CN112741612B - Magnetic resonance imaging method, device, storage medium and computer equipment - Google Patents
Magnetic resonance imaging method, device, storage medium and computer equipment Download PDFInfo
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Abstract
The application relates to a magnetic resonance imaging method, a device, a storage medium and computer equipment, wherein when magnetic resonance scanning is carried out, data filling of a K space is carried out according to a preset data filling mode corresponding to gradient change types of different phases, wherein the final gradient of a previous phase in an adjacent phase is an initial gradient of a next phase, that is, the gradients of the adjacent phases are mutually connected, so that gradient change among the phases can be greatly reduced in the data filling process, vortex flow generated due to gradient change can be greatly weakened, vortex artifact generation is reduced, and imaging effect is improved.
Description
Technical Field
The present disclosure relates to the field of magnetic resonance technologies, and in particular, to a magnetic resonance imaging method, apparatus, storage medium, and computer device.
Background
The magnetic resonance imaging (Magnetic Resonance Imaging, abbreviated as MRI) uses the principle of nuclear magnetic resonance, and detects the emitted electromagnetic waves by externally applying a gradient magnetic field according to different attenuations of the released energy in different structural environments inside the material, so as to obtain the positions and types of nuclei constituting the object, and thereby, the structural image inside the object can be drawn. The magnetic resonance imaging technology can be used for acquiring images of internal structures of a human body, and the application of a rapidly-changing gradient magnetic field greatly accelerates the speed of magnetic resonance imaging, so that the magnetic resonance imaging technology has become a common technical means in modern medical diagnosis.
In magnetic resonance imaging techniques, acquired scan data is filled into K-space. In the prior art, when data is filled, filling is generally performed along the phase encoding direction of the K space. However, in the filling process, a large gradient change exists, so that a strong vortex is generated, and motion artifacts are generated, so that the imaging effect is influenced.
Disclosure of Invention
In view of the foregoing, it is desirable to provide a method, apparatus, storage medium, and computer device for magnetic resonance imaging that attenuate eddy currents in response to the problems associated with the prior art.
A magnetic resonance imaging method, comprising:
acquiring magnetic resonance scanning data corresponding to the current period;
filling the magnetic resonance scanning data into a K space corresponding to the current period according to a preset data filling mode corresponding to the gradient change type of the current period;
taking the phase next to the current phase as a new current phase, and returning to the step of acquiring magnetic resonance scanning data corresponding to the current phase until the magnetic resonance scanning is finished;
after the magnetic resonance scanning is finished, obtaining a corresponding magnetic resonance image according to magnetic resonance scanning data stored in the K space corresponding to all periods;
wherein the final gradient of the previous phase in the adjacent phase is the initial gradient of the next phase.
A magnetic resonance imaging apparatus comprising:
the data acquisition module is used for acquiring magnetic resonance scanning data corresponding to the current period;
the data filling module is used for filling the magnetic resonance scanning data into the K space corresponding to the current period according to a preset data filling mode corresponding to the gradient change type of the current period; taking the phase next to the current phase as a new current phase, and returning to the step of acquiring magnetic resonance scanning data corresponding to the current phase until the magnetic resonance scanning is finished;
the image reconstruction module is used for obtaining a corresponding magnetic resonance image according to the magnetic resonance scanning data stored in the K space corresponding to all periods after the magnetic resonance scanning is finished;
wherein the final gradient of the previous phase in the adjacent phase is the initial gradient of the next phase.
A computer device comprising a memory storing a computer program and a processor implementing the steps of the method described above when the processor executes the computer program.
A computer readable storage medium having stored thereon a computer program which, when executed by a processor, performs the steps of the method described above.
The magnetic resonance imaging method, the magnetic resonance imaging device, the storage medium and the computer equipment acquire magnetic resonance scanning data corresponding to the current period; filling magnetic resonance scanning data into a K space corresponding to the current phase according to a preset data filling mode corresponding to the gradient change type of the current phase; taking the phase next to the current phase as a new current phase, and returning to the step of acquiring magnetic resonance scanning data corresponding to the current phase until the magnetic resonance scanning is finished; after the magnetic resonance scanning is finished, obtaining a corresponding magnetic resonance image according to magnetic resonance scanning data stored in the K space corresponding to all periods; wherein the final gradient of the previous phase in the adjacent phase is the initial gradient of the next phase. When magnetic resonance scanning is performed, data filling of the K space is performed according to preset data filling modes corresponding to gradient change types of different phases, wherein the final gradient of the previous phase in the adjacent phase is the initial gradient of the next phase, that is, the gradients of the adjacent phases are mutually connected, so that gradient change among the phases can be greatly reduced in the data filling process, vortex generated due to the gradient change can be greatly weakened, generation of vortex artifacts is reduced, and imaging effect is improved.
Drawings
FIG. 1 (a) is a schematic diagram showing gradient changes of different phases during magnetic resonance scanning in the prior art;
FIG. 1 (b) is a prior art K-space filling schematic diagram;
FIG. 1 (c) is a schematic diagram of a phase encoding gradient change in the prior art;
figure 2 is a diagram of an application environment of a magnetic resonance imaging method in one embodiment;
FIG. 3 is a flow chart of a method of magnetic resonance imaging in one embodiment;
FIG. 4 (a) is a schematic diagram of gradient changes of different phases in one embodiment;
FIG. 4 (b) is a schematic diagram of the phase encoding gradient applied by the mid-phase P1 and the phase P2 of FIG. 4 (a);
FIG. 4 (c) is a schematic diagram illustrating K-space filling corresponding to the middle phase P1 and the phase P2 in FIG. 4 (a);
FIG. 5 (a) is a schematic diagram showing gradient changes of different phases in another embodiment;
FIG. 5 (b) is a schematic diagram of the applied phase encoding gradients of the mid-phase P1 to the phase P4 of FIG. 5 (a);
FIG. 5 (c) is a schematic diagram illustrating K space filling corresponding to the middle phase P1 to the phase P4 in FIG. 5 (a);
FIG. 6 is a schematic diagram of a magnetic resonance imaging apparatus in one embodiment;
fig. 7 is an internal structural diagram of a computer device in one embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.
As shown in fig. 1 (a), a schematic diagram of gradient changes of different phases (phase) during magnetic resonance scanning in the prior art is shown, where the gradient change condition of each phase is the same, i.e. the phase changes from a certain fixed extremum-a to another fixed extremum-a. Specifically, taking a two-dimensional MR image with a matrix of 256×256 as an example, as shown in fig. 1 (b) and fig. 1 (c), a K-space filling schematic diagram and a corresponding phase encoding gradient change schematic diagram in the prior art (only a part of the phase encoding lines and a part of the phase encoding gradient field changes in the K-space are drawn in the figure for simplicity), refer to fig. 1 (b), where Kx represents a frequency encoding direction, ky represents a phase encoding direction, and a plurality of phase encoding lines (arrows from left to right in the figure) arranged along the phase encoding direction are included in the K-space. Wherein the phase encoding gradient field of the MR signal filled with Ky= -127 is high on one side and low on the other side, and the gradient field intensity is maximum; the high-low direction of the phase encoding gradient field of the MR signal filled with Ky= -126 is not changed, but the gradient field intensity is reduced; the high and low directions of the gradient field are kept unchanged, and the gradient field intensity is gradually reduced; by the time the MR signal with ky=0 is filled, the phase encoding gradient field is equal to zero; after that, the high-low direction of the phase encoding gradient field is switched to the opposite direction, the gradient field intensity is gradually increased, and the phase encoding gradient field intensity reaches the highest by the time of acquiring MR signals filled with Ky= +128. In the prior art, the gradient change condition of each phase is the same, that is, the gradient of each phase is changed from-127 to +128, and when the scanning data of each phase is filled, the phase encoding line of ky= -127 is filled to the phase encoding line of ky= +128 according to the gradient encoding direction. However, since there is a large gradient change between adjacent phases (the final gradient of the former phase is +128 and the initial gradient of the next phase is-127), the rapid switching change of the gradient field causes the gradient coil to generate a strong gradient eddy current, the gradient eddy current causes a time-varying magnetic field or the gradient field to be superimposed in the main field, so that the linearity of the gradient field is poor, and ghosts (one of the artifacts) appear in the finally acquired image, which affects the imaging effect.
Aiming at the problems in the prior art, the application provides a magnetic resonance scanning method, which can avoid the condition of large gradient change by designing the gradient change condition of adjacent phases into a mutually connected mode so as to reduce gradient eddy current artifact, and mainly comprises the following steps: monitoring cardiac motion of the subject to obtain a cardiac motion profile, for example, using an electrocardiographic monitoring (ECG, EKG) instrument or applying an electrocardiographic sequence to the subject; determining a cardiac cycle of the subject from the cardiac motion profile, and each cardiac cycle comprising two or more phase, which may be, for example, isovolumetric systolic, fast ejection, slow ejection, pre-diastole, isovolumetric diastole, fast filling, slow filling, atrial systole, etc.; the imaging sequence is used for exciting a target part of a subject in each cardiac cycle, the directions of the phase encoding gradients applied by adjacent phases in each cardiac cycle are the same or opposite, and the intensities of the phase encoding gradients applied by the adjacent phases are connected. The phase encoding gradients applied in adjacent phases in each cardiac cycle are the same in height, e.g., for one of the phase encoding positions in any phase, its gradient field is set to be left high and right low; the gradient field setting is also left high and right low at the position corresponding to the phase coding position or the next position in the adjacent phase. The phase encoding gradient intensity phase applied by the adjacent phase can be gradually increased or gradually decreased in gradient field intensity, for example, the gradient field intensity is gradually increased or gradually decreased, or the field intensity in any phase reaches the maximum, and the field intensity in the position corresponding to the phase encoding position or the next position in the adjacent phase is set to be the maximum or slightly smaller than the maximum field intensity.
Corresponding to the magnetic resonance scanning method, the application also provides a magnetic resonance imaging method, and the magnetic resonance scanning method mainly comprises the following steps: acquiring a heart motion curve of a subject; determining a cardiac cycle of the subject from the cardiac motion profile, and each cardiac cycle comprising two or more phase phases; acquiring magnetic resonance signals generated by exciting a subject by an imaging sequence, and carrying out phase encoding on the magnetic resonance signals to obtain a plurality of data lines, wherein the data lines belonging to the same phase are distributed into the same K space, and filling sequences of the corresponding K spaces in adjacent phases are connected; reconstructing the plurality of K-space data to obtain images corresponding to the plurality of phases, and obtaining a heart cine image from the images corresponding to the plurality of phases.
It should be noted that the magnetic resonance imaging method provided by the application can be applied to magnetic resonance dynamic imaging of a moving organ, for example, cardiac function detection. It can also be applied in dynamic enhancement imaging, such as arterial vessel imaging with drug infusion, without specific limitation.
Referring to fig. 2, which is a diagram of an application environment of the magnetic resonance imaging method of the present application, the magnetic resonance imaging method may be applied to a magnetic resonance imaging system, where the magnetic resonance imaging system includes a magnetic resonance scanner 10, a processing device 20, a storage device 30, one or more terminals 40 (such as a mobile phone 40-1, a tablet 40-2, a notebook 40-3, etc.) and a network 50, where the magnetic resonance scanner 10 is used to acquire magnetic resonance scan data and send the magnetic resonance scan data to the processing device 20, the processing device 20 is used to obtain a corresponding magnetic resonance image according to the magnetic resonance scan data by the magnetic resonance imaging method of the present application, the storage device 30 is used to store the magnetic resonance scan data and the magnetic resonance image, and the terminal 40 is used to display the magnetic resonance image so as to facilitate a user to observe and analyze. Components in a magnetic resonance imaging system may be connected in one or more ways. For example only, as shown in fig. 2, the magnetic resonance scanner 10 may be connected to the processing device 20 via a network 50. As another example, the magnetic resonance scanner 10 may be directly connected to the processing device 20, as indicated by the double-headed arrow in the dashed line connecting the magnetic resonance imaging scanner and the processing device 20. For another example, the storage device 30 may be directly connected to the processing device 20 (not shown) or connected via the network 50. As yet another example, the terminal 40 may be connected directly to the processing device 20 (as indicated by the double-headed arrow in the dashed line connecting the terminal 40 and the processing device 20) or through the network 50.
As shown in fig. 3, in one embodiment, a magnetic resonance imaging method is provided, and the method is applied to the processing device in fig. 2, and is explained by taking as an example, the method specifically includes the following steps:
step S100, acquiring magnetic resonance scanning data corresponding to the current period.
Taking heart detection as an example, a magnetic resonance heart movie generally uses electrocardio to trigger multi-section scanning, acquires one section of K space data in one cardiac cycle, and then acquires the next section of K space data in the next cardiac cycle, so as to obtain multi-frame complete K space data, and reconstruct a heart voltage image. Within a single cardiac cycle, a plurality of different phase phases are contained, and therefore the processing device first acquires magnetic resonance scan data corresponding to each phase.
Step S200, filling magnetic resonance scanning data into a K space corresponding to the current period according to a preset data filling mode corresponding to the gradient change type of the current period.
And a plurality of deadlines in the same period respectively correspond to the corresponding K spaces. The present application differs from the prior art in that the final gradient of the previous phase in the adjacent phase in the present application is the initial gradient of the subsequent phase, that is, the gradient changes of the adjacent phases are mutually linked, so that gradient abrupt changes between the phases can be reduced. In the embodiment of the application, the gradient change may be a direction change of the gradient field or an intensity change of the gradient field. Correspondingly, as the gradient change type is changed, the preset data filling mode adopted in the method is different from the prior art when the magnetic resonance scanning data are filled into the K space.
Step S300, taking the phase next to the current phase as a new current phase, and returning to the step of acquiring magnetic resonance scanning data corresponding to the current phase in the magnetic resonance scanning sequence until the magnetic resonance scanning is finished.
After the magnetic resonance scanning data of the current phase is filled into the K space, the data filling work of the next phase can be executed, namely the flow of the steps S100 to S200 is repeated until the magnetic resonance scanning is finished.
Step S400, after the magnetic resonance scanning is finished, obtaining a corresponding magnetic resonance image according to magnetic resonance scanning data stored in the K space corresponding to all periods;
after the magnetic resonance scanning is finished, image reconstruction can be carried out according to all data stored in the K space, so that a corresponding magnetic resonance image is obtained. The image reconstruction may specifically be performed by an IFT (Inverse Fourier Transform ) method or the like, and is not particularly limited herein.
In the embodiment, when performing magnetic resonance scanning, the data filling of the K space is performed according to the preset data filling modes corresponding to the gradient change types of different phases, wherein the final gradient of the previous phase in the adjacent phase is the initial gradient of the next phase, that is, the gradients of the adjacent phases are mutually connected, so that the gradient change between the phases can be greatly reduced in the data filling process, the eddy current generated by the gradient change can be greatly reduced, the generation of eddy current artifacts is reduced, and the imaging effect is improved.
In one embodiment, the gradient change type includes: the gradient change direction of the single phase is changed from a first extreme value to a second extreme value or from the second extreme value to the first extreme value in a stepping mode, and the gradient change directions of two adjacent phases are opposite; the first extreme value is the minimum value in the gradient change range, and the second extreme value is the maximum value in the gradient change range.
Specifically, as shown in fig. 4 (a), for example, the gradient change of different phases is shown, in this embodiment, the gradient difference between the final gradient and the initial gradient of the single phase is equal to the gradient change range (-the gradient change range formed by a and a), for example, the gradient strength of phase P1 is changed from-a to a, and the gradient strength of phase P2 is changed from-a to-a, instead of from-a to a in the prior art, so that the gradient abrupt change between phases can be reduced.
Taking one cycle as an example, fig. 4 (b) is a schematic diagram of the phase encoding gradient applied by the middle phase P1 and the phase P2 in fig. 4 (a).
For phase P1, the gradient field at ky= -127 is set to be high to the left and low in the phase encoding direction (Ky), and the gradient strength is the maximum value; the gradient field strength is gradually reduced after that, the high-low direction of the gradient field is kept unchanged; gradient strength at ky=0 is 0; subsequently, the gradient field at each position is set to be low on the left and high on the right, the gradient intensity is gradually increased, and the gradient intensity at ky= +128 is maximum.
For phase P2, the gradient field at ky= +128 is set to be low to high and the gradient strength is maximum in the phase encoding direction (Ky); the gradient field strength is gradually reduced after that, the high-low direction of the gradient field is kept unchanged; gradient strength at ky=0 is 0; subsequently, the gradient field at each position is set to be high on the left and low on the right, the gradient intensity is gradually increased, and the gradient intensity at ky= -127 is maximum.
In one embodiment, when the gradient change direction of the current phase is changed from the first extremum to the second extremum, the preset data filling mode includes: sequentially filling a preset number of phase encoding lines according to a preset phase encoding direction; when the gradient change direction of the current phase is changed from the second level value to the first extreme value, the preset data filling mode comprises the following steps: and filling a preset number of phase encoding lines in sequence according to the direction opposite to the preset phase encoding direction.
In the magnetic resonance scanning process, the scanning data of a single period cannot fill the whole K space, so that a plurality of periods of scanning are generally required, correspondingly, when the scanning data of different periods are filled into the corresponding K space, the scanning data of a first period phase in the first period is firstly filled into the K space corresponding to the period, and then the scanning data of a second period phase is filled into the K space corresponding to the period until the scanning data of all period phases of the first period are filled into the corresponding K space. At this time, the K space is not filled, so that scanning of the next cycle is required, and the filling principle is the same as that of the first cycle when data filling of the second cycle is performed, and thus, no description is repeated here.
Specifically, as shown in fig. 4 (c), a schematic diagram of K space filling of each phase in one period is shown, where K1 represents a K space corresponding to a first phase P1, and K2 represents a K space corresponding to a second phase P2. When filling the magnetic resonance scanning data of the first period, the phase P1 is to fill a preset number of phase encoding lines along a preset phase encoding direction (the direction indicated by an arrow in the figure), wherein the preset number is 3 (ky= -127, ky= -126, ky= -125, or other numbers), that is, each period is filled with 3 phase encoding lines; phase P2 is along the direction opposite to the preset phase encoding direction 3 phase encoding lines (ky= +128, ky= +127, ky= +126) are filled.
When the second period is reached, phase P1 again fills 3 phase code lines (ky= -124, ky= -123, ky= -122) along the preset phase code direction, i.e. six phase code lines have been filled at this time, phase P2 again fills 3 phase code lines (ky= +125, ky= +124, ky= +123) along the opposite direction to the preset phase code direction, i.e. six phase code lines have been filled at this time; and the like, until the mth period, the magnetic resonance scanning data of each phase fills the K space, and the completion of the magnetic resonance scanning can be determined at the moment.
In one embodiment, the gradient change type includes: when the gradient difference between the final gradient and the initial gradient of the single phase is smaller than the gradient change range formed by the first extreme value and the second extreme value, the adjacent phase with the same gradient change direction forms a unidirectional change phase set, the overall gradient change direction of the unidirectional change phase set is changed from the first extreme value to the second extreme value or from the second extreme value to the first extreme value, and the overall gradient change directions of the adjacent two unidirectional change phase sets are opposite; the first extreme value is the minimum value in the gradient change range, and the second extreme value is the maximum value in the gradient change range.
Specifically, as shown in fig. 5 (a), the gradient change diagrams of different phases are shown, in this embodiment, the gradient difference between the final gradient and the initial gradient of a single phase is smaller than the gradient change range (-a and a is a gradient change range), so that adjacent phases with the same gradient change direction can form a unidirectional change phase set, and the total gradient difference of the unidirectional change phase set is equal to the gradient change range.
Taking one cycle as an example, fig. 5 (b) is a schematic diagram of the phase encoding gradient applied from the middle phase P1 to the phase P4 in fig. 5 (a).
For phase P1, the gradient field at ky= -127 is set to be high to the left and low in the phase encoding direction (Ky), and the gradient strength is the maximum value; the gradient field strength is gradually reduced after that, the high-low direction of the gradient field is kept unchanged; until the gradient strength is 0 at ky=0.
For phase P2, the gradient strength is 0 at ky=0 in the phase encoding direction (Ky), and then the gradient field at each position is set to be low to high, the gradient strength is gradually increased, and the gradient strength is maximum at ky= +128.
For phase P3, the gradient field at ky= +128 is set to be low to high and the gradient strength is maximum in the phase encoding direction (Ky); the gradient field strength is gradually reduced after that, the high-low direction of the gradient field is kept unchanged; until the gradient strength is 0 at ky=0.
For phase P4, the gradient strength is 0 at ky=0 in the phase encoding direction (Ky), then the gradient field at each position is set to be high-right low, the gradient strength is gradually increased, and the gradient strength is maximum at ky= -127.
In one embodiment, when the overall gradient change direction of the unidirectional change phase set in which the current phase is located is changed from the first extremum to the second extremum, the preset data filling manner includes: sequentially filling a preset number of phase encoding lines to preset filling positions according to a preset phase encoding direction; when the overall gradient change direction of the unidirectional change phase set where the current phase is located is changed from the second level value to the first extreme value, the preset data filling mode comprises the following steps: and sequentially filling a preset number of phase coding lines to preset filling positions according to the direction opposite to the preset phase coding direction.
Specifically, as shown in fig. 5 (c), a schematic diagram of K space filling of each phase in one period is shown, where K1 represents a K space corresponding to a first phase P1, K2 represents a K space corresponding to a second phase P2, K3 represents a K space corresponding to a third phase P3, and K4 represents a K space corresponding to a fourth phase P4.
When filling the magnetic resonance scan data of the first period, the phase P1 is a preset number of phase encoding lines filled along the preset phase encoding direction, wherein the preset number is 2 (ky= -127, ky= -126, or other number), that is, 2 phase encoding lines are filled in each period, and in addition, the preset filling position corresponding to the phase P1 is the upper half part of K1, that is, the phase P1 is filled from ky= -127 to ky=0 at most. The phase P2 is filled with 2 phase encoding lines (ky=0, ky= +1) along the predetermined phase encoding direction, and the predetermined filling position corresponding to the phase P2 is the lower half of K2, i.e. the phase P1 is filled up to ky= +128 from ky=0. The phase P3 is filled with 2 phase encoding lines (ky= +128, ky= +127) along the direction opposite to the preset phase encoding direction, and the preset filling position corresponding to the phase P3 is the upper half of K3, i.e. the phase P3 is filled up to ky=0 from ky= +128. The phase P4 is filled with 2 phase encoding lines (ky=0, ky= -1) along the opposite direction to the preset phase encoding direction, and the preset filling position corresponding to the phase P2 is the upper half of K4, i.e. the phase P4 is filled from ky=0 to ky= -127 at most.
And when the second period is reached, 2 phase encoding lines are sequentially filled in each K space according to a corresponding filling mode, and the like, until the nth period, the corresponding preset filling positions are filled with the magnetic resonance scanning data of each phase, and at the moment, the completion of the magnetic resonance scanning can be determined.
In one embodiment, the preset fill position is determined based on the number of phase phases in the unidirectional change phase set. Specifically, the K space may be equally divided according to the number of phase phases in the unidirectional change phase set, and then the preset filling positions corresponding to each phase are sequentially determined, that is, the preset filling positions of all phase phases in the unidirectional change phase set form a complete K space.
Referring to fig. 5 (c), it can be seen that when the number of phases in the unidirectional variation phase set is 2, the K space can be equally divided into two preset filling positions of an upper half and a lower half, where the ith phase corresponds to the ith preset filling position, i.e., phase P1 corresponds to the upper half and phase P2 corresponds to the lower half.
It is understood that the number of phase phases in the unidirectional change phase set is not limited to two, but may be other numbers, for example, when the number of phase phases in the unidirectional change phase set is 3, the preset filling position corresponding to the first phase is 1/3 position filled from ky= -127 to K space, the preset filling position corresponding to the second phase is 2/3 position filled from 1/3 position to K space, and the preset filling position corresponding to the third phase is 2/3 position filled from K space to ky= +128.
In one embodiment, before the step S400 obtains the corresponding magnetic resonance image according to the magnetic resonance scan data stored in the K space corresponding to all phases, the method further includes: and carrying out averaging treatment on tail data of magnetic resonance scanning data corresponding to the previous period in the adjacent period and head data of magnetic resonance scanning data corresponding to the next period.
Specifically, the averaging process includes: an average or weighted average of the header data and the trailer data is calculated, and the header data and the trailer data are replaced by the average or weighted average. For example, if the tail data of the former phase is a and the head data of the latter phase is B, the average value (a+b)/2 or the weighted average value a×a++b×b% may be used to replace a and B. According to the embodiment, the motion artifact can be further weakened and the image quality can be improved by carrying out the averaging processing on the K space data at the intersection of adjacent periods.
It should be understood that, under reasonable conditions, although the steps in the flowcharts referred to in the foregoing embodiments are shown in order as indicated by the arrows, these steps are not necessarily performed in order as indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least some of the steps in the flowcharts may include a plurality of sub-steps or stages that are not necessarily performed at the same time, but may be performed at different times, and the order of execution of the sub-steps or stages is not necessarily sequential, but may be performed in rotation or alternately with at least a portion of the sub-steps or stages of other steps or other steps.
As shown in fig. 6, in one embodiment, a magnetic resonance imaging apparatus is improved, the apparatus comprising the following modules:
a data acquisition module 100, configured to acquire magnetic resonance scan data corresponding to a current period;
the data filling module 200 is configured to fill magnetic resonance scan data into a K space corresponding to the current period according to a preset data filling manner corresponding to a gradient change type of the current period; taking the phase next to the current phase as a new current phase, and returning to the step of acquiring magnetic resonance scanning data corresponding to the current phase until the magnetic resonance scanning is finished;
the image reconstruction module 300 is configured to obtain a corresponding magnetic resonance image according to magnetic resonance scan data stored in K space corresponding to all phases after the magnetic resonance scan is completed;
wherein the final gradient of the previous phase in the adjacent phase is the initial gradient of the next phase.
For specific limitations of the magnetic resonance imaging apparatus, reference is made to the above limitations of the magnetic resonance imaging method, which are not repeated here. The various modules in the magnetic resonance imaging apparatus described above may be implemented in whole or in part by software, hardware, or a combination thereof. The above modules may be embedded in hardware or may be independent of a processor in the computer device, or may be stored in software in a memory in the computer device, so that the processor may call and execute operations corresponding to the above modules.
In one embodiment, a computer device is provided comprising a memory and a processor, the memory having stored therein a computer program, the processor when executing the computer program performing the steps of: acquiring magnetic resonance scanning data corresponding to the current period; filling magnetic resonance scanning data into a K space corresponding to the current phase according to a preset data filling mode corresponding to the gradient change type of the current phase; taking the phase next to the current phase as a new current phase, and returning to the step of acquiring magnetic resonance scanning data corresponding to the current phase until the magnetic resonance scanning is finished; after the magnetic resonance scanning is finished, obtaining a corresponding magnetic resonance image according to magnetic resonance scanning data stored in the K space corresponding to all periods; wherein the final gradient of the previous phase in the adjacent phase is the initial gradient of the next phase.
In one embodiment, the processor when executing the computer program further performs the steps of: and carrying out averaging treatment on tail data of magnetic resonance scanning data corresponding to the previous period in the adjacent period and head data of magnetic resonance scanning data corresponding to the next period.
Fig. 7 is an internal structural diagram of a computer device in one embodiment. The computer device may in particular be a terminal (or a server). As shown in fig. 7, the computer device includes a processor, a memory, a network interface, an input device, and a display screen connected by a system bus. The memory includes a nonvolatile storage medium and an internal memory. The non-volatile storage medium of the computer device stores an operating system and may also store a computer program which, when executed by a processor, causes the processor to implement a magnetic resonance imaging method. The internal memory may also have stored therein a computer program which, when executed by the processor, causes the processor to perform a magnetic resonance imaging method. The display screen of the computer equipment can be a liquid crystal display screen or an electronic ink display screen, the input device of the computer equipment can be a touch layer covered on the display screen, can also be keys, a track ball or a touch pad arranged on the shell of the computer equipment, and can also be an external keyboard, a touch pad or a mouse and the like.
It will be appreciated by those skilled in the art that the structure shown in fig. 7 is merely a block diagram of some of the structures associated with the present application and is not limiting of the computer device to which the present application may be applied, and that a particular computer device may include more or fewer components than shown, or may combine certain components, or have a different arrangement of components.
In one embodiment, a computer readable storage medium is provided having a computer program stored thereon, which when executed by a processor, performs the steps of: acquiring magnetic resonance scanning data corresponding to the current period; filling magnetic resonance scanning data into a K space corresponding to the current phase according to a preset data filling mode corresponding to the gradient change type of the current phase; taking the phase next to the current phase as a new current phase, and returning to the step of acquiring magnetic resonance scanning data corresponding to the current phase until the magnetic resonance scanning is finished; after the magnetic resonance scanning is finished, obtaining a corresponding magnetic resonance image according to magnetic resonance scanning data stored in the K space corresponding to all periods; wherein the final gradient of the previous phase in the adjacent phase is the initial gradient of the next phase.
In one embodiment, the computer program when executed by the processor further performs the steps of: and carrying out averaging treatment on tail data of magnetic resonance scanning data corresponding to the previous period in the adjacent period and head data of magnetic resonance scanning data corresponding to the next period.
Those skilled in the art will appreciate that implementing all or part of the above-described methods may be accomplished by way of a computer program, which may be stored on a non-transitory computer readable storage medium and which, when executed, may comprise the steps of the above-described embodiments of the methods. Any reference to memory, storage, database, or other medium used in the various embodiments provided herein may include non-volatile and/or volatile memory. The nonvolatile memory can include Read Only Memory (ROM), programmable ROM (PROM), electrically Programmable ROM (EPROM), electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double Data Rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous Link DRAM (SLDRAM), memory bus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), among others.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The foregoing examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (10)
1. A method of magnetic resonance imaging comprising:
acquiring magnetic resonance scanning data corresponding to the current period;
filling the magnetic resonance scanning data into a K space corresponding to the current period according to a preset data filling mode corresponding to the gradient change type of the current period;
taking the phase next to the current phase as a new current phase, and returning to the step of acquiring magnetic resonance scanning data corresponding to the current phase until the magnetic resonance scanning is finished;
after the magnetic resonance scanning is finished, obtaining a corresponding magnetic resonance image according to magnetic resonance scanning data stored in the K space corresponding to all periods;
wherein the gradient strength applied by adjacent phases are linked.
2. The method of claim 1, wherein the gradient change type comprises: the gradient change direction of the single phase is changed from a first extreme value to a second extreme value or from the second extreme value to the first extreme value, and the gradient change directions of two adjacent phase phases are opposite;
the first extreme value is the minimum value in the gradient change range, and the second extreme value is the maximum value in the gradient change range.
3. The method according to claim 2, wherein when the gradient change direction of the current phase is changed from the first extremum to the second extremum, the preset data filling manner comprises: sequentially filling a preset number of phase encoding lines according to a preset phase encoding direction;
when the gradient change direction of the current phase is changed from the second polarity value to the first extreme value, the preset data filling mode includes: and filling a preset number of phase coding lines in sequence according to the direction opposite to the preset phase coding direction.
4. The method of claim 1, wherein the gradient change type comprises: when the gradient difference between the final gradient and the initial gradient of a single phase is smaller than the gradient change range formed by a first extreme value and a second extreme value, adjacent phase with the same gradient change direction form a unidirectional change phase set, the overall gradient change direction of the unidirectional change phase set is changed from the first extreme value to the second extreme value or from the second extreme value to the first extreme value, and the overall gradient change directions of two adjacent unidirectional change phase sets are opposite;
the first extreme value is the minimum value in the gradient change range, and the second extreme value is the maximum value in the gradient change range.
5. The method of claim 4, wherein when the overall gradient change direction of the unidirectional change phase set in which the current phase is located is changed from the first extremum to the second extremum, the preset data filling manner comprises: sequentially filling a preset number of phase encoding lines to preset filling positions according to a preset phase encoding direction;
when the overall gradient change direction of the unidirectional change phase set where the current phase is located is changed from the second polarity value to the first extreme value, the preset data filling mode includes: and sequentially filling a preset number of phase coding lines to preset filling positions according to the direction opposite to the preset phase coding direction.
6. The method of claim 5, wherein the preset fill location is determined based on a number of phases in the unidirectional varying set of phases.
7. The method of claim 1, further comprising, prior to deriving a corresponding magnetic resonance image from the magnetic resonance scan data stored in the K-space:
and carrying out averaging treatment on tail data of the magnetic resonance scanning data corresponding to the previous period in the adjacent period and head data of the magnetic resonance scanning data corresponding to the next period.
8. A magnetic resonance imaging apparatus, comprising:
the data acquisition module is used for acquiring magnetic resonance scanning data corresponding to the current period;
the data filling module is used for filling the magnetic resonance scanning data into the K space corresponding to the current period according to a preset data filling mode corresponding to the gradient change type of the current period; taking the phase next to the current phase as a new current phase, and returning to the step of acquiring magnetic resonance scanning data corresponding to the current phase until the magnetic resonance scanning is finished;
the image reconstruction module is used for obtaining a corresponding magnetic resonance image according to the magnetic resonance scanning data stored in the K space corresponding to all periods after the magnetic resonance scanning is finished;
wherein the gradient strength applied by adjacent phases are linked.
9. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor implements the steps of the method of any of claims 1 to 7 when the computer program is executed.
10. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the method of any of claims 1 to 7.
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