Magnetic resonance imaging method, apparatus, computer equipment and storage medium

Abstract

The present application relates to a magnetic resonance imaging method, apparatus, computer device, and storage medium. The method comprises: transmitting a first inversion recovery pulse, executing an imaging sequence during the longitudinal magnetization relaxation interval of the first inversion recovery pulse to acquire a first set of magnetic resonance signals from multiple slices, and executing a reference sequence to acquire reference signals from multiple slices; transmitting a second inversion recovery pulse, executing an imaging sequence during the longitudinal magnetization relaxation interval of the second inversion recovery pulse to acquire a second set of magnetic resonance signals from multiple slices, thereby obtaining a first set of magnetic resonance images and a second set of magnetic resonance images; acquiring a first image and a second image of each slice after deallapping based on the reference signal, the first set of magnetic resonance images, and the second set of magnetic resonance images; and acquiring relaxation parameter values ​​of the subject based on the first image and the second image of each slice after deallapping. This method can reduce magnetic resonance scanning time.

Description

Technical Field

[0001] The present application relates to the field of magnetic resonance imaging technology, and in particular to a magnetic resonance imaging method, apparatus, computer equipment, and storage medium. Background Art

[0002] With the development of magnetic resonance imaging technology, cardiac magnetic resonance imaging has been widely used. Cardiac magnetic resonance imaging has good soft tissue contrast resolution, a large scanning field of view, and can obtain oblique cross-sectional images in various directions and angles, thereby enabling multi-dimensional evaluation of the structure of the heart.

[0003] Traditional cardiac magnetic resonance imaging uses an inversion recovery (IR) preparation pulse in combination with different imaging sequences using different inversion recovery times (TI) to image the heart, thereby fitting the T1 value of the material.

[0004] Therefore, the traditional cardiac magnetic resonance imaging method has the problem of long scanning time. Summary of the Invention

[0005] Based on this, it is necessary to provide a magnetic resonance imaging method, apparatus, computer equipment and storage medium that can reduce scanning time to address the above technical problems.

[0006] A magnetic resonance imaging method, comprising:

[0007] transmitting a first inversion recovery pulse to the subject, executing an imaging sequence during a longitudinal magnetization relaxation interval of the first inversion recovery pulse to simultaneously acquire a first set of magnetic resonance signals of a plurality of slices, and executing a reference sequence to acquire reference signals of the plurality of slices;

[0008] transmitting a second inversion recovery pulse to the detection object, performing an imaging sequence during a longitudinal magnetization relaxation interval of the second inversion recovery pulse, and simultaneously acquiring a second set of magnetic resonance signals of the plurality of slices;

[0009] Reconstructing the first set of magnetic resonance signals and the second set of magnetic resonance signals respectively to obtain a first set of magnetic resonance images and a second set of magnetic resonance images;

[0010] acquiring, according to the reference signal, the first set of magnetic resonance images, and the second set of magnetic resonance images, a first image for each slice dealiased and a second image for each slice dealiased;

[0011] The relaxation parameter value of the detection object is acquired according to the first image after dealiasing of each slice and the second image after dealiasing of each slice.

[0012] In one embodiment, acquiring the first image and the second image of each slice dealiased according to the reference signal, the first set of magnetic resonance images, and the second set of magnetic resonance images, respectively, includes:

[0013] obtaining, according to the reference signal, a magnetic resonance coil sensitivity corresponding to the reference signal;

[0014] Obtaining a first image with dealiasing of each slice according to the magnetic resonance coil sensitivity, the reference signal and the first set of magnetic resonance images;

[0015] A second image with dealiasing of each slice is obtained according to the magnetic resonance coil sensitivity, the reference signal and the second set of magnetic resonance images.

[0016] In one embodiment, obtaining the relaxation parameter value of the detection object according to the first image corresponding to each slice and the second image corresponding to each slice includes:

[0017] Curve fitting is performed on each point in the first image space coordinates and each point in the second image space coordinates to obtain a relaxation parameter value of the detection object.

[0018] In one embodiment, there is an idle cardiac cycle between transmitting the first inversion recovery pulse and transmitting the second inversion recovery pulse, and the reference sequence is performed during the idle cardiac cycle.

[0019] In one embodiment, the reference signal is at least one of a reference signal for a multi-layer simultaneous imaging technique, a reference signal for parallel imaging, and a reference signal used for both parallel imaging and multi-layer simultaneous imaging techniques.

[0020] In one embodiment, the relaxation parameter value of the detection object is a longitudinal relaxation constant.

[0021] In one embodiment, before acquiring the relaxation parameter value of the detection object based on the first image and the second image of each slice de-aliasing, the method further includes:

[0022] The first image after deallocation of each slice and the second image after deallocation of each slice are registered respectively.

[0023] A magnetic resonance imaging apparatus, comprising:

[0024] a first acquisition module, configured to transmit a first inversion recovery pulse to the subject, execute an imaging sequence during a longitudinal magnetization relaxation interval of the first inversion recovery pulse to simultaneously acquire a first set of magnetic resonance signals of a plurality of slices, and execute a reference sequence to acquire reference signals of the plurality of slices;

[0025] a second acquisition module, configured to transmit a second inversion recovery pulse to the detection object, execute an imaging sequence during a longitudinal magnetization relaxation interval of the second inversion recovery pulse, and simultaneously acquire a second set of magnetic resonance signals of the plurality of slices;

[0026] a reconstruction module, configured to reconstruct the first set of magnetic resonance signals and the second set of magnetic resonance signals, respectively, to obtain a first set of magnetic resonance images and a second set of magnetic resonance images;

[0027] a third acquisition module, configured to acquire, according to the reference signal, the first set of magnetic resonance images, and the second set of magnetic resonance images, a first image for each slice dealiased and a second image for each slice dealiased;

[0028] The fourth acquisition module acquires the relaxation parameter value of the detection object according to the first image of each slice deallocation and the second image of each slice deallocation.

[0029] A computer device includes a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:

[0030] transmitting a first inversion recovery pulse to the subject, executing an imaging sequence during a longitudinal magnetization relaxation interval of the first inversion recovery pulse to simultaneously acquire a first set of magnetic resonance signals of a plurality of slices, and executing a reference sequence to acquire reference signals of the plurality of slices;

[0031] transmitting a second inversion recovery pulse to the detection object, performing an imaging sequence during a longitudinal magnetization relaxation interval of the second inversion recovery pulse, and simultaneously acquiring a second set of magnetic resonance signals of the plurality of slices;

[0032] Reconstructing the first set of magnetic resonance signals and the second set of magnetic resonance signals respectively to obtain a first set of magnetic resonance images and a second set of magnetic resonance images;

[0033] acquiring, according to the reference signal, the first set of magnetic resonance images, and the second set of magnetic resonance images, a first image for each slice dealiased and a second image for each slice dealiased;

[0034] The relaxation parameter value of the detection object is acquired according to the first image after dealiasing of each slice and the second image after dealiasing of each slice.

[0035] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the following steps:

[0036] transmitting a first inversion recovery pulse to the subject, executing an imaging sequence during a longitudinal magnetization relaxation interval of the first inversion recovery pulse to simultaneously acquire a first set of magnetic resonance signals of a plurality of slices, and executing a reference sequence to acquire reference signals of the plurality of slices;

[0037] transmitting a second inversion recovery pulse to the detection object, performing an imaging sequence during a longitudinal magnetization relaxation interval of the second inversion recovery pulse, and simultaneously acquiring a second set of magnetic resonance signals of the plurality of slices;

[0038] Reconstructing the first set of magnetic resonance signals and the second set of magnetic resonance signals respectively to obtain a first set of magnetic resonance images and a second set of magnetic resonance images;

[0039] acquiring, according to the reference signal, the first set of magnetic resonance images, and the second set of magnetic resonance images, a first image for each slice dealiased and a second image for each slice dealiased;

[0040] The relaxation parameter value of the detection object is acquired according to the first image after dealiasing of each slice and the second image after dealiasing of each slice.

[0041] The magnetic resonance imaging method, apparatus, computer device and storage medium described above can simultaneously acquire a first set of magnetic resonance signals of multiple slices by transmitting a first inversion recovery pulse to the detection object and executing an imaging sequence during the longitudinal magnetization relaxation interval of the first inversion recovery pulse, and can simultaneously acquire a first set of magnetic resonance signals of multiple slices by executing a reference sequence, and can simultaneously acquire a second set of magnetic resonance signals of multiple slices by transmitting a second inversion recovery pulse to the detection object and executing an imaging sequence during the longitudinal magnetization relaxation interval of the second inversion recovery pulse, thereby respectively reconstructing the first set of magnetic resonance signals and the second set of magnetic resonance signals. A magnetic resonance image sensor is used to obtain a first set of magnetic resonance images and a second set of magnetic resonance images. Then, based on the reference signal, the first set of magnetic resonance images, and the second set of magnetic resonance images, a first image of each slice and a second image of each slice can be respectively obtained. Based on the first image of each slice and the second image of each slice, a relaxation parameter value of the detection object can be obtained. Because in the process of obtaining the first image of each slice and the second image of each slice, it is no longer necessary to execute a reference sequence to obtain reference signals of multiple slices, the magnetic resonance scanning time is reduced by multiplexing the reference signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a schematic diagram of a magnetic resonance imaging apparatus according to an embodiment;

[0043] Figure 2 is a schematic flow chart of a magnetic resonance imaging method according to an embodiment;

[0044] Figure 2a A schematic diagram of relaxation parameter value fitting in one embodiment;

[0045] Figure 3 is a schematic flow chart of a magnetic resonance imaging method according to another embodiment;

[0046] Figure 3a A schematic diagram of a process for obtaining magnetic resonance coil sensitivity in one embodiment;

[0047] Figure 4 A schematic diagram of a process for respectively registering the first image with each slice being deallocated and the second image with each slice being deallocated in one embodiment;

[0048] Figure 5 A schematic diagram of a timing diagram for collecting a small-angle reference image Ref using all idle periods of a traditional timing sequence in one embodiment;

[0049] Figure 6 A schematic diagram of a timing diagram for collecting a small-angle reference image Ref using a portion of an idle period of a traditional timing sequence in one embodiment;

[0050] Figure 7 A schematic diagram of the longitudinal magnetic moment obtained by excitation with different flip angles in one embodiment;

[0051] Figure 8 A schematic diagram of a timing diagram for collecting a low-resolution, small-angle reference image Ref using all idle periods of a traditional timing sequence in one embodiment;

[0052] Figure 9 is a structural block diagram of a magnetic resonance imaging device in one embodiment;

[0053] Figure 10 FIG. 1 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0055] The magnetic resonance imaging method provided in the embodiment of the present application can be applied to Figure 1The magnetic resonance imaging device shown in the figure. The magnetic resonance imaging device includes a processor and a memory connected via a system bus, wherein a computer program is stored in the memory, and when the processor executes the computer program, the steps of the following method embodiment can be executed. Optionally, the computer device may also include a network interface, a display screen and an input device. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory, wherein the non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface of the computer device is used to communicate with an external terminal via a network connection. Optionally, the computer device may be a server, a personal computer, a personal digital assistant, or other terminal devices, such as a tablet computer, a mobile phone, etc., or a cloud or remote server. The embodiments of the present application do not limit the specific form of the computer device.

[0056] Cardiac magnetic resonance longitudinal relaxation time quantitative imaging (T1 mapping) can directly quantify the T1 value of myocardial tissue. The basic principle of the T1 mapping pulse sequence is that the longitudinal magnetization vector begins to relax and recover after the application of an inversion recovery pulse (IR). After a specific inversion time (TI), a single spin echo signal is acquired. This sequence is then repeated at a series of TIs to acquire multiple points of inversion recovery signals. Finally, the T1 value is calculated using a monoexponential function. During the data acquisition process, there are generally idle cardiac cycles for signal recovery. Traditional cardiac T1 mapping imaging sequences such as MOLLI (Modified Look-Locker Inversion Recovery) generally use two inversion recovery pulses (IR). Using a fast magnetic resonance imaging sequence over multiple cardiac cycles, imaging data at different inversion recovery times (TIs) are acquired. The data are then fitted to obtain the T1 (longitudinal relaxation time) value of the myocardial tissue.

[0057] In one embodiment, Figure 2 As shown, a magnetic resonance imaging method is provided, which is applied to Figure 1 The magnetic resonance imaging device in the embodiment is used as an example to illustrate the method, which includes the following steps:

[0058] S201 , transmitting a first inversion recovery pulse to a subject, executing an imaging sequence during a longitudinal magnetization relaxation interval of the first inversion recovery pulse to simultaneously acquire a first set of magnetic resonance signals of a plurality of slices, and executing a reference sequence to acquire reference signals of a plurality of slices.

[0059] During a cardiac magnetic resonance scan, after an inversion recovery pulse is applied to the subject, the longitudinal magnetization vector begins to relax and recover. The recovery interval is an idle cardiac cycle, during which no image data is collected. The subject includes multiple slices.

[0060] Specifically, in this embodiment, after a magnetic resonance imaging device transmits a first inversion recovery pulse to a subject comprising multiple slices, it executes an imaging sequence during the longitudinal magnetization relaxation interval of the first inversion recovery pulse to simultaneously acquire a first set of magnetic resonance signals from the multiple slices, and executes a reference sequence to acquire reference signals from the multiple slices. Optionally, the imaging sequence executed in this embodiment may be a gradient echo (GRE) sequence or a gradient echo equilibrium steady-state free precession (Gre_bssfp) sequence. Optionally, the subject in this application may be a human or a living animal, and the subject may comprise multiple slices. Optionally, the process of executing the reference sequence to acquire reference signals from the multiple slices may be to acquire reference lines required for multi-slice simultaneous imaging (SMS) using small-angle excitation to obtain reference signals from the multiple slices. It should be noted that the reference signals for the multiple slices include reference signals corresponding to each slice, and the acquired reference lines required for SMS may also serve as reference lines (or calibration data) for GeneRalized Autocalibrating Partial Parallel Acquisition (GRAPPA). Optionally, the reference signal may also be a reference signal collected by a parallel imaging method, or a reference signal used for both parallel imaging and multi-layer simultaneous imaging techniques, or a combination of both.

[0061] S202 , transmitting a second inversion recovery pulse to the subject, performing an imaging sequence during a longitudinal magnetization relaxation interval of the second inversion recovery pulse, and simultaneously acquiring a second set of magnetic resonance signals of a plurality of slices.

[0062] Specifically, after transmitting a first inversion recovery pulse to the subject, the magnetic resonance imaging device transmits a second inversion recovery pulse to the subject at intervals corresponding to a predetermined physiological motion period. An imaging sequence is performed during the longitudinal magnetization relaxation interval of the second inversion recovery pulse, thereby simultaneously acquiring a second set of magnetic resonance signals from multiple slices of the subject. Optionally, the imaging sequence performed in this embodiment may be a gradient echo (GRE) sequence or a balanced steady-state free precession (Gre_bssfp) sequence within a gradient echo.

[0063] S203 , reconstructing the first set of magnetic resonance signals and the second set of magnetic resonance signals respectively to obtain a first set of magnetic resonance images and a second set of magnetic resonance images.

[0064] Specifically, the magnetic resonance imaging device reconstructs the first group of magnetic resonance signals and the second group of magnetic resonance signals, respectively, to obtain the first group of magnetic resonance images and the second group of magnetic resonance images. Optionally, the magnetic resonance imaging device may use a compressed sensing algorithm to reconstruct the first group of magnetic resonance signals and the second group of magnetic resonance signals, respectively, to obtain the first group of magnetic resonance images and the second group of magnetic resonance images. It should be noted that the first group of magnetic resonance images and the second group of magnetic resonance images here are both multi-layer aliasing magnetic resonance images. Optionally, before reconstructing the first group of magnetic resonance signals and the second group of magnetic resonance signals, the magnetic resonance imaging device may preprocess the first group of magnetic resonance signals and the second group of magnetic resonance signals, respectively, to eliminate abnormal signals in the first group of magnetic resonance signals and the second group of magnetic resonance signals.

[0065] S204 , acquiring a first image with dealiased image of each slice and a second image with dealiased image of each slice respectively according to the reference signal, the first set of magnetic resonance images, and the second set of magnetic resonance images.

[0066] Specifically, the magnetic resonance imaging device acquires, based on the reference signal obtained above, the first set of magnetic resonance images, and the second set of magnetic resonance images, a first image with deallapping of each slice and a second image with deallapping of each slice, respectively. Optionally, the magnetic resonance imaging device may perform deallapping processing on the first set of magnetic resonance images based on the reference signal to acquire the first image with deallapping of each slice corresponding to the first set of magnetic resonance images, and perform deallapping processing on the second set of magnetic resonance images based on the reference signal to acquire the second image with deallapping of each slice corresponding to the second set of magnetic resonance images.

[0067] S205 : Acquire a relaxation parameter value of the detection object according to the first image after deallocation of each slice and the second image after deallocation of each slice.

[0068] Specifically, the magnetic resonance imaging device obtains the relaxation parameter value of the above-mentioned detection object based on the first image of each slice and the second image of each slice. Optionally, the magnetic resonance imaging device can use a fitting method to obtain the relaxation parameter value of the detection object based on the first image of each slice and the second image of each slice. Optionally, the fitting process for obtaining the relaxation parameter value of the detection object can be referred to as follows. Figure 2a The relaxation parameter value fitting diagram shown in the figure, in which each box represents a pixel point, magnetic resonance imaging can fit the relaxation parameter value of the detection object according to the pixel points represented by each box. It should be noted here that the relaxation time of the pixel points represented by each box in the figure is different. Figure 2a where S is the signal measured at time point T1 (inversion time), A and B are parameters related to inversion efficiency and proton density, and T1* is the modulated relaxation time, i.e., the time constant of exponential recovery. This T1* is then converted to a T1 value using T1=T1*(B / A-1).

[0069] In the above-mentioned magnetic resonance imaging method, the magnetic resonance imaging apparatus transmits a first inversion recovery pulse to the subject and executes an imaging sequence during the longitudinal magnetization relaxation interval of the first inversion recovery pulse to simultaneously acquire a first set of magnetic resonance signals from multiple slices. A reference sequence is also executed to simultaneously acquire reference signals from multiple slices. A second inversion recovery pulse is transmitted to the subject and an imaging sequence is executed during the longitudinal magnetization relaxation interval of the second inversion recovery pulse to simultaneously acquire a second set of magnetic resonance signals from multiple slices. The first and second sets of magnetic resonance signals are then reconstructed to acquire a first and second set of magnetic resonance images. Based on the reference signals, the first and second sets of magnetic resonance images, a first image and a second image of each slice are respectively acquired after deallapping. Based on the first and second images of each slice, relaxation parameter values ​​of the subject are acquired. Because the reference sequence does not need to be executed to acquire reference signals from multiple slices during the process of acquiring the first and second images of each slice, the magnetic resonance scanning time is reduced through the reuse of reference signals.

[0070] In the scenario described above where the first image and the second image of each slice are respectively acquired based on the reference signals of the plurality of slices, the first set of magnetic resonance images, and the second set of magnetic resonance images, in one embodiment, Figure 3 As shown, the above S204 includes:

[0071] S301 : Obtain, according to a reference signal, a magnetic resonance coil sensitivity corresponding to the reference signal.

[0072] Specifically, the magnetic resonance imaging device obtains the magnetic resonance coil sensitivity corresponding to the reference signal based on the reference signal of the multiple slices. It should be noted here that the process of using the reference signal to obtain the magnetic resonance coil sensitivity corresponding to the reference signal can be referred to. Figure 3a As shown in the schematic diagram, after obtaining the magnetic resonance coil sensitivity corresponding to the reference signal, the unacquired lines can be calculated using the magnetic resonance coil sensitivity and the acquisition line (i.e., the reference signal), thereby accelerating data acquisition. Optionally, the reference signals of the multiple slices obtained above are reference signals for multi-slice simultaneous imaging technology.

[0073] S302 : Obtain a first image with dealiasing of each slice according to the magnetic resonance coil sensitivity, the reference signal, and the first set of magnetic resonance images.

[0074] Specifically, the magnetic resonance imaging apparatus obtains a first image with dealiased images for each slice based on the obtained magnetic resonance coil sensitivity, the reference signal, and the first set of magnetic resonance images. Optionally, the magnetic resonance imaging apparatus may obtain unacquired magnetic resonance signals corresponding to the first set of magnetic resonance images based on the magnetic resonance coil sensitivity and the reference signal, and further obtain the first image with dealiased images for each slice based on the first set of magnetic resonance images and the unacquired magnetic resonance signals.

[0075] S303 : Obtain a second image with dealiasing of each slice according to the sensitivity of the magnetic resonance coil, the reference signal, and the second set of magnetic resonance images.

[0076] Specifically, the magnetic resonance imaging apparatus obtains a second image with dealiased for each slice based on the obtained magnetic resonance coil sensitivity, the reference signal, and the second set of magnetic resonance images. Optionally, the magnetic resonance imaging apparatus may obtain unacquired magnetic resonance signals corresponding to the second set of magnetic resonance images based on the magnetic resonance coil sensitivity and the reference signal, and further obtain the second image with dealiased for each slice based on the second set of magnetic resonance images and the unacquired magnetic resonance signals.

[0077] In this embodiment, the magnetic resonance imaging device can obtain the magnetic resonance coil sensitivity corresponding to the reference signal based on the obtained reference signal, and can further obtain the first image of each slice after deallocation based on the magnetic resonance coil sensitivity corresponding to the reference signal, the reference signal, and the first set of magnetic resonance images. It can also obtain the second image of each slice after deallocation based on the magnetic resonance coil sensitivity corresponding to the reference signal, the reference signal, and the second set of magnetic resonance images. Because the reference signal is acquired by executing a reference sequence in the interval between the first inversion recovery pulse and the second inversion recovery pulse, the time for additionally acquiring the reference signal is reduced, thereby reducing the time for obtaining the first image of each slice after deallocation and the second image of each slice after deallocation, and further reducing the time of the magnetic resonance scan.

[0078] In the above scenario of obtaining the relaxation parameters of the detection object based on the first image corresponding to each slice and the second image corresponding to each slice, in one embodiment, the above S205 includes: performing curve fitting on each point in the first image space coordinates and each point in the second image space coordinates to obtain the relaxation parameter value of the detection object.

[0079] Specifically, the magnetic resonance imaging device performs curve fitting on each point in the obtained first image space coordinates and each point in the obtained second image space coordinates to obtain a relaxation parameter value of the subject. That is, the magnetic resonance imaging device performs curve fitting on each pixel point in the first image and each pixel point in the second image to obtain a relaxation parameter value of the subject. Optionally, the relaxation parameter value of the subject is the longitudinal relaxation constant T1.

[0080] In this embodiment, the magnetic resonance imaging device performs curve fitting on each point in the first image space coordinate and each point in the second image space coordinate. The operation is relatively simple, and the relaxation parameter value of the detection object can be quickly obtained through fitting, thereby improving the efficiency of obtaining the relaxation parameter value of the detection object.

[0081] In the scenario where the magnetic resonance imaging device transmits a first inversion recovery pulse and a second inversion recovery pulse to the subject, in one embodiment, there is an idle cardiac cycle between the transmission of the first inversion recovery pulse and the second inversion recovery pulse, and the reference sequence is executed during the idle cardiac cycle.

[0082] Specifically, after transmitting a first inversion recovery pulse to the detection object, the magnetic resonance imaging executes a reference sequence in an idle cardiac cycle between transmitting a second inversion recovery pulse and the first inversion recovery pulse to obtain reference signals of multiple slices included in the detection object.

[0083] In this embodiment, there is an idle cardiac cycle between the first inversion recovery pulse and the second inversion recovery pulse emitted by the magnetic resonance imaging to the detection object, and the reference sequence is executed within the cardiac cycle, thereby saving the time for additional execution of the reference sequence. Since the time for executing the reference sequence is shortened, the time for performing the magnetic resonance scan is shortened.

[0084] In the above scenario of obtaining the relaxation parameter value of the detection object based on the first image of each slice and the second image of each slice, in one embodiment, before the above S205, the above method further includes: aligning the first image of each slice and the second image of each slice. Specifically, the magnetic resonance imaging device aligns the first image of each slice and the second image of each slice, and obtains the relaxation parameter value of the detection object based on the aligned first image and second image of each slice. Optionally, the magnetic resonance imaging device can select an image with the best contrast as a reference image from the first image and the second image of each slice, and then align the first image and the second image of each slice with the reference image. For example, the process of aligning the first image of each slice and the second image of each slice can be found in Figure 4 The registration process is shown.

[0085] In one embodiment, the first image and the second image of each slice after de-aliasing are registered by the following process: a T1 recovery curve is estimated based on the first and second images of each slice after de-aliasing; then, based on the TI values ​​corresponding to the first and second images of each slice after de-aliasing, multiple fitted images corresponding to the TI moments are generated. The fitted images can correspond to images of the object in a static state, and each fitted image has its own contrast, that is, images of different contrasts are obtained at the same position; then, the first and second images of each slice after de-aliasing are respectively registered with the fitted images corresponding to each TI moment, to obtain the registered first and second images of each slice after de-aliasing. Optionally, the T1 recovery curve can be selected from the image first acquired after the inversion recovery pulse is applied and the image acquired after the longitudinal magnetization vector reaches equilibrium.

[0086] In this embodiment, before acquiring the relaxation parameter value of the detection object based on the first image and the second image after de-aliasing of each slice, the magnetic resonance imaging device separately registers the first image and the second image after de-aliasing of each slice. The relaxation parameter of the detection object can be accurately acquired based on the registered first image and the registered second image after de-aliasing of each slice, thereby improving the accuracy of the acquired relaxation parameter of the detection object.

[0087] For example, the magnetic resonance imaging method provided by the present application is described in the following specific embodiment. In conventional cardiac T1mapping imaging, in order to ensure the complete recovery of the longitudinal magnetic moment Mz signal of the tissue, after continuously acquiring signals of 5 cardiac cycles, 3 cardiac cycles are idle, such as Figure 5 As shown, signal acquisition is performed in the S1 cardiac cycle and the S3 cardiac cycle, and the S2 cardiac cycle is idle. The magnetic resonance imaging method provided by the present application is Figure 5On the basis shown in the figure, in the S1 cardiac cycle and the S3 cardiac cycle, multi-layer simultaneous imaging SMS technology is used to simultaneously collect multi-layer signals. It is assumed that the detection object includes three layers, which are recorded as s1+s2+s3. In each cardiac cycle of S2, small-angle excitation is performed to collect the reference image Ref of each layer of the corresponding multi-layer signals in S1 and S3. The image corresponding to the reference signal of the first layer is recorded as ss1, the image corresponding to the reference signal of the second layer is ss2, and the image corresponding to the reference signal of the third layer is ss3. The reference lines required for GRAPPA and SMS are solved using the single-layer Ref images ss1, ss2, and ss3. Finally, GRAPPA and SMS are used to reconstruct each layer s1, s2, and s3 of the multi-layer image IMG (s1+s2+s3). Then, the fitting method for solving T1Mapping is used to solve the cardiac mapping map. During S2, small-angle excitation is performed to collect low-resolution images, that is, reference maps for multi-layer simultaneous excitation and reference lines for parallel imaging. The timing diagram of the small-angle reference map Ref collected during S2 is as follows: Figure 6 As shown in Figure 2, the small-angle excitation rapid imaging sequence used in Ref acquisition can be either a balanced steady-state free precession sequence used in traditional imaging or a gradient echo sequence. Figure 2a In addition, it should be noted that when small-angle excitation is performed, the longitudinal magnetic moment Mz has little effect and can be fully recovered in a short time, which does not affect the initial Mz during subsequent imaging. Among them, the Mz obtained by excitation at different flip angles can be as follows Figure 7 As shown: The time required for Mz1, Mz2, and Mz3 obtained by excitation at different angles to recover to Mz is different. Among them, Mz1 obtained at a small angle can recover to Mz in the shortest time, so as not to affect the Mz during subsequent imaging. Mz2 takes the second longest time, and Mz3 takes the longest time. The magnetic resonance imaging method provided by this application performs small-angle excitation during the idle cardiac cycle and collects low-resolution images, that is, a reference image of multi-layer simultaneous excitation and a reference line of parallel imaging. The obtained timing diagram is shown in FIG. Figure 8 As shown, the multi-layer simultaneous imaging SMS technology is used to simultaneously under-sample multiple layers of signals during the S1 and S3 cardiac cycles; the reference signal corresponding to each layer is collected during the S2 interval; the reference signal is first used as a reference image to achieve dealiasing between different layers during the reconstruction of the S1 and S3 cardiac cycle signals; then the reference signal is used as a reference line in K space to achieve parallel reconstruction of the dealiased image. It should be noted that the magnetic resonance imaging method provided in this application can also be used for cardiac mapping imaging methods with multiple recovery times and is not limited to the above-mentioned timing structure.

[0088] It should be understood that although Figure 2-8The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. In addition, Figure 2-8 At least part of the steps may include multiple steps or multiple stages. These steps or stages are not necessarily performed at the same time, but can be performed at different times. The order of execution of these steps or stages is not necessarily one by one, but can be performed in turn or alternately with other steps or at least part of the steps or stages in other steps.

[0089] In one embodiment, Figure 9 As shown, a magnetic resonance imaging device is provided, comprising: a first acquisition module, a second acquisition module, a reconstruction module, a third acquisition module and a fourth acquisition module, wherein:

[0090] The first acquisition module is used to transmit a first inversion recovery pulse to the detection object, execute an imaging sequence during the longitudinal magnetization relaxation interval of the first inversion recovery pulse, simultaneously acquire a first group of magnetic resonance signals of multiple slices, and execute a reference sequence to acquire reference signals of multiple slices.

[0091] The second acquisition module is used to transmit a second inversion recovery pulse to the detection object, perform an imaging sequence during the longitudinal magnetization relaxation interval of the second inversion recovery pulse, and simultaneously acquire a second group of magnetic resonance signals of multiple slices.

[0092] The reconstruction module is used to reconstruct the first group of magnetic resonance signals and the second group of magnetic resonance signals respectively to obtain the first group of magnetic resonance images and the second group of magnetic resonance images.

[0093] The third acquisition module is configured to respectively acquire a first image and a second image of each slice dealiased according to the reference signal, the first set of magnetic resonance images, and the second set of magnetic resonance images.

[0094] The fourth acquisition module acquires the relaxation parameter value of the detection object according to the first image after deallocation of each slice and the second image after deallocation of each slice.

[0095] Optionally, there is an idle cardiac cycle between transmitting the first inversion recovery pulse and transmitting the second inversion recovery pulse, and the reference sequence is executed in the idle cardiac cycle.

[0096] Optionally, the reference signal is at least one of a reference signal for a multi-layer simultaneous imaging technology, a reference signal for parallel imaging, and a reference signal used for both parallel imaging and multi-layer simultaneous imaging technologies.

[0097] Optionally, the relaxation parameter value of the detection object is the longitudinal relaxation constant T1.

[0098] The magnetic resonance imaging device provided in this embodiment can execute the above method embodiment, and its implementation principle and technical effects are similar, which will not be repeated here.

[0099] Based on the above embodiment, optionally, the third acquisition module includes: a first acquisition unit, a second acquisition unit, and a third acquisition unit, wherein:

[0100] The first acquiring unit is configured to obtain, based on the reference signal, the magnetic resonance coil sensitivity corresponding to the reference signal.

[0101] The second acquisition unit is configured to obtain a first image with dealiasing of each slice according to the sensitivity of the magnetic resonance coil, the reference signal and the first set of magnetic resonance images.

[0102] The third acquisition unit is configured to obtain a second image with dealiasing of each slice according to the sensitivity of the magnetic resonance coil, the reference signal and the second set of magnetic resonance images.

[0103] The magnetic resonance imaging device provided in this embodiment can execute the above method embodiment, and its implementation principle and technical effects are similar, which will not be repeated here.

[0104] Based on the above embodiment, optionally, the fourth acquisition module includes: a fourth acquisition unit, wherein:

[0105] The fourth acquisition unit is used to perform curve fitting on each point in the first image space coordinate and each point in the second image space coordinate to obtain the relaxation parameter value of the detection object.

[0106] The magnetic resonance imaging device provided in this embodiment can execute the above method embodiment, and its implementation principle and technical effects are similar, which will not be repeated here.

[0107] The magnetic resonance imaging device provided in this embodiment can execute the above method embodiment, and its implementation principle and technical effects are similar, which will not be repeated here.

[0108] Based on the above embodiment, optionally, the above apparatus further includes: a registration module, wherein:

[0109] The registration module is used to respectively register the first image after deallocation of each slice and the second image after deallocation of each slice.

[0110] The magnetic resonance imaging device provided in this embodiment can execute the above method embodiment, and its implementation principle and technical effects are similar, which will not be repeated here.

[0111] The specific definition of the magnetic resonance imaging apparatus can be found in the definition of the magnetic resonance imaging method above and will not be repeated here. Each module in the magnetic resonance imaging apparatus described above may be implemented in whole or in part through software, hardware, or a combination thereof. Each of the modules described above may be embedded in or independent of a processor in a computer device in hardware form, or may be stored in a computer device memory in software form, so that the processor can call and execute the corresponding operations of each module.

[0112] In one embodiment, a computer device is provided. The computer device may be a terminal, and its internal structure diagram may be as follows: Figure 10 As shown. The computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a magnetic resonance imaging method is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covering the display screen, or a button, trackball or touchpad provided on the computer device housing, or an external keyboard, touchpad or mouse.

[0113] Those skilled in the art will understand that Figure 10 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0114] In one embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and when the processor executes the computer program, the following steps are implemented:

[0115] transmitting a first inversion recovery pulse to the subject, executing an imaging sequence during a longitudinal magnetization relaxation interval of the first inversion recovery pulse to simultaneously acquire a first set of magnetic resonance signals of a plurality of slices, and executing a reference sequence to acquire reference signals of the plurality of slices;

[0116] transmitting a second inversion recovery pulse to the subject, performing an imaging sequence during a longitudinal magnetization relaxation interval of the second inversion recovery pulse, and simultaneously acquiring a second set of magnetic resonance signals of the plurality of slices;

[0117] Reconstructing the first set of magnetic resonance signals and the second set of magnetic resonance signals respectively to obtain the first set of magnetic resonance images and the second set of magnetic resonance images;

[0118] acquiring, according to the reference signal, the first set of magnetic resonance images and the second set of magnetic resonance images, a first image for each slice being deallocated and a second image for each slice being deallocated;

[0119] The relaxation parameter value of the detection object is obtained according to the first image after dealiasing of each slice and the second image after dealiasing of each slice.

[0120] The implementation principle and technical effects of the computer device provided in the above embodiment are similar to those of the above method embodiment and will not be repeated here.

[0121] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0122] transmitting a first inversion recovery pulse to the subject, executing an imaging sequence during a longitudinal magnetization relaxation interval of the first inversion recovery pulse to simultaneously acquire a first set of magnetic resonance signals of a plurality of slices, and executing a reference sequence to acquire reference signals of the plurality of slices;

[0123] transmitting a second inversion recovery pulse to the subject, performing an imaging sequence during a longitudinal magnetization relaxation interval of the second inversion recovery pulse, and simultaneously acquiring a second set of magnetic resonance signals of the plurality of slices;

[0124] Reconstructing the first set of magnetic resonance signals and the second set of magnetic resonance signals respectively to obtain the first set of magnetic resonance images and the second set of magnetic resonance images;

[0125] acquiring, according to the reference signal, the first set of magnetic resonance images and the second set of magnetic resonance images, a first image for each slice being deallocated and a second image for each slice being deallocated;

[0126] The relaxation parameter value of the detection object is obtained according to the first image after dealiasing of each slice and the second image after dealiasing of each slice.

[0127] The computer-readable storage medium provided in the above embodiment has similar implementation principles and technical effects to those of the above method embodiment, and will not be described in detail here.

[0128] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0129] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0130] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A magnetic resonance imaging method, characterized in that: The method comprises: A first inversion recovery pulse is emitted to the subject, an imaging sequence is executed during the longitudinal magnetization relaxation interval of the first inversion recovery pulse to simultaneously acquire a first set of magnetic resonance signals of a plurality of slices, and a reference sequence is executed to acquire reference signals of the plurality of slices; the reference signals are acquired when the reference sequence is executed during an idle cardiac cycle between the first inversion recovery pulse and the second inversion recovery pulse; the idle cardiac cycle includes a first cardiac cycle, a second cardiac cycle, and a third cardiac cycle, multi-slice signals are acquired simultaneously during the first cardiac cycle and the third cardiac cycle, and reference signals corresponding to each slice are acquired separately during the second cardiac cycle; transmitting the second inversion recovery pulse to the detection object, performing an imaging sequence during a longitudinal magnetization relaxation interval of the second inversion recovery pulse, and simultaneously acquiring a second set of magnetic resonance signals of the plurality of slices; Reconstructing the first set of magnetic resonance signals and the second set of magnetic resonance signals respectively to obtain a first set of magnetic resonance images and a second set of magnetic resonance images; performing a dealiasing process on the first set of magnetic resonance images according to the reference signal to obtain dealiasing first images corresponding to the first set of magnetic resonance images, and performing a dealiasing process on the second set of magnetic resonance images according to the reference signal to obtain dealiasing second images corresponding to the second set of magnetic resonance images; The relaxation parameter value of the detection object is acquired according to the first image after dealiasing of each slice and the second image after dealiasing of each slice.

2. The method according to claim 1, characterized in that The step of performing a dealisim processing on the first set of magnetic resonance images according to the reference signal to obtain dealisimulated first images corresponding to the first set of magnetic resonance images, and performing a dealisim processing on the second set of magnetic resonance images according to the reference signal to obtain dealisimulated second images corresponding to the second set of magnetic resonance images, comprises: obtaining, according to the reference signal, a magnetic resonance coil sensitivity corresponding to the reference signal; Obtaining a first image with dealiasing of each slice according to the magnetic resonance coil sensitivity, the reference signal and the first set of magnetic resonance images; A second image with dealiasing of each slice is obtained according to the magnetic resonance coil sensitivity, the reference signal and the second set of magnetic resonance images.

3. The method according to claim 2, characterized in that The obtaining of the relaxation parameter value of the detection object according to the first image corresponding to each slice and the second image corresponding to each slice includes: Curve fitting is performed on each point in the first image space coordinates and each point in the second image space coordinates to obtain a relaxation parameter value of the detection object.

4. The method according to claim 1, wherein There is an idle cardiac cycle between transmitting the first inversion recovery pulse and transmitting the second inversion recovery pulse, and the reference sequence is performed during the idle cardiac cycle.

5. The method according to claim 1, wherein The reference signal is at least one of a reference signal for a multi-layer simultaneous imaging technology, a reference signal for parallel imaging, and a reference signal used for both parallel imaging and multi-layer simultaneous imaging technologies.

6. The method according to claim 1, characterized in that The relaxation parameter value of the detection object is the longitudinal relaxation constant.

7. The method according to claim 1, characterized in that Before acquiring the relaxation parameter value of the detection object based on the first image and the second image of each slice de-aliasing, the method further includes: The first image after deallocation of each slice and the second image after deallocation of each slice are registered respectively.

8. A magnetic resonance imaging apparatus, characterized in that: The device comprises: a first acquisition module, configured to transmit a first inversion recovery pulse to the subject, execute an imaging sequence during a longitudinal magnetization relaxation interval of the first inversion recovery pulse, simultaneously acquire a first set of magnetic resonance signals of a plurality of slices, and execute a reference sequence to acquire reference signals of the plurality of slices; the reference signals are acquired when executing the reference sequence during an idle cardiac cycle between the first inversion recovery pulse and a second inversion recovery pulse; the idle cardiac cycle includes a first cardiac cycle, a second cardiac cycle, and a third cardiac cycle, and multiple layers of signals are simultaneously acquired during the first and third cardiac cycles, and reference signals corresponding to each layer are acquired separately during the second cardiac cycle; a second acquisition module, configured to transmit the second inversion recovery pulse to the detection object, execute an imaging sequence during a longitudinal magnetization relaxation interval of the second inversion recovery pulse, and simultaneously acquire a second set of magnetic resonance signals of the plurality of slices; a reconstruction module, configured to reconstruct the first set of magnetic resonance signals and the second set of magnetic resonance signals, respectively, to obtain a first set of magnetic resonance images and a second set of magnetic resonance images; a third acquisition module, configured to perform a dealiasing process on the first set of magnetic resonance images according to the reference signal to obtain dealiasing first images of each slice corresponding to the first set of magnetic resonance images, and to perform a dealiasing process on the second set of magnetic resonance images according to the reference signal to obtain dealiasing second images of each slice corresponding to the second set of magnetic resonance images; The fourth acquisition module acquires the relaxation parameter value of the detection object according to the first image of each slice deallocation and the second image of each slice deallocation.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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