CN103271740A - Nuclear magnetic resonance imaging method and system - Google Patents

Abstract

The invention relates to a nuclear magnetic resonance imaging method and system. The nuclear magnetic resonance imaging method includes detecting whether the predetermined scanning conditions are met through the navigation module; when the scanning conditions are met, scanning the area to be imaged and collecting data through the scanning module; sending a breathing reminder message, and continuing to detect whether the predetermined scanning conditions are met through the navigation module. Scanning conditions; imaging based on this data. The MRI method and system of the present invention can enable the patient to perform detection according to the breathing prompt information in cooperation with the present invention, and the breathing prompt information can remind the patient to perform breathing exercise according to the preset rules, so that the scanning and imaging can effectively avoid errors caused by breathing movement , so that the imaging precision of this method is higher.

Description

Magnetic resonance imaging method and system

technical field

The invention relates to a medical imaging method, in particular to a nuclear magnetic resonance imaging method.

In addition, the present invention also relates to a medical imaging system, especially a nuclear magnetic resonance imaging system.

Background technique

With the development of medical technology, magnetic resonance imaging (Magnetic Resonance Imaging, MRI) equipment has increasingly become an important equipment for detecting serious and critical diseases. Medical images of the internal organs of the body obtained through MRI can provide vital information for doctors to determine a patient's condition.

Generally, MRI has two important functional imaging methods: one is Diffusion Weighted Imaging (DWI), and the other is Dynamic Contrast-enhanced magnetic resonance imaging (DCE). The accuracy of medical images obtained by these two imaging methods has become an important indicator for evaluating MRI.

Taking the DWI or DCE of the human liver as an example, the main reason affecting the accuracy of DWI and DCE of the liver comes from human breathing. When a person breathes, the liver moves with the breathing. The displacement of the liver during the imaging process will cause serious artifacts, which will cause large errors in the imaging results.

Taking liver DWI acquisition technology as an example, in the prior art, liver DWI acquisition technology includes free-breath technology (free-breath), single-breath-hold technology (Single-shot), respiratory-gated technology (respiratory-gated) and respiratory navigation technology (navigator) and so on.

Free-breathing DWI clearly has significant motion information. Although single-breath-hold DWI can minimize the impact of motion, it has disadvantages such as low image signal-to-noise ratio and thick scan slices, and many patients often have small breathing movements in the late stage of breath-hold, so there are also some motion artifacts Influence.

Respiratory-gated DWI and respiratory-navigated DWI can reduce motion artifacts to a certain extent by acquiring images when the diaphragm’s motion range is minimal, but within the acquisition time window of these two methods, the liver and diaphragm still move, and the motion artifacts remain the same. severe. Moreover, DWI data acquisition is mostly multiple acquisitions (multiple NEXs, number of excitations), and there must be incomplete movement between the NEXs in the volume, while the MRI scanner uses multiple NEXs when reconstructing images. The data are averaged and reconstructed, so the DWI image contains information about motion artifacts.

Take hepatic DCE again as an example. In the prior art, the acquisition time of liver DCE usually lasts several minutes, and breath-hold scanning cannot be realized. Since the time resolution of DCE is required to be within 10 seconds (usually 5 to 8 seconds), the respiratory gating and respiratory navigation technologies in the prior art not only have motion artifacts, but also have the problem that the acquisition window is too narrow. For the calm breathing method mentioned in the prior art, an oblique coronal or sagittal scan is performed (in order to include the diaphragm, it is used for image registration of DCE data processing). Therefore, the liver is constantly in motion during image acquisition.

To sum up, both DWI and DCE acquisition technologies in the prior art have motion artifacts, which lead to image blurring in image morphology. When processing DWI and DCE data, the parameter values of the Region of Interests (ROI) will seriously deviate from the true value (relative to the static state), and the more serious cases cannot calculate the relevant parameters.

In addition, some artifact removal methods in the prior art are also difficult to meet actual needs.

There are mainly two methods for motion artifact correction in the prior art, one is a retrospective image registration method, and the other is a prospective motion correction method.

For the retrospective image registration method, special image registration software (such as 3D-slicer) is used to register the images according to certain anatomical landmarks (such as blood vessels) according to the principle of rigidity or non-rigidity, and correct each acquisition volume. A method to reduce the impact of motion artifacts on the results. However, the current commonly used clinical method is to register the reconstructed DWI and DCE images (that is, the images presented by the MRI scanner). As mentioned earlier, the images used to calculate DWI and DCE parameters themselves contain motion artifact information, and the traditional image registration method can only correct inter-volume variation between different acquisition volumes, but not Position error within the acquisition volume (intra-volume variation).

For the prospective motion correction method, the motion is corrected when the data is collected. During data acquisition by conventional acquisition methods, the spatial position of the excitation pulse remains unchanged. If there is movement (continuous movement, such as free breathing, breath gating, and breath navigation; or non-navigation multiple breath-hold methods), at different times, the center of the target layer The position does not coincide with the center position of the radio frequency excitation, so the radio frequency excitation received by the target layer is not completely consistent, and the resulting echo signal strength is also different. However, the parameters of DWI and DCE are derived and calculated based on the signal, which eventually leads to errors in various parameter values calculated based on the signal. Through the above-mentioned image registration, such errors caused by signal inconsistency cannot be avoided even if they are completely matched, so the accuracy of the corresponding image biomarkers will inevitably be affected.

It can be seen from the above that even if the motion artifact correction method mentioned in the prior art is adopted, the accuracy of the corrected DCE and DWI images obtained still has a large error, which is not conducive to the accurate presentation of the image and has a large disadvantages.

Therefore, the image obtained by the nuclear magnetic resonance imaging method in the prior art has a technical problem of large error, and the image obtained by the nuclear magnetic resonance imaging system in the prior art also has the technical problem of large error.

Contents of the invention

In view of the technical problem of relatively large errors in images obtained by nuclear magnetic resonance imaging methods in the prior art, it is necessary to provide a nuclear magnetic resonance imaging method with relatively small errors in obtained images.

At the same time, in view of the technical problem of large errors in the images obtained by the nuclear magnetic resonance imaging system in the prior art, it is also necessary to provide a nuclear magnetic resonance imaging system with a small error in the obtained images.

Concrete technical scheme of the present invention is as follows:

The invention provides a nuclear magnetic resonance imaging method. The nuclear magnetic resonance imaging method includes the steps of: using the navigation module to detect whether the predetermined scanning condition is met; scanning conditions; imaging is performed based on this data.

In a further optimized specific implementation, the step of continuing to detect whether the predetermined scanning condition is met through the navigation module includes: transmitting a detection signal to the navigation bar to obtain the physical position of the navigation bar; calculating the navigation bar acquired twice adjacently displacement.

In a further optimized specific implementation, the nuclear magnetic resonance imaging method further includes the step of: acquiring the physical position of the navigation bar every 50 milliseconds; when the displacement of the navigation bar is less than 1 mm for three consecutive times, the scanning module The imaging area is scanned and data is collected.

In a further optimized specific embodiment, the step of sending out a reminder message includes the steps: the reminder message includes the first reminder message and the second reminder message; when the scanning module scans the area to be imaged and collects data for more than or equal to 6 seconds, sends out The first reminder message; the second reminder message is issued after 1.5 seconds or more after the first reminder message is sent; the first reminder message and the second reminder message are displayed by a display device, and the first reminder message is used to remind To take a breath, the second reminder message is used to remind you to hold your breath.

In a further optimized specific embodiment, the nuclear magnetic resonance imaging method also includes: performing the following steps cyclically: the navigation module detects whether the predetermined scanning conditions are met; when the scanning conditions are met, the scanning module scans the area to be imaged and collects data ; send a reminder message; perform imaging according to the data; or execute the steps in a loop: check whether the predetermined scanning condition is met through the navigation module; when the scanning condition is met, scan the area to be imaged and collect data through the scanning module;

The invention also provides a nuclear magnetic resonance imaging system. The nuclear magnetic resonance imaging system includes: a navigation module, which is used to detect whether the predetermined scanning conditions are met; a scanning module, which is used to scan the area to be imaged and collect data when the scanning conditions are met; a reminder module, which is used to issue breathing reminder information; imaging module for imaging based on the data.

In a further optimized specific embodiment, the navigation module includes: a signal transmitting unit, used for transmitting a detection signal to the navigation bar; a position acquisition unit, used for acquiring the physical position of the navigation bar; a displacement calculation unit, used for calculating the relative The displacement of the navigation bar acquired twice.

In a further optimized specific implementation, the position acquisition unit is also used to acquire the physical position of the navigation bar every 50 milliseconds; the navigation module also includes a condition judgment unit, and the condition judgment unit is used for When the displacement is less than 1 mm for three consecutive times, the scanning module is notified to scan the imaging area of the belt and collect data.

In a further optimized specific embodiment, the reminder module includes a first reminder information unit and a second reminder information unit; the first reminder information unit is used to scan the area to be imaged in the scanning module and collect data for greater than or equal to 6 seconds The first reminder message is issued at any time; the second information reminder unit is used to send the second reminder message after 1.5 seconds or more after the first reminder message is sent; the reminder module is also used to combine the first reminder message with the The second reminder information is displayed by the display device, the first reminder information is used to remind ventilation, and the second reminder information is used to remind breath-holding.

In a further optimized specific embodiment, the nuclear magnetic resonance imaging system also includes: a cyclic execution module for cyclically starting the navigation module, scanning module, reminder module and imaging module; or, the cyclic execution module is used for cyclically starting the Navigation module, scanning module and reminder module.

Compared with the prior art, the main beneficial effects of the present invention are:

Because the nuclear magnetic resonance imaging method of the present invention includes the steps of: detecting whether the predetermined scanning condition is met through the navigation module; when the scanning condition is met, scanning the area to be imaged through the scanning module and collecting data; sending a breathing reminder message, and continuing to detect through the navigation module Whether the predetermined scanning conditions are met; imaging is performed according to the data; the magnetic resonance imaging method of the present invention can enable the patient to cooperate with the present invention for detection according to the breathing prompt information, and the breathing prompt information can remind the patient to perform breathing exercises according to preset rules, so that During scanning and imaging, the error caused by respiratory movement can be effectively avoided, so that the imaging accuracy of the method is relatively high.

Because the nuclear magnetic resonance imaging system of the present invention includes: a navigation module, used to detect whether a predetermined scan condition is met; a scan module, used to scan and collect data in the area to be imaged when the scan condition is met; a reminder module, used to issue a breath Reminder information; imaging module, used for imaging according to the data; enabling the MRI method of the present invention to enable the patient to cooperate with the present invention for detection according to the breathing prompt information, and the breathing prompt information can remind the patient to perform respiratory exercise according to preset rules, This makes it possible to effectively avoid errors caused by respiratory movement during scanning and imaging, thus making the imaging accuracy of the method higher.

Description of drawings

Fig. 1 is a schematic flow sheet of a preferred embodiment of the nuclear magnetic resonance imaging method of the present invention;

Fig. 2 is a block diagram of a preferred embodiment of the nuclear magnetic resonance imaging system of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Please refer to Fig. 1 and Fig. 2, Fig. 1 is a schematic flow chart of a preferred embodiment of the nuclear magnetic resonance imaging method of the present invention; Fig. 2 is a schematic block diagram of a preferred embodiment of the magnetic resonance imaging system of the present invention.

The magnetic resonance imaging system 2 of the present invention includes a navigation module 21 , a scanning module 22 , a reminder module 23 and an imaging module 24 . The navigation module is used to detect whether the predetermined scanning conditions are met; the scanning module 22 is used to scan the area to be imaged and collect data when the scanning conditions are met; the reminder module 23 is used to send breathing reminder information; the imaging module 24, Used for imaging from this data.

The navigation sequence is based on spin echo (spin echo) work. When using layer selection gradients in two directions, only the spins at the intersection of the two directions will reunite and generate echo signals. This narrow band at the intersection is usually called a navigator. When the navigation bar is set on the diaphragm, it can be used to track the movement of the diaphragm. The navigation signal generated on the diaphragm is transmitted to the external computer through RT-Hawk (Reference: Santos JM, Wright GA, Pauly JM. Flexible real-time magnetic resonance imaging framework. Conf Proc IEEE Eng Med Biol Soc2004; 2:1048-1051), and after The relative displacement of the diaphragm can be obtained after real-time processing. The relative displacement will be immediately fed back to the MRI control computer system, and the scanning parameters will be adjusted within 50ms to achieve real-time tracking and correction of motion.

The navigation module 21 includes a detection device for transmitting and detecting signals, and a computer system for converting the detection signals into relative displacements of the navigation bar. Specifically, the navigation module includes: a signal transmitting unit, configured to transmit a detection signal to the navigation bar; a position acquisition unit, configured to acquire the physical position of the navigation bar; a displacement calculation unit, configured to calculate the The displacement of the navigation bar.

The scanning module 22 may be a common DWI sequence scanning or a DCE sequence scanning.

The reminder module 23 is usually a display device. The reminder module 23 can be used to display ventilation information or breath holding information. The ventilation information is used to tell the patient to take a breath, and the breath holding information is used to tell the patient to hold their breath. In another embodiment, the reminder module 23 may also include a sound device. While displaying ventilation information and breath holding information with text or images, a reminder sound can also be issued to avoid omissions by patients.

The imaging module 24 receives data information from the scanning module 22, and converts the data into visible medical images according to preset parameters.

The nuclear magnetic resonance imaging method of the present invention comprises steps:

S11. Detecting whether a predetermined scanning condition is met through the navigation module;

First, a detection signal is transmitted to the navigation bar through the signal transmitting unit. The navigation bar is acquired by the position obtaining unit by generating an echo signal, and the physical position of the navigation bar is calculated through the echo signal. The displacement calculation unit records the physical position of the navigation bar at each sampling time according to time, and calculates the displacement of two adjacent navigation bars. That is, the displacement is the absolute value of the difference between the physical position of the navigation bar at the current time and the physical position of the navigation bar at the last sampling time.

Normally, at intervals of 50 milliseconds, the signal transmitting unit, the position obtaining unit and the displacement calculating unit execute the above-mentioned working steps to obtain the position and displacement of the navigation bar.

In a preferred embodiment of the magnetic resonance imaging method of the present invention, the predetermined scanning condition is: the displacement of the navigation bar is less than 1 mm for three consecutive times. In another embodiment, the predetermined scanning condition may also be that the displacement of the navigation bar is less than 1 mm, 2 mm or 0.8 mm for four, five or more consecutive times. The specific preset scanning conditions can also be adjusted according to the actual situation, and the preset scanning conditions are mainly for determining that the region to be imaged is suspended or basically suspended. As long as it can be determined that the region to be imaged has suspended movement or has basically suspended movement, it can be set as the predetermined scanning condition.

S12. When the scanning conditions are met, scan the area to be imaged through the scanning module and collect data;

When the displacement of the navigation bar is less than 1 mm for three consecutive times, the scanning unit is activated to scan the area to be imaged, so as to obtain corresponding data.

Usually, in order to obtain imaging data clearly, in a preferred embodiment of the magnetic resonance imaging method of the present invention, the scanning time of the scanning module for the area to be imaged is preset at 6 seconds. In another embodiment, the preset scanning time may also be more than 6 seconds. The length of the specific preset time can be determined according to the ability of the patient to take breath and hold the breath. For example, if a person has a small lung capacity and a short breath-hold time, the preset scan time can be set at 6 seconds; 10 seconds, then the predetermined time can be set at any value from 6 to 10 seconds.

After the scanning module 22 acquires the data for imaging, it transmits the data to the imaging unit 24, and the imaging unit 24 performs imaging according to the data to form a medical image that can be referred to by doctors.

The scanning module 22 can start DCE-3D SPGR (three-dimensional gradient echo sequence, 3dimensional spoiled gradient-recalled acquisition, 3D-SPGR) or DWI-EPI (diffusion weighted echo planar imaging, echo planar imaging diffusion-weighted magnetic Resonance imaging (EPI-DWI) sequence scans the area to be imaged. During scanning, the scanning parameters of the MRI system 2 of the present invention, including RF transmit and receive frequencies and phases, need to be adjusted relative to the values in step S11.

S13. Send a breathing reminder message, and continue to detect whether the predetermined scanning condition is met through the navigation module;

The reminder information includes the first reminder information and the second reminder information; when the scanning module scans the area to be imaged and collects data for more than or equal to 6 seconds, it sends the first reminder information; after the first reminder information is sent, it is greater than or equal to 1.5 seconds Afterwards, the second reminder message is issued; the first reminder message and the second reminder message are displayed by the display device, the first reminder message is used to remind breath taking, and the second reminder message is used to remind breath-holding information.

Specifically, the first reminder message may be "please take a breath, and the time for breathing is 1.5 seconds"; the second reminder message may be "please hold your breath, please hold your breath for more than 6 seconds". At the same time, the reminding module 23 can also include a timing unit, which can remind the patient how long it is before the ventilation by counting down. As mentioned above, when the scanning time in step S12 is 7 seconds, 8 seconds or 9 seconds, the breath-hold reminder time is divided into 7 seconds, 8 seconds or 9 seconds.

Of course, the time for a person to take a breath can also be preset, depending on the patient's own situation.

In another embodiment, after step S12 is executed, step S11 is executed at the same time as prompting for ventilation, that is, step S11 and step S12 are alternately executed. The step of reminding ventilation and step S11 can be executed simultaneously, that is, step S13 includes reminding ventilation and step S11. Here, for the convenience of description, in different implementation manners, the prompting for ventilation and step S11 may also be described separately.

S14. Perform imaging according to the data.

After step S12 is executed, the imaging module 24 may process the data collected by the scanning module 22 to convert the data into a medical image. Usually, for different practical applications, the data obtained by each scan can only form a sub-section of a complete medical image. That is to say, generally, the scanning of an internal organ of the body needs to be scanned multiple times, and each scan is only for a part of the internal organ. Therefore, in another embodiment, if it is necessary to perform medical imaging on the whole organ or on a larger area, and since each scan can only scan a small area, the MRI method of the present invention requires multiple scans. Specifically, a large area is divided into several or dozens of small areas, and one of the areas is scanned once with a breath-hold, and the scans of the multiple small areas are completed multiple times with a breath-hold, and the data scanned by the multiple small areas are summarized To the imaging module, the imaging module processes the multiple data, and finally obtains the required medical image.

In summary, the MRI method and system of the present invention adopt intermittent ventilation and breath-holding methods, guide the patient to perform ventilation and breath-holding, and detect the displacement of the diaphragm after breath-holding through a linear navigation sequence. And the patient is scanned to obtain data when the diaphragm is basically inactive. After each scan, the patient is prompted to ventilate and hold the breath, and then the next scan is performed; finally, imaging is performed based on the scanned data. Therefore, compared with the prior art, the magnetic resonance imaging method and system of the present invention can effectively eliminate the artifact problem caused by internal organ movement caused by respiration, so that the accuracy of the finally obtained medical image is higher.

Those skilled in the art should understand that the embodiments of the present invention may be provided as methods, systems, or computer program products. When it is a computer program product, by loading a computer program that can embody the method of the present invention, the nuclear magnetic resonance imaging equipment can be mobilized to operate according to the method of the present invention, thereby achieving various purposes described in the present invention and solving corresponding technical problems. achieve technical results.

Accordingly, the present invention can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, terminals (systems), and computer program products according to embodiments of the invention. It should be understood that each procedure and/or block in the flowchart and/or block diagram, and combinations of procedures and/or blocks in the flowchart and/or block diagram can be realized by computer program instructions. These computer program instructions may be provided to a general purpose computer, special purpose computer, embedded processor, or processor of other programmable data processing equipment to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing equipment produce a Means for realizing the functions specified in one or more steps of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to operate in a specific manner, such that the instructions stored in the computer-readable memory produce an article of manufacture comprising instruction means, the instructions The device realizes the function specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions can also be loaded onto a computer or other programmable data processing device, causing a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process, thereby The instructions provide steps for implementing the functions specified in the flow chart flow or flows and/or block diagram block or blocks.

It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation, although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements without departing from the spirit and scope of the technical solution of the present invention shall be covered by the claims of the present invention.

Claims (10)

1. A nuclear magnetic resonance imaging method, comprising the steps of: Detect whether the predetermined scanning conditions are met through the navigation module; When the scanning conditions are met, scan the area to be imaged through the scanning module and collect data; Send a breathing reminder message, and continue to detect whether the predetermined scanning conditions are met through the navigation module; Imaging is performed based on this data. 2. nuclear magnetic resonance imaging method according to claim 1, is characterized in that, step detects whether to meet predetermined scanning condition by navigation module and comprises: Send a detection signal to the navigation bar to obtain the physical location of the navigation bar; Calculate the displacement of the navigation bar acquired twice adjacently. 3. nuclear magnetic resonance imaging method according to claim 2, is characterized in that, this nuclear magnetic resonance imaging method also comprises the step: Get the physical position of the navigation bar every 50 milliseconds; When the displacement of the navigation bar is less than 1 millimeter for three consecutive times, the scanning module scans the imaging area of the strip and collects data. 4. nuclear magnetic resonance imaging method according to claim 1, is characterized in that, step sends reminder message and comprises steps: The reminder information includes the first reminder information and the second reminder information; when the scanning module scans the area to be imaged and collects data for more than or equal to 6 seconds, it sends the first reminder information; after the first reminder information is sent, it is greater than or equal to 1.5 seconds After that, send the second reminder message; The first reminder information and the second reminder information are displayed by the display device, the first reminder information is used to remind ventilation, and the second reminder information is used to remind breath-holding. 5. nuclear magnetic resonance imaging method according to claim 1, is characterized in that, this nuclear magnetic resonance imaging method also comprises: Perform the following steps cyclically: the navigation module detects whether the predetermined scanning conditions are met; when the scanning conditions are met, scan the area to be imaged through the scanning module and collect data; send a reminder message; perform imaging based on the data; Alternatively, the following steps are executed cyclically: detecting whether the predetermined scanning condition is met through the navigation module; when the scanning condition is met, scanning the area to be imaged and collecting data through the scanning module; sending a reminder message. 6. A nuclear magnetic resonance imaging system, comprising: A navigation module, configured to detect whether a predetermined scanning condition is met; A scanning module, configured to scan the area to be imaged and collect data when the scanning conditions are met; Reminder module, used to send out breathing reminder information; The imaging module is used for imaging according to the data. 7. nuclear magnetic resonance imaging system according to claim 6, is characterized in that, this navigation module comprises: a signal transmitting unit, configured to transmit a detection signal to the navigation bar; a location obtaining unit, configured to obtain the physical location of the navigation bar; The displacement calculation unit is configured to calculate the displacement of the navigation bar obtained twice adjacently. 8. The nuclear magnetic resonance imaging system according to claim 7, characterized in that: The location obtaining unit is also used to obtain the physical location of the navigation bar every 50 milliseconds; The navigation module also includes a condition judging unit, which is used to notify the scanning module to scan the imaging area of the strip and collect data when the displacement of the navigation bar is less than 1 mm for three consecutive times. 9. The nuclear magnetic resonance imaging system according to claim 6, characterized in that: The reminder module includes a first reminder information unit and a second reminder information unit; The first reminder information unit is used to send the first reminder information when the scanning module scans the area to be imaged and collects data for more than or equal to 6 seconds; the second information reminder unit is used to issue the first reminder information after the first reminder information is sent Send out the second reminder message after 1.5 seconds; The reminding module is also used to display the first reminding information and the second reminding information through the display device, the first reminding information is used to remind ventilation, and the second reminding information is used to remind breath-holding. 10. The nuclear magnetic resonance imaging system according to claim 6, wherein the nuclear magnetic resonance imaging system further comprises: The cyclic execution module is used for cyclically starting the navigation module, the scanning module, the reminder module and the imaging module; or, the cyclic execution module is used for cyclically starting the navigation module, the scanning module and the reminder module.

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