CN112731235B - Magnetic resonance chemical exchange saturation transfer imaging method and related equipment - Google Patents
Magnetic resonance chemical exchange saturation transfer imaging method and related equipment Download PDFInfo
- Publication number
- CN112731235B CN112731235B CN202011451417.1A CN202011451417A CN112731235B CN 112731235 B CN112731235 B CN 112731235B CN 202011451417 A CN202011451417 A CN 202011451417A CN 112731235 B CN112731235 B CN 112731235B
- Authority
- CN
- China
- Prior art keywords
- magnetic resonance
- flip angle
- target tissue
- variable flip
- pulse
- 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.)
- Active
Links
- 230000005291 magnetic effect Effects 0.000 title claims abstract description 81
- 238000003384 imaging method Methods 0.000 title claims abstract description 36
- 239000000126 substance Substances 0.000 title claims abstract description 17
- 238000012546 transfer Methods 0.000 title claims abstract description 16
- 230000005415 magnetization Effects 0.000 claims abstract description 70
- 238000001208 nuclear magnetic resonance pulse sequence Methods 0.000 claims abstract description 39
- 238000000034 method Methods 0.000 claims abstract description 8
- 238000004590 computer program Methods 0.000 claims description 11
- 238000005259 measurement Methods 0.000 claims description 6
- 238000013461 design Methods 0.000 abstract description 5
- 238000010586 diagram Methods 0.000 description 15
- 210000005013 brain tissue Anatomy 0.000 description 7
- 230000005284 excitation Effects 0.000 description 5
- 210000004884 grey matter Anatomy 0.000 description 3
- 239000002872 contrast media Substances 0.000 description 2
- 238000002592 echocardiography Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 1
- 229920002527 Glycogen Polymers 0.000 description 1
- 206010028980 Neoplasm Diseases 0.000 description 1
- 208000006011 Stroke Diseases 0.000 description 1
- 150000001408 amides Chemical group 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000005292 diamagnetic effect Effects 0.000 description 1
- 201000010099 disease Diseases 0.000 description 1
- 208000037265 diseases, disorders, signs and symptoms Diseases 0.000 description 1
- 206010015037 epilepsy Diseases 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 239000008103 glucose Substances 0.000 description 1
- 229940096919 glycogen Drugs 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000002595 magnetic resonance imaging Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000002207 metabolite Substances 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 230000005298 paramagnetic effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000009278 visceral effect Effects 0.000 description 1
- 210000004885 white matter Anatomy 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
- G01R33/48—NMR imaging systems
- G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
- A61B5/055—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
Landscapes
- Health & Medical Sciences (AREA)
- Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Biophysics (AREA)
- Heart & Thoracic Surgery (AREA)
- Radiology & Medical Imaging (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Signal Processing (AREA)
- Pathology (AREA)
- Biomedical Technology (AREA)
- General Physics & Mathematics (AREA)
- Medical Informatics (AREA)
- Molecular Biology (AREA)
- Surgery (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Magnetic Resonance Imaging Apparatus (AREA)
Abstract
The application discloses a magnetic resonance chemical exchange saturation transfer imaging method and related equipment, wherein the method comprises the following steps: obtaining a corresponding variable flip angle chain according to the longitudinal magnetization vector relaxation time T 1 and the transverse magnetization vector relaxation time T 2 of the target tissue to be imaged; setting a radio frequency pulse sequence according to the variable flip angle chain, and acting the radio frequency pulse sequence on a target tissue; and acquiring magnetic resonance signals generated by the target tissue, and obtaining a magnetic resonance image of the target tissue according to the magnetic resonance signals. Through the design scheme, the intensity of the magnetic resonance signal can be kept through the variable flip angle chain corresponding to the target tissue, and the problem of magnetic resonance signal loss generated by the target tissue due to transverse magnetization vector attenuation can be solved, so that a magnetic resonance image with high contrast and high signal-to-noise ratio of the target tissue can be obtained.
Description
Technical Field
The application relates to the technical field of magnetic resonance imaging, in particular to a magnetic resonance chemical exchange saturation transfer imaging method and related equipment.
Background
Magnetic resonance Chemical Exchange Saturation Transfer (CEST) imaging is an important imaging method for noninvasively acquiring molecular information of biological tissues by using endogenous or exogenous CEST contrast agents, can measure endogenous metabolites, compounds (such as glucose, glycogen, amide protons and the like) and exogenous paramagnetic/diamagnetic CEST contrast agents, and provides a new method for imaging various diseases (such as stroke, tumor, epilepsy and the like). Fig. 1 is a schematic diagram of a conventional CEST imaging sequence, which generally consists of three parts, namely a radio frequency pulse saturation module (Ts), a data readout module (Te), and a signal recovery module (Td). The overall imaging time is t= (ts+te+td) ·n. Wherein, N is the chemical shift number, and is set according to experimental requirements. In order to ensure adequate saturation and signal recovery, ts, td is determined by the longitudinal magnetization vector relaxation time of the tissue. Therefore, in order to shorten the imaging time T, te needs to be reduced as much as possible. The readout mode of multiple excitation can reduce image distortion to a certain extent and improve contrast and signal to noise ratio, however, the corresponding imaging time is multiplied, and the imaging efficiency is greatly reduced. Existing methods typically employ a single shot to acquire a readout pattern of all K-space data (i.e., single shot) to shorten imaging time.
The currently adopted single-excitation EPI reading mode is very sensitive to magnetic field non-uniformity, and images are easy to distort; and the signal has obvious attenuation effect by transverse magnetization vector due to longer echo time in the readout modes such as single-excitation Fast Spin Echo (FSE), single-excitation fast gradient echo (GRE) or fast small-angle excitation (FLASH). Fig. 2 is a schematic diagram of a conventional single excitation FSE sequence with a fixed flip angle, and fig. 3 is a schematic diagram of echo signal attenuation corresponding to the single excitation FSE sequence, which shows that as the number of echoes increases, the attenuation effect of the magnetic resonance signals due to the transverse magnetization vector is obvious, so that the contrast and the signal-to-noise ratio of the whole magnetic resonance image are affected. Reducing the number of echoes may partially solve the above problem, but the spatial resolution of the image may be significantly reduced. Therefore, there is a need to propose a new magnetic resonance chemical exchange saturation transfer imaging method to solve the above-mentioned problems.
Disclosure of Invention
The application mainly solves the technical problem of providing a magnetic resonance chemical exchange saturation transfer imaging method and related equipment, which can solve the problem of magnetic resonance signal loss generated by target tissues due to transverse magnetization vector attenuation so as to obtain magnetic resonance images with high contrast ratio and high signal to noise ratio of the target tissues.
In order to solve the technical problems, the application adopts the following scheme: there is provided a magnetic resonance chemical exchange saturation transfer imaging method comprising: obtaining a corresponding variable flip angle chain according to the longitudinal magnetization vector relaxation time T 1 and the transverse magnetization vector relaxation time T 2 of the target tissue to be imaged; setting a radio frequency pulse sequence according to the variable flip angle chain, and acting the radio frequency pulse sequence on the target tissue; and acquiring magnetic resonance signals generated by the target tissue, and obtaining a magnetic resonance image of the target tissue according to the magnetic resonance signals.
Wherein the step of obtaining the variable flip angle chain from the longitudinal magnetization vector relaxation time T 1 and the transverse magnetization vector relaxation time T 2 of the target tissue comprises: obtaining a given echo signal evolution curve according to a bloch equation, the longitudinal magnetization vector relaxation time T 1 and the transverse magnetization vector relaxation time T 2; and obtaining the variable flip angle chain by using the set echo signal evolution curve, wherein the variable flip angle chain is a curve formed by time and variable flip angle.
The radio frequency pulse sequence comprises a plurality of variable flip angle pulses, wherein the variable flip angle pulses comprise alpha 1 DEG pulses, alpha 2 DEG pulses … … and alpha n DEG pulses according to time sequence, n is the number of phase codes actually acquired by the radio frequency pulse sequence, and alpha n DEG is the variable flip angle corresponding to the number of phase codes.
Wherein the radio frequency pulse sequence further comprises a 90 pulse and a 180 pulse before the alpha 1 pulse, and the 180 pulse is located between the alpha 1 pulse and the 90 pulse.
The time interval between the 90-degree pulse and the 180-degree pulse is half 180-degree echo interval time, and the time interval between the 180-degree pulse and the alpha 1 -degree pulse is the sum of half 180-degree echo interval time and the time interval between half adjacent variable flip angle pulses.
The set echo signal evolution curve is connected with each other and comprises a first attenuation part, a flat part and a second attenuation part; the step of acquiring magnetic resonance signals generated by the target tissue comprises: and acquiring the magnetic resonance signals in a time range corresponding to the flat part.
Wherein prior to the step of obtaining the variable flip angle chain from the longitudinal magnetization vector relaxation time T 1 and the transverse magnetization vector relaxation time T 2 of the target tissue, the step of obtaining the variable flip angle chain comprises: the longitudinal magnetization relaxation time T 1 and the transverse magnetization relaxation time T 2 of the target tissue are obtained using a longitudinal magnetization relaxation time measurement sequence and a longitudinal magnetization relaxation time measurement sequence, respectively.
In order to solve the technical problems, the application adopts another scheme that: there is provided a magnetic resonance chemical exchange saturation transfer imaging apparatus, the apparatus comprising: the radio frequency pulse generation unit is used for obtaining a corresponding variable flip angle chain according to the longitudinal magnetization vector relaxation time T 1 and the transverse magnetization vector relaxation time T 2 of the target tissue to be imaged; setting a radio frequency pulse sequence according to the variable flip angle chain, and acting the radio frequency pulse sequence on the target tissue; the data acquisition unit is used for acquiring magnetic resonance signals generated by the target tissue; and the magnetic resonance image generation unit is used for obtaining a magnetic resonance image of the target tissue according to the magnetic resonance signals.
In order to solve the technical problem, the application adopts the following scheme: providing a computer device comprising a memory and a processor coupled to each other; the memory is used for storing a computer program; the processor is configured to execute the computer program to implement the imaging method according to any of the above embodiments.
In order to solve the technical problem, the application adopts the following scheme: there is provided a computer readable storage medium storing a computer program executable by a processor for implementing the imaging method according to any one of the above embodiments.
Unlike the prior art, the application has the beneficial effects that: according to the application, a corresponding variable flip angle chain is obtained according to longitudinal magnetization vector relaxation time T 1 and transverse magnetization vector relaxation time T 2 of target tissue to be imaged, a radio frequency pulse sequence is set according to the variable flip angle chain, the radio frequency pulse sequence acts on the target tissue, magnetic resonance signals generated by the target tissue are acquired, and a magnetic resonance image of the target tissue is obtained according to the magnetic resonance signals. Through the design scheme, the intensity of the magnetic resonance signal can be kept through the variable flip angle chain corresponding to the target tissue, and the problem of magnetic resonance signal loss generated by the target tissue due to transverse magnetization vector attenuation can be solved, so that a magnetic resonance image with high contrast and high signal-to-noise ratio of the target tissue can be obtained.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. Wherein:
FIG. 1 is a schematic diagram of a conventional CEST imaging sequence;
FIG. 2 is a schematic diagram of a conventional fixed flip angle single shot FSE sequence;
FIG. 3 is a schematic diagram of echo signal attenuation corresponding to a single excitation FSE sequence;
FIG. 4 is a flow chart of an embodiment of a magnetic resonance chemical exchange saturation transfer imaging method of the present application;
FIG. 5 is a flow chart of an embodiment of the step S1 in FIG. 4;
FIG. 6 is a graph showing the evolution of a predetermined echo signal according to the present application;
FIG. 7 is a variable flip angle chain derived from the given echo signal evolution curve shown in FIG. 6;
FIG. 8 is a schematic diagram of a set RF pulse sequence in accordance with the present application;
FIG. 9 is a schematic diagram of a frame of an embodiment of a magnetic resonance chemical exchange saturation transfer imaging apparatus of the present application;
FIG. 10 is a schematic diagram of a computer device according to an embodiment of the present application;
FIG. 11 is a schematic diagram of a framework of an embodiment of a computer readable storage medium of the present application.
Detailed Description
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
Referring to fig. 4, fig. 4 is a flow chart illustrating an embodiment of a magnetic resonance chemical exchange saturation transfer imaging method according to the present application. The imaging method comprises the following steps:
S1: corresponding variable flip angle chains are obtained from the longitudinal magnetization vector relaxation time T 1 and the transverse magnetization vector relaxation time T 2 of the target tissue to be imaged.
Specifically, in the present embodiment, the target tissue to be imaged may be one or more tissues of brain tissue, and of course, in other embodiments, may be one or more tissues of visceral tissue, etc., which is not limited in this application.
In one embodiment, the step before the step S1 includes: and respectively obtaining longitudinal magnetization vector relaxation time T 1 and transverse magnetization vector relaxation time T 2 of the target tissue by using the longitudinal magnetization vector relaxation time measurement sequence and the longitudinal magnetization vector relaxation time measurement sequence. Of course, in other embodiments, the longitudinal magnetization vector relaxation time T 1 and the transverse magnetization vector relaxation time T 2 of the target tissue may be obtained according to the existing research results, which is not limited by the present application. In this way, the longitudinal magnetization vector relaxation time T 1 and the transverse magnetization vector relaxation time T 2 of the target tissue to be imaged can be obtained to obtain a variable flip angle chain corresponding to the target tissue.
In order to obtain the variable flip angle chain corresponding to the target organization, please refer to fig. 5, fig. 5 is a flowchart illustrating an embodiment of step S1 in fig. 4. The step S1 specifically includes:
S10: a given echo signal evolution curve is obtained from the bloch equation, the longitudinal magnetization vector relaxation time T 1 and the transverse magnetization vector relaxation time T 2.
Specifically, in the present embodiment, from the longitudinal magnetization vector relaxation time T 1 and the transverse magnetization vector relaxation time T 2 obtained in step S1, the formula of the bloch equation is used: A given echo signal evolution curve is obtained, wherein M 0 represents a magnetization vector in an equilibrium state, B represents magnetic induction intensity of a position where a target tissue is located, gamma represents gyromagnetic ratio of atomic nuclei, and R represents a relaxation matrix. Referring to fig. 6, fig. 6 is a schematic diagram of a predetermined echo signal evolution curve according to the present application. The abscissa of the predetermined echo signal evolution curve represents time, and the ordinate represents normalized intensity of the echo signal at a certain time. The predetermined echo signal evolution curve includes a first attenuation portion 101, a flat portion 102, and a second attenuation portion 103 connected to each other. The different parts of a given echo signal evolution curve play different roles. Wherein the first decay portion 101 is operable to drive the transverse magnetization vector to steady state; the echo signal of the middle flat part 102 can be used to fill K space, is the most important part in the echo chain, can directly determine the signal-to-noise ratio, contrast ratio and point spread function of single pixel of the image, and can be seen from fig. 6, the signal intensity is effectively maintained in the period of time; the signal of the second attenuation section 103 is mainly used to adjust the strength of the intermediate signal, the faster it attenuates, indicating a greater overall signal strength.
S12: and obtaining a variable flip angle chain corresponding to the target tissue by using a set echo signal evolution curve, wherein the variable flip angle chain is a curve formed by time and the variable flip angle.
Specifically, in the present embodiment, an expression for calculating the flip angle can be obtained based on an extended phase algorithm (EPG) as follows:
Based on the above formula, the echo signal intensity F 1 is taken as a known quantity, and the corresponding variable flip angle can be calculated iteratively by inputting the above formula: wherein α n is the variable flip angle of the nth refocusing pulse. AndIs a relaxation factor. F 1 (n-1) can be considered as the transverse echo signal after the n-1 th RF pulse is applied, and Z 1 (n-1) is the longitudinal magnetization after the n-1 th RF pulse is applied. Wherein the initial states of F and Z are [ F 1(0),F-1(0),Z1 (0) ]= [1, 0], which are generated by 90 ° pulses. I n is the signal strength of the nth echo, which is equal to E 2F-1 (n). By the mode, the variable flip angles of a plurality of corresponding echo pulses can be obtained by utilizing the given echo signal evolution curve.
Referring to fig. 7, fig. 7 is a variable flip angle chain obtained according to the predetermined echo signal evolution curve shown in fig. 6. The abscissa of the variable flip angle chain represents time, and the ordinate represents the variable flip angle of the refocusing pulse corresponding to a certain moment.
S2: and setting a radio frequency pulse sequence according to the variable flip angle chain, and applying the radio frequency pulse sequence to the target tissue.
Specifically, in this embodiment, a radio frequency pulse sequence is set according to the variable flip angle chain obtained according to the predetermined echo signal evolution curve, and the radio frequency pulse sequence is applied to the target tissue to acquire the magnetic resonance signal of the target tissue. For example, magnetic resonance signals generated by the brain tissue are acquired using a radio frequency pulse sequence that obtains a variable flip angle chain from longitudinal magnetization vector time T 1 and transverse magnetization vector time T 2 of grey matter in the brain tissue. The design scheme can keep the intensity of the magnetic resonance signals, and the problem of loss of the magnetic resonance signals generated by the target tissue due to the attenuation of the transverse magnetization vector can be avoided, so that the magnetic resonance image with high contrast and high signal-to-noise ratio of the target tissue can be obtained.
Specifically, in the present embodiment, please refer to fig. 8, fig. 8 is a schematic diagram of the rf pulse sequence of the present application. The radio frequency pulse sequence comprises a plurality of variable flip angle pulses, wherein the variable flip angle pulses comprise alpha 1 DEG pulses, alpha 2 DEG pulses … … and alpha n DEG pulses according to time sequence, n is the number of phase codes actually acquired by the radio frequency pulse sequence, and alpha n DEG is the variable flip angle corresponding to the number of phase codes. The variable flip angles alpha 1°、α2 degrees … … and alpha n degrees are ordinate values of a variable flip angle chain in fig. 4, and the number of the variable flip angles in the variable flip angle chain determines the number of phase codes actually acquired by the radio frequency pulse sequence for the variable flip angles of the back focusing pulse corresponding to each moment.
In this embodiment, with continued reference to fig. 8, the rf pulse sequence further includes a 90 ° pulse and a 180 ° pulse before the α 1 ° pulse, and the 180 ° pulse is located between the α 1 ° pulse and the 90 ° pulse. Wherein the 180 pulse echo interval time is ESP 1, the echo interval time between adjacent variable flip angle pulses is ESP 2, the time interval between 90 pulse and 180 pulse is ESP 1/2, and the time interval between 180 pulse and alpha 1 pulse is ESP 1/2+ESP2/2. The 180 ° pulse echo interval time ESP 1 and the echo interval time ESP 2 between adjacent variable flip angle pulses may be set to be the same or different, which is not limited in the present application. Preferably, the 180 ° pulse echo interval time ESP 1 and the echo interval time ESP 2 between adjacent variable flip angle pulses take as small values as possible, for example, the minimum echo interval time allowed by the magnetic resonance system, without limitation.
S3: and acquiring magnetic resonance signals generated by the target tissue, and obtaining a magnetic resonance image of the target tissue according to the magnetic resonance signals.
Specifically, in the present embodiment, please continue to refer to fig. 6, the step of acquiring the magnetic resonance signal generated by the target tissue specifically includes: magnetic resonance signals of the target tissue are acquired within a time range corresponding to the flat portion 102 of the predetermined echo signal evolution curve, and the intensity of the magnetic resonance signals within the time range can be effectively maintained.
Specifically, the target tissue may be one or more of brain tissues, for example, may be one or more of gray matter, white matter, and the like in brain tissues. Since the longitudinal magnetization vector relaxation time T 1 and the transverse magnetization vector relaxation time T 2 of the target tissue of the same kind are intrinsic characteristic parameters and are unchanged under certain temperature and conditions, a set radio frequency pulse sequence is obtained according to the longitudinal magnetization vector relaxation time T 1 and the transverse magnetization vector relaxation time T 2 of the target tissue, and magnetic resonance signals generated by the target tissue are acquired by using the set radio frequency pulse sequence. Specifically, for example, magnetic resonance signals generated by the brain tissue are acquired using a radio frequency pulse sequence of variable flip angles obtained from longitudinal magnetization vector relaxation time T 1 and transverse magnetization vector relaxation time T 2 of gray matter in the brain tissue. Through the design mode, the intensity of the magnetic resonance signals can be kept through the variable flip angle chain, and the problem that the magnetic resonance signals generated by the target tissue are lost due to the attenuation of the transverse magnetization vector can be solved, so that the magnetic resonance image with high contrast ratio and high signal-to-noise ratio of the target tissue can be obtained.
Referring to fig. 9, fig. 9 is a schematic diagram of a frame of an embodiment of a magnetic resonance chemical exchange saturation transfer imaging apparatus according to the present application. The magnetic resonance chemical exchange saturation transfer imaging device comprises: a radio frequency pulse generation unit 10, a data acquisition unit 12 and a magnetic resonance image generation unit 14. The radio frequency pulse generating unit 10 is configured to obtain a corresponding variable flip angle chain according to a longitudinal magnetization vector relaxation time T 1 and a transverse magnetization vector relaxation time T 2 of a target tissue to be imaged, set a radio frequency pulse sequence according to the variable flip angle chain, and apply the radio frequency pulse sequence to the target tissue. A data acquisition unit 12 for acquiring magnetic resonance signals generated by the target tissue. A magnetic resonance image generation unit 14 for obtaining a magnetic resonance image of the target tissue from the magnetic resonance signals.
Referring to fig. 10, fig. 10 is a schematic structural diagram of a computer device according to an embodiment of the application. The computer device includes a memory 200 and a processor 202 coupled to each other. The memory 200 is used for storing a computer program, and the processor 202 is used for executing the computer program to implement the imaging method according to any of the embodiments described above.
Specifically, the processor 202 may also be referred to as a CPU (Central Processing Unit ). The processor 202 may be an integrated circuit chip with signal processing capabilities. The Processor 202 may also be a general purpose Processor, a digital signal Processor (DIGITAL SIGNAL Processor, DSP), an Application SPECIFIC INTEGRATED Circuit (ASIC), a Field-Programmable gate array (Field-Programmable GATE ARRAY, FPGA) or other Programmable logic device, a discrete gate or transistor logic device, a discrete hardware component. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. In addition, the processor 202 may be commonly implemented by a plurality of integrated circuit chips.
Referring to fig. 11, fig. 11 is a schematic diagram illustrating a frame of an embodiment of a computer readable storage medium according to the present application. The computer-readable storage medium 30 stores a computer program 300, and the computer program 300 is used to implement the imaging method according to any of the above embodiments. The computer program 300 may be stored in the storage device as a software product, and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor (processor) to execute all or part of the steps of the methods according to the embodiments of the present application. The aforementioned storage device includes: a U-disk, a removable hard disk, a read-only memory (ROM), a random access memory (RAM, random Access Memory), a magnetic disk, an optical disk, or other various media capable of storing program codes, or a terminal device such as a computer, a server, a mobile phone, a tablet, or the like.
In summary, unlike the prior art, the present application obtains a corresponding variable flip angle chain according to the longitudinal magnetization vector relaxation time T 1 and the transverse magnetization vector relaxation time T 2 of the target tissue to be imaged, sets a radio frequency pulse sequence according to the variable flip angle chain, applies the radio frequency pulse sequence to the target tissue, acquires a magnetic resonance signal generated by the target tissue, and obtains a magnetic resonance image of the target tissue according to the magnetic resonance signal. Through the design scheme, the signal intensity can be kept through the variable flip angle chain corresponding to the target tissue, the problem of magnetic resonance signal loss generated by the target tissue due to transverse magnetization vector attenuation can be solved, and in addition, the method is based on the FSE sequence, so that the method has better robustness on magnetic field non-uniformity, and a magnetic resonance image with high contrast ratio and high signal to noise ratio of the target tissue can be obtained.
The foregoing description is only of embodiments of the present application, and is not intended to limit the scope of the application, and all equivalent structures or equivalent processes using the descriptions and the drawings of the present application or directly or indirectly applied to other related technical fields are included in the scope of the present application.
Claims (7)
1. A method of magnetic resonance chemical exchange saturation transfer imaging, comprising:
Obtaining a corresponding variable flip angle chain according to the longitudinal magnetization vector relaxation time T 1 and the transverse magnetization vector relaxation time T 2 of the target tissue to be imaged; in particular, a given echo signal evolution curve is obtained from the bloch equation, the longitudinal magnetization vector relaxation time T 1 and the transverse magnetization vector relaxation time T 2; the variable flip angle chain is obtained by utilizing the set echo signal evolution curve, wherein the variable flip angle chain is a curve formed by time and variable flip angle;
Setting a radio frequency pulse sequence according to the variable flip angle chain, and acting the radio frequency pulse sequence on the target tissue;
Acquiring a magnetic resonance signal generated by the target tissue, and obtaining a magnetic resonance image of the target tissue according to the magnetic resonance signal;
The radio frequency pulse sequence comprises a plurality of variable flip angle pulses, wherein the variable flip angle pulses comprise alpha 1 DEG pulses, alpha 2 DEG pulses … … and alpha n DEG pulses according to time sequence, n is the number of phase codes actually acquired by the radio frequency pulse sequence, and alpha n DEG is the variable flip angle corresponding to the number of phase codes; wherein the radio frequency pulse sequence further comprises a 90 pulse and a 180 pulse before the alpha 1 pulse, and the 180 pulse is located between the alpha 1 pulse and the 90 pulse.
2. The imaging method of claim 1, wherein the imaging method comprises the steps of,
The time interval between the 90 DEG pulse and the 180 DEG pulse is half 180 DEG echo interval time, and the time interval between the 180 DEG pulse and the alpha 1 DEG pulse is the sum of half 180 DEG echo interval time and half adjacent variable flip angle pulse time interval.
3. The imaging method of claim 1, wherein the given echo signal evolution curve comprises a first attenuation portion, a flat portion, a second attenuation portion, connected to each other; the step of acquiring magnetic resonance signals generated by the target tissue comprises: and acquiring the magnetic resonance signals in a time range corresponding to the flat part.
4. The imaging method according to claim 1, characterized in that before the step of obtaining the variable flip angle chain from the longitudinal magnetization vector relaxation time T 1 and the transverse magnetization vector relaxation time T 2 of the target tissue, it comprises:
The longitudinal magnetization relaxation time T 1 and the transverse magnetization relaxation time T 2 of the target tissue are obtained using a longitudinal magnetization relaxation time measurement sequence and a longitudinal magnetization relaxation time measurement sequence, respectively.
5. A magnetic resonance chemical exchange saturation transfer imaging apparatus, the apparatus comprising:
The radio frequency pulse generation unit is used for obtaining a corresponding variable flip angle chain according to the longitudinal magnetization vector relaxation time T 1 and the transverse magnetization vector relaxation time T 2 of the target tissue to be imaged; setting a radio frequency pulse sequence according to the variable flip angle chain, and acting the radio frequency pulse sequence on the target tissue; in particular, a given echo signal evolution curve is obtained from the bloch equation, the longitudinal magnetization vector relaxation time T 1 and the transverse magnetization vector relaxation time T 2; the variable flip angle chain is obtained by utilizing the set echo signal evolution curve, wherein the variable flip angle chain is a curve formed by time and variable flip angle; the radio frequency pulse sequence comprises a plurality of variable flip angle pulses, wherein the variable flip angle pulses comprise alpha 1 DEG pulses, alpha 2 DEG pulses … … and alpha n DEG pulses according to time sequence, n is the number of phase codes actually acquired by the radio frequency pulse sequence, and alpha n DEG is the variable flip angle corresponding to the number of phase codes; wherein the radio frequency pulse sequence further comprises a 90 DEG pulse and a 180 DEG pulse before the alpha 1 DEG pulse, and the 180 DEG pulse is positioned between the alpha 1 DEG pulse and the 90 DEG pulse;
The data acquisition unit is used for acquiring magnetic resonance signals generated by the target tissue;
And the magnetic resonance image generation unit is used for obtaining a magnetic resonance image of the target tissue according to the magnetic resonance signals.
6. A computer device comprising a memory and a processor coupled to each other; the memory is used for storing a computer program; the processor is configured to execute the computer program to implement the imaging method as claimed in any one of claims 1-4.
7. A computer readable storage medium storing a computer program executable by a processor for implementing the imaging method according to any one of claims 1-4.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011451417.1A CN112731235B (en) | 2020-12-09 | 2020-12-09 | Magnetic resonance chemical exchange saturation transfer imaging method and related equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011451417.1A CN112731235B (en) | 2020-12-09 | 2020-12-09 | Magnetic resonance chemical exchange saturation transfer imaging method and related equipment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112731235A CN112731235A (en) | 2021-04-30 |
| CN112731235B true CN112731235B (en) | 2024-04-19 |
Family
ID=75599311
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011451417.1A Active CN112731235B (en) | 2020-12-09 | 2020-12-09 | Magnetic resonance chemical exchange saturation transfer imaging method and related equipment |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112731235B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2022120740A1 (en) * | 2020-12-10 | 2022-06-16 | 中国科学院深圳先进技术研究院 | Magnetic resonance chemical exchange saturation transfer imaging method and related device |
| CN114089242B (en) * | 2021-11-03 | 2024-08-23 | 深圳市联影高端医疗装备创新研究院 | Excitation pulse design method, excitation pulse design device, computer equipment and storage medium |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009101133A (en) * | 2007-10-04 | 2009-05-14 | Toshiba Corp | Mri apparatus |
| WO2018085970A1 (en) * | 2016-11-08 | 2018-05-17 | 中国科学院深圳先进技术研究院 | Magnetic resonance vessel wall imaging method and device |
| CN108369266A (en) * | 2015-12-23 | 2018-08-03 | 伯拉考成像股份公司 | Ratiometric pulsed cest imaging |
| EP3451009A1 (en) * | 2017-08-28 | 2019-03-06 | Shanghai United Imaging Healthcare Co., Ltd. | System and method for determining flip angles of refocusing radio frequency pulses in magnetic resonance imaging |
| CN109521383A (en) * | 2018-10-17 | 2019-03-26 | 浙江大学 | A kind of magnetic resonance CEST imaging sequence and device based on frequency stabilization module |
| CN111537931A (en) * | 2020-04-28 | 2020-08-14 | 深圳先进技术研究院 | Fast magnetic resonance multi-parameter imaging method and device |
| CN111722167A (en) * | 2019-03-19 | 2020-09-29 | 浙江大学 | Generation method, device and readable storage medium of chemical exchange saturation transfer-magnetic resonance imaging CEST-MRI sequence |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5835989B2 (en) * | 2010-08-11 | 2015-12-24 | 株式会社東芝 | Magnetic resonance imaging apparatus and magnetic resonance imaging method |
| US9638781B2 (en) * | 2014-02-03 | 2017-05-02 | Toshiba Medical Systems Corporation | Enhancement of MT effect and/or CEST effect |
| CN107638179B (en) * | 2017-08-28 | 2020-09-04 | 上海联影医疗科技有限公司 | Method, system and computer readable storage medium for calculating magnetic resonance flip angle |
| CN111381204B (en) * | 2018-12-28 | 2022-07-12 | 西门子(深圳)磁共振有限公司 | Magnetic resonance imaging method and device based on two-dimensional fast spin echo |
-
2020
- 2020-12-09 CN CN202011451417.1A patent/CN112731235B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009101133A (en) * | 2007-10-04 | 2009-05-14 | Toshiba Corp | Mri apparatus |
| CN108369266A (en) * | 2015-12-23 | 2018-08-03 | 伯拉考成像股份公司 | Ratiometric pulsed cest imaging |
| WO2018085970A1 (en) * | 2016-11-08 | 2018-05-17 | 中国科学院深圳先进技术研究院 | Magnetic resonance vessel wall imaging method and device |
| EP3451009A1 (en) * | 2017-08-28 | 2019-03-06 | Shanghai United Imaging Healthcare Co., Ltd. | System and method for determining flip angles of refocusing radio frequency pulses in magnetic resonance imaging |
| CN109521383A (en) * | 2018-10-17 | 2019-03-26 | 浙江大学 | A kind of magnetic resonance CEST imaging sequence and device based on frequency stabilization module |
| CN111722167A (en) * | 2019-03-19 | 2020-09-29 | 浙江大学 | Generation method, device and readable storage medium of chemical exchange saturation transfer-magnetic resonance imaging CEST-MRI sequence |
| CN111537931A (en) * | 2020-04-28 | 2020-08-14 | 深圳先进技术研究院 | Fast magnetic resonance multi-parameter imaging method and device |
Non-Patent Citations (2)
| Title |
|---|
| Fast and equilibrium CEST imaging of brain tumor patients at 3T;Yin Wu et al.;NeuroImage: Clinical;20221231;第33卷;第102890页 * |
| Whole brain snapshot CEST at 3T using 3D-EPI: Aiming for speed, volume, and homogeneity;Sebastian Mueller et al.;Magnetic Resonance in Medicine;20200509;第84卷(第5期);第2469-2483页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112731235A (en) | 2021-04-30 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Barth et al. | Simultaneous multislice (SMS) imaging techniques | |
| Jiang et al. | MR fingerprinting using fast imaging with steady state precession (FISP) with spiral readout | |
| Hargreaves et al. | Variable‐rate selective excitation for rapid MRI sequences | |
| Ehses et al. | IR TrueFISP with a golden‐ratio‐based radial readout: fast quantification of T1, T2, and proton density | |
| US7298143B2 (en) | Reduction of susceptibility artifacts in subencoded single-shot magnetic resonance imaging | |
| Wang et al. | Single shot three‐dimensional pulse sequence for hyperpolarized 13C MRI | |
| Zhang et al. | Motion‐robust and blood‐suppressed M1‐optimized diffusion MR imaging of the liver | |
| US7906964B2 (en) | Method and system for determining acquisition parameters associated with magnetic resonance imaging for a particular measurement time | |
| CN112731235B (en) | Magnetic resonance chemical exchange saturation transfer imaging method and related equipment | |
| She et al. | Accelerating chemical exchange saturation transfer MRI with parallel blind compressed sensing | |
| Nielsen et al. | Functional perfusion imaging using pseudocontinuous arterial spin labeling with low‐flip‐angle segmented 3D spiral readouts | |
| US7538550B2 (en) | Magnetic resonance imaging apparatus, magnetic resonance imaging method, scan apparatus, program and storage medium | |
| Pipe | Pulse sequences for diffusion-weighted MRI | |
| US8648593B2 (en) | Dark blood balanced steady state free precession imaging | |
| CN113030817B (en) | Magnetic resonance imaging method, equipment and storage medium | |
| US7603157B2 (en) | Method and magnetic resonance imaging apparatus for compensating contrast inhomogeneities in magnetic resonance images | |
| Demirel et al. | Improved simultaneous multislice cardiac MRI using readout concatenated k‐space SPIRiT (ROCK‐SPIRiT) | |
| CN115639510A (en) | Magnetic resonance imaging method, spectroscopic imaging method, apparatus, device, and storage medium | |
| US10054657B2 (en) | Apparatus and method for multishot diffusion weighted imaging with array spatial pseudo-sensitivity encoding technique | |
| WO2022120740A1 (en) | Magnetic resonance chemical exchange saturation transfer imaging method and related device | |
| Ehses et al. | Efficient generation of T 2*‐weighted contrast by interslice echo‐shifting for human functional and anatomical imaging at 9.4 Tesla | |
| US7560925B1 (en) | Multiple repetition time steady-state free precession imaging | |
| JP4263015B2 (en) | Magnetic resonance imaging system | |
| JP2022002762A (en) | Processing method of image obtained by magnetic resonance imaging, image processing program, and computer | |
| CN116973823B (en) | Line scanning magnetic resonance imaging method and system based on full steady-state balance precession |
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 |