CN116942134A - Magnetic resonance imaging method, device, equipment and storage medium - Google Patents
Magnetic resonance imaging method, device, equipment and storage medium Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 64
- 238000002595 magnetic resonance imaging Methods 0.000 title claims abstract description 43
- 230000005284 excitation Effects 0.000 claims abstract description 82
- 238000002075 inversion recovery Methods 0.000 claims abstract description 19
- 238000004590 computer program Methods 0.000 claims description 12
- 230000005540 biological transmission Effects 0.000 claims description 8
- 230000009191 jumping Effects 0.000 claims description 5
- 238000011084 recovery Methods 0.000 claims description 4
- 238000000264 spin echo pulse sequence Methods 0.000 claims description 4
- 238000003384 imaging method Methods 0.000 description 11
- 238000010586 diagram Methods 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 238000004891 communication Methods 0.000 description 5
- 238000003825 pressing Methods 0.000 description 5
- 239000011800 void material Substances 0.000 description 4
- 238000001208 nuclear magnetic resonance pulse sequence Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000004422 calculation algorithm Methods 0.000 description 2
- 210000001015 abdomen Anatomy 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 238000002059 diagnostic imaging Methods 0.000 description 1
- 201000010099 disease Diseases 0.000 description 1
- 208000037265 diseases, disorders, signs and symptoms Diseases 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000012772 sequence design Methods 0.000 description 1
- 210000000323 shoulder joint Anatomy 0.000 description 1
- 210000004872 soft tissue Anatomy 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
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- 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
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
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- 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
Abstract
The application discloses a magnetic resonance imaging method, a device, equipment and a storage medium, which relate to the field of magnetic resonance and comprise the following steps: transmitting an inversion pulse inversion current magnetic resonance signal to an object to be scanned; determining the inversion time of the signal component to be suppressed; timing after transmitting the inversion pulse, if the inversion time is reached, transmitting an excitation pulse to the object to be scanned based on a preset time sequence so as to eliminate the signal component to be suppressed; the preset time sequence is determined based on a preset pulse embedding rule, and the preset pulse embedding rule is to embed excitation pulses between inversion pulses of adjacent layers in one inversion time; the remaining target magnetic resonance signal components are acquired to generate a magnetic resonance image. In the magnetic resonance imaging of the short-time inversion recovery sequence fat-liquoring, a new pulse time sequence is determined based on a pulse embedding rule, and inversion pulses and excitation pulses are sequentially filled in the gap time of the inversion time, so that all the inversion time is effectively utilized, the pulse efficiency is improved, and the scanning time of the magnetic resonance imaging is reduced.
Description
Technical Field
The present application relates to the field of magnetic resonance, and in particular, to a magnetic resonance imaging method, apparatus, device, and storage medium.
Background
Magnetic resonance imaging (MRI, magnetic Resonance Imaging) technology has been widely used in the medical imaging field due to its excellent soft tissue contrast, multiple weighted images, and arbitrary slice imaging. However, the scanning speed of MRI is much slower than other imaging devices, especially when special imaging, such as fat-imaging, is performed.
Magnetic resonance imaging is a common imaging technique in clinic, which suppresses fat signals and thus allows a doctor to diagnose better. Common Fat-pressing methods include chemical shift methods, such as Fat Saturation (FS) sequences, and relaxation time methods, wherein the principle of the chemical shift method is realized by using the frequency difference (3.4 ppm) between Fat and water plus saturation pulses with specific frequency selection, and the disadvantage is that the requirement on MRI system hardware, especially the uniformity of main magnetic field, is very high, and the effect is very poor when imaging a wide range of shoulder joints, abdomen and the like; the relaxation time method is realized by using the difference of TI time (inversion time) and inversion pulse of water and fat, has low requirement on the uniformity of a magnetic field, is suitable for large-scale imaging, and has the defect of slow scanning speed.
The pulse sequence currently most used clinically for fat liquoring by relaxation time method is short-time inversion recovery sequence (stur, short time inversion recovery), but because of the TI time, the conventional stur scan time is typically 2 to 3 times that of other sequences. As can be seen from FIG. 1, the scan time of the inversion pulse embedding method described above is about 1/3 of that of the conventional STIR. To make the STIR scan faster, the void in TI time can be utilized by inversion pulse embedding, placing the IR pulse of the second layer into the void while the Host sequence follows the first layer Host sequence, and if the void is still sufficient, placing the third layer into it as shown in fig. 1, where IR1, IR2, IR3. However, although the above-described STIR sequence designed by the inversion pulse embedding method has a high scanning speed, the TI time is still underutilized, and many voids remain, and the scanning time is still twice longer than that of the Fat Saturation (FS) sequence by the chemical shift method. Therefore, how to perform magnetic resonance imaging based on the STIR sequence of the inversion pulse embedding method more quickly is a problem to be solved in the art.
Disclosure of Invention
In view of the above, an object of the present application is to provide a magnetic resonance imaging method, apparatus, device and storage medium, in the magnetic resonance imaging for realizing fat-liquoring by short-time inversion recovery sequence, a new pulse sequence is determined based on a preset pulse embedding rule, and inversion pulses and excitation pulses are sequentially filled into a gap time of inversion time, so that all inversion time is effectively utilized, pulse efficiency is improved, and scanning time of the magnetic resonance imaging is reduced. The specific scheme is as follows:
in a first aspect, the application provides a magnetic resonance imaging method comprising:
transmitting inversion pulse to an object to be scanned so as to invert the current magnetic resonance signal of the object to be scanned;
determining the inversion time corresponding to the signal component to be suppressed in the current magnetic resonance signal;
after the inversion pulse is transmitted to the object to be scanned, timing is carried out, if the timing duration reaches the inversion time, an excitation pulse is transmitted to the object to be scanned based on a preset time sequence, so that the signal component to be suppressed in the current magnetic resonance signal is eliminated; the preset time sequence is determined based on a preset pulse embedding rule, and the preset pulse embedding rule is to embed excitation pulses between the inversion pulses of adjacent layers in one inversion time;
and collecting and removing the target magnetic resonance signal component remained in the current magnetic resonance signal after the signal component to be suppressed, and generating a magnetic resonance image of the object to be scanned based on the target magnetic resonance signal component.
Optionally, the transmitting the inversion pulse to the object to be scanned includes:
transmitting an inversion pulse to the object to be scanned based on a target short-time inversion recovery sequence; the target short-time reversal recovery sequence is a sequence constructed based on the purpose of suppressing a magnetic resonance signal component corresponding to fat of the object to be scanned;
correspondingly, the determining the inversion time corresponding to the signal component to be suppressed in the current magnetic resonance signal includes:
an inversion time in the current magnetic resonance signal corresponding to a magnetic resonance signal component corresponding to fat of the subject to be scanned is determined.
Optionally, the determining an inversion time of the current magnetic resonance signal corresponding to a magnetic resonance signal component corresponding to fat of the object to be scanned includes:
and determining relaxation time corresponding to the fat of the object to be scanned in the current magnetic resonance signal, and determining inversion time corresponding to a magnetic resonance signal component corresponding to the fat of the object to be scanned according to the relaxation time.
Optionally, the transmitting the excitation pulse to the object to be scanned based on the preset time sequence includes:
and transmitting a rapid spin echo sequence to the object to be scanned based on the preset time sequence so as to eliminate magnetic resonance signal components corresponding to fat of the object to be scanned in the current magnetic resonance signals.
Optionally, the transmitting the excitation pulse to the object to be scanned based on the preset time sequence includes:
transmitting a current target excitation pulse corresponding to a current target history inversion pulse to the object to be scanned based on a preset time sequence; the current target history inversion pulse is the current last history inversion pulse which just passes through the inversion time;
and after the current target excitation pulse is transmitted to the object to be scanned, transmitting the inversion pulse of the current next layer to the object to be scanned so as to invert the current magnetic resonance signal of the object to be scanned, and after the inversion pulse of the current next layer is transmitted to the object to be scanned, jumping to the step of transmitting the target excitation pulse corresponding to the current target history inversion pulse to the object to be scanned based on a preset time sequence.
Optionally, in the process of transmitting the current target excitation pulse corresponding to the current target history inversion pulse to the object to be scanned based on the preset time sequence, the method further includes:
and if the current target excitation pulse corresponding to the current target history inversion pulse does not exist currently, transmitting a preset excitation pulse for keeping the current magnetic resonance signal steady to the object to be scanned.
Optionally, the transmitting a preset excitation pulse for maintaining the steady state of the current magnetic resonance signal to the object to be scanned includes:
determining the sum of the first duration of the inversion pulse and the second duration of the excitation pulse to obtain total duration, and rounding down the quotient of the inversion time and the total duration to obtain the transmission times of the preset excitation pulse;
transmitting the preset excitation pulse for maintaining the steady state of the current magnetic resonance signal to the object to be scanned based on the transmission times.
In a second aspect, the application provides a magnetic resonance imaging apparatus comprising:
the signal inversion module is used for transmitting inversion pulses to an object to be scanned so as to invert the current magnetic resonance signal of the object to be scanned;
the time determining module is used for determining the inversion time corresponding to the signal component to be suppressed in the current magnetic resonance signal;
the pulse transmitting module is used for timing after transmitting the inversion pulse to the object to be scanned, and transmitting an excitation pulse to the object to be scanned based on a preset time sequence if the timing duration reaches the inversion time so as to eliminate the signal component to be suppressed in the current magnetic resonance signal; the preset time sequence is determined based on a preset pulse embedding rule, and the preset pulse embedding rule is to embed excitation pulses between the inversion pulses of adjacent layers in one inversion time;
the image generation module is used for collecting and rejecting the target magnetic resonance signal components remained in the current magnetic resonance signal after the signal components to be suppressed, and generating a magnetic resonance image of the object to be scanned based on the target magnetic resonance signal components.
In a third aspect, the present application provides an electronic device comprising a processor and a memory; wherein the memory is for storing a computer program to be loaded and executed by the processor for implementing the magnetic resonance imaging method as described above.
In a fourth aspect, the application provides a computer readable storage medium storing a computer program which when executed by a processor implements the magnetic resonance imaging method as described above.
Firstly, transmitting inversion pulse to an object to be scanned so as to invert the current magnetic resonance signal of the object to be scanned; then determining the inversion time corresponding to the signal component to be suppressed in the current magnetic resonance signal; and timing after transmitting the inversion pulse to the object to be scanned, if the timing duration reaches the inversion time, transmitting an excitation pulse to the object to be scanned based on a preset time sequence so as to eliminate the signal component to be suppressed in the current magnetic resonance signal; the preset time sequence is determined based on a preset pulse embedding rule, and the preset pulse embedding rule is to embed excitation pulses between the inversion pulses of adjacent layers in one inversion time; and collecting and removing the target magnetic resonance signal component remained in the current magnetic resonance signal after the signal component to be suppressed, and generating a magnetic resonance image of the object to be scanned based on the target magnetic resonance signal component. According to the technical scheme, when the magnetic resonance imaging of the fat is realized through the short-time inversion recovery sequence, the new pulse time sequence is determined based on the preset pulse embedding rule, and the inversion pulse and the excitation pulse are sequentially filled into the gap time of the inversion time.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present application, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a conventional inversion pulse embedding method according to the present application;
FIG. 2 is a flow chart of a magnetic resonance imaging method provided by the application;
FIG. 3 is a timing diagram of a short-time inversion recovery sequence according to the present application;
FIG. 4 is a schematic diagram of an inversion pulse embedding method according to the present application;
FIG. 5 is a flowchart of a specific pulse embedding method according to the present application;
fig. 6 is a schematic structural diagram of a magnetic resonance imaging apparatus according to the present application;
fig. 7 is a block diagram of an electronic device according to 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.
The pulse sequence for fat pressing by using a relaxation time method, which is most commonly used for magnetic resonance fat pressing imaging clinically at present, is a short-time inversion recovery sequence, but the conventional STIR scanning time is longer because of the existence of TI time. Even if the STIR sequence is designed by using the inversion pulse embedding method, the TI time is still underutilized, and a plurality of gaps still exist, but when the magnetic resonance imaging of the fat is realized by the short-time inversion recovery sequence, the application can determine a new pulse time sequence based on the preset pulse embedding rule, and sequentially fill the inversion pulse and the excitation pulse into the gap time of the inversion time, thereby more effectively utilizing the whole inversion time and reducing the scanning time of the magnetic resonance imaging.
Referring to fig. 2, an embodiment of the present application discloses a magnetic resonance imaging method, including:
step S11, transmitting inversion pulse to the object to be scanned so as to invert the current magnetic resonance signal of the object to be scanned.
The magnetic resonance imaging in this embodiment is mainly fat pressing imaging, suppresses fat signals, and is shown as black on an image, which is helpful for diagnosis of certain diseases. The fat-pressing method in this embodiment is a relaxation time method, and suppression of signals corresponding to fat is achieved by short-time inversion recovery (STIR).
Since it is first necessary to invert the magnetic resonance signals corresponding to water and fat to 180 ° by using one Inversion (IR) pulse when fat is clinically pressed by a short-time inversion recovery Sequence (STIR) using a relaxation time method, the embodiment first transmits an inversion pulse to the object to be scanned based on a target short-time inversion recovery sequence; the target short-time reversal recovery sequence is a sequence constructed based on the purpose of suppressing a magnetic resonance signal component corresponding to fat of the object to be scanned, and signal reversal of the current magnetic resonance signal of the object to be scanned is realized by the sequence.
Step S12, determining the inversion time corresponding to the signal component to be suppressed in the current magnetic resonance signal.
In this embodiment, when the inversion pulse ends, a relaxation process of the water and fat occurs, based on which the inversion time of the fat can be determined. Thus, the magnetic resonance signal component of the current magnetic resonance signal corresponding to the fat of the object to be scanned, i.e. the inversion time corresponding to the signal component to be suppressed, can be determined. In particular, the current magnetic resonance signal can be determined firstA relaxation time corresponding to the fat of the object to be scanned, and an inversion time corresponding to a magnetic resonance signal component corresponding to the fat of the object to be scanned is determined from the relaxation time. For example, the relaxation time of water is about 4000ms, the relaxation time of fat is 250ms, as shown in fig. 3, wherein,is 180 DEG inverted pulse, ">For 90 ° excitation pulse, TI is inversion time, the Host sequence may be any sequence, usually a Fast Spin Echo (FSE) sequence, after a specific time TI (generally 220 ms), the fat signal will return to 90 °, while the water signal is still substantially near 180 °, and then the fat will be saturated by adding 90 ° excitation pulse.
Step S13, timing after the inversion pulse is transmitted to the object to be scanned, and transmitting an excitation pulse to the object to be scanned based on a preset time sequence if the timing duration reaches the inversion time so as to eliminate the signal component to be suppressed in the current magnetic resonance signal; the preset time sequence is determined based on a preset pulse embedding rule, and the preset pulse embedding rule is that excitation pulses are embedded between the inversion pulses of adjacent layers in one inversion time.
In this embodiment, in order to suppress the influence of the signal component to be suppressed, as shown in fig. 3, timing is performed after the inversion pulse is transmitted to the object to be scanned, and if the timing length reaches the inversion time, the excitation pulse is transmitted to the object to be scanned based on the preset time sequence, so as to eliminate the signal component corresponding to the fat in the current magnetic resonance signal. As shown in fig. 4, the preset timing is a timing determined based on a preset pulse embedding rule that embeds the excitation pulse between inversion pulses of adjacent layers in one inversion time. Therefore, the present embodiment can transmit a fast spin echo sequence to the subject to be scanned based on a preset timing sequence to eliminate the magnetic resonance signal component corresponding to the fat of the subject to be scanned in the current magnetic resonance signal. In this embodiment, the timing design of the STIR sequence is performed again, and different TI filling methods are adopted, so that compared with filling only the IR module, filling the ir+host module can greatly reduce the scanning time.
And S14, collecting and removing the residual target magnetic resonance signal component in the current magnetic resonance signal after the signal component to be suppressed, and generating a magnetic resonance image of the object to be scanned based on the target magnetic resonance signal component.
In this embodiment, after eliminating the influence of the signal component to be suppressed in the current magnetic resonance signal, the remaining target magnetic resonance signal component in the current magnetic resonance signal is collected, and a plurality of magnetic resonance images of the object to be scanned are generated based on the target magnetic resonance signal component.
Through the above technical scheme, in the embodiment, the inversion pulse is transmitted to the object to be scanned based on the target short-time inversion recovery sequence, so as to realize signal inversion of the current magnetic resonance signal of the object to be scanned. Determining the inversion time of a magnetic resonance signal component corresponding to fat of an object to be scanned in a current magnetic resonance signal, timing after transmitting inversion pulse to the object to be scanned, and transmitting excitation pulse to the object to be scanned based on a preset time sequence if the timing time length reaches the inversion time so as to eliminate the signal component to be suppressed in the current magnetic resonance signal; and finally, collecting and removing the residual target magnetic resonance signal component in the current magnetic resonance signal after the signal component to be suppressed is removed, and generating a magnetic resonance image of the object to be scanned based on the target magnetic resonance signal component. When the short-time inversion recovery sequence is utilized to realize the magnetic resonance imaging of the fat-liquoring, a new pulse time sequence is determined based on a preset pulse embedding rule, the inversion pulse and the excitation pulse are sequentially filled into the gap time of the inversion time, the time sequence design of the STIR sequence is carried out again, and compared with the process of filling only the IR module and filling the IR+host module, the scanning time can be greatly reduced, the whole inversion time is more effectively utilized, and the efficiency of utilizing the pulse is improved.
As can be seen from the above embodiment, the present application can sequentially fill the inversion pulse and the excitation pulse into the gap time of the inversion time based on the preset pulse embedding rule for performing magnetic resonance imaging, and the pulse timing determined based on the preset pulse embedding rule will be described in detail in this embodiment. Referring to fig. 5, an embodiment of the present application discloses a specific pulse embedding method, which includes:
step S21, timing is carried out after the inversion pulse is transmitted to the object to be scanned, and if the timing duration reaches the inversion time, the current target excitation pulse corresponding to the current target history inversion pulse is transmitted to the object to be scanned based on a preset time sequence; the current target history inversion pulse is the current last history inversion pulse which has just passed the inversion time.
The short-time inversion recovery sequence timing in this embodiment may be referred to as a Host embedding method, and is different from an embedding method that embeds only IR, in which the method makes full use of all TI time, greatly improves pulse efficiency, and reduces scanning time. And (3) timing after transmitting the inversion pulse to the object to be scanned, and transmitting a current target excitation pulse corresponding to a current last historical inversion pulse which has just passed the inversion time to the object to be scanned if the timing time length reaches the inversion time. As shown in fig. 1, the conventional embedding method has the following sequence: ir1.ir2.ir3.host1.host2.host3, if the Host sequence, i.e. the excitation sequence, is too long, e.g. FSE, to ensure that the TI time is fixed, the unused void time is:
TI-T_IR*n；
where TI is the inversion time, T_IR is the time of the inversion pulse, n is the downward rounding of TI/T_Host, and T_Host is the time of the Host sequence, i.e., the excitation sequence.
And as shown in fig. 4, in the process of transmitting the current target excitation pulse corresponding to the current target history inversion pulse to the object to be scanned, if the current target excitation pulse corresponding to the current target history inversion pulse does not exist currently, a preset excitation pulse for keeping the steady state of the current magnetic resonance signal, that is, a Host0 (steady-state blank scan) is transmitted to the object to be scanned, so that the time sequence adopted by the Host embedding method in this embodiment is ir1..host0..ir2..host0..ir3..host1..ir4..host2. By embedding the Host0 in the inversion time, the stability of the sequence can be improved and the image quality can be improved by the additional blank scan.
Specifically, regarding the foregoing Host0, when a preset excitation pulse for maintaining the steady state of the current magnetic resonance signal is transmitted to the object to be scanned, the sum of the first duration of the inversion pulse and the second duration of the excitation pulse is first determined to obtain a total duration, and the quotient of the inversion time and the total duration is rounded down to obtain the number of transmission times of the preset excitation pulse, and then the preset excitation pulse for maintaining the steady state of the current magnetic resonance signal is transmitted to the object to be scanned based on the number of transmission times, where the preset excitation pulse is Host0, and only needs to be added once in the whole scanning process. The specific calculation process of the number n of Host0 is as follows:
n=floor(TI/(T_Host+T_IR))；
wherein floor is a downward rounding function, TI is inversion time, T_IR is inversion pulse time, T_host is Host sequence, i.e. excitation sequence time, and n is typically 2 to 3. It will be appreciated that Host0 need only be added at the beginning of the entire scan, since in the next TR (repetition time) it can correspond to the first n IR findings, and therefore can be ignored for the entire scan time.
Step S22, after the current target excitation pulse is transmitted to the object to be scanned, transmitting a current next layer inversion pulse to the object to be scanned to invert the current magnetic resonance signal of the object to be scanned, and after the current next layer inversion pulse is transmitted to the object to be scanned, jumping to the step of transmitting a target excitation pulse corresponding to the current target history inversion pulse to the object to be scanned based on a preset time sequence.
In this embodiment, as shown in fig. 4, after transmitting a current target excitation pulse to an object to be scanned, a current next layer of inversion pulse needs to be transmitted to the object to be scanned to invert a current magnetic resonance signal of the object to be scanned, and after transmitting the current next layer of inversion pulse to the object to be scanned, the method jumps to a step of transmitting a target excitation pulse corresponding to a current target history inversion pulse to the object to be scanned based on a preset time sequence in the previous step. It will be appreciated that the magnetic resonance in this embodiment is a tomographic imaging, and the slice selection principle is that a gradient magnetic field is added in the slice direction, and under the action of the gradient magnetic field, the resonance frequency changes with the change of the slice position, and then the radio frequency pulse frequency is adjusted to selectively excite a specific slice. The increase in the number of slices increases the imaging time, and all slices are placed in a repetition time TR, which represents the time required for a cycle, for a total time TR times the number of phase direction steps for magnetic resonance imaging if a multi-slice scanning technique is applied. Thus, the current jump step may be stopped after the end of the repetition time.
And S23, collecting and removing the residual target magnetic resonance signal component in the current magnetic resonance signal after the signal component to be suppressed, and generating a magnetic resonance image of the object to be scanned based on the target magnetic resonance signal component.
For more specific processing in step S23, reference may be made to the corresponding content disclosed in the foregoing embodiment, and no further description is given here.
In this embodiment, after transmitting inversion pulse to the object to be scanned, timing is performed, and if the timing duration reaches the inversion time, a current target excitation pulse corresponding to a history inversion pulse that has just passed the inversion time is transmitted to the object to be scanned; transmitting an inversion pulse of the current next layer to the object to be scanned so as to invert the current magnetic resonance signal of the object to be scanned, and jumping to a step of transmitting a target excitation pulse corresponding to the current target history inversion pulse to the object to be scanned based on a preset time sequence. And then collecting and removing the residual target magnetic resonance signal component in the current magnetic resonance signal after the signal component to be suppressed is removed, and generating a magnetic resonance image of the object to be scanned based on the target magnetic resonance signal component. Through the technical scheme, the circulation mode of the pulse in the repetition time is changed, the inversion pulse and the excitation pulse are sequentially filled into the gap time of the inversion time, compared with a short-time inversion recovery sequence in which only the IR pulse is filled into the inversion time, the whole inversion time is utilized more effectively, the scanning time of the magnetic resonance imaging is reduced, and the extra air scan can improve the stability of the sequence and the image quality by embedding the Host0 into the inversion time.
Referring to fig. 6, the embodiment of the application also discloses a magnetic resonance imaging device, which comprises:
a signal inversion module 11, configured to transmit an inversion pulse to an object to be scanned, so as to invert a current magnetic resonance signal of the object to be scanned;
a time determining module 12, configured to determine an inversion time corresponding to a signal component to be suppressed in the current magnetic resonance signal;
the pulse transmitting module 13 is configured to perform timing after transmitting the inversion pulse to the object to be scanned, and if the timing length reaches the inversion time, transmit an excitation pulse to the object to be scanned based on a preset time sequence, so as to eliminate the signal component to be suppressed in the current magnetic resonance signal; the preset time sequence is determined based on a preset pulse embedding rule, and the preset pulse embedding rule is to embed excitation pulses between the inversion pulses of adjacent layers in one inversion time;
the image generating module 14 is configured to collect a target magnetic resonance signal component remaining in the current magnetic resonance signal after the signal component to be suppressed is removed, and generate a magnetic resonance image of the object to be scanned based on the target magnetic resonance signal component.
In this embodiment, an inversion pulse is first transmitted to an object to be scanned to invert a current magnetic resonance signal of the object to be scanned; then determining the inversion time corresponding to the signal component to be suppressed in the current magnetic resonance signal; and timing after transmitting the inversion pulse to the object to be scanned, if the timing duration reaches the inversion time, transmitting an excitation pulse to the object to be scanned based on a preset time sequence so as to eliminate the signal component to be suppressed in the current magnetic resonance signal; the preset time sequence is determined based on a preset pulse embedding rule, and the preset pulse embedding rule is to embed excitation pulses between the inversion pulses of adjacent layers in one inversion time; and collecting and removing the target magnetic resonance signal component remained in the current magnetic resonance signal after the signal component to be suppressed, and generating a magnetic resonance image of the object to be scanned based on the target magnetic resonance signal component. According to the technical scheme, when the magnetic resonance imaging of the fat is realized through the short-time inversion recovery sequence, the new pulse time sequence is determined based on the preset pulse embedding rule, and the inversion pulse and the excitation pulse are sequentially filled into the gap time of the inversion time.
In some embodiments, the signal inversion module 11 specifically includes:
a sequence transmitting unit for transmitting an inversion pulse to the object to be scanned based on a target short-time inversion recovery sequence; the target short-time reversal recovery sequence is a sequence constructed based on the purpose of suppressing a magnetic resonance signal component corresponding to fat of the object to be scanned;
correspondingly, the time determining module 12 specifically includes:
a first time determining unit for determining an inversion time of a magnetic resonance signal component of the current magnetic resonance signal corresponding to fat of the object to be scanned.
In some embodiments, the time determination module 12 specifically includes:
a second time determining unit, configured to determine a relaxation time corresponding to fat of the object to be scanned in the current magnetic resonance signal, and determine an inversion time corresponding to a magnetic resonance signal component corresponding to fat of the object to be scanned according to the relaxation time.
In some embodiments, the pulse transmitting module 13 specifically includes:
and the first pulse transmitting unit is used for transmitting a rapid spin echo sequence to the object to be scanned based on the preset time sequence so as to eliminate magnetic resonance signal components corresponding to fat of the object to be scanned in the current magnetic resonance signals.
In some embodiments, the pulse transmitting module 13 specifically includes:
the pulse transmitting sub-module is used for transmitting a current target excitation pulse corresponding to the current target history inversion pulse to the object to be scanned based on a preset time sequence; the current target history inversion pulse is the current last history inversion pulse which just passes through the inversion time;
and the second pulse transmitting unit is used for transmitting the current target excitation pulse to the object to be scanned, transmitting the inversion pulse of the current next layer to the object to be scanned so as to invert the current magnetic resonance signal of the object to be scanned, and jumping to the step of transmitting the target excitation pulse corresponding to the current target history inversion pulse to the object to be scanned based on a preset time sequence after transmitting the inversion pulse of the current next layer to the object to be scanned.
In some embodiments, the pulse transmitting sub-module further comprises:
and the third pulse transmitting unit is used for transmitting a preset excitation pulse for keeping the steady state of the current magnetic resonance signal to the object to be scanned if the current target excitation pulse corresponding to the current target history inversion pulse does not exist currently.
In some embodiments, the pulse transmitting sub-module specifically includes:
the pulse emission frequency determining unit is used for determining the sum of the first duration time of the inversion pulse and the second duration time of the excitation pulse to obtain total duration time, and rounding down the quotient of the inversion time and the total duration time to obtain the emission frequency of the preset excitation pulse;
and a fourth pulse transmitting unit, configured to transmit the preset excitation pulse for maintaining the steady state of the current magnetic resonance signal to the object to be scanned based on the transmission times.
Further, the embodiment of the present application further discloses an electronic device, and fig. 7 is a block diagram of an electronic device 20 according to an exemplary embodiment, where the content of the figure is not to be considered as any limitation on the scope of use of the present application.
Fig. 7 is a schematic structural diagram of an electronic device 20 according to an embodiment of the present application. The electronic device 20 may specifically include: at least one processor 21, at least one memory 22, a power supply 23, a communication interface 24, an input output interface 25, and a communication bus 26. Wherein the memory 22 is adapted to store a computer program to be loaded and executed by the processor 21 for carrying out the relevant steps of the magnetic resonance imaging method disclosed in any of the previous embodiments. In addition, the electronic device 20 in the present embodiment may be specifically an electronic computer.
In this embodiment, the power supply 23 is configured to provide an operating voltage for each hardware device on the electronic device 20; the communication interface 24 can create a data transmission channel between the electronic device 20 and an external device, and the communication protocol to be followed is any communication protocol applicable to the technical solution of the present application, which is not specifically limited herein; the input/output interface 25 is used for acquiring external input data or outputting external output data, and the specific interface type thereof may be selected according to the specific application requirement, which is not limited herein.
The memory 22 may be a carrier for storing resources, such as a read-only memory, a random access memory, a magnetic disk, or an optical disk, and the resources stored thereon may include an operating system 221, a computer program 222, and the like, and the storage may be temporary storage or permanent storage.
The operating system 221 is used for managing and controlling various hardware devices on the electronic device 20 and computer programs 222, which may be Windows Server, netware, unix, linux, etc. The computer program 222 may further comprise a computer program capable of performing other specific tasks in addition to the computer program capable of performing the magnetic resonance imaging method performed by the electronic device 20 as disclosed in any of the previous embodiments.
Further, the application also discloses a computer readable storage medium for storing a computer program; wherein the computer program, when executed by a processor, implements the magnetic resonance imaging method of the foregoing disclosure. For specific steps of the method, reference may be made to the corresponding contents disclosed in the foregoing embodiments, and no further description is given here.
In this specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, so that the same or similar parts between the embodiments are referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative elements and steps are described above generally in terms of functionality in order to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software modules may be disposed in Random Access Memory (RAM), memory, read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
Finally, it is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The foregoing has outlined rather broadly the more detailed description of the application in order that the detailed description of the application that follows may be better understood, and in order that the present principles and embodiments may be better understood; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present application, the present description should not be construed as limiting the present application in view of the above.
Claims (10)
1. A method of magnetic resonance imaging comprising:
transmitting inversion pulse to an object to be scanned so as to invert the current magnetic resonance signal of the object to be scanned;
determining the inversion time corresponding to the signal component to be suppressed in the current magnetic resonance signal;
after the inversion pulse is transmitted to the object to be scanned, timing is carried out, if the timing duration reaches the inversion time, an excitation pulse is transmitted to the object to be scanned based on a preset time sequence, so that the signal component to be suppressed in the current magnetic resonance signal is eliminated; the preset time sequence is determined based on a preset pulse embedding rule, and the preset pulse embedding rule is to embed excitation pulses between the inversion pulses of adjacent layers in one inversion time;
and collecting and removing the target magnetic resonance signal component remained in the current magnetic resonance signal after the signal component to be suppressed, and generating a magnetic resonance image of the object to be scanned based on the target magnetic resonance signal component.
2. The method of magnetic resonance imaging according to claim 1, wherein said transmitting the inversion pulse to the object to be scanned comprises:
transmitting an inversion pulse to the object to be scanned based on a target short-time inversion recovery sequence; the target short-time reversal recovery sequence is a sequence constructed based on the purpose of suppressing a magnetic resonance signal component corresponding to fat of the object to be scanned;
correspondingly, the determining the inversion time corresponding to the signal component to be suppressed in the current magnetic resonance signal includes:
an inversion time in the current magnetic resonance signal corresponding to a magnetic resonance signal component corresponding to fat of the subject to be scanned is determined.
3. The method of magnetic resonance imaging according to claim 2, wherein the determining of the inversion time of the current magnetic resonance signal corresponding to the magnetic resonance signal component of the fat of the subject to be scanned comprises:
and determining relaxation time corresponding to the fat of the object to be scanned in the current magnetic resonance signal, and determining inversion time corresponding to a magnetic resonance signal component corresponding to the fat of the object to be scanned according to the relaxation time.
4. The method of claim 2, wherein the transmitting excitation pulses to the object to be scanned based on a preset timing sequence comprises:
and transmitting a rapid spin echo sequence to the object to be scanned based on the preset time sequence so as to eliminate magnetic resonance signal components corresponding to fat of the object to be scanned in the current magnetic resonance signals.
5. The method according to any one of claims 1 to 4, wherein the transmitting excitation pulses to the object to be scanned based on a preset timing sequence comprises:
transmitting a current target excitation pulse corresponding to a current target history inversion pulse to the object to be scanned based on a preset time sequence; the current target history inversion pulse is the current last history inversion pulse which just passes through the inversion time;
and after the current target excitation pulse is transmitted to the object to be scanned, transmitting the inversion pulse of the current next layer to the object to be scanned so as to invert the current magnetic resonance signal of the object to be scanned, and after the inversion pulse of the current next layer is transmitted to the object to be scanned, jumping to the step of transmitting the target excitation pulse corresponding to the current target history inversion pulse to the object to be scanned based on a preset time sequence.
6. The method according to claim 5, wherein the transmitting the current target excitation pulse corresponding to the current target history inversion pulse to the object to be scanned based on the preset time sequence further comprises:
and if the current target excitation pulse corresponding to the current target history inversion pulse does not exist currently, transmitting a preset excitation pulse for keeping the current magnetic resonance signal steady to the object to be scanned.
7. The method of magnetic resonance imaging according to claim 6, wherein the transmitting of a preset excitation pulse for maintaining the steady state of the current magnetic resonance signal to the object to be scanned comprises:
determining the sum of the first duration of the inversion pulse and the second duration of the excitation pulse to obtain total duration, and rounding down the quotient of the inversion time and the total duration to obtain the transmission times of the preset excitation pulse;
transmitting the preset excitation pulse for maintaining the steady state of the current magnetic resonance signal to the object to be scanned based on the transmission times.
8. A magnetic resonance imaging apparatus, comprising:
the signal inversion module is used for transmitting inversion pulses to an object to be scanned so as to invert the current magnetic resonance signal of the object to be scanned;
the time determining module is used for determining the inversion time corresponding to the signal component to be suppressed in the current magnetic resonance signal;
the pulse transmitting module is used for timing after transmitting the inversion pulse to the object to be scanned, and transmitting an excitation pulse to the object to be scanned based on a preset time sequence if the timing duration reaches the inversion time so as to eliminate the signal component to be suppressed in the current magnetic resonance signal; the preset time sequence is determined based on a preset pulse embedding rule, and the preset pulse embedding rule is to embed excitation pulses between the inversion pulses of adjacent layers in one inversion time;
the image generation module is used for collecting and rejecting the target magnetic resonance signal components remained in the current magnetic resonance signal after the signal components to be suppressed, and generating a magnetic resonance image of the object to be scanned based on the target magnetic resonance signal components.
9. An electronic device comprising a processor and a memory; wherein the memory is for storing a computer program to be loaded and executed by the processor for implementing a magnetic resonance imaging method as claimed in any one of claims 1 to 7.
10. A computer readable storage medium for storing a computer program which, when executed by a processor, implements the magnetic resonance imaging method according to any one of claims 1 to 7.
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