CN115656900A - Method and device for reducing influence of system error on magnetic resonance imaging - Google Patents
Method and device for reducing influence of system error on magnetic resonance imaging Download PDFInfo
- Publication number
- CN115656900A CN115656900A CN202211363402.9A CN202211363402A CN115656900A CN 115656900 A CN115656900 A CN 115656900A CN 202211363402 A CN202211363402 A CN 202211363402A CN 115656900 A CN115656900 A CN 115656900A
- Authority
- CN
- China
- Prior art keywords
- preset position
- pulse
- gradient
- eddy current
- amplitude value
- 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
Images
Classifications
-
- 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
- Magnetic Resonance Imaging Apparatus (AREA)
Abstract
The invention discloses a method and a device for reducing the influence of system errors on magnetic resonance imaging, wherein the method comprises the following steps: determining a first pulse preset position and a second pulse preset position of different gradients of the spin echo; on the basis of applying the diffusion gradient, applying amplitude values with equal magnitude and opposite directions at the first pulse preset position and the second pulse preset position; calculating the eddy current generated by any gradient according to the amplitude value, and determining that the eddy current generated by the amplitude value becomes smaller according to the condition that the amplitude value applied to the second pulse preset position is smaller than the dispersion gradient value; offsetting residual magnetism generated by the diffusion gradient by the amplitude value applied to the preset position of the second pulse being smaller than the diffusion gradient value and having opposite directions; based on the reduction of eddy current and the reduction of remanence, the influence of system errors caused by diffusion gradients on magnetic resonance imaging is reduced.
Description
Technical Field
The invention relates to the technical field of magnetic resonance imaging, in particular to a method and a device for reducing the influence of system errors on magnetic resonance imaging.
Background
Diffusion weighted imaging is a new magnetic resonance imaging technology, and hydrogen protons show different signal amplitudes in the gradient direction after applying a diffusion gradient by using the water molecule movement diffusion characteristic. Different tissues can be distinguished by signal intensity because of different diffusion coefficients of different tissues.
The fast spin echo in the diffusion weighted imaging has the characteristics of high scanning speed, low requirement on shimming conditions and small motion artifact, and can effectively reduce the deformation and the artifact of a plane echo type image when used in the diffusion weighted imaging. The fast spin echo has some disadvantages, and because the system is difficult to reach the ideal state of theory, a large number of rephasing pulses and gradients cause the signal phase in the echo chain to have difference, which is reflected in the image with non-negligible artifacts.
Disclosure of Invention
In view of the above problem, the present invention provides a method for reducing the influence of system errors on magnetic resonance imaging, comprising:
determining a first pulse preset position and a second pulse preset position of different gradients of the spin echo;
on the basis of applying the diffusion gradient, applying amplitude values with equal magnitude and opposite directions at the first pulse preset position and the second pulse preset position;
calculating the eddy current generated by any gradient according to the amplitude value, and determining that the eddy current generated by the amplitude value is reduced according to the condition that the amplitude value applied to the second pulse preset position is smaller than the dispersion gradient value; offsetting residual magnetism generated by the diffusion gradient by the amplitude value applied to the preset position of the second pulse being smaller than the diffusion gradient value and having opposite directions; based on the reduction of eddy current and the reduction of remanence, the influence of system errors caused by diffusion gradients on magnetic resonance imaging is reduced.
Further, the method also comprises the following steps:
the stimulated echo is shifted out of an imaging space through the amplitude values applied by the first pulse preset position and the second pulse preset position, so that the influence of system errors caused by diffusion gradients on magnetic resonance imaging is reduced.
Further, determining a first pulse preset position and a second pulse preset position of different gradients of the spin echo comprises:
the first pulse preset position is before the first diffusion gradient, and the second pulse preset position is after the last diffusion gradient.
Further, the amplitude value is smaller than the dispersion gradient value.
Further, calculating the eddy current generated by any gradient, wherein the specific calculation formula is as follows:
wherein G is the eddy current generated by the gradient, G is the gradient,
for the convolution symbol, e (t) is the function used to calculate the eddy current response.
Further, determining that the eddy current generated by the amplitude value becomes small according to the amplitude value applied to the preset position of the second pulse being smaller than the dispersion gradient value, includes:
according to the calculation formula of the eddy current, the amplitude value gradient applied to the preset position of the second pulse is smaller than the dispersion gradient, so that the eddy current generated by the amplitude value is determined to be smaller.
The invention also provides a device for reducing the influence of system errors on magnetic resonance imaging, which comprises:
a preset position determining unit for determining a first pulse preset position and a second pulse preset position of different gradients of the spin echo;
the amplitude value applying unit is used for simultaneously applying amplitude values with equal size and opposite directions at the first pulse preset position and the second pulse preset position on the basis of applying the diffusion gradient;
the influence reduction unit is used for calculating the eddy current generated by any gradient according to the amplitude value, and determining that the eddy current generated by the amplitude value becomes smaller according to the condition that the amplitude value applied to the second pulse preset position is smaller than the dispersion gradient value; offsetting residual magnetism generated by the diffusion gradient by the amplitude value applied to the preset position of the second pulse being smaller than the diffusion gradient value and having opposite directions; based on the reduction of eddy current and the reduction of remanence, the influence of system errors caused by diffusion gradients on magnetic resonance imaging is reduced.
Further, the method also comprises the following steps:
and the stimulated echo shifting-out unit is used for shifting the stimulated echo out of the imaging space through the amplitude value applied by the first pulse preset position and the second pulse preset position, so that the influence of the system error caused by the diffusion gradient on the magnetic resonance imaging is reduced.
Further, the preset position determining unit includes:
and the preset position determining subunit is used for determining that the first pulse preset position is before the first diffusion gradient and the second pulse preset position is after the last diffusion gradient.
Further, the influence reduction unit includes:
and the eddy current reduction determining subunit is used for determining that the eddy current generated by the amplitude value is reduced, wherein the amplitude value gradient applied to the preset position of the second pulse is smaller than the diffusion gradient according to the calculation formula of the eddy current.
The invention provides a method and a device for reducing the influence of system errors on magnetic resonance imaging, wherein amplitude values with equal magnitude and opposite directions are applied at a first pulse preset position and a second pulse preset position on the basis of applying a diffusion gradient; because the amplitude value is smaller than the diffusion gradient, dG/dt is smaller, and the eddy influence caused by the rising edge and the falling edge of the gradient can be effectively reduced; the positive and negative gradient switching can offset the influence of residual magnetism on the image to a certain degree; because the applied diffusion gradient 1,2 is very small, in the image with b =0, the two gradients can be selectively not closed, after the second 180 ° rephasing pulse, the stimulated echo signal is subjected to the dephasing action of the two gradients, and in the subsequent echo signal, the stimulated echo is the same as the diffusion gradient, so that the stimulated echo cannot be generated in the image space, and the consistency of the signals is maintained.
Drawings
FIG. 1 is a flow chart illustrating a method for reducing the effect of systematic errors on MRI provided by the present invention;
FIG. 2 is a timing diagram of eddy current effects produced by a dual-phasing RF pulse reduction system in accordance with the present invention;
FIG. 3 is a position of application of a diffusion gradient according to the present invention;
FIG. 4 is a comparison before and after the magnetic resonance image processing according to the present invention;
fig. 5 is a schematic structural diagram of an apparatus for reducing the influence of system errors on magnetic resonance imaging provided by the invention.
Detailed Description
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may be embodied in many different forms than those herein set forth and should be readily appreciated by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
In the article of Reduction of edge-current-induced displacement in diffusion MRI using a twist-refocused spot, it is proposed that the eddy current effect generated by the system can be reduced by using a two-phase focusing rf pulse, and the image quality can be improved, as shown in fig. 2. The method can eliminate the influence of the eddy current to a certain degree, but from the formula (1), the eddy current is only related to the gradient change,
wherein G is the eddy current generated by the gradient, G is the gradient,
for the convolution symbol, e (t) is the function used to calculate the eddy current response.
The mode has small influence on the rising edge and the falling edge and has limited effect. In addition, such a gradient causes a stimulated echo to be generated when b =0, which affects an image signal value and ultimately affects the accuracy of the ADC.
In order to solve the above mentioned problems, the present invention provides a method for reducing the influence of system errors on magnetic resonance imaging, as shown in fig. 1, comprising the following steps:
step S101, determining a first pulse preset position and a second pulse preset position of different gradients of the spin echo.
As shown in fig. 3, the first pulse preset position is before the first diffusion gradient, i.e. the position indicated by the arrow 1 in fig. 3, and the second pulse preset position is after the last diffusion gradient, i.e. the position indicated by the arrow 2 in fig. 3.
And S102, simultaneously applying amplitude values with equal magnitude and opposite directions at the first pulse preset position and the second pulse preset position on the basis of applying the diffusion gradient.
The diffusion gradients 1 and 2, are added at the locations shown in FIG. 3 with equal and opposite polarity, and then equal and opposite magnitude values are applied simultaneously based on the application of the diffusion gradients, the magnitude values being less than the diffusion gradient values. The amplitudes of 1 and 2 are smaller than the dispersion gradient, and the value range of the dispersion gradient is generally 0.2-0.6.
Step S103, calculating the eddy current generated by any gradient according to the amplitude value, and determining that the eddy current generated by the amplitude value is reduced according to the condition that the amplitude value applied to the second pulse preset position is smaller than the dispersion gradient value; offsetting residual magnetism generated by the diffusion gradient by the amplitude value applied to the preset position of the second pulse being smaller than the diffusion gradient value and in opposite directions; based on the fact that eddy current becomes small and remanent magnetization becomes small, the influence of system errors caused by diffusion gradients on magnetic resonance imaging is reduced.
Calculating the eddy current generated by any gradient according to the formula (1), and further determining that the gradient of the amplitude value applied to the preset position of the second pulse is smaller than the diffusion gradient according to the formula (1), so that the eddy current generated by the amplitude value is determined to be smaller.
Offsetting residual magnetism generated by the diffusion gradient by the amplitude value applied to the preset position of the second pulse being smaller than the diffusion gradient value and in opposite directions; based on the fact that eddy current becomes small and remanence becomes small, the stimulated echo is shifted out of an imaging space through amplitude values applied by the first pulse preset position and the second pulse preset position, and therefore the influence of system errors caused by diffusion gradients on magnetic resonance imaging is reduced.
By the above method, the magnetic resonance image is processed, and fig. 4 (a) is an ADC image before improvement and fig. 4 (b) is an ADC image after improvement. From the results, it can be seen that there are obvious gradient distortion, blurring blur artifact and signal disappearance caused by dephasing at the arrow of fig. 4 (a), and blurring artifact can be slightly seen in fig. 4 (b), and other problems are obviously improved.
Based on the same inventive concept, the present invention provides an apparatus 500 for reducing the influence of system errors on magnetic resonance imaging, as shown in fig. 5, comprising:
a preset position determination unit 510 for determining a first pulse preset position and a second pulse preset position of different gradients of the spin echo;
an amplitude value applying unit 520, configured to apply amplitude values with equal magnitude and opposite directions at the first pulse preset position and the second pulse preset position simultaneously on the basis of applying the diffusion gradient;
the influence reduction unit 530 is configured to calculate an eddy current generated by any gradient according to the amplitude value, and determine that the eddy current generated by the amplitude value becomes smaller according to the fact that the amplitude value applied to the second pulse preset position is smaller than the dispersion gradient value; offsetting residual magnetism generated by the diffusion gradient by the amplitude value applied to the preset position of the second pulse being smaller than the diffusion gradient value and in opposite directions; based on the reduction of eddy current and the reduction of remanence, the influence of system errors caused by diffusion gradients on magnetic resonance imaging is reduced.
Further, the method also comprises the following steps:
and the stimulated echo shifting-out unit is used for shifting the stimulated echo out of the imaging space through the amplitude value applied by the first pulse preset position and the second pulse preset position, so that the influence of the system error caused by the diffusion gradient on the magnetic resonance imaging is reduced.
Further, the preset position determination unit includes:
and the preset position determining subunit is used for determining that the first pulse preset position is before the first diffusion gradient and the second pulse preset position is after the last diffusion gradient.
Further, the influence reducing unit includes:
and the eddy current reduction determining subunit is used for determining that the eddy current generated by the amplitude value is reduced, wherein the amplitude value gradient applied to the preset position of the second pulse is smaller than the diffusion gradient according to the calculation formula of the eddy current.
The invention provides a method and a device for reducing the influence of system errors on magnetic resonance imaging, wherein amplitude values with equal magnitude and opposite directions are applied at a first pulse preset position and a second pulse preset position on the basis of applying a diffusion gradient; because the amplitude value is smaller than the diffusion gradient, dG/dt is smaller, and the eddy influence caused by the rising edge and the falling edge of the gradient can be effectively reduced; the positive and negative gradient switching can offset the influence of residual magnetism on the image to a certain degree; because the applied diffusion gradient 1,2 is very small, in the image with b =0, the two gradients can be selectively not closed, after the second 180 ° rephasing pulse, the stimulated echo signal is subjected to the dephasing action of the two gradients, and in the subsequent echo signal, the stimulated echo is the same as the diffusion gradient, so that the stimulated echo cannot be generated in the image space, and the consistency of the signals is maintained.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention.
Claims (10)
1. A method for reducing the effect of systematic errors on magnetic resonance imaging, comprising:
determining a first pulse preset position and a second pulse preset position of different gradients of the spin echo;
on the basis of applying the diffusion gradient, applying amplitude values with equal magnitude and opposite directions at the first pulse preset position and the second pulse preset position;
calculating the eddy current generated by any gradient according to the amplitude value, and determining that the eddy current generated by the amplitude value is reduced according to the condition that the amplitude value applied to the second pulse preset position is smaller than the dispersion gradient value; offsetting residual magnetism generated by the diffusion gradient by the amplitude value applied to the preset position of the second pulse being smaller than the diffusion gradient value and having opposite directions; based on the reduction of eddy current and the reduction of remanence, the influence of system errors caused by diffusion gradients on magnetic resonance imaging is reduced.
2. The method of claim 1, further comprising:
and moving the stimulated echo out of an imaging space through the amplitude values applied by the first pulse preset position and the second pulse preset position, thereby reducing the influence of system errors caused by diffusion gradients on magnetic resonance imaging.
3. The method of claim 1, wherein determining the first and second pulse preset positions for different gradients of the spin echo comprises:
the first pulse preset position is before the first diffusion gradient, and the second pulse preset position is after the last diffusion gradient.
4. The method of claim 1, wherein the amplitude values are less than the dispersion gradient values.
5. The method of claim 1, wherein the eddy currents generated by any one of the gradients are calculated by the following formula:
wherein g is the eddy current generated by the gradient,g is the gradient of the light beam and the light beam,
for the convolution symbol, e (t) is the function used to calculate the eddy current response.
6. The method according to claim 1 or 4, wherein determining that the eddy current generated by the amplitude value becomes small in accordance with the amplitude value applied to the preset position of the second pulse being smaller than the dispersion gradient value comprises:
according to the calculation formula of the eddy current, the gradient of the amplitude value applied to the preset position of the second pulse is smaller than the diffusion gradient, so that the eddy current generated by the amplitude value is determined to be smaller.
7. An apparatus for reducing the effect of systematic errors on magnetic resonance imaging, comprising:
a preset position determining unit for determining a first pulse preset position and a second pulse preset position of different gradients of the spin echo;
the amplitude value applying unit is used for simultaneously applying amplitude values with equal magnitude and opposite directions on the basis of applying the diffusion gradient at the first pulse preset position and the second pulse preset position;
the influence reduction unit is used for calculating the eddy current generated by any gradient according to the amplitude value, and determining that the eddy current generated by the amplitude value becomes smaller according to the condition that the amplitude value applied to the second pulse preset position is smaller than the dispersion gradient value; offsetting residual magnetism generated by the diffusion gradient by the amplitude value applied to the preset position of the second pulse being smaller than the diffusion gradient value and in opposite directions; based on the reduction of eddy current and the reduction of remanence, the influence of system errors caused by diffusion gradients on magnetic resonance imaging is reduced.
8. The apparatus of claim 7, further comprising:
and the stimulated echo shifting-out unit is used for shifting the stimulated echo out of the imaging space through the amplitude values applied by the first pulse preset position and the second pulse preset position, so that the influence of system errors caused by diffusion gradients on magnetic resonance imaging is reduced.
9. The apparatus of claim 7, wherein the preset position determination unit comprises:
and the preset position determining subunit is used for determining that the first pulse preset position is before the first diffusion gradient and the second pulse preset position is after the last diffusion gradient.
10. The apparatus of claim 7, wherein the impact reduction unit comprises:
and the eddy current reduction determining subunit is used for determining that the eddy current generated by the amplitude value is reduced, wherein the amplitude value gradient applied to the preset position of the second pulse is smaller than the diffusion gradient according to the calculation formula of the eddy current.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211363402.9A CN115656900B (en) | 2022-11-02 | 2022-11-02 | Method and device for reducing influence of system error on magnetic resonance imaging |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211363402.9A CN115656900B (en) | 2022-11-02 | 2022-11-02 | Method and device for reducing influence of system error on magnetic resonance imaging |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN115656900A true CN115656900A (en) | 2023-01-31 |
| CN115656900B CN115656900B (en) | 2023-06-23 |
Family
ID=84995459
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211363402.9A Active CN115656900B (en) | 2022-11-02 | 2022-11-02 | Method and device for reducing influence of system error on magnetic resonance imaging |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115656900B (en) |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH11123184A (en) * | 1997-10-21 | 1999-05-11 | Ge Yokogawa Medical Systems Ltd | Diffusion and enhancement imaging method and mri system |
| JPH11285481A (en) * | 1998-04-02 | 1999-10-19 | Toshiba Corp | Mr apparatus and mr data collection method |
| US6265872B1 (en) * | 1997-08-19 | 2001-07-24 | Siemens Aktiengesellschaft | Diffusion detection by means of magnetic resonance |
| CN102670202A (en) * | 2011-03-15 | 2012-09-19 | 株式会社东芝 | Magnetic resonance imaging apparatus |
| CN105785298A (en) * | 2016-03-10 | 2016-07-20 | 大连锐谱科技有限责任公司 | High-precision three-dimensional chemical shift imaging method |
| CN109085522A (en) * | 2018-07-02 | 2018-12-25 | 上海东软医疗科技有限公司 | A kind of acquisition method and device of Diffusion-weighted imaging and spectroscopic signal |
| CN109242847A (en) * | 2018-09-20 | 2019-01-18 | 上海东软医疗科技有限公司 | A kind of Diffusion-weighted imaging method and apparatus |
| CN112881959A (en) * | 2020-06-10 | 2021-06-01 | 苏州纽迈分析仪器股份有限公司 | Gradient eddy current compensation method and system for magnetic resonance imaging |
| CN113391251A (en) * | 2020-03-12 | 2021-09-14 | 上海联影医疗科技股份有限公司 | Magnetic resonance image reconstruction method, device and equipment |
| CN114442016A (en) * | 2022-01-24 | 2022-05-06 | 武汉联影生命科学仪器有限公司 | Magnetic resonance pulse generation method and magnetic resonance imaging method |
-
2022
- 2022-11-02 CN CN202211363402.9A patent/CN115656900B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6265872B1 (en) * | 1997-08-19 | 2001-07-24 | Siemens Aktiengesellschaft | Diffusion detection by means of magnetic resonance |
| JPH11123184A (en) * | 1997-10-21 | 1999-05-11 | Ge Yokogawa Medical Systems Ltd | Diffusion and enhancement imaging method and mri system |
| JPH11285481A (en) * | 1998-04-02 | 1999-10-19 | Toshiba Corp | Mr apparatus and mr data collection method |
| CN102670202A (en) * | 2011-03-15 | 2012-09-19 | 株式会社东芝 | Magnetic resonance imaging apparatus |
| CN105785298A (en) * | 2016-03-10 | 2016-07-20 | 大连锐谱科技有限责任公司 | High-precision three-dimensional chemical shift imaging method |
| CN109085522A (en) * | 2018-07-02 | 2018-12-25 | 上海东软医疗科技有限公司 | A kind of acquisition method and device of Diffusion-weighted imaging and spectroscopic signal |
| CN109242847A (en) * | 2018-09-20 | 2019-01-18 | 上海东软医疗科技有限公司 | A kind of Diffusion-weighted imaging method and apparatus |
| CN113391251A (en) * | 2020-03-12 | 2021-09-14 | 上海联影医疗科技股份有限公司 | Magnetic resonance image reconstruction method, device and equipment |
| CN112881959A (en) * | 2020-06-10 | 2021-06-01 | 苏州纽迈分析仪器股份有限公司 | Gradient eddy current compensation method and system for magnetic resonance imaging |
| CN114442016A (en) * | 2022-01-24 | 2022-05-06 | 武汉联影生命科学仪器有限公司 | Magnetic resonance pulse generation method and magnetic resonance imaging method |
Non-Patent Citations (2)
| Title |
|---|
| T.G.REESE ET AL.: "Reduction of eddy-current-induced distortion in diffusion MRIusing a twice-refocused spin echo", 《MAGNETIC RESONANCE IN MEDICINE》 * |
| 白秋云 等: "磁共振多模态影像技术在短暂性脑缺血发作中的临床应用价值", 《医学影像学杂志》 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN115656900B (en) | 2023-06-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Morgan et al. | Correction of spatial distortion in EPI due to inhomogeneous static magnetic fields using the reversed gradient method | |
| Block et al. | Spiral imaging: a critical appraisal | |
| KR100225321B1 (en) | Mri apparatus | |
| JP5868160B2 (en) | Magnetic resonance imaging system | |
| US5581184A (en) | Method for phase correction of nuclear magnetic resonance signals | |
| US6043651A (en) | Method for the phase correction of nuclear magnetic resonance signals | |
| US7154269B1 (en) | Iterative method for correction of geometric distortion resulting from phase evolution during segmented echo planar nuclear magnetic resonance imaging and apparatus therefor | |
| US6483305B1 (en) | Magnetic resonance method for reducing residual magnetization and adjusting the amplitude of gradient pulses | |
| CN112763958B (en) | Multi-excitation plane echo magnetic resonance imaging method based on neural network | |
| JP4433344B2 (en) | Method of operating phase sensitive MR imaging apparatus and MR imaging apparatus | |
| US6528996B1 (en) | Diffusion-weighted imaging method and apparatus for fast pulse sequence with MPG pulses | |
| US5309101A (en) | Magnetic resonance imaging in an inhomogeneous magnetic field | |
| JP3853585B2 (en) | MRI equipment | |
| US7154268B2 (en) | Method and apparatus to improve an MRI image using regularization | |
| CN115656900A (en) | Method and device for reducing influence of system error on magnetic resonance imaging | |
| US20100085049A1 (en) | Method of obtaining a magnetic resonance image in which the streak artifacts are corrected using non-linear phase correction | |
| KR19990088424A (en) | Mr imaging method and apparatus | |
| JP3987337B2 (en) | Multi-echo imaging device | |
| KR100331449B1 (en) | Phase error compensation method of phase encoding gradient pulse in fast spin echo pulse sequence | |
| CN111830450A (en) | Method for determining and eliminating time delay between radio frequency pulse and selective layer gradient in magnetic resonance equipment | |
| Zur | Two‐dimensional phase correction method for single and multi‐shot echo planar imaging | |
| CN111142056B (en) | Method for correcting planar echo two-dimensional space selective pulse | |
| KR20020033550A (en) | Mr imaging method, phase error measuring method, and mri apparatus | |
| JP2011206493A (en) | Magnetic resonance imaging apparatus | |
| JP2020175194A (en) | Magnetic resonance imaging apparatus and magnetic resonance imaging method |
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 |