Posture control system and posture control method

Abstract

To accurately adjust an imaging posture of an imaging portion.SOLUTION: A posture control system according to an embodiment controls an imaging posture of an imaging portion of a subject in imaging by a magnetic resonance imaging apparatus, and includes a posture fixing device, a posture control device, and a display device. The posture fixing device adjusts and fixes the imaging posture of the imaging portion by deformation. The posture control device controls the deformation of the posture fixing device by transmitting deformation parameters to the posture fixing device. The display device displays an image. The posture control device sets the deformation parameters, transmits them to the posture fixing device, and executes parameter setting processing to cause the posture fixing device to adjust the imaging posture of the imaging portion.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The embodiments disclosed in this specification and the drawings relate to a posture control system and a posture control method. [Background technology]

[0002] A magnetic resonance imaging device is a non-invasive medical imaging diagnostic device that utilizes the magnetic resonance phenomenon in which hydrogen nuclei placed in a static magnetic field resonate with a radio frequency magnetic field of a specific frequency. Magnetic resonance imaging technology has the characteristics of high resolution, no damage, and no radiation, and can examine various substantial organs of the human body, so it is widely applied to the diagnosis of clinical diseases. A magnetic resonance imaging device includes a magnetic resonance imaging device that images a subject, and a magnetic resonance image reconstruction device that reconstructs an image based on the captured image.

[0003] Magnetic resonance imaging includes three imaging methods: T1 weighted imaging, T2 weighted imaging, and proton density weighted imaging. T1 weighted imaging uses a short repetition time and echo time to generate a T1 weighted image that shows the difference in T1 relaxation time between tissues and is used to observe fat, blood, etc. T2 weighted imaging uses a long repetition time and echo time to generate a T2 weighted image that shows the difference in T2 relaxation time between tissues and is used to observe cerebrospinal fluid, tumors, etc. And proton density weighted imaging uses a long repetition time and a short echo time to generate a proton density weighted image that shows the difference in particle concentration between regions and is used in conjunction with the T1 weighted image and the T2 weighted image.

[0004] In magnetic resonance imaging, the imaging position of the subject during imaging may affect image quality. As an example, when the angle between a structure containing collagen fibers such as tendons and cartilage and the main magnetic field is about 55° during magnetic resonance imaging, the corresponding structure is displayed as a high signal in T1 weighted images and proton density weighted images with short repetition times. This phenomenon is called the magic angle effect. The magic angle effect can improve the sharpness of low signal areas in the above structure, but it makes it impossible to distinguish low signal areas from high signal areas. In order to suppress or utilize the magic angle effect, a position control system and method that can accurately control the angle between the part of the subject where imaging is performed (hereinafter referred to as the imaging part) and the main magnetic field is required.

[0005] Conventionally, a support member is known that is placed on the imaging site of a subject during magnetic resonance imaging to fix the imaging site of the subject at a certain angle and maintain the subject's position during imaging. However, when using the support member, when the position of the subject needs to be adjusted, for example, when a different scan sequence is performed, an operator needs to enter the imaging room and adjust the position of the subject.

[0006] For example, a magnetic resonance imaging system has been proposed that includes a holder that holds the entire body of a subject, and adjusts the patient's position by rotating and deforming the holder.

[0007] However, in the proposed magnetic resonance imaging system, the subject's whole body position must be changed in order to change the angle of the imaging site of the subject, which may cause the patient to assume an uncomfortable position. In addition, the proposed magnetic resonance imaging system cannot accurately set the imaging position of the subject's imaging site, and cannot set the angle between the collagen fiber-containing structure in the imaging site and the main magnetic field. Therefore, the occurrence or suppression of the magic angle effect may fail, which may cause repeated imaging. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] U.S. Pat. No. 8,111,067 Summary of the Invention [Problem to be solved by the invention]

[0009] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to accurately adjust the imaging position of the imaging region. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems. [Means for solving the problem]

[0010] A posture control system according to an embodiment is a posture control system for controlling an imaging posture of an imaging region of a subject in imaging by a magnetic resonance imaging apparatus, and includes a posture fixing device, a posture control device, and a display device. The posture fixing device adjusts and fixes the imaging posture of the imaging region by deformation. The posture control device controls the deformation of the posture fixing device by transmitting deformation parameters to the posture fixing device. The display device displays an image. The posture control device executes a parameter setting process for setting the deformation parameters and transmitting them to the posture fixing device, and causing the posture fixing device to adjust the imaging posture of the imaging region. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing the configuration of a body position control system according to the first embodiment. [Diagram 2] FIG. 2 is a diagram showing the configuration of the body position fixing device used in the first embodiment. [Diagram 3] FIG. 3 is a flowchart showing the posture control method according to the first embodiment. [Figure 4]FIG. 4 is an explanatory diagram for explaining how to wear the body position fixing device. [Diagram 5] FIG. 5 is a schematic diagram showing a first graphical user interface displayed in the body posture control method according to the first embodiment. [Figure 6] FIG. 6 is an explanatory diagram for explaining the relationship between the angle between the direction of the ankle and the direction of the main magnetic field, and the opening angle of the body position fixing device. [Figure 7] FIG. 7 is a diagram showing an example of a second graphical user interface for measuring the angle between the axial direction of the Achilles tendon and the direction of the main magnetic field. [Figure 8] FIG. 8 is an explanatory diagram for explaining image rotation. [Figure 9] FIG. 9 is a block diagram showing the configuration of a body position control system according to the second embodiment. [Figure 10] FIG. 10 is a flowchart showing a body posture control method according to the second embodiment. [Figure 11] FIG. 11 is a diagram showing the configuration of a body position fixing device used in the third embodiment. [Figure 12] FIG. 12 is a flowchart showing a body posture control method according to the third embodiment. [Figure 13] FIG. 13 is an explanatory diagram for explaining how the postural stability device and the imaging coil are attached. [Figure 14] FIG. 14 is a schematic diagram showing a third graphical user interface displayed in the body posture control method according to the third embodiment. [Figure 15] FIG. 15 is an explanatory diagram for explaining the relationship between the angle between the surface direction of the knee joint and the direction of the main magnetic field, and the elevation height of the body position fixing device. [Figure 16] FIG. 16 is a diagram showing an example of a fourth graphical user interface for measuring the angle between the axial direction of the patella ligament and the direction of the main magnetic field. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, a posture control system and a posture control method according to an embodiment will be described with reference to the drawings. The posture control system and the posture control method according to the present embodiment control the imaging posture of the imaging part of a subject (patient) in the imaging stage of magnetic resonance imaging.

[0013] (First embodiment) In a first embodiment, a posture control system and a posture control method are applied to a magnetic resonance imaging examination of an Achilles tendon.

[0014] 1 is a block diagram showing the configuration of a posture control system 1 according to the first embodiment. The posture control system 1 according to this embodiment includes a posture fixing device 10, a posture control device 20, and a display device 30. Here, the posture control device 20 and the display device 30 may be provided separately from the console of the magnetic resonance imaging device, or may be built into the console.

[0015] The positioning device 10 is a mechanical device that adjusts and fixes the imaging position of the subject's imaging region by deformation. The positioning device 10 directly contacts the imaging region of the subject to support the imaging region, and adjusts the imaging position of the imaging region by deformation. The deformation of the positioning device 10 includes, but is not limited to, vertical movement, horizontal movement, expansion and contraction, rotational movement, etc. The positioning device 10 is fixed to a bed on which the subject is placed during use, and can be removed from the bed after use. The positioning device 10 has a built-in communication unit 11 and a sensor 12.

[0016] The communication unit 11 is a network adapter including a network interface, and controls data exchange between the body position fixing device 10 and the body position control device 20 via the network N. The network N may be a LAN (Local Area Network), a WAN (Wide Area Network), the Internet, a dedicated line, or the like. The network N may be connected by wire or wirelessly. When connected by wire, the connection may be made using, for example, a twisted pair, a coaxial cable, an optical fiber, or the like. When connected wirelessly, the connection may be made using, for example, Wi-Fi, a cellular mobile network (4G LTE, 5G), or the like.

[0017] The sensor 12 detects the current deformation amount, such as the displacement amount, rotation amount, etc., of the body position fixing device 10. Information on the deformation amount, etc. detected by the sensor 12 is transmitted to the body position control device 20 by the communication unit 11 via the network N.

[0018] The body position fixing device 10 includes a plurality of body position fixing devices corresponding to various examination locations. For example, the body position fixing device 10 may include body position fixing devices corresponding to the lower legs, thighs, knees, forearms, upper arms, waist, etc. In this embodiment, the body position fixing device 10a corresponding to the lower legs is used.

[0019] FIG. 2 is a diagram showing the configuration of the body position fixing device used in the first embodiment.

[0020] As shown in FIG. 2, the body position fixing device 10a has an upper arm section 13a, a lower arm section 14a, and a rotating section 15a.

[0021] The upper arm 13a is formed in a rectangular parallelepiped shape, and is in direct contact with the lower leg of the subject, supporting the lower leg and fixing the imaging position of the lower leg. The lower arm 14a is formed in a rectangular parallelepiped shape, and is placed on the bed 2 to fix the position fixing device 10a to the bed 2. For example, the lower surface of the lower arm 14a may be roughened to increase the friction between the lower arm 14a and the bed 2 so that the position fixing device 10a and the bed 2 do not move relative to each other. The upper arm 13a and the lower arm 14a are made of a non-magnetic material such as plastic, ceramic, or glass. The rotating unit 15a rotatably connects the upper arm 13a and the lower arm 14a, and rotates the upper arm 13a relative to the lower arm 14a in response to an instruction from the position control device 20 to fix the angle between the upper arm 13a and the lower arm 14a to a specified angle. The rotating part 15a is a non-magnetic motor that does not include a permanent magnet, an electromagnetic coil, an iron core, etc., and is, for example, a piezoelectric motor, an air motor, etc. Since the body position fixing device 10a is made of a non-magnetic material, the quality of the captured image does not deteriorate even if the body position fixing device 10a enters the FOV (Field Of View).

[0022] The posture control device 20 controls the deformation of the posture fixing device 10. The posture control device 20 is connected to the posture fixing device 10 via a network N, and controls the deformation of the posture fixing device 10 by transmitting deformation parameters to the posture fixing device 10 so that the imaging part of the subject is in a desired imaging position. The posture control device 20 includes an input unit 21, a control unit 22, a display control unit 23, a storage unit 24, and a communication unit 25.

[0023] The input unit 21 accepts operations by an operator. The input unit 21 includes an input interface and an input device. The input interface is, for example, a serial bus interface such as a Universal Serial Bus (USB) and is used to exchange information with the input device. The input device includes a mouse, keyboard, trackball, switch, button, joystick, touch screen, microphone, etc., and is used to input information.

[0024] The control unit 22 executes various programs stored in the storage unit 24 to realize functions described below. The control unit 22 is configured with hardware such as a CPU (Central Processing Unit), a Field Programmable Gate Array (FPGA), an Application Specific Integrated Circuit (ASIC), a programmable logic device (e.g., a Simple Programmable Logic Device (SPLD), a Complex Programmable Logic Device (CPLD)), etc. The control unit 22 is not limited to being configured as a single circuit, and may be configured as a single hardware processor in which multiple independent circuits are combined to realize each function.

[0025] The display control unit 23 is connected to the display device 30 via a display interface, and causes the display device 30 to display an image. The display control unit 23 is configured, for example, with a GPU (Graphics Processing Unit) etc. The display interface is, for example, a video output interface such as a Digital Visual Interface (DVI) or a High-Definition Multimedia Interface (HDMI (registered trademark)).

[0026] The storage unit 24 stores various parameters used in the posture control method and various programs executed by the control unit 22. The storage unit 24 is realized by a storage device such as a read-only memory (ROM), a flash memory, a random access memory (RAM), a hard disk drive (HDD), a solid state drive (SSD), a register, etc. The flash memory, HDD, SSD, etc. are non-volatile storage media. These non-volatile storage media may be realized by other storage devices connected via a network, such as a network attached storage (NAS) or an external storage server device.

[0027] The communication unit 25 is a network adapter including a network interface, and controls data exchange between the body position fixing device 10 and the body position control device 20 via the network N. The configuration of the communication unit 25 is similar to that of the communication unit 11, so a detailed description will be omitted here.

[0028] The display device 30 is controlled by the display control unit 23 of the posture control device 20, and displays images of a user interface for receiving input operations from the worker. The user interface is, for example, a GUI (Graphical User Interface), etc. The display device 30 is, for example, an LCD (Liquid Crystal Display), an organic EL (Electroluminescence) display, etc.

[0029] (Achilles tendon magic angle effect) When magnetic resonance imaging is performed on the Achilles tendon, when the angle between the axial direction of the Achilles tendon and the main magnetic field direction is close to 54.74°, the Achilles tendon containing collagen fibers appears as a higher signal than other structures in T1-weighted images or proton density-weighted images using a short echo time. This phenomenon is called the magic angle effect of the Achilles tendon. When the magic angle effect occurs, the resolution of the fiber structure is improved, providing clearer fiber structure information. This is suitable for displaying partial tears of the Achilles tendon, and is of great significance for timely, accurate and early surgical repair and functional reconstruction.

[0030] In the posture control method according to this embodiment, in order to induce a magic angle effect in the Achilles tendon, the imaging posture of the subject's lower leg is adjusted so that the angle between the axial direction of the subject's Achilles tendon and the direction of the main magnetic field is approximately 54.74°.

[0031] 3 is a flowchart showing the posture control method according to the first embodiment. Hereinafter, the posture control method according to the first embodiment will be described with reference to FIG.

[0032] In step S100, the operator enters the imaging room and attaches the positioning device 10a to the lower leg of the subject. FIG. 4 is an explanatory diagram for explaining the attachment of the positioning device 10a. As shown in FIG. 4, when imaging the Achilles tendon near the ankle, the subject lies prone on the bed 2, and the positioning device 10a is attached between the lower leg of the subject to be examined and the bed 2 with the opening angle reduced. When the process of step S100 is completed, the process proceeds to step S200.

[0033] In step S200, the operator checks whether the subject and the body positioning device 10a are securely fixed to the bed 2, and then moves the bed 2 to the magnetic resonance imaging apparatus. When the process of step S200 is completed, the process proceeds to step S300.

[0034] In step S300, the operator sets parameters of a scan sequence for magnetic resonance imaging. The parameters of the scan sequence include an imaging method, a repetition time, an echo time, a resolution, a magnetic field strength, etc. When the process of step S300 is completed, the process proceeds to step S400.

[0035] In step S400, the position control device 20 judges whether the set imaging method is T1 weighted imaging or proton density weighted imaging with a short echo time based on the parameters of the scan sequence set by the operator. If the judgment is Yes, the process proceeds to step S500, and if the judgment is No, the process proceeds to step S600.

[0036] In step S500, the position control device 20 displays a message on the display device 30 saying, "The set scan sequence has a magic angle effect on the Achilles tendon and cartilage, so please adjust the patient's position." to alert the operator to the magic angle effect. Note that the above message is an example, and the displayed message is not limited to this. When the process of step S500 is completed, the process proceeds to step S600.

[0037] In step S600, the operator uses the posture control device 20 to set deformation parameters for controlling the deformation of the posture fixing device 10a, and causes the posture fixing device 10a to adjust the imaging posture of the subject's imaging region.

[0038] Specifically, first, the operator inputs parameters for controlling the deformation of the body position fixing device 10a into the first graphical user interface displayed on the display device 30. FIG. 5 is a schematic diagram showing the first graphical user interface G1 displayed in the body position control method according to the first embodiment. As shown in FIG. 5, the display device 30 displays the first graphical user interface G1, in which the operator inputs parameters for controlling the deformation of the body position fixing device 10a. In the first graphical user interface G1, a message "Please input the opening angle of the body position fixing device" is displayed in the lower area of ​​the screen, and an input box for inputting the opening angle of the body position fixing device 10a is provided in the upper area of ​​the screen. The settable range of the opening angle of the body position fixing device 10a is from 0° to 120°, and if the operator inputs an angle that exceeds the settable range, the operator is requested to redo the input. Note that, for visual confirmation, a schematic diagram of the main magnetic field direction B0 and the body position fixing device 10a opened at the set opening angle is displayed near the input box.

[0039] Next, when the operator confirms the opening angle, the position control device 20 transmits the opening angle to the position fixing device 10a. When the position fixing device 10a receives the opening angle set by the operator, it rotates the rotating part 15a to fix the angle between the upper arm part 13a and the lower arm part 14a to the opening angle set. This adjusts the imaging position of the subject's lower leg.

[0040] Here, the relationship between the angle between the axial direction of the Achilles tendon and the main magnetic field direction B0, and the opening angle of the body position fixing device 10a will be described.

[0041] FIG. 6 is an explanatory diagram for explaining the relationship between the angle α3 between the ankle direction and the main magnetic field direction B0 and the opening angle α1 of the positioning device 10a. As shown in FIG. 6, in a magnetic resonance imaging device, the main magnetic field direction B0 is generally a horizontal direction parallel to the bed 2, so the main magnetic field direction B0 is also parallel to the longitudinal direction of the lower arm 14a of the positioning device 10a horizontally installed on the bed 2. Furthermore, since the subject's lower leg is placed on the upper arm 13a, the longitudinal direction of the upper arm 13a is approximately parallel to the direction of the subject's ankle. Therefore, the angle α3 between the ankle direction and the main magnetic field direction B0 is approximately equal to the opening angle α1 of the positioning device 10a.

[0042] In addition, since the direction of the ankle is approximately parallel to the axial direction of the Achilles tendon, the angle between the axial direction of the Achilles tendon and the main magnetic field direction B0 is approximately equal to the opening angle α1 of the positioning device 10a. In this embodiment, it is preferable to set the angle between the axial direction of the Achilles tendon and the main magnetic field direction B0 to 54.74° and enhance the image of the Achilles tendon by the magic angle effect. In this embodiment, by setting the opening angle α1 of the positioning device 10a to 54.74°, the angle between the axial direction of the Achilles tendon and the main magnetic field direction B0 can be made close to 54.74°, and the magic angle effect can be generated.

[0043] When the process of step S600 is completed, the process proceeds to step S700.

[0044] In step S700, the magnetic resonance imaging apparatus uses the set scan sequence to image the ankle, which is the imaging site of the subject. Specifically, the magnetic resonance imaging apparatus first acquires a transverse and coronal scout image of the ankle. Next, the magnetic resonance imaging apparatus identifies a transverse section in which the medial and lateral malleoli are most accurately depicted in the acquired scout images of the transverse sections, and sets the positioning line of the sagittal plane perpendicular to the connecting line between the medial and lateral malleoli. Then, the magnetic resonance imaging apparatus adjusts the angle of the positioning line in the coronal plane so that the sagittal plane positioning line is parallel to the direction of the Achilles tendon. Then, the magnetic resonance imaging apparatus images the ankle of the subject in the identified sagittal plane. When the process of step S700 is completed, the process proceeds to step S800.

[0045] In step S800, the posture control device 20 measures the difference between the angle between the axial direction of the Achilles tendon and the main magnetic field direction B0 and 54.74°.

[0046] Specifically, first, the body position control device 20 displays on the display device 30 a second graphical user interface for measuring the angle between the axial direction of the Achilles tendon and the main magnetic field direction B0. FIG. 7 is a diagram showing an example of the second graphical user interface G2 for measuring the angle α2 between the axial direction of the Achilles tendon and the main magnetic field direction B0. As shown in FIG. 7, the second graphical user interface G2 displays the captured image of the subject's ankle acquired in step S700, and further displays an indicator I that can be moved arbitrarily superimposed on the captured image. The indicator I includes an arrow indicating the main magnetic field direction B0, an auxiliary line A1 that makes an angle of 54.74° clockwise from the main magnetic field direction B0 and intersects with the arrow indicating the main magnetic field direction B0 at an intersection point D, and an auxiliary line A2 that makes an angle of 54.74° counterclockwise from the main magnetic field direction B0 and intersects with the arrow indicating the main magnetic field direction B0 at an intersection point D. In FIG. 7, the position of the Achilles tendon is indicated by a thick solid line, and the axial direction of the Achilles tendon is indicated by an arrow L1.

[0047] Next, the operator moves the indicator I so that the intersection point D is located on the inside of the Achilles tendon. Then, the operator selects one of the auxiliary lines A1 and A2 according to the direction of the Achilles tendon, and rotates the captured image so that the selected auxiliary line coincides with the arrow L1. Note that instead of rotating the captured image, the indicator I itself may be rotated. FIG. 8 is an explanatory diagram for explaining the rotation of an image. FIG. 8 shows an example in which the operator rotates the image of the ankle so that the arrow L1 of the Achilles tendon coincides with the direction of the auxiliary line A1. At this time, the angle α2 between the arrow L1 and the main magnetic field direction B0 is 54.74°.

[0048] Thereafter, the posture control device 20 calculates the angle of rotation, and sets the calculated angle as the difference between the angle α2 between the axial direction of the tendon and the main magnetic field direction B0 and 54.74°.

[0049] When the process of step S800 is completed, the process proceeds to step S900.

[0050] In step S900, the posture control device 20 judges whether the difference between the angle α2 between the axial direction of the Achilles tendon and the main magnetic field direction B0 and 54.74° is within a threshold range, and if it is within the threshold range (Yes), the processing of the posture control method according to this embodiment ends, and if it is not within the threshold range (No), the process proceeds to step S1000. The threshold range is preferably 1° or less.

[0051] In step S1000, the posture control device 20 resets the deformation parameters for controlling the deformation of the posture fixation device 10a based on the difference between the angle α2 between the axial direction of the Achilles tendon and the main magnetic field direction B0 and 54.74°, and causes the posture fixation device 10a to adjust the imaging position of the subject's imaging area.

[0052] Specifically, when the angle α2 between the current axial direction of the Achilles tendon and the main magnetic field direction B0 is less than 54.74°, the position control device 20 adds the difference between the angle α2 between the axial direction of the Achilles tendon and the main magnetic field direction B0 and 54.74° to the opening angle α1, and transmits the added opening angle α1 to the position fixing device 10a. When the angle α2 between the current axial direction of the Achilles tendon and the main magnetic field direction B0 is greater than 54.74°, the position control device 20 subtracts the difference between the angle α2 between the axial direction of the Achilles tendon and the main magnetic field direction B0 and 54.74° from the opening angle α1, and transmits the subtracted opening angle α1 to the position fixing device 10a. When the position fixing device 10a receives the calculated opening angle α1, it rotates the rotating unit 15a to fix the upper arm unit 13a to the calculated opening angle α1 with respect to the lower arm unit 14a.

[0053] When the process of step S1000 is completed, the process proceeds to step S700, and the magnetic resonance imaging apparatus again images the imaging region of the subject.

[0054] According to the above embodiment, since the body position fixing device 10 that adjusts and fixes the imaging position of the imaging part of the subject is provided, the imaging part can be fixed in a desired imaging position without adjusting the body position of the whole body of the subject, and the subject does not feel uncomfortable. In addition, since the imaging part is supported by the body position fixing device 10 during imaging, no artifacts are generated due to the imaging part moving during imaging.

[0055] In addition, by using the indicator I, the difference between the angle α2 between the axial direction of the Achilles tendon and the main magnetic field direction B0 and 54.74° can be accurately measured, and the imaging position of the imaging part can be accurately adjusted to ensure that the magic angle effect occurs at the Achilles tendon. This makes it possible to avoid duplicate imaging due to the magic angle effect not occurring accurately, and shorten the imaging time.

[0056] Second Embodiment A posture control system and a posture control method according to the second embodiment will be described below. In the second embodiment, differences from the first embodiment will be mainly described, and commonalities with the first embodiment will be omitted. In the description of the second embodiment, the same parts as those in the first embodiment will be denoted by the same reference numerals.

[0057] In the second embodiment, the posture control system and posture control method are applied to a magnetic resonance imaging examination of the Achilles tendon, similarly to the first embodiment. Fig. 9 is a block diagram showing the configuration of a posture control system 1a according to the second embodiment. Compared with the posture control system 1 according to the first embodiment, the posture control system 1a according to the second embodiment further includes an optical imaging device 40.

[0058] The optical imaging device 40 is attached to the magnetic resonance imaging device and captures an image of an imaging part of a subject. The optical imaging device 40 is, for example, a non-magnetic camera made of a non-magnetic material and dedicated to magnetic resonance imaging. The optical imaging device 40 includes a communication unit (not shown) and is connected to the position control device 20 via a network N.

[0059] 10 is a flowchart showing a posture control method according to the second embodiment. Compared to the first embodiment, the posture control method according to the second embodiment has step S600a instead of step S600. The other steps are the same as those of the first embodiment.

[0060] In step S600a, the optical imaging device 40 captures an optical image of the subject's ankle, and the posture control device 20 estimates the angle between the axial direction of the Achilles tendon and the main magnetic field direction B0 based on the optical image of the ankle captured by the optical imaging device 40, sets deformation parameters for controlling the deformation of the posture fixation device 10a, and causes the posture fixation device 10a to adjust the imaging position of the subject's imaging area.

[0061] Specifically, first, the optical imaging device 40 captures an optical image of the subject's ankle and transmits it to the posture control device 20. The posture control device 20 processes the received optical image of the ankle, identifies the position of the axial direction of the Achilles tendon in the image, and calculates the difference between the angle α2 between the axial direction of the Achilles tendon and the main magnetic field direction B0 and 54.74°. The posture control device 20 preferably performs image processing using a trained neural network model. The neural network model may be a feedforward neural network, a convolutional neural network, a Transformer, or the like.

[0062] Thereafter, if the angle α2 between the current axial direction of the Achilles tendon and the main magnetic field direction B0 is less than 54.74°, the position control device 20 adds the difference between the angle α2 between the axial direction of the Achilles tendon and the main magnetic field direction B0 and 54.74° to the opening angle α1, and transmits the added opening angle α1 to the position fixing device 10a. If the angle α2 between the current axial direction of the Achilles tendon and the main magnetic field direction B0 is greater than 54.74°, the position control device 20 subtracts the difference between the angle α2 between the axial direction of the Achilles tendon and the main magnetic field direction B0 and 54.74° from the opening angle α1, and transmits the subtracted opening angle α1 to the position fixing device 10a. When the position fixing device 10a receives the calculated opening angle α1, it rotates the rotating unit 15a to fix the upper arm unit 13a to the calculated opening angle α1 with respect to the lower arm unit 14a.

[0063] When the process of step S600a is completed, the process proceeds to step S700.

[0064] According to the above embodiment, the imaging position of the imaging region can be accurately adjusted before the first imaging, the magic angle effect can be reliably generated in the Achilles tendon, and duplicate imaging can be avoided.

[0065] (Third embodiment) Hereinafter, a posture control system and a posture control method according to the third embodiment will be described. In the third embodiment, differences from the first embodiment will be mainly described, and commonalities with the first embodiment will be omitted. In addition, in the description of the third embodiment, the same parts as those in the first embodiment will be denoted by the same reference numerals.

[0066] In a third embodiment, the position control system and method are applied to a magnetic resonance imaging examination on the patellar ligament.

[0067] (Magic angle effect of the patellar ligament) When performing a magnetic resonance imaging test on the patellar ligament, the affected area of ​​the ligament is displayed as a high signal. On the other hand, when the angle between the axial direction of the ligament containing collagen fibers and the main magnetic field direction B0 is close to 54.74°, the entire ligament is displayed as a high signal due to the magic angle effect in T1 weighted images or proton density weighted images using a short echo time, which can easily lead to a misdiagnosis by a doctor.

[0068] In the posture control method according to this embodiment, in order to suppress the magic angle effect in the patellar ligament, the imaging posture of the subject's knee is adjusted so that the angle between the ligament axial direction and the main magnetic field direction B0 is away from 54.74°.

[0069] Fig. 11 is a diagram showing the configuration of a body position fixing device used in the third embodiment. As shown in Fig. 11, a body position fixing device 10b has a base part 16b and an expandable part 17b.

[0070] The base part 16b is formed in a platform shape with a trapezoidal cross section, and is placed on the bed 2 to fix the body position fixing device 10b to the bed 2. For example, the lower surface of the base part 16b may be roughened to increase the friction between the base part 16b and the bed 2 so that the body position fixing device 10b does not move relative to the bed 2. The expandable part 17b is configured to be expandable in the vertical direction, and directly contacts the knee of the subject, supports the knee, and fixes the knee in the imaging position. The base part 16b and the expandable part 17b are made of a non-magnetic material such as plastic, ceramic, or glass.

[0071] 12 is a flowchart showing a posture control method according to the third embodiment. Compared with the first embodiment, the posture control method according to the third embodiment has steps S100b, and S600b to S1000b instead of steps S100, and S600 to S1000.

[0072] In step S100b, the operator enters the imaging room and attaches the positioning device 10b and the imaging coil C to the knee of the subject. FIG. 13 is an explanatory diagram for explaining the attachment of the positioning device 10b and the imaging coil C. As shown in FIG. 13, when imaging the patellar ligament, the subject lies on the bed 2 in a supine position, and the operator attaches the imaging coil C to the knee joint of the subject, contracts the expandable part 17b of the positioning device 10b to the lowest height, and attaches the positioning device 10b under the knee of the subject. The imaging coil C may be a knee joint dedicated coil or a surface coil. In this embodiment, an example in which the imaging coil C is a knee joint dedicated coil will be described. When the process of step S100b is completed, the process proceeds to step S200b.

[0073] In step S600b, the operator uses the posture control device 20 to set parameters for controlling the deformation of the posture fixing device 10b, and causes the posture fixing device 10b to adjust the imaging position of the subject's imaging region.

[0074] Specifically, first, the worker inputs parameters for controlling the deformation of the body position fixing device 10b into the third graphical user interface displayed on the display device 30. FIG. 14 is a schematic diagram showing a third graphical user interface G3 displayed in the body position control method according to the third embodiment. As shown in FIG. 14, the display device 30 displays the third graphical user interface G3 in which the worker inputs parameters for controlling the deformation of the body position fixing device 10b. In the third graphical user interface G3, a message "Please input the elevation altitude of the body position fixing device" is displayed in the lower area of ​​the screen, and an input box for inputting the elevation altitude of the body position fixing device 10b is provided in the upper area of ​​the screen. The possible setting range of the elevation altitude of the body position fixing device 10b is from 0 cm to 30 cm, and if the worker inputs an elevation that exceeds the possible setting range, the worker is requested to redo the input.

[0075] Next, when the operator confirms the ascent altitude, the body position control device 20 transmits the ascent altitude to the body position fixing device 10b. When the body position fixing device 10b receives the ascent altitude set by the operator, it expands and contracts the expandable part 17b so that the body position fixing device 10b is at the ascent altitude set by the operator. This adjusts the imaging position of the knee joint of the subject.

[0076] Here, the relationship between the angle between the axial direction of the patellar ligament and the main magnetic field direction B0, and the elevation height of the body position fixing device 10b will be described.

[0077] The patellar ligament is located in the knee joint, and the axial direction of the patellar ligament forms a certain angle with the surface direction of the knee joint. Therefore, by adjusting the angle between the surface direction of the knee joint and the main magnetic field direction B0, the angle between the axial direction of the patellar ligament and the main magnetic field direction B0 can be adjusted. FIG. 15 is an explanatory diagram for explaining the relationship between the angle α4 between the surface direction of the knee joint and the main magnetic field direction B0 and the elevation height h of the position fixing device 10b. As shown in FIG. 15(a), by lowering the elevation height h of the position fixing device 10b, the angle α4 between the surface direction of the knee joint and the horizontal direction (main magnetic field direction B0) can be reduced, and the angle between the axial direction of the patellar ligament and the main magnetic field direction B0 can be reduced. On the other hand, as shown in FIG. 15(b), by increasing the elevation height h of the positioning device 10b, the angle α4 between the surface direction of the knee joint and the horizontal direction (main magnetic field direction B0) can be increased, and the angle between the axial direction of the patellar ligament and the main magnetic field direction B0 can be increased.

[0078] When the process of step S600b is completed, the process proceeds to step S700b.

[0079] In step S700b, the magnetic resonance imaging apparatus uses the set scan sequence to image the knee joint, which is the imaging site of the subject. Specifically, the magnetic resonance imaging apparatus first acquires scout images of the transverse and coronal planes of the knee joint. Next, the magnetic resonance imaging apparatus identifies the transverse plane in which the femoral medial condyle and the femoral lateral condyle are most accurately depicted in the acquired scout images of the transverse planes, and sets the positioning line of the sagittal plane perpendicular to the line between the posterior edges of the femoral medial condyle and the femoral lateral condyle. Then, the magnetic resonance imaging apparatus adjusts the angle of the positioning line in the coronal plane so that the positioning line of the sagittal plane is perpendicular to the joint surface, the center is located at the lower edge of the patella, and includes the femoral medial condyle and the femoral lateral condyle. Then, the magnetic resonance imaging apparatus images the knee joint of the subject in the identified sagittal plane. When the process of step S700b is completed, the process proceeds to step S800b.

[0080] In step S800b, the posture control device 20 measures the difference between the angle between the axial direction of the patellar ligament and the main magnetic field direction B0 and 54.74°.

[0081] Specifically, first, the body position control device 20 displays on the display device 30 a fourth graphical user interface for measuring the angle between the axial direction of the patellar ligament and the main magnetic field direction B0. FIG. 16 is a diagram showing an example of the fourth graphical user interface G4 for measuring the angle between the axial direction of the patellar ligament and the main magnetic field direction B0. As shown in FIG. 16, the fourth graphical user interface G4 displays the captured image of the subject's knee acquired in step S700b, and further displays an indicator I that can be moved arbitrarily superimposed on the captured image. The structure of the indicator I has been described in the first embodiment, so a redundant description will be omitted here. In FIG. 16, the position of the patellar ligament is indicated by a thick solid line, and the patellar ligament is a broken line and has two axial directions. In FIG. 16, the two axial directions of the patellar ligament are indicated by arrows L2 and L3, respectively.

[0082] Next, the operator moves the indicator I so that the intersection point D is located inside the patellar ligament. Then, the operator selects one of the auxiliary lines A1 and A2 for each of the two axial directions of the patellar ligament, and rotates the captured image so that the selected auxiliary line coincides with the axial direction L2 or L3. Note that instead of rotating the captured image, the indicator I itself may be rotated.

[0083] Thereafter, the posture control device 20 calculates the angle of rotation for each axis direction, and sets each angle to the difference between the angle between the two axis directions of the patella ligament and the main magnetic field direction B0 and 54.74°.

[0084] When the process of step S800b is completed, the process proceeds to step S900b.

[0085] In step S900b, the posture control device 20 judges whether the difference between the angle between the two axial directions of the patellar ligament and the main magnetic field direction B0 and 54.74° is within a threshold range, and if both are within the threshold range (Yes), the processing of the posture control method according to this embodiment ends, and if any difference is not within the threshold range (No), the processing proceeds to step S1000b. The threshold range is preferably 10° or more and 55° or less.

[0086] In step S1000b, the position control device 20 resets the deformation parameters for controlling the deformation of the position fixing device 10b based on the difference between the angle between the two axial directions of the patellar ligament and the main magnetic field direction B0 and 54.74°, and adjusts the imaging position of the knee. Specifically, the position control device 20 changes the angle between the two axial directions of the patellar ligament and the main magnetic field direction B0 from 54.74° to 10° or more and 55° or less.

[0087] According to the above embodiment, since the body position fixing device 10 that adjusts and fixes the imaging position of the imaging part of the subject is provided, the imaging part can be fixed in a desired imaging position without adjusting the body position of the whole body of the subject, and the subject does not feel uncomfortable. In addition, since the imaging part is supported by the body position fixing device 10 during imaging, no artifacts are generated due to the imaging part moving during imaging.

[0088] In addition, by using the indicator I, the difference between the angle α2 between the ligament axis direction and the main magnetic field direction B0 and 54.74° can be accurately measured, and the imaging position of the imaging part can be accurately adjusted to ensure that the magic angle effect does not occur in the ligament. This makes it possible to avoid overlapping imaging due to the inability to suppress the magic angle effect, and shorten the imaging time.

[0089] In the above embodiments, examples have been described in which the posture control system and posture control method are applied to control the imaging posture when performing magnetic resonance imaging of the ankle and knee. However, the above-mentioned posture control system and posture control method can also be applied to control the imaging posture for other parts of the body.

[0090] In the above embodiment, the indicator I includes two auxiliary lines. However, the number of auxiliary lines may be one.

[0091] The various data handled in this specification are typically digital data.

[0092] According to at least one of the embodiments described above, the imaging position of the imaging region can be accurately adjusted.

[0093] Although some embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0094] 1,1a Posture control system 10,10a,10b Body positioning device 20 Posture control device 30 Display device 40 Optical imaging device

Claims

1. A posture control system for controlling an imaging posture of an imaging region of a subject in imaging by a magnetic resonance imaging apparatus, comprising: a position fixing device that adjusts and fixes the imaging position of the imaging region by deformation; a posture control device that controls the deformation of the posture fixing device by transmitting deformation parameters to the posture fixing device; A display device for displaying an image; Equipped with the body position control device sets the deformation parameters, transmits them to the body position fixing device, and executes a parameter setting process to cause the body position fixing device to adjust the imaging position of the imaging region; Posture control system.

2. The posture control device includes: a differential measurement process for measuring a difference between an angle between an axial direction of a structure having collagen fibers in the imaging region and a main magnetic field direction of the magnetic resonance imaging apparatus and 54.74°; a first determination process for determining whether or not the difference is within a threshold range, and resetting the transformation parameters based on the difference when the difference is not within the threshold range; Further execute The posture control system according to claim 1 .

3. In the differential measurement process, the body position control device displays a graphical user interface on the display device, and displays on the graphical user interface an image of the imaging site, an indicator including an arrow indicating the main magnetic field direction, and an auxiliary line that is at an angle of 54.74° from the main magnetic field direction and intersects with the arrow at an intersection point, and measures the difference by moving the intersection point into the structure in the graphical user interface and rotating the image so that the axial direction of the structure coincides with the auxiliary line. The posture control system according to claim 2 .

4. an optical imaging device for imaging the imaging site of the subject; In the parameter setting process, the body position control device sets the deformation parameters based on the optical image captured by the optical imaging device, and causes the body position fixing device to adjust the imaging position of the imaging portion. The posture control system according to claim 2 .

5. In the parameter setting process, the body position control device performs image processing on the optical image using a neural network model to estimate an angle between the structure and the main magnetic field direction. The posture control system according to claim 4.

6. The structure is an Achilles tendon. The posture control system according to claim 2 .

7. The threshold range is 1° or less. The posture control system according to claim 6.

8. The structure is a ligament. The posture control system according to claim 2 .

9. The threshold range is 10° or more and 55° or less. The posture control system according to claim 8.

10. The posture control device includes: A second determination process is further performed to determine whether the imaging method of the imaging is T1 weighted imaging or proton density weighted imaging with a short echo time; When the imaging method is T1 weighted imaging or proton density weighted imaging with a short echo time, a message is displayed on the display device to warn an operator of the magic angle effect. The posture control system according to claim 1 .

11. The body positioning device is made of a non-magnetic material. The posture control system according to claim 1 .

12. The optical imaging device is made of a non-magnetic material. The posture control system according to claim 4.

13. A posture control method for controlling an imaging posture of an imaging region of a subject in imaging by a magnetic resonance imaging apparatus, comprising: a step of adjusting and fixing an imaging position of the imaging region by a deformation of a posture fixing device; A step of controlling the deformation of the body position fixing device by transmitting deformation parameters to the body position fixing device by a body position control device; A display device displays an image. Including, the body position control device sets the deformation parameters, transmits them to the body position fixing device, and executes a parameter setting process to cause the body position fixing device to adjust the imaging position of the imaging region; Posture control method.

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