WO2023108314A1

WO2023108314A1 - Main magnetic field three-dimensional non-uniformity correction method, apparatus and device, and storage medium thereof

Info

Publication number: WO2023108314A1
Application number: PCT/CN2021/137343
Authority: WO
Inventors: 吴垠; 郑海荣; 刘新
Original assignee: 中国科学院深圳先进技术研究院
Priority date: 2021-12-13
Filing date: 2021-12-13
Publication date: 2023-06-22

Abstract

Disclosed in the present application are a main magnetic field three-dimensional non-uniformity correction method, apparatus and device, and a storage medium thereof. The method comprises: acquiring a three-dimensional high-resolution main magnetic field non-uniformity imaging map; and correcting non-uniformity of a main magnetic field in a CEST voxel. The solution provided by the present application removes an effect of non-uniformity of a main magnetic field in a voxel by utilizing a high-resolution main magnetic field offset graph, and improves the accuracy of CEST quantification.

Description

Method, device, equipment and storage medium for correcting three-dimensional inhomogeneity of main magnetic field

technical field

The invention relates to biomedical engineering, in particular to a method, device, equipment and storage medium for correcting the three-dimensional inhomogeneity of a main magnetic field.

Background technique

Magnetic resonance chemical exchange saturation transfer (CEST) imaging is a magnetic resonance molecular imaging method that can detect the micro-environmental characteristics of biological tissues. It can measure endogenous metabolites, compounds, and exogenous paramagnetic/diamagnetic CEST contrast agents. Provide new methods for imaging a variety of diseases. The basic principle of CEST imaging is to use radio frequency pulses to implement saturation labeling at the resonance frequency point of the target exchange group, causing its signal to decrease. Since there is a chemical exchange process between the exchange group and water molecules, the change of the exchange group signal will be Transferred to water molecules, resulting in a decrease in the water molecule signal. The chemical exchange characteristics of the target exchange group can be obtained through the change of the water molecule signal.

Since CEST imaging involves signal acquisition at specific frequency points, it has higher requirements for the uniformity of the main magnetic field. The existing main magnetic field correction mainly uses the water saturation shift referencing (WASSR) technique. This technology uses the symmetry of the CEST signal on both sides of the resonance frequency of water molecules to correct the overall inhomogeneity of the main magnetic field at each voxel point of CEST. Since the signal of the target exchange group detected by CEST technology is weak, the detection sensitivity is usually improved by reducing the image resolution. Therefore, the main magnetic field inhomogeneity within each pixel will affect the CEST quantification accuracy.

Contents of the invention

In view of the above defects or deficiencies in the prior art, it is desired to provide a method, device, equipment and storage medium for correcting the three-dimensional inhomogeneity of the main magnetic field.

In the first aspect, the embodiment of the present application provides a method for correcting the three-dimensional inhomogeneity of the main magnetic field, the method comprising:

Obtain three-dimensional high-resolution main magnetic field inhomogeneity imaging map;

Correction for the inhomogeneity of the main magnetic field within the CEST voxel.

In one of the embodiments, the acquiring a three-dimensional high-resolution main magnetic field inhomogeneity imaging map includes: acquiring a three-dimensional high-resolution main magnetic field map ΔB ₀ by using a double-echo gradient echo technique, wherein,

In the formula, γ is the gyromagnetic ratio, ΔΦ is the phase without winding, and ΔTE is the time difference between two echoes.

In one embodiment, the ΔB ₀ imaging field of view is consistent with the CEST image, and the resolution of the ΔB ₀ is more than twice that of the CEST image.

In one of the embodiments, the correction of the inhomogeneity of the main magnetic field in the CEST voxel includes: setting the Z spectrum broadening or offset of the CEST signal in each voxel as Z _meas , without the influence of the inhomogeneity of the main magnetic field The Z spectrum is marked as Z _orig , where Z _meas =Z _orig *ΔB ₀ ; the Z _orig without the influence of the main magnetic field inhomogeneity is solved by deconvolution.

In the second aspect, the embodiment of the present application also provides a three-dimensional inhomogeneity correction device for the main magnetic field, which includes:

An acquisition unit, configured to acquire a three-dimensional high-resolution main magnetic field inhomogeneity imaging map;

The correction unit is used for correcting the inhomogeneity of the main magnetic field in the CEST voxel.

In the third aspect, the embodiment of the present application also provides a computer device, including a memory, a processor, and a computer program stored in the memory and operable on the processor. When the processor executes the program, it implements the The method described in any one of the descriptions of the examples.

In a fourth aspect, the embodiment of the present application also provides a computer device, a computer-readable storage medium, on which a computer program is stored, and the computer program is used for: when the computer program is executed by a processor, the computer program according to the present application is implemented. The method described in any one of the descriptions of the examples.

Beneficial effects of the present invention:

The method for correcting the three-dimensional inhomogeneity of the main magnetic field provided by the present invention uses a high-resolution main magnetic field offset map to remove the influence of the inhomogeneity of the main magnetic field in a voxel and improve the accuracy of CEST quantification.

Description of drawings

Other characteristics, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

Fig. 1 shows a schematic flow chart of the method for correcting the three-dimensional inhomogeneity of the main magnetic field provided by the embodiment of the present application;

FIG. 2 shows an exemplary structural block diagram of a main magnetic field three-dimensional non-uniformity correction device 200 according to an embodiment of the present application;

Fig. 3 shows a schematic structural diagram of a computer system suitable for implementing a terminal device according to an embodiment of the present application;

Fig. 4 shows the high-resolution main magnetic field diagram ΔB ₀ based on the double-echo gradient echo provided by the embodiment of the present application;

FIG. 5 shows a schematic diagram of the correction results provided by the embodiment of the present application.

Detailed ways

In order to make the above objects, features and advantages of the present invention more comprehensible, specific implementations of the present invention will be described in detail below in conjunction with the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described here, and those skilled in the art can make similar improvements without departing from the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " Back", "Left", "Right", "Vertical", "Horizontal", "Top", "Bottom", "Inner", "Outer", "Clockwise", "Counterclockwise", "Axial" , "radial", "circumferential" and other indicated orientations or positional relationships are based on the orientations or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying the referred device or Elements must have certain orientations, be constructed and operate in certain orientations, and therefore should not be construed as limitations on the invention.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

In the present invention, terms such as "installation", "connection", "connection" and "fixation" should be interpreted in a broad sense, for example, it can be a fixed connection or a detachable connection, unless otherwise clearly specified and limited. , or integrated; it may be mechanically connected or electrically connected; it may be directly connected or indirectly connected through an intermediary, and it may be the internal communication of two components or the interaction relationship between two components, unless otherwise specified limit. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

In the present invention, unless otherwise clearly specified and limited, the first feature may be in direct contact with the first feature or the first and second feature may be in direct contact with the second feature through an intermediary. touch. Moreover, "above", "above" and "above" the first feature on the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. "Below", "beneath" and "beneath" the first feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is less horizontally than the second feature.

It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or intervening elements may also be present. As used herein, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions are for the purpose of illustration only and are not intended to represent the only embodiments.

Please refer to FIG. 1 , which shows a schematic flowchart of a method for correcting three-dimensional inhomogeneity of a main magnetic field provided by an embodiment of the present application.

As shown in Figure 1, the method includes:

Step 110, obtaining a three-dimensional high-resolution main magnetic field inhomogeneity imaging map;

Step 120, correcting the inhomogeneity of the main magnetic field in the CEST voxel.

Using the above-mentioned technical scheme, the high-resolution main magnetic field offset map is used to remove the influence of the inhomogeneity of the main magnetic field in the voxel, and improve the accuracy of CEST quantification.

In some embodiments, the obtaining a three-dimensional high-resolution main magnetic field inhomogeneity imaging map includes: obtaining a three-dimensional high-resolution main magnetic field map ΔB ₀ by using a double-echo gradient echo technique, wherein,

In some embodiments, the ΔB ₀ imaging field of view is consistent with the CEST image, and the resolution of the ΔB ₀ is more than twice that of the CEST image.

In some embodiments, the correction of the inhomogeneity of the main magnetic field in the CEST voxel includes: setting the Z spectrum broadening or offset of the CEST signal in each voxel as Z meas , the Z _meas without the influence of the inhomogeneity of the main magnetic field The spectrum is marked as Z _orig , where Z _meas =Z _orig *ΔB ₀ ; Z _orig without the influence of main magnetic field inhomogeneity is solved by deconvolution.

Figure 4 shows the high-resolution main magnetic field map ΔB ₀ obtained by the double-echo gradient echo technique, and its resolution is 32 times that of the CEST image (that is, there are 32 ΔB ₀ voxels in one voxel of the CEST image). It can be seen from Figure 4 that the inhomogeneity of the main magnetic field in the voxel is very obvious. Compared with the results of the conventional WASSR correction technique (Figure 5a), the method proposed by the present invention can effectively solve the influence of the inhomogeneity of the main magnetic field in the voxel (Figure 5b), such as the CEST signal caused by the inhomogeneity of the main magnetic field in the frontal lobe The underestimation is significantly improved (arrow), confirming the effectiveness of the proposed method.

Further, referring to FIG. 2 , FIG. 2 shows an exemplary structural block diagram of an apparatus 200 for correcting three-dimensional inhomogeneity of the main magnetic field according to an embodiment of the present application.

As shown in Figure 2, the device includes:

An acquisition unit 210, configured to acquire a three-dimensional high-resolution main magnetic field inhomogeneity imaging map;

The correction unit 220 is configured to correct the inhomogeneity of the main magnetic field in the CEST voxel.

It should be understood that the units or modules recorded in the device 200 correspond to the steps in the method described with reference to FIG. 1 . Therefore, the operations and features described above for the method are also applicable to the device 200 and the units contained therein, and will not be repeated here. Apparatus 200 may be pre-implemented in the browser of the electronic device or other security applications, and may also be loaded into the browser of the electronic device or its security applications by downloading or other means. The corresponding units in the apparatus 200 may cooperate with the units in the electronic device to implement the solutions of the embodiments of the present application.

Referring now to FIG. 3 , it shows a schematic structural diagram of a computer system 300 suitable for implementing a terminal device or a server according to an embodiment of the present application.

As shown in FIG. 3 , a computer system 300 includes a central processing unit (CPU) 301 that can operate according to a program stored in a read-only memory (ROM) 302 or a program loaded from a storage section 308 into a random-access memory (RAM) 303 Instead, various appropriate actions and processes are performed. In the RAM 303, various programs and data required for the operation of the system 300 are also stored. The CPU 301, ROM 302, and RAM 303 are connected to each other through a bus 304. An input/output (I/O) interface 305 is also connected to the bus 304 .

The following components are connected to the I/O interface 305: an input section 306 including a keyboard, a mouse, etc.; an output section 307 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker; a storage section 308 including a hard disk, etc. and a communication section 309 including a network interface card such as a LAN card, a modem, or the like. The communication section 309 performs communication processing via a network such as the Internet. A drive 310 is also connected to the I/O interface 305 as needed. A removable medium 311, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is mounted on the drive 310 as necessary so that a computer program read therefrom is installed into the storage section 308 as necessary.

In particular, according to an embodiment of the present disclosure, the process described above with reference to FIG. 1 may be implemented as a computer software program. For example, embodiments of the present disclosure include a method for correcting three-dimensional inhomogeneity of a main magnetic field, which includes a computer program tangibly embodied on a machine-readable medium, the computer program including program code for executing the method of FIG. 1 . In such an embodiment, the computer program may be downloaded and installed from a network via communication portion 309 and/or installed from removable media 311 .

The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, program segment, or part of code that includes one or more logical functions for implementing specified executable instructions. It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or they may sometimes be executed in the reverse order, depending upon the functionality involved. It should also be noted that each block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by a dedicated hardware-based system that performs the specified functions or operations , or may be implemented by a combination of dedicated hardware and computer instructions.

The units or modules involved in the embodiments described in the present application may be implemented by means of software or by means of hardware. The described units or modules may also be set in a processor. For example, it may be described as: a processor includes a first sub-region generating unit, a second sub-region generating unit, and a display region generating unit. Wherein, the names of these units or modules do not constitute limitations on the units or modules themselves in some cases, for example, the display area generation unit can also be described as "used to generate The cell of the display area of the text".

As another aspect, the present application also provides a computer-readable storage medium, which may be the computer-readable storage medium contained in the aforementioned devices in the above-mentioned embodiments; computer-readable storage media stored in the device. The computer-readable storage medium stores one or more programs, and the aforementioned programs are used by one or more processors to execute the text generation method applied to transparent window envelopes described in this application.

The above description is only a preferred embodiment of the present application and an illustration of the applied technical principle. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solution formed by the specific combination of the above-mentioned technical features, and should also cover the technical solutions formed by the above-mentioned technical features or without departing from the aforementioned inventive concept. Other technical solutions formed by any combination of equivalent features. For example, a technical solution formed by replacing the above-mentioned features with technical features with similar functions disclosed in (but not limited to) this application.

Claims

A method for correcting three-dimensional inhomogeneity of a main magnetic field, characterized in that the method comprises:

Obtain three-dimensional high-resolution main magnetic field inhomogeneity imaging map;

Correction for the inhomogeneity of the main magnetic field within the CEST voxel.
The method for correcting the three-dimensional inhomogeneity of the main magnetic field according to claim 1, wherein said obtaining a three-dimensional high-resolution main magnetic field inhomogeneity imaging image comprises:

Through the dual-echo gradient echo technique, the three-dimensional high-resolution main magnetic field map ΔB 0 is obtained, where,
In the formula, γ is the gyromagnetic ratio, ΔΦ is the phase without winding, and ΔTE is the time difference between two echoes.
The method for correcting the three-dimensional inhomogeneity of the main magnetic field according to claim 2, wherein the ΔB 0 imaging field of view is consistent with the CEST image, and the resolution of the ΔB 0 is more than twice that of the CEST image.
The method for correcting the three-dimensional inhomogeneity of the main magnetic field according to claim 2, wherein the correction of the inhomogeneity of the main magnetic field in the CEST voxel comprises:

Let Z meas be the broadening or offset of the Z spectrum composed of the CEST signal in each voxel, and the Z spectrum without the influence of the inhomogeneity of the main magnetic field is marked as Z orig , where Z meas =Z orig *ΔB 0 ;

Solve Z orig for the effect of non-dominant magnetic field inhomogeneity by deconvolution.
A device for correcting three-dimensional inhomogeneity of a main magnetic field, characterized in that the device comprises:

An acquisition unit, configured to acquire a three-dimensional high-resolution main magnetic field inhomogeneity imaging map;

The correction unit is used for correcting the inhomogeneity of the main magnetic field in the CEST voxel.
The device for correcting the three-dimensional inhomogeneity of the main magnetic field according to claim 5, wherein said obtaining a three-dimensional high-resolution main magnetic field inhomogeneity imaging image comprises:

Through the dual-echo gradient echo technique, the three-dimensional high-resolution main magnetic field map ΔB 0 is obtained, where,
In the formula, γ is the gyromagnetic ratio, ΔΦ is the phase without winding, and ΔTE is the time difference between two echoes.
The device for correcting three-dimensional inhomogeneity of the main magnetic field according to claim 6, wherein the ΔB 0 imaging field of view is consistent with the CEST image, and the resolution of the ΔB 0 is more than twice that of the CEST image.
The device for correcting the three-dimensional inhomogeneity of the main magnetic field according to claim 6, wherein the correction of the inhomogeneity of the main magnetic field in the CEST voxel comprises:

Let Z meas be the broadening or offset of the Z spectrum composed of the CEST signal in each voxel, and the Z spectrum without the influence of the inhomogeneity of the main magnetic field is marked as Z orig , where Z meas =Z orig *ΔB 0 ;

Solve Z orig for the effect of non-dominant magnetic field inhomogeneity by deconvolution.
A computer device, comprising a memory, a processor, and a computer program stored on the memory and operable on the processor, characterized in that, when the processor executes the program, it implements any of claims 1-4 described method.
A computer-readable storage medium having stored thereon a computer program for:

When the computer program is executed by the processor, the method according to any one of claims 1-4 is implemented.