In power and variable, remaining parameter of 90 degree of chirp pulses and the relevant parameter of visual field are set, checking experiment parameter setting is
It is no correct；
6) click scan performs the single sweep space-time code imaging sequence for setting, and carries out data acquisition；Data acquisition is completed
Afterwards, data are preserved；
7) the water fat signal S for collecting is pre-processed, obtains the priori of water and fat；
8) lifted with super-resolution and edge goes artifact algorithm respectively to the coarse time-domain signal S of waterwWith the coarse time-domain signal S of fatf
Rebuild, obtained the priori image of waterWith the priori image of fat
9) enter the super-resolution rebuilding of water-filling fat separation to water fat signal S, obtain the water of high-quality and the final image of fat.
2. a kind of reconstructing water fat separated method based on single sweep space-time code magnetic resonance imaging as claimed in claim 1, it is special
Levy is in step 3) in, the measurement sequence of the chirp pulse powers is an one-dimensional space-time code sequence, by one
Chirp pulses are constituted with the composite module and decoding gradient of coding gradient, wherein decoding the gradient area of gradient and coding gradient
It is equal, in the opposite direction.
3. a kind of reconstructing water fat separated method based on single sweep space-time code magnetic resonance imaging as claimed in claim 1, it is special
Levy is in step 4) in, the single sweep space-time code imaging sequence includes：90 degree of chirp pulses, 180 degree sinc pulses,
Phase dimension coding gradient Ge, layer choosing gradient Gss, phase dimensional decoding gradient GaWith frequency dimension readout gradient Gro；90 degree of chirp
Pulse combines coding gradient GePE directions are spatially encoded；The 180 degree sinc pulses combination layer choosing gradient GssCarry out layer
Choosing；And then in phase dimensional decoding gradient GaWith frequency dimension readout gradient GroCollective effect under, realization spin signals are adopted
Collection.
4. a kind of reconstructing water fat separated method based on single sweep space-time code magnetic resonance imaging as claimed in claim 1, it is special
Levy is in step 7) in, the detailed process that the described couple of water fat signal S for collecting is pre-processed is as follows：(a) to S when
Sky coding dimension carries out one-dimensional Fourier transform, obtains frequency domain water fat signal S'；B () chooses appropriate wave filter to frequency-region signal S'
Split, obtained the coarse frequency-region signal S' of water and fatwAnd S'f；C () is respectively to S'wAnd S'fSpace-time code dimension carry out one
Dimension inversefouriertransform, obtains the coarse time-domain signal S of water and fatwAnd Sf。
5. a kind of reconstructing water fat separated method based on single sweep space-time code magnetic resonance imaging as claimed in claim 1, it is special
Levy is in step 8) in, the edge goes artifact algorithm using SEED algorithms, and the SEED algorithms are a kind of advanced space-time
Code super-resolution algorithm for reconstructing, the algorithm, using the relation between actual signal and aliasing artefacts, is that single sweep space-time is compiled
Code imaging reconstruction goes out high-resolution and the image without aliasing artefacts.
6. a kind of reconstructing water fat separated method based on single sweep space-time code magnetic resonance imaging as claimed in claim 1, it is special
Levy is in step 9) in, the method for the super-resolution rebuilding for entering the separation of water-filling fat to water fat signal S is by the elder generation of water fat
Test knowledge to be combined with the SEED algorithms under water alicyclic ring border, specific formula is：
WhereinIt is the merging matrix of the space-time code matrix of the water and fat being calculated by experiment parameter；It is the merging matrix of the aliasing artefacts extra phase matrix of water and fat；W is for minimizing water and fat
Final image in residual signal, that is, minimize water images in fat signal, minimize fat image in water signal；ψ is represented
Wavelet transformation, TV represents full variation, and the two belongs to sparse transformation；α and β are the weighting factors of sparse transformation and fidelity；Profit
The solution of the linear equation is solved with Nonlinear conjugate gradient descent method, whereinIt is finally to solve the figure for obtaining
Picture, wherein ρwIt is the final image of water, wherein ρfIt is the final image of fat.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710288050.8A CN106841273B (en) | 2017-04-27 | 2017-04-27 | A kind of reconstructing water fat separated method based on single sweep space-time code magnetic resonance imaging |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710288050.8A CN106841273B (en) | 2017-04-27 | 2017-04-27 | A kind of reconstructing water fat separated method based on single sweep space-time code magnetic resonance imaging |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN106841273A true CN106841273A (en) | 2017-06-13 |
| CN106841273B CN106841273B (en) | 2018-04-24 |
Family
ID=59143103
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710288050.8A Active CN106841273B (en) | 2017-04-27 | 2017-04-27 | A kind of reconstructing water fat separated method based on single sweep space-time code magnetic resonance imaging |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN106841273B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108010100A (en) * | 2017-12-07 | 2018-05-08 | 厦门大学 | A kind of single sweep magnetic resonance based on residual error network quantifies T2Imaging reconstruction method |
| CN108663644A (en) * | 2018-03-14 | 2018-10-16 | 厦门大学 | Single sweep Quantitative MRI Measurement T based on residual error network reconnection2* imaging method |
| CN109752683A (en) * | 2018-12-26 | 2019-05-14 | 鑫高益医疗设备股份有限公司 | Image distortion correction method based on single sweep mixing space-time code magnetic resonance imaging |
| CN112924913A (en) * | 2021-02-02 | 2021-06-08 | 厦门大学 | Space-time coding magnetic resonance imaging super-resolution reconstruction method and system |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013098060A1 (en) * | 2011-12-29 | 2013-07-04 | Koninklijke Philips Electronics N.V. | Mri with dixon-type water/fat separation and prior knowledge about inhomogeneity of the main magnetic field |
| US20140103923A1 (en) * | 2012-10-11 | 2014-04-17 | Siemens Medical Solutions Usa, Inc. | Using Single Continuous Pulses for Manipulating Water and Fat Signals in Magnetic Resonance Imaging |
| CN103809140A (en) * | 2014-02-20 | 2014-05-21 | 厦门大学 | Small-view-field magnetic resonance imaging method based on single-sweep super-speed orthogonal space-time coding |
| CN103885017A (en) * | 2014-02-20 | 2014-06-25 | 厦门大学 | Image distortion correction method based on single sweep quadrature space-time coding magnetic resonance imaging |
| WO2015036238A1 (en) * | 2013-09-16 | 2015-03-19 | Koninklijke Philips N.V. | Mr imaging with dixon-type water/fat separation |
| CN104965184A (en) * | 2015-05-25 | 2015-10-07 | 厦门大学 | SPEN single-scanning magnetic resonance imaging spiral sampling and reconstructing method |
| CN105548928A (en) * | 2015-12-04 | 2016-05-04 | 厦门大学 | Multilayer super-rapid magnetic resonance imaging method based on segmental excitation space-time coding |
-
2017
- 2017-04-27 CN CN201710288050.8A patent/CN106841273B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013098060A1 (en) * | 2011-12-29 | 2013-07-04 | Koninklijke Philips Electronics N.V. | Mri with dixon-type water/fat separation and prior knowledge about inhomogeneity of the main magnetic field |
| US20140103923A1 (en) * | 2012-10-11 | 2014-04-17 | Siemens Medical Solutions Usa, Inc. | Using Single Continuous Pulses for Manipulating Water and Fat Signals in Magnetic Resonance Imaging |
| WO2015036238A1 (en) * | 2013-09-16 | 2015-03-19 | Koninklijke Philips N.V. | Mr imaging with dixon-type water/fat separation |
| CN103809140A (en) * | 2014-02-20 | 2014-05-21 | 厦门大学 | Small-view-field magnetic resonance imaging method based on single-sweep super-speed orthogonal space-time coding |
| CN103885017A (en) * | 2014-02-20 | 2014-06-25 | 厦门大学 | Image distortion correction method based on single sweep quadrature space-time coding magnetic resonance imaging |
| CN104965184A (en) * | 2015-05-25 | 2015-10-07 | 厦门大学 | SPEN single-scanning magnetic resonance imaging spiral sampling and reconstructing method |
| CN105548928A (en) * | 2015-12-04 | 2016-05-04 | 厦门大学 | Multilayer super-rapid magnetic resonance imaging method based on segmental excitation space-time coding |
Non-Patent Citations (2)
| Title |
|---|
| LIN CHEN ET AL.: "Super-resolved enhancing and edge deghosting (SEED) for spatiotemporally encoded single-shot MRI", 《MEDICAL IMAGE ANALYSIS》 * |
| 张婷 等: "时空编码单扫描磁共振成像的基本原理及重建方法", 《磁共振成像》 * |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108010100A (en) * | 2017-12-07 | 2018-05-08 | 厦门大学 | A kind of single sweep magnetic resonance based on residual error network quantifies T2Imaging reconstruction method |
| CN108663644A (en) * | 2018-03-14 | 2018-10-16 | 厦门大学 | Single sweep Quantitative MRI Measurement T based on residual error network reconnection2* imaging method |
| CN109752683A (en) * | 2018-12-26 | 2019-05-14 | 鑫高益医疗设备股份有限公司 | Image distortion correction method based on single sweep mixing space-time code magnetic resonance imaging |
| CN109752683B (en) * | 2018-12-26 | 2021-03-02 | 鑫高益医疗设备股份有限公司 | Image distortion correction method based on single-scanning mixed space-time coding magnetic resonance imaging |
| CN112924913A (en) * | 2021-02-02 | 2021-06-08 | 厦门大学 | Space-time coding magnetic resonance imaging super-resolution reconstruction method and system |
| CN112924913B (en) * | 2021-02-02 | 2022-08-12 | 厦门大学 | Space-time coding magnetic resonance imaging super-resolution reconstruction method and system |
Also Published As
| Publication number | Publication date |
|---|---|
| CN106841273B (en) | 2018-04-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP6188597B2 (en) | Method and controller for operating magnetic resonance system | |
| Qian et al. | Acquisition‐weighted stack of spirals for fast high‐resolution three‐dimensional ultra‐short echo time MR imaging | |
| US8228063B2 (en) | Magnetic resonance imaging apparatus and magnetic resonance imaging method | |
| DE102010039693B4 (en) | Phase-sensitive magnetic resonance imaging | |
| CN104685368B (en) | The method and apparatus being imaged for the MR of resistance to metal | |
| CN106841273B (en) | A kind of reconstructing water fat separated method based on single sweep space-time code magnetic resonance imaging | |
| JP5127841B2 (en) | Magnetic resonance imaging apparatus and magnetic susceptibility weighted imaging method | |
| JP5196408B2 (en) | Magnetic resonance spectroscopy of species with multiple peaks. | |
| EP1449004B1 (en) | Multiple gradient echo type projection reconstruction sequence for mri and especially diffusion weighted mri | |
| Wech et al. | Whole-heart cine MRI in a single breath-hold–a compressed sensing accelerated 3D acquisition technique for assessment of cardiac function | |
| JP5666779B2 (en) | Magnetic resonance imaging system | |
| Wang et al. | Model‐based reconstruction for simultaneous multi‐slice mapping using single‐shot inversion‐recovery radial FLASH | |
| JPH0919417A (en) | Pulse sequence method for nuclear spin tomograph | |
| JP6762284B2 (en) | Magnetic resonance imaging device and noise removal method | |
| Manhard et al. | A multi‐inversion multi‐echo spin and gradient echo echo planar imaging sequence with low image distortion for rapid quantitative parameter mapping and synthetic image contrasts | |
| Gibbons et al. | Body diffusion‐weighted imaging using magnetization prepared single‐shot fast spin echo and extended parallel imaging signal averaging | |
| Kee et al. | Free‐breathing mapping of hepatic iron overload in children using 3D multi‐echo UTE cones MRI | |
| Bachrata et al. | Simultaneous Multiple Resonance Frequency imaging (SMURF): Fat‐water imaging using multi‐band principles | |
| JPH0795972A (en) | Nuclear spin laminagraph | |
| JP5278914B2 (en) | Magnetic resonance imaging apparatus and magnetic susceptibility weighted imaging method | |
| Schulte et al. | Silent T2* and T2 encoding using ZTE combined with BURST | |
| CN110109036B (en) | Two-dimensional space-time coding multi-scan magnetic resonance imaging non-Cartesian sampling and reconstruction method | |
| Claeser et al. | Sub‐millimeter T1 mapping of rapidly relaxing compartments with gradient delay corrected spiral TAPIR and compressed sensing at 3T | |
| Okanovic et al. | Increasing robustness of radial GRASE acquisition for SAR-reduced brain imaging | |
| DE112020002706T5 (en) | OPTIMIZED K-SPACE PROFILE ORDER FOR 3D RADIAL MR IMAGING |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |