CN102008305B - Dynamic magnetic resonance imaging method - Google Patents

Abstract

The invention discloses a dynamic magnetic resonance imaging method, comprising the following steps: scanning the whole visual field by a radio frequency coil, sampling to obtain a first image signal, and rebuilding a first image according to the first image signal; sampling to obtain a second image signal and a third image signal, namely sampling to obtain the second image signal and the third image signal according to the sampling rate of the second image and the third image after lowering the sampling rate of the second image and the third image; constructing a target function about the second image and the third image according to the second image signal and the third image signal; optimizing and solving the target function about the second image and the third image; reconstructing the second image and the third image according to the solution; sampling to obtain a fourth image signal; according to the third image signal and the fourth image signal constructing the target function about the third image and the fourth image; optimizing and solving the target function about the third image and the fourth image; and reconstructing the third image and the fourth image according to the solution.

Description

Magnetic resonance dynamic imaging method

[technical field]

The present invention relates to magnetic resonance, especially magnetic resonance dynamic imaging method.

[background technology]

Magnetic resonance dynamic imaging is a kind of technology that often can use in the medical diagnosis.Because the motion of tissue or internal organs, magnetic resonance equipment will produce pseudo-shadow in the process of imaging, image is thickened, thereby has reduced resolution and the diagnostic value of image.

Traditional gate monitoring technology supposition object under test movement locus periodically repeats, thereby the period of motion that can measure first object under test by monitor, then, carry out the discontinuous magnetic resonance imaging at the object under test point that arbitrary periodicity repeats in the period of motion, until scanning sequence is finished, obtain clear artifact-free image.

Because propose on the basis that this method is supposition object under test movement locus periodically to be repeated, but in fact, tissue or internal organs are within the different periods of motion, movement locus is also not exclusively overlapping, and therefore, still there is pseudo-shadow in the image that the method obtains.Simultaneously, magnetic resonance imaging must be waited for the arrival of the next period of motion after upper once been scanned, just can carry out scanning next time, and therefore, the time that scanning sequence is finished has been extended.

[summary of the invention]

Based on this, be necessary to provide image taking speed fast, the magnetic resonance dynamic imaging method that imaging effect is good.

A kind of magnetic resonance dynamic imaging method may further comprise the steps:

Radio-frequency coil scans the whole visual field, and sampling obtains the first picture signal, rebuilds the first image according to described the first picture signal; Reduce the sample rate of described the second image and described the 3rd image according to the relation between described the first image, the second image, the 3rd image, described radio-frequency coil is by the sample rate scanning sample of described the second image, obtain the second picture signal, described radio-frequency coil is by the sample rate scanning sample of described the 3rd image, obtain the 3rd image signal, rebuild described the second image, the 3rd image according to the second picture signal and the 3rd picture signal; Sampling obtains the second picture signal and the 3rd picture signal, namely reduce the sample rate of the second image and the 3rd image after, obtain the second picture signal and the 3rd picture signal by the sample rate sampling of the second image and the 3rd image; Make up the object function about the second image and the 3rd image according to described the second picture signal, described the 3rd picture signal; Object function about described the second image and described the 3rd image is optimized finds the solution; Rebuild described the second image, the 3rd image according to the gained solution; Reduce the sample rate of described the 4th image according to the relation of the image of rebuilding before the 4th image and described the 4th image, described radio-frequency coil is by the sample rate scanning sample of described the 4th image, obtain the 4th picture signal, according to described the 3rd image of the 4th picture signal correction and rebuild described the 4th image; Sampling obtains the 4th picture signal; Make up the object function about described the 3rd image and the 4th image according to described the 3rd picture signal, the 4th picture signal; The object function of described the 3rd image and described the 4th image is optimized finds the solution; According to described the 3rd image of gained solution correction and rebuild described the 4th image; The described step that reduces the sample rate of described the second image and described the 3rd image according to the relation between described the first image, the second image, the 3rd image is:

Require to reduce the sample rate of described the second image and described the 3rd image according to the reconstruction of the first residual image and the second residual image, described the first residual image is the part of subtracting each other the variation that obtains with the first image and the second image, and described the second residual image is the part of subtracting each other the variation that obtains with the first image and the second image.

In preferred embodiment, described radio-frequency coil scans the whole visual field, and sampling obtains the first picture signal, and the step of rebuilding the first image according to described the first picture signal comprises the steps: that sampling obtains the first picture signal; According to the object function of described the first picture signal structure about the first image; The object function of described the first image is optimized finds the solution; Rebuild described the first image according to the gained solution.

Above-mentioned magnetic resonance dynamic imaging method reduces the sample rate of the second image, the 3rd image by the first image of having rebuild, rebuild the second image and the 3rd image by the second picture signal and the 3rd picture signal again, then reduce the sample rate of the 4th image by the image of rebuilding before the 4th image, again by the 4th picture signal correction the 3rd image and rebuild the 4th image, reduce sweep time thereby both reach, guaranteed again the effect of image.

In preferred embodiment, described radio-frequency coil is single coil.

In preferred embodiment, described radio-frequency coil is the phased-array coil that is comprised of a plurality of coil arrays.

In preferred embodiment, describedly also comprise before rebuilding the step of the first image according to described the first picture signal: the sensitivity function of obtaining each coil in the described phased-array coil.

In preferred embodiment, the described step of obtaining the sensitivity function of each coil in the described phased-array coil comprises the steps: the whole visual field of prescan, and each coil obtains respectively a frame combination picture in the described phased-array coil; Calculate these combination pictures Square Graphs picture separately, all Square Graphs are looked like to be averaging rear extraction of square root, obtain a frame Square Root Graphs picture; Sensitivity value to each pixel of described Square Root Graphs picture is carried out match optimization, obtains the sensitivity function of each coil.

Above-mentioned magnetic resonance dynamic imaging method, a plurality of coil parallel imagings have been adopted, with the shortening that repeats the time that exchanges in space and under the priori of the slow conversion of object of sample-based, reduce the second image by the first image of having rebuild, the sample rate of the 3rd image, rebuild the second image and the 3rd image by the second picture signal and the 3rd picture signal again, then reduce the sample rate of the 4th image by the image of rebuilding before the 4th image, again by the 4th picture signal correction the 3rd image and rebuild the 4th image, reduce sweep time thereby both reach, guaranteed again the effect of image.

[description of drawings]

Fig. 1 is the magnetic resonance dynamic imaging flow chart among the embodiment one;

Fig. 2 is reconstruction the first image flow chart among the embodiment one;

Fig. 3 is the k-spatial radial sample graph among the embodiment one;

Fig. 4 is that k-space phase among the embodiment one is to variable density nonuniform sampling figure;

Fig. 5 is second, third image flow chart of reconstruction among the embodiment one;

Fig. 6 is passing through the 3rd picture signal, the 4th picture signal correction the 3rd image, rebuild the 4th image flow chart among the embodiment one;

Fig. 7 is passing through the 3rd image, the 4th picture signal correction the 3rd image, rebuild the 4th image flow chart among the embodiment one;

Fig. 8 is the magnetic resonance dynamic imaging flow chart among the embodiment two;

Fig. 9 is each coil sensitivity function flow chart separately in the phased-array coil of obtaining among the embodiment two.

[specific embodiment]

Introduce the present invention below in conjunction with concrete embodiment.

Embodiment one, when radio-frequency coil is single coil, as shown in Figure 1:

Step S100, radio-frequency coil scan the whole visual field, and sampling obtains the first picture signal, rebuilds the first image according to the first picture signal.Step S100 is further comprising the steps of, as shown in Figure 2:

Step S110, sampling obtains the first picture signal.In magnetic resonance device, radio-frequency coil is signal receiving terminal and transmitting terminal simultaneously; Also can be put into the function that receives signal and transmit respectively on two radio-frequency coils, the radio-frequency coil with the function of transmitting is called transmitting coil, and the radio-frequency coil with receiving function is called receiving coil.The said radio-frequency coil of this paper is mainly for its receiving function that has.The visual field refers to centered by region-of-interest, the zone that radio-frequency coil can scan, for example, focus zone, internal organs zone etc.In arbitrary moment after beginning to measure, radio-frequency coil can scan the whole visual field, the then sample mode sampling by the non-Cartesian sampling, such as k-spatial radial sampling (such as Fig. 3) or k-space phase to variable density nonuniform sampling (such as Fig. 4).Traditional Descartes samples needs each point on the k-space to sample, and part (corresponding low frequency information) intensive sampling to k-space center is adopted in the non-Cartesian sampling, and to the mode of k-spatial edge part (corresponding high-frequency information) sparse sampling, under the prerequisite of the quality that does not affect image, reduced sample rate.Because the present invention has adopted the compressed sensing technology, can sample to be lower than the nyquist sampling rate.

Step S120 is according to the object function of the first picture signal structure about the first image.After the sampling, obtain the first picture signal Y ^I-1, according to formula (1), have

Y ^i-1＝A ^i-1ρ ^i-1 （1）

Wherein

Wherein, Δ x, Δ y are the discrete interval of the first image, and m, n are the image pixel coordinate;

During for data acquisition, the track that the k space covers, ρ ^I-1It is the first image.Because this equation is a underdetermined equation, can not directly rebuild the first image according to this equation.Thereby make up one about the object function of the first image, such as formula (2):

${\left|\right|{\mathrm{\Ψ\ρ}}^{i-1}\left|\right|}_1+\frac{1}{2\mathrm{\μ}}{\left|\right|Y^{i-1}-A^{i-1}{\mathrm{\ρ}}^{i-1}\left|\right|}_2^2---\left(2\right)$

Wherein Ψ is wavelet transformation, and μ is a regularization coefficient, ρ ^I-1Be the first image, Y ^I-1It is the first picture signal.

Step S130 is optimized the object function of the first image and finds the solution.Object function is optimized finds the solution, find its sparse solution, mathematic(al) representation such as formula (3):

${\mathrm{\ρ}}^{i-1}=\underset{{\mathrm{\ρ}}^{i-1}}{\arg \min }{\left|\right|{\mathrm{\Ψ\ρ}}^{i-1}\left|\right|}_1+\frac{1}{2\mathrm{\μ}}{\left|\right|Y^{i-1}-A^{i-1}{\mathrm{\ρ}}^{i-1}\left|\right|}_2^2---\left(3\right)$

Wherein, wherein Ψ is wavelet transformation, and μ is a regularization coefficient, ρ ^I-1Be the first image, Y ^I-1It is the first picture signal.

Step S140 rebuilds the first image according to the gained solution.

Step S200, reduce the sample rate of described the second image and described the 3rd image according to the relation between described the first image, the second image, the 3rd image, described radio-frequency coil is by the sample rate scanning sample of described the second image, obtain the second picture signal, described radio-frequency coil is by the sample rate scanning sample of described the 3rd image, obtain the 3rd picture signal, rebuild described the second image, the 3rd image according to the second picture signal and the 3rd picture signal.The first image comprises identical part and the part of variation with the second image, the 3rd image, because area-of-interest is slowly to change, identical part has occupied the overwhelming majority.The part that the second image and the first image subtraction can be obtained changing, i.e. the first residual image; The part that the 3rd image and the first image subtraction can be obtained changing, i.e. the second residual image.Only need satisfy reconstruction requirement to the first residual image and the second residual image to the sampling of the second image and the 3rd image, can rebuild the second image and the 3rd image, thereby can reduce the sample rate of the second image and the 3rd image.This step comprises the steps, as shown in Figure 5:

S210, sampling obtains described the second picture signal and described the 3rd picture signal.After reducing the sample rate of the second image and the 3rd image, by sample rate sampling acquisition the second picture signal and the 3rd picture signal of the second image and the 3rd image.

S220 makes up the object function about described the second image and described the 3rd image according to described the second picture signal, described the 3rd picture signal.Joint sparse by the first image, the second image, the 3rd image obtains formula (4),

$\left|\right|{\mathrm{Wu}}^i\left|\right|+\left|\right|{\mathrm{W\Δu}}^{i-1}\left|\right|+\left|\right|{\mathrm{W\Δu}}^i\left|\right|+\left|\right|{\mathrm{W\Δu}}^{i+1}\left|\right|$

（4）

$+\frac{1}{2\mathrm{\μ}}[{\left|\right|Y^{i-1}-A^{i-1}(u^i+{\mathrm{\Δu}}^{i-1})\left|\right|}_2^2+{\left|\right|Y^i-A^i(u^i+{\mathrm{\Δu}}^i)\left|\right|}_2^2+{\left|\right|Y^{i+1}-A^{i+1}(u^i+{\mathrm{\Δu}}^{i+1})\left|\right|}_2^2]$

Wherein, u ⁱBe the same section of the first image, the second image, the 3rd image, Δ u ^I-1Be the exclusive part of the first image, Δ u ⁱBe the exclusive part of the second image, Δ u ^I+1The exclusive part of the 3rd image, W is the wavelet transformation base, μ is a regularization coefficient, $A^{i-1}=e^{-j2\mathrm{\π}({\mathrm{m\Δxk}}_x^{i-1}+{\mathrm{n\Δyk}}_y^{i-1}),}$ $A^i=e^{-j2\mathrm{\π}({\mathrm{m\Δxk}}_x^i+{\mathrm{n\Δyk}}_y^i)},$ $A^{i+1}=e^{-j2\mathrm{\π}({\mathrm{m\Δxk}}_x^{i+1}+{\mathrm{n\Δyk}}_y^{i+1})},$ Y ^I-1Be the first picture signal, Y ⁱBe the second picture signal that the sample rate by before not reducing of hypothesis is sampled and obtained, Y ^I+1The 3rd picture signal that obtains for the sample rate sampling by before not reducing of hypothesis.

S230 is optimized the object function about described the second image and described the 3rd image and finds the solution.Find the sparse solution of object function by Optimization Solution, the mathematic(al) representation of object function such as formula (5)

$(u^i,{\mathrm{\Δu}}^{i-1},{\mathrm{\Δu}}^i,{\mathrm{\Δu}}^{i+1})=\underset{u^i,{\mathrm{\Δu}}^{i-1},{\mathrm{\Δu}}^i,{\mathrm{\Δu}}^{i+1}}{\arg \min }\left|\right|{\mathrm{Wu}}^i\left|\right|+\left|\right|{\mathrm{W\Δu}}^{i-1}\left|\right|+\left|\right|{\mathrm{W\Δu}}^i\left|\right|+\left|\right|{\mathrm{W\Δu}}^{i+1}\left|\right|$ （5）

$+\frac{1}{2\mathrm{\μ}}[{\left|\right|Y^{i-1}-A^{i-1}(u^i+{\mathrm{\Δu}}^{i-1})\left|\right|}_2^2+{\left|\right|Y^i-A^i(u^i+{\mathrm{\Δu}}^i)\left|\right|}_2^2+{\left|\right|Y^{i+1}-A^{i+1}(u^i+{\mathrm{\Δu}}^{i+1})\left|\right|}_2^2]$

Wherein, u ⁱBe the same section of the first image, the second image, the 3rd image, Δ u ^I-1Be the exclusive part of the first image, Δ u ⁱBe the exclusive part of the second image, Δ u ^I+1The exclusive part of the 3rd image, W is the wavelet transformation base, μ is a regularization coefficient, $A^{i-1}=e^{-j2\mathrm{\π}({\mathrm{m\Δxk}}_x^{i-1}+{\mathrm{n\Δyk}}_y^{i-1}),}$ $A^i=e^{-j2\mathrm{\π}({\mathrm{m\Δxk}}_x^i+{\mathrm{n\Δyk}}_y^i)},$ $A^{i+1}=e^{-j2\mathrm{\π}({\mathrm{m\Δxk}}_x^{i+1}+{\mathrm{n\Δyk}}_y^{i+1})},$ Y ^I-1Be the first picture signal, Y ⁱBe the second picture signal that the sample rate by before not reducing of hypothesis is sampled and obtained, Y ^I+1The 3rd picture signal that obtains for the sample rate sampling by before not reducing of hypothesis.Considering that the first image has been rebuild obtains, and the Optimization Solution problem of formula (5) changes into following formula (6) Optimization Solution problem.

$({\mathrm{\Δ\ρ}}^i,{\mathrm{\Δ\ρ}}^{i+1})=\underset{{\mathrm{\Δ\ρ}}^i,{\mathrm{\Δ\ρ}}^{i+1}}{\arg \min }\left|\right|{\mathrm{W\Δ\ρ}}^i\left|\right|+\left|\right|{\mathrm{W\Δ\ρ}}^{i+1}\left|\right|+\frac{1}{2\mathrm{\μ}}[{\left|\right|Y_{\mathrm{residul}}^i-A^i{\mathrm{\Δ\ρ}}^i\left|\right|}_2^2+{\left|\right|Y_{\mathrm{residul}}^{i+1}-A^{i+1}{\mathrm{\Δ\ρ}}^{i+1}\left|\right|}_2^2]---\left(6\right)$

Wherein, Δ ρ ⁱ=Δ u ⁱ-Δ u ^I-1, i.e. the first residual image, Δ ρ ^I+1=Δ u ^I+1-Δ u ^I-1, i.e. the second residual image, $Y_{\mathrm{residul}}^i=Y^i-A^i{\mathrm{\ρ}}^{i-1},$ I.e. the second picture signal, $A^{i-1}=e^{-j2\mathrm{\π}({\mathrm{m\Δxk}}_x^{i-1}+{\mathrm{n\Δyk}}_y^{i-1}),}$ $Y_{\mathrm{residul}}^{i+1}=Y^{i+1}-A^{i+1}{\mathrm{\ρ}}^{i-1},$ I.e. the 3rd picture signal,

W is the wavelet transformation base, and μ is a regularization coefficient.

S240 rebuilds described the second image, the 3rd image according to the gained solution.

S300, reduce the sample rate of described the 4th image according to the relation of the image of rebuilding before the 4th image and described the 4th image, described radio-frequency coil is by the sample rate scanning sample of described the 4th image, obtain the 4th picture signal, according to described the 3rd image of the 4th picture signal correction and rebuild described the 4th image.The first image comprises identical part and the part of variation with the second image, the 3rd image, the 4th image, because area-of-interest is slowly to change, identical part has occupied the overwhelming majority.Thereby, can reduce according to the relation of the first image, the second image, the 3rd image and the 4th image the sample rate of described the 4th image.In one embodiment, this step comprises the steps, as shown in Figure 6:

S310, sampling obtains described the 4th picture signal.After reducing the sample rate of the 4th image, radio-frequency coil obtains the 4th picture signal by the sample rate sampling of the 4th image.

S330 makes up the object function about described the 3rd image and described the 4th image according to described the 3rd picture signal, the 4th picture signal.

S350 is optimized the object function of described the 3rd image and described the 4th image and finds the solution.

S370 is according to described the 3rd image of gained solution correction and rebuild described the 4th image.

In another embodiment, step S300 comprises the steps, as shown in Figure 7:

S320, sampling obtains described the 4th picture signal.After reducing the sample rate of the 4th image, radio-frequency coil obtains the 4th picture signal by the sample rate sampling of the 4th image.

S340 makes up the object function about described the 3rd image and described the 4th image according to described the 3rd image, the 4th picture signal.The method that makes up is as described in the S220.

S360 is optimized the object function of described the 3rd image and described the 4th image and finds the solution.In order to revise the 3rd image, in formula (7), add revision matrix Λ ⁱ, have

$({\mathrm{\Δ\ρ}}^{i+1},{\mathrm{\Δ\ρ}}^{i+2})=\underset{{\mathrm{\Δ\ρ}}^i,{\mathrm{\Δ\ρ}}^{i+1}}{\arg \min }\left|\right|{{\mathrm{\Λ}}^{i+1}\mathrm{W\Δ\ρ}}^{i+1}\left|\right|+\left|\right|{\mathrm{W\Δ\ρ}}^{i+2}\left|\right|+\frac{1}{2\mathrm{\μ}}[{\left|\right|Y_{\mathrm{residul}}^{i+1}-A^{i+1}{\mathrm{\Δ\ρ}}^{i+1}\left|\right|}_2^2+{\left|\right|Y_{\mathrm{residul}}^{i+2}-A^{i+2}{\mathrm{\Δ\ρ}}^{i+2}\left|\right|}_2^2]---\left(7\right)$

Wherein, Δ ρ ^I+1=Δ u ^I+1-Δ u ⁱ, Δ ρ ^I+2=Δ u ^I+2-Δ u ⁱ,

I.e. the 3rd picture signal, $A^{i+1}=e^{-j2\mathrm{\π}({\mathrm{m\Δxk}}_x^{i+1}+{\mathrm{n\Δyk}}_y^{i+1}),}$ $Y_{\mathrm{residul}}^{i+2}=Y^{i+2}-A^{i+2}{\mathrm{\ρ}}^i,$ I.e. the 4th picture signal, $A^{i+2}=e^{-j2\mathrm{\π}({\mathrm{m\Δxk}}_x^{i+2}+{\mathrm{n\Δyk}}_y^{i+2})},$ W is the wavelet transformation base, and μ is a regularization coefficient.

S380 is according to described the 3rd image of gained solution correction and rebuild described the 4th image.

When radio-frequency coil is phased-array coil, as shown in Figure 8:

Step S410 obtains the sensitivity function of each coil in the described phased-array coil.Phased-array coil is comprised of a plurality of coil arrays.The position that each coil in the phased-array coil is put is different, thereby imaging region is also different, the synthetic two field picture of the multiple image signal that phased-array coil obtains, must utilize sensitivity function.Step S410 also comprises the steps, as shown in Figure 9:

Step S411, the whole visual field of prescan, each coil obtains respectively a frame combination picture in the described phased-array coil;

Step S412 calculates these combination pictures Square Graphs picture separately, and all Square Graphs are looked like to be averaging rear extraction of square root, and obtaining that a frame Square Root Graphs looks like is f _Sos

Step S413 carries out match optimization to the sensitivity value of each pixel of described Square Root Graphs picture, obtains the sensitivity function of each coil.It is concrete such as formula (8),

$E_{\mathrm{rr}}=\underset{x,y}{\mathrm{\Σ}}{(f_l(x,y)-P_l(x,y)f_{\mathrm{sos}}(x,y))}^2---\left(8\right)$

Wherein,

P _l(x, y) for treating the multinomial of match, wherein K is polynomial exponent number, b _{L, i, j}For treating the polynomial coefficient of match, f _l(x, y) is that the l passage is rebuild the image that obtains, f _Sos(x, y) is required Square Root Graphs picture.

Step S420, radio-frequency coil is in the whole visual field of scanning, and sampling obtains the first picture signal, rebuilds the first image according to the first picture signal.The radio-frequency coil here is phased-array coil, and each coil samples respectively a frame the first picture signal,

$Y^{i-1}=\left[\begin{array}{c}{y}_1^{i-1}\\ .\\ .\\ .\\ y_L^{i-1}\end{array}\right]$

Known Y ^I-1=A ^I-1ρ ^I-1, A ^I-1Can be obtained by sensitivity function:

$A^{i-1}=\left[\begin{array}{c}{E}_1^{i-1}\\ .\\ .\\ .\\ E_L^{i-1}\end{array}\right],$ Wherein $E_L^{i-1}=s_L(\mathrm{m\Δx},\mathrm{n\Δy})e^{-j2\mathrm{\π}({\mathrm{m\Δxk}}_x^{i-1}+{\mathrm{n\Δyk}}_y^{i-1})},$ The sensitivity function of certain coil that obtains for prescan.Structure is about the object function of the first image,

${\mathrm{\ρ}}^{i-1}=\underset{{\mathrm{\ρ}}^{i-1}}{\arg \min }{\left|\right|{\mathrm{\Ψ\ρ}}^{i-1}\left|\right|}_1+\frac{1}{2\mathrm{\μ}}{\left|\right|Y^{-i-1}{-A}^{i-1}{\mathrm{\ρ}}^{i-1}\left|\right|}_2^2$

Be optimized reconstruction the first image by embodiment one described method.

Step S430, the S200 among the specific embodiment of S440 such as the embodiment one, S300.

The above embodiment has only expressed several embodiment of the present invention, and it describes comparatively concrete and detailed, but can not therefore be interpreted as the restriction to claim of the present invention.Should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection domain of patent of the present invention should be as the criterion with claims.

Claims (6)

1. magnetic resonance dynamic imaging method may further comprise the steps:

Radio-frequency coil scans the whole visual field, and sampling obtains the first picture signal, rebuilds the first image according to described the first picture signal; The first image, the second image, the 3rd image and the 4th image are obtainable four continuous images in chronological order;

Reduce the sample rate of described the second image and described the 3rd image according to the relation between described the first image, the second image, the 3rd image, described radio-frequency coil is by the sample rate scanning sample of described the second image, obtain the second picture signal, described radio-frequency coil is by the sample rate scanning sample of described the 3rd image, obtain the 3rd picture signal, rebuild described the second image, the 3rd image according to the second picture signal and the 3rd picture signal;

Sampling obtains the second picture signal and the 3rd picture signal, namely reduce the sample rate of the second image and the 3rd image after, obtain the second picture signal and the 3rd picture signal by the sample rate sampling of the second image and the 3rd image; Make up the object function about described the second image and the 3rd image according to described the second picture signal, described the 3rd picture signal; Object function about described the second image and described the 3rd image is optimized finds the solution; Rebuild described the second image, the 3rd image according to the gained solution;

Reduce the sample rate of described the 4th image according to the relation of described the first image, the second image, the 3rd image and the 4th image, described radio-frequency coil is by the sample rate scanning sample of described the 4th image, obtain the 4th picture signal, according to described the 3rd image of described the 4th picture signal correction and rebuild described the 4th image;

Describedly according to described the 3rd image of the 4th picture signal correction and the step of rebuilding described the 4th image be: make up the object function about described the 3rd image and the 4th image according to described the 3rd picture signal, the 4th picture signal; The object function of described the 3rd image and described the 4th image is optimized finds the solution; According to described the 3rd image of gained solution correction and rebuild described the 4th image;

The described step that reduces the sample rate of described the second image and described the 3rd image according to the relation between described the first image, the second image, the 3rd image is:

Require to reduce the sample rate of described the second image and described the 3rd image according to the reconstruction of the first residual image and the second residual image, described the first residual image is the part of subtracting each other the variation that obtains with the first image and the second image, and described the second residual image is the part of subtracting each other the variation that obtains with the first image and the 3rd image.

2. magnetic resonance dynamic imaging method according to claim 1 is characterized in that, described radio-frequency coil scans the whole visual field, and sampling obtains the first picture signal, and the step of rebuilding the first image according to described the first picture signal comprises the steps:

Sampling obtains the first picture signal;

According to the object function of described the first picture signal structure about the first image;

The object function of described the first image is optimized finds the solution;

Rebuild described the first image according to the gained solution.

3. according to claim 1 to the described magnetic resonance dynamic imaging method of 2 arbitrary claim, it is characterized in that, described radio-frequency coil is single coil.

4. according to claim 1 to the described magnetic resonance dynamic imaging method of 2 arbitrary claim, it is characterized in that, described radio-frequency coil is the phased-array coil that is comprised of a plurality of coil arrays.

5. magnetic resonance dynamic imaging method according to claim 4 is characterized in that, describedly also comprises before rebuilding the step of the first image according to described the first picture signal:

Obtain the sensitivity function of each coil in the described phased-array coil.

6. magnetic resonance dynamic imaging method according to claim 5 is characterized in that, the described step of obtaining the sensitivity function of each coil in the described phased-array coil comprises the steps:

Each coil obtains respectively a frame combination picture in the whole visual field of prescan, described phased-array coil;

Calculate these combination pictures Square Graphs picture separately, all Square Graphs are looked like to be averaging rear extraction of square root, obtain a frame Square Root Graphs picture;

Sensitivity value to each pixel of described Square Root Graphs picture is carried out match optimization, obtains the sensitivity function of each coil.

Images