Body movement display device, method for operating body movement display device, and diagnostic imaging system

Abstract

To provide a body movement display device, an operation method of the body movement display device, and an image diagnostic system capable of suppressing the movement of the line of sight of a subject and enabling the subject to satisfactorily recognize his / her own body movement.SOLUTION: In a body movement display 200 including a processor 210, a projection device 230 configured to display an image in a mode visually recognizable by a subject during an examination of the subject by an MRI device 100, and a body movement detection sensor including a first camera 220A and a second camera 220B configured to detect a body movement of the subject, the processor 210 generates a rotationally symmetric first diagram having a fixed center and a size that changes according to a magnitude of the body movement of the subject detected by the body movement detection sensor, and causes the projection device 230 to project the generated first diagram into a bore of the MRI device 100 as an image.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a body movement display device, a method for operating a body movement display device, and an image diagnostic system, and more particularly to a technique that allows a subject to clearly recognize his or her own body movement. [Background technology]

[0002] Magnetic resonance imaging (MRI) devices, used for diagnostic imaging, are widely used in the medical field because they can obtain information from the entire body of a living organism non-invasively.

[0003] MRI systems with these characteristics have long imaging times and are easily affected by the subject's movements during data acquisition, which affects image quality. Therefore, it is necessary to reduce the subject's movements during data acquisition. If the subject is notified of their own movements, they will pay more attention to them, which is expected to reduce their movements during imaging.

[0004] As a method for notifying the subject of body movements, a method of notifying by using graphics has been proposed (Patent Document 1).

[0005] The MRI device described in Patent Document 1 displays the respiratory state in a manner that can be visually recognized by the subject, and in particular, displays the depth of breathing using a scale and the position of a light spot, in order to efficiently perform respiratory-gated imaging. This allows the subject to adjust their own respiratory state. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-158762 Summary of the Invention [Problem to be solved by the invention]

[0007] In the case of the MRI device described in Patent Document 1, the subject moves his or her eyes when checking the scale indicating the depth of breathing or the light spot's light emission position, which raises the problem that the movement of the eyes is likely to induce movement of the head and movement of other parts of the body being imaged besides the head.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide a body movement display device, a method of operating a body movement display device, and an image diagnostic system that can further reduce the movement of the subject's line of sight and allow the subject to clearly recognize his or her own body movements. [Means for solving the problem]

[0009] The invention according to a first aspect is a body movement display device comprising a processor, a display that displays an image in a manner that is visible to the subject during examination of the subject using an imaging diagnostic device, and a body movement detection sensor that detects the body movement of the subject, wherein the processor generates a rotationally symmetric first figure with a fixed center that changes in size depending on the magnitude of the body movement of the subject detected by the body movement detection sensor, and displays the generated first figure as an image on the display.

[0010] According to the first aspect of the present invention, a subject undergoing an examination using an imaging diagnostic device can confirm the magnitude of his or her own body movement by looking at a rotationally symmetric first figure with a fixed center, the size of which changes according to the magnitude of the subject's movement, and in particular, since the center of the first figure (the center of rotational symmetry) does not move, the subject can fix his or her gaze when looking at the first figure. In other words, the movement of the subject's gaze can be further suppressed, and the movement of the head due to the movement of the gaze and the induction of movements of other imaging target parts other than the head can be reduced.

[0011] In the body movement display device according to the second aspect of the present invention, in the first aspect, it is preferable that the processor converts the magnitude of the subject's body movement into the size of a first figure and generates a first figure corresponding to the size of the converted first figure.

[0012] In a body movement display device according to a third aspect of the present invention, in the second aspect, the conversion of the magnitude of the subject's body movement into the size of the first figure is a linear conversion or a nonlinear conversion. When a linear conversion is used, the size of the first figure changes in a fixed relationship according to the magnitude of the body movement, making it an easy-to-understand method for displaying the state of body movement. On the other hand, when a nonlinear conversion is used, the first figure can be displayed with increased sensitivity for a magnitude of body movement for which further suppression is desired, thereby encouraging the subject to adjust their body movement.

[0013] In the body movement display device according to the fourth aspect of the present invention, in the second or third aspect, it is preferable that the conversion of the magnitude of the subject's body movement into the size of the first figure is a conversion weighted according to the magnitude of the effect of the subject's body movement on imaging by the imaging diagnostic device.

[0014] A body motion display device according to a fifth aspect of the present invention is the fourth aspect, wherein the magnitude of the effect of the body motion of the subject on imaging by the diagnostic imaging device varies depending on at least one of the region to be imaged of the subject by the diagnostic imaging device, the imaging sequence, and the k-space filling method. When converting the magnitude of the body motion of the subject into the size of the first figure, the conversion is weighted in consideration of the imaging conditions of the region to be imaged, the imaging sequence, and the k-space filling method, thereby making it possible to perform a conversion more suitable for displaying the state of the body motion affecting imaging.

[0015] A sixth aspect of the present invention is a body movement display device according to any one of the first to fifth aspects, wherein a boundary value is set as a boundary value for the magnitude of the body movement of the subject that is acceptable to the diagnostic imaging device, and which indicates a relationship with the size of the first graphic, and the processor preferably causes a second graphic, which has a size corresponding to the boundary value and is similar in shape to the first graphic, to be displayed on the display by aligning the center of the first graphic. By displaying the second graphic of a size corresponding to the boundary value on the display, the subject can adjust their body movement so that it does not exceed the second graphic, and since the second graphic is similar in shape to the first graphic and is aligned with the center of the first graphic, the first and second graphics can be simultaneously viewed without moving the subject's line of sight.

[0016] In the body movement display device according to a seventh aspect of the present invention, in the sixth aspect, it is preferable that the boundary value is set by at least one of the region to be imaged of the subject by the diagnostic imaging device, the imaging sequence, and the k-space filling method. When the magnitude of the body movement of the subject that the diagnostic imaging device allows can change depending on imaging conditions such as the region to be imaged of the subject, the imaging sequence, and the k-space filling method, it is preferable to set the boundary value according to the imaging conditions.

[0017] In the body movement display device according to the eighth aspect of the present invention, in the sixth or seventh aspect, it is preferable that the processor displays the first figure and the second figure on the display device with at least one of the color, line type, and brightness being different.

[0018] In a body movement display device according to a ninth aspect of the present invention, in any of the sixth to eighth aspects, the processor preferably generates a warning when the magnitude of the subject's body movement approaches a threshold value or exceeds a boundary value, thereby further encouraging the subject to suppress their body movement.

[0019] A body movement display device according to a tenth aspect of the present invention is the ninth aspect, wherein the warning is preferably given by one or more of a warning sound generator, a display, a lighting device in the gantry of the imaging diagnostic device, and a vibration generator.

[0020] In an eleventh aspect of the present invention, in any of the first to tenth aspects, the body movement display device is configured such that the body movement detection sensor comprises a camera that photographs the subject and outputs the image of the subject, and an image processing unit that processes the image to detect the subject's body movement, and the image processing unit preferably extracts an area of ​​the subject that is to be imaged by an imaging diagnostic device and is included in the image, obtains the movement of the extracted area between successive frames of the image as a body movement vector of the area to be imaged, and detects the magnitude of the subject's body movement from the body movement vector.

[0021] A twelfth aspect of the present invention is directed to the body movement display device of any of the first to eleventh aspects, wherein the first figure preferably has an outer shape of a circle or a regular polygon.

[0022] A thirteenth aspect of the invention is an image diagnostic system including an image diagnostic device and the body movement display device of any one of the first to twelfth aspects.

[0023] A fourteenth aspect of the present invention provides an imaging diagnostic system according to the thirteenth aspect, wherein the imaging diagnostic device includes a magnetic resonance imaging device or an X-ray CT device.

[0024] The invention according to a fifteenth aspect is a method for operating a body movement display device comprising a processor, a display that displays an image in a manner visible to the subject during examination of the subject by an imaging diagnostic device, and a body movement detection sensor that detects the subject's body movement, the method including the steps of: the processor acquiring the magnitude of the subject's body movement from the body movement detection sensor; the processor generating a first figure that is rotationally symmetric with a fixed center and whose size changes depending on the acquired magnitude of the subject's body movement; and the processor displaying the generated first figure as an image on the display. [Effects of the Invention]

[0025] According to the present invention, a subject undergoing an examination using an imaging diagnostic device can view a rotationally symmetric first figure with a fixed center, the size of which changes in response to the magnitude of the subject's body movement, allowing the subject to clearly recognize his or her own body movement. In particular, by viewing the rotationally symmetric first figure with a fixed center, the subject's line of sight movement can be further suppressed, and the movement of the head due to line of sight movement and the induction of movements of parts other than the head can be reduced. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a perspective view showing the appearance of a magnetic resonance imaging apparatus (MRI apparatus) to which the breathing movement display device according to the present invention is applied. [Figure 2] FIG. 2 is a diagram showing a schematic internal configuration of the MRI apparatus shown in FIG. [Figure 3]FIG. 3 is a diagram showing the external configuration of the main part of the body movement display device according to the present invention. [Figure 4] FIG. 4 is a block diagram showing an embodiment of an image diagnostic system according to the present invention. [Figure 5] FIG. 5 is a diagram showing an example of an image projected by a projector, and in particular a diagram showing an image in which a first graphic C1 and a second graphic C2 are combined. [Figure 6] FIG. 6 is a graph showing an example of the relationship between the magnitude of the subject's body movement and the size of the object (first figure). [Figure 7] FIG. 7 is a graph showing another example of the relationship between the magnitude of the subject's body movement and the size of the object (first figure). [Figure 8] FIG. 8 is a diagram showing the relationship between the change in size of the object (first figure) accompanying the change in the body movement of the subject and the change in the display of the object presented to the subject. [Figure 9] FIG. 9 is a flowchart showing an embodiment of a method for operating a body movement display device according to the present invention. [Figure 10] FIG. 10 is a diagram showing a part of a figure projected by a projector, and in particular a diagram showing a mark for fixing the line of sight. [Figure 11] FIG. 11 is a diagram showing a graphic formed by combining a first graphic H1 and a second graphic H2. DETAILED DESCRIPTION OF THE INVENTION

[0027] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a body movement display device, a method for operating a body movement display device, and an image diagnostic system according to the present invention will now be described with reference to the accompanying drawings.

[0028] FIG. 1 is a perspective view showing the appearance of a magnetic resonance imaging apparatus (MRI apparatus) to which the body movement display device according to the present invention is applied.

[0029] The MRI apparatus 100 shown in FIG. 1 includes a gantry 110 and a bed 130 having a top plate 130A arranged in front of a bore 120, which is a cylindrical imaging space provided in the gantry 110.

[0030] [Internal structure of an MRI device] FIG. 2 is a diagram showing a schematic internal configuration of the MRI apparatus shown in FIG.

[0031] As shown in FIG. 2, the MRI apparatus 100 includes a static magnetic field generating magnet 104 that generates a uniform static magnetic field in an imaging space in which a subject 102 is placed, a gradient magnetic field coil (GC: Gradient Coil) 106, an RF (Radio Frequency) coil (transmitting coil) 108, a receiving coil 140, a high frequency magnetic field generator 112, a receiver 114, and a gradient magnetic field power supply 116.

[0032] The gradient magnetic field coil 106 is composed of gradient magnetic field coils in three directions, X, Y, and Z, and generates gradient magnetic field pulses in the imaging space in response to signals from a gradient magnetic field power supply 116. The transmission coil 108 generates a high-frequency magnetic field in response to signals from a high-frequency magnetic field generator 112, which generates nuclear magnetic resonance (NMR) signals in the nuclei of atoms that make up the tissue of the subject 102.

[0033] The receiving coil 140 detects an NMR signal generated from the subject 102. The detected NMR signal is transmitted to the receiver 114 via a signal cable 142. The signal is converted from analog to digital by an AD (analog-to-digital) converter in the receiver 114, and measurement data (raw data) is generated.

[0034] The MRI apparatus 100 further includes a signal processing unit 118, a control unit 150, an operation unit 160, and a display unit 170.

[0035] The signal processing unit 118 performs an inverse Fourier transform on the measurement data generated by the receiver 114 to reconstruct an image, and outputs the reconstructed image signal to the control unit 150 and the display unit 170 .

[0036] 2 has been described as an example in which the receiving coil 140 is connected to the signal processing unit 118 and the control unit 150 via the signal cable 142, but the connection between the receiving coil 140 and the signal processing unit 118 and / or the control unit 150 is not limited to being wired, and may be wireless. As an example of a wireless connection, the receiving coil 140 further includes an AD converter and a wireless communication module, and digital data (e.g., measurement data) generated by the receiving coil 140 is sent wirelessly to the wireless communication module in the signal processing unit 118 and / or the control unit 150.

[0037] The control unit 150 has a measurement control unit and a calculation unit (not shown), and controls the entire device including the high-frequency magnetic field generator 112, the gradient magnetic field power supply 116, and the display unit 170. The display unit 170 displays the reconstructed image and the video of the subject 102 captured by the first camera 220A and the second camera 220B shown in Fig. 3, and also functions as a part of a user interface when the operator inputs various parameters, etc.

[0038] The control unit 150 sends commands to the high-frequency magnetic field generator 112 and the gradient magnetic field power supply 116 according to the area to be imaged of the subject (position and size of the specific area) and the imaging sequence (examination protocol (imaging plan), pulse sequence according to the imaging plan) determined by the operator operating the operation unit 160, and generates a high-frequency magnetic field and a gradient magnetic field, respectively.

[0039] There are multiple k-space filling methods for filling k-space (Fourier space) with data necessary for image reconstruction, and the k-space filling method is also set appropriately. Note that the k-space filling methods will be described in detail later.

[0040] Furthermore, the control unit 150 generates a file in a medical image format from the image signal designated by the operation unit 160 among the image signals processed by the signal processing unit 118, and registers it in an image database (not shown) or the like.

[0041] The signal processing unit 118 and the control unit 150 can be realized, for example, by a computer having a processor such as a CPU (Central Processing Unit) and a memory for storing control programs and parameters, etc., which executes calculation and control programs.

[0042] Fig. 3 is a diagram showing the external configuration of the main parts of a body movement display device according to the present invention. In Fig. 3, parts that are common to Figs. 1 and 2 are given the same reference numerals, and detailed description thereof will be omitted.

[0043] 3, a first camera 220A and a second camera 220B are arranged on the gantry 110 to capture images of the subject 102 in the bore 120. The first camera 220A and the second camera 220B function as part of a body movement detection sensor that detects body movements of the subject 102.

[0044] That is, the body movement detection sensor in this example includes a first camera 220A and a second camera 220B, and an image processing unit that detects body movement of the imaging target part of the subject 102 from images captured by at least one of the first camera 220A and the second camera 220B.

[0045] The image processing unit extracts the area of ​​the subject 102 to be imaged by the MRI device 100, which is included in the image captured by at least one of the first camera 220A and the second camera 220B, obtains the movement of the extracted area to be imaged between successive frames of the image as a body movement vector (displacement vector) of the area to be imaged, and detects the magnitude of the body movement of the subject from the obtained body movement vector.

[0046] Furthermore, when the imaging target area is the chest and / or abdomen, the respiratory bands 222A and 222B attached to the chest and / or abdomen of the subject 102 function as part of a body movement detection sensor for detecting body movement (respiratory movement) of the chest and / or abdomen of the subject 102, respectively.

[0047] The number of cameras is not limited to two, but may be one, or three or more. The installation position of the camera is not limited to diagonally above the subject or to the bore 120. Furthermore, the camera is not limited to a visible light camera, but may be, for example, an infrared camera.

[0048] The body movement detection sensor may be a sheet with multiple built-in pressure sensors that is placed under the subject. Body movement information of the subject can be obtained from pressure signals detected by the pressure sensors in the sheet in response to the movements of the subject 102.

[0049] The projector 230 projects an image into the bore 120 and functions as a display that displays the image in a manner that can be seen by the subject 102 during the examination of the subject 102.

[0050] [Imaging diagnostic system] FIG. 4 is a block diagram showing an embodiment of an image diagnostic system according to the present invention.

[0051] The image diagnostic system shown in Fig. 4 includes an MRI apparatus 100, which is an image diagnostic apparatus, and a body motion display device 200. The configuration of the MRI apparatus 100 is as specifically shown in Figs.

[0052] The body movement display device 200 is composed of a processor 210, a first camera 220A, a second camera 220B, and a projector 230.

[0053] The first camera 220A and the second camera 220B may be cameras that are originally provided in the MRI apparatus 100 for capturing images of the subject 102. Furthermore, instead of the first camera 220A and the second camera 220B, respiration bands 222A and 222B or other body movement detection sensors may be used.

[0054] Processor 210 is composed of a CPU and the like, and controls each part of body movement display device 200 , and executes various processes including a process for generating an image to be projected from projector 230 .

[0055] The processor 210 and the control unit 150 of the MRI apparatus 100 are capable of communicating with each other, and the processor 210 causes the projector 230 to project an image showing the body movements of the subject 102 into the bore 120 during an examination using the MRI apparatus 100.

[0056] In addition, when the signal processing unit 118 and the control unit 150 of the MRI apparatus 100 are configured by a computer equipped with a processor and memory as described above, the processor of the MRI apparatus 100 may function as the processor 210 of the body movement display device 200.

[0057] <First embodiment of body movement display device> Next, a first embodiment of a body movement display device according to the present invention will be described.

[0058] When a subject 102 enters an examination room in which an MRI device 100 is installed and lies down on the bed 130 of the MRI device 100, the top plate 130A of the bed 130 is controlled so that the imaging target area of ​​the subject 102 is positioned at the center of the imaging area within the bore 120, and then the MRI device 100 begins imaging the imaging target area of ​​the subject 102 according to the imaging sequence.

[0059] The processor 210 of the body movement display device 200 shown in FIG. 4 acquires an image captured by at least one of the first camera 220A and the second camera 220B during imaging (examination) by the MRI apparatus 100.

[0060] The processor 210 analyzes the acquired video of the subject 102 and extracts a video showing the imaging target region of the subject 102 or the vicinity of the imaging target region including the imaging target region. For example, if the imaging target region of the subject 102 is the abdomen, a video of the abdomen of the subject 102 or the vicinity of the abdomen including the abdomen is extracted from the video captured by at least one of the first camera 220A and the second camera 220B. If the imaging target region of the subject 102 is the head, a video of the head of the subject 102 or the vicinity of the head including the head is extracted from the video captured by at least one of the first camera 220A and the second camera 220B. It goes without saying that if the imaging target region is the head, a receiving coil that detects NMR signals generated from the head of the subject 102 is used. The imaging target region of the subject 102 can be acquired from the examination information of the subject 102.

[0061] Next, processor 210 acquires a body motion vector of the imaging target region using the extracted optical flow of the image. That is, processor 210 acquires a displacement vector of the imaging target region between adjacent frames of the image or of the periphery of the imaging target region including the imaging target region as a body motion vector (body motion information).

[0062] Then, processor 210 detects the magnitude of the subject's body movement from the body movement vector. Specifically, the magnitude of the subject's body movement is detected as the integral (area) of the body movement vector over a certain period of time. The certain period of time can be approximately the period during which the NMR signal is received within the TR (time to repeat), but is not limited to this and can be set appropriately.

[0063] In this example, the processor 210 functions as an image processing unit that analyzes the acquired video of the subject 102 and detects the magnitude of the subject's body movement, but an image processing unit different from the processor 210 may acquire video of the subject 102 from at least one of the first camera 220A and the second camera 220B, analyze the acquired video, and detect the magnitude of the subject's body movement. In addition, it is preferable to continuously detect the magnitude of the subject's body movement for each frame of the acquired video.

[0064] The processor 210 generates a rotationally symmetric object (first figure C1) with a fixed center whose size changes depending on the magnitude of the detected body movement of the subject 102, and projects the generated first figure C1 as an image from the projector 230 into the bore 120 (see Figure 5).

[0065] That is, the processor 210 converts the magnitude of the subject's body movement into the size of the first figure C1, and generates a first figure C1 corresponding to the size of the converted first figure C1. Details of the conversion of the magnitude of the subject's body movement into the size of the first figure C1 will be described later.

[0066] FIG. 5 is a diagram showing an example of an image projected by a projector, and in particular a diagram showing an image in which a first graphic C1 and a second graphic C2 are combined.

[0067] A boundary value is set as a value representing a relationship between the magnitude of the body movement of the subject 102 that is acceptable to the MRI apparatus 100 and the size of the first figure. Here, the boundary value is preferably set as a value of the magnitude of body movement (affecting imaging) at a level that may result in a body movement artifact. Therefore, as long as the magnitude of the body movement of the subject 102 does not exceed the boundary value, the image quality of the image captured by the MRI apparatus 100 will be acceptable.

[0068] The second graphic C2 has a size corresponding to the boundary value and is a graphic similar in external shape to the first graphic C1, and is a circle in this example.

[0069] The processor 210 can acquire the second figure C2 from memory within the processor 210 or from an external memory, and generates the image Im to be projected by combining the generated first figure C1 with the acquired second figure C2.

[0070] The size of the image Im shown in FIG. 5 (the size of the projection area projected into the bore 120 from the projector 230) can be, for example, about 20 cm×30 cm.

[0071] If the size of the image Im is 20 cm × 30 cm, the diameter of the second figure C2 can be about 15 cm. Although it is common to remove glasses during MRI imaging, even subjects with poor eyesight who cannot wear glasses can clearly see the second figure C2 of the above size.

[0072] The first graphic C1 included in the image Im generated by the processor 210 preferably differs from the second graphic C2 in at least one of color, line type, and brightness. The first graphic C1 shown in Fig. 5 is filled with a color and / or brightness different from that of the second graphic C2.

[0073] 3, the subject 102 is in a supine position, so the image projected from the projector 230 is projected onto the ceiling inside the bore 120 so that it can be seen by the subject 102, but if the subject is positioned in a lateral position, it is preferable to project the image onto the side of the bore 120 so that it can be seen by the subject in a lateral position. In other words, it is preferable that the processor 210 projects the image at a position inside the bore 120 that is easy for the subject to see, based on information about the subject's position.

[0074] <First embodiment of conversion of magnitude of subject's body movement into size of first figure> Processor 210 converts the magnitude of the subject's body movement into the size of first figure C1 and generates first figure C1 corresponding to the size of the converted first figure C1. Therefore, if the magnitude of the subject's body movement is large, the generated first figure C1 will also be large.

[0075] FIG. 6 is a graph showing an example of the relationship between the magnitude of the subject's body movement and the size of the object (first figure).

[0076] Processor 210 detects the magnitude of the subject's body movement from the image of the subject, and when converting the detected magnitude of the body movement into the size (diameter or area of ​​the circle) of the object (first figure C1), performs a linear conversion using the parameters shown in the dotted line graph in Figure 6, or a non-linear conversion using the parameters shown in the solid line graph in Figure 6.

[0077] Now, if the size (diameter or area) of the first figure is Cmax when the magnitude of the subject's body movement (integral value of the body movement vector over a certain time period) becomes the boundary value allowed by the MRI device 100, the processor 210 performs a linear or nonlinear transformation so that the size of the first figure changes in the range of 0 to Cmax when the magnitude of the subject's body movement changes in the range of 0 to the boundary value.

[0078] When linear conversion is performed, the size of the first figure C1 shown in Figure 5 changes in a fixed manner according to the magnitude of the body movement, making it an easy-to-understand method for displaying the state of body movement. On the other hand, when nonlinear conversion is performed, the sensitivity can be increased to display the first figure C1 for the magnitude of body movement for which further suppression is desired, thereby encouraging the subject to adjust their body movement.

[0079] In the case of the solid line graph showing the nonlinear transformation in FIG. 6, the closer the magnitude of the body movement is to the boundary value, the more abrupt the change in the size of the first figure becomes (the higher the sensitivity becomes).

[0080] FIG. 7 is a graph showing another example of the relationship between the magnitude of the subject's body movement and the size of the object (first figure).

[0081] In the case of the solid line graph showing the nonlinear transformation in Figure 7, in the range where the magnitude of the body movement is small, the change in size of the first figure in response to changes in the magnitude of the body movement is small (low sensitivity), in the range where the magnitude of the body movement is medium, the change in size of the first figure in response to changes in the magnitude of the body movement is steep (high sensitivity), and in the range where the magnitude of the body movement is large, the change in size of the first figure in response to changes in the magnitude of the body movement is almost the same as in the case of the dotted line graph showing the linear transformation.

[0082] In the case of the solid line graph showing the nonlinear transformation in Figure 6, the change in size of the first figure becomes more abrupt as the magnitude of the body movement approaches the boundary value, making the subject more conscious of trying to stop moving. On the other hand, in the case of the solid line graph showing the nonlinear transformation in Figure 7 (where the change in the first figure becomes more abrupt midway), the first figure is displayed large even for body movements that are not as large as those near the boundary value, so the subject can always be conscious of not moving.

[0083] FIG. 8 is a diagram showing the relationship between the change in size of the object (first figure) accompanying the change in the body movement of the subject and the change in the display of the object presented to the subject.

[0084] 8, processor 210 converts the body movement information into the size of the object (first graphic C1) (FIGS. 8(A) and (B)). In FIG. 8(B), the size of first graphic C1 in states A, B, and C is shown by a bar graph.

[0085] Here, state A indicates the state before body movement becomes large, state B indicates the state after state A when body movement becomes large, and state C indicates the state after state B when body movement becomes small.

[0086] Processor 210 generates a first figure C1 corresponding to the size of first figure C1 in states A, B, and C shown in Fig. 8(B), and combines the generated first figure C1 with a second figure C2 having a size corresponding to the boundary value to generate images in states A, B, and C. Processor 210 then causes projector 230 to project the generated images (images in states A, B, and C, etc.) into bore 120 (Fig. 8(C)).

[0087] During an examination by the MRI apparatus 100, the subject 102 can observe images of the object (first figure C1) display in the following order: state A → state B → state C (FIG. 8(C)). If the subject is observing state A of the object display and there is body movement of the region to be imaged, the object display transitions to state B. The subject looks at the object display and adjusts his or her body movement so as not to move the region to be imaged. Then, when the subject's movement is suppressed and the object display transitions from state B to state C, the subject can confirm by looking at the object display in state C that the movement of the region to be imaged has been reduced.

[0088] Note that the object displays in states A, B, and C shown in Figure 8 are shown in relation to changes in the body movements of the subject 102, but the image actually projected from the projector 230 into the bore 120 is a moving image that can change continuously in response to the body movements, and it is preferable that it is a moving image that changes continuously in accordance with the frame rate of the moving image (30 frames / second or 60 frames / second).

[0089] By viewing the image projected into the bore 120, the subject 102 can grasp the magnitude of his or her own body movement in real time and can suppress the body movement as necessary. Furthermore, the first figure C1 representing the magnitude of body movement in the image Im is a rotationally symmetric figure with a fixed center (in this example, the outer shape is circular), and only the size fluctuates and does not move. Therefore, the subject 102 can view the display without moving his or her line of sight, thereby minimizing eye movement and reducing head movement associated with eye movement and the induction of movements of parts other than the head.

[0090] Furthermore, in addition to the first graphic C1 representing the magnitude of the body movement, a second graphic C2 representing the magnitude of the boundary value is displayed concentrically with the first graphic C1, allowing the subject 102 to compare the first graphic C1 with the second graphic C2. This allows the subject 102 to understand the current magnitude of his or her body movement, and to suppress the body movement so that the first graphic C1 does not exceed the second graphic C2.

[0091] <Second embodiment of conversion of magnitude of subject's body movement into size of first figure> The magnitude of the body movement of the subject 102 and the magnitude of the effect on imaging by the MRI apparatus 100 due to the magnitude of the body movement of the subject 102 do not necessarily correspond one-to-one.

[0092] That is, the magnitude of the effect of the body movement of the subject 102 on the imaging of the MRI device 100 varies depending on, for example, the part of the subject to be imaged by the MRI device 100, the imaging sequence, and the space filling method. For example, even if the magnitude of the body movement of the subject 102 is the same, the effect on the imaging of the MRI device 100 varies depending on the part of the subject to be imaged, the imaging sequence, or the k-space filling method.

[0093] Therefore, when the processor 210 converts the magnitude of the subject's 102 body movement into the size of the first figure C1, it is preferable that the processor 210 performs a weighted conversion according to the magnitude of the effect of the subject's 102 body movement on the imaging of the MRI device 100.

[0094] The processor 210 acquires imaging conditions such as the imaging target area of ​​the subject 102, the imaging sequence, and the k-space filling method from the MRI device 100, and when converting the magnitude of the body movement of the subject 102 into the size of the first figure C1, it determines a weight corresponding to at least one of the imaging conditions (a weight according to the magnitude of the influence on the imaging of the MRI device 100) and performs the conversion with the determined weight.

[0095] For example, since it is necessary to reduce the body movement of the imaging target region during the acquisition period of the low-frequency region of k-space more than during the acquisition period of the high-frequency region of k-space, it is preferable to perform weighting so that the size of the circular area of ​​the first figure C1 changes more sharply during the period when signals of the low-frequency region are acquired. Furthermore, since the acquisition period of k-space differs depending on the imaging sequence and the k-space filling method, it is preferable to determine the height of the spatial frequency at a certain timing based on the parameters of the imaging sequence and the k-space filling method.

[0096] The specific details will be explained below.

[0097] K-space has low-frequency and high-frequency regions, with signals of high power present in the low-frequency region. Body movement during low-frequency signal acquisition results in artifacts (false images) that extend across the entire image when the inverse Fourier transform is performed. Therefore, it is even more important to avoid moving the imaging area during low-frequency signal acquisition. Therefore, when converting the magnitude of body movement into the size of the first figure C1, the conversion coefficient is weighted according to the height of the spatial frequency of the acquired signal. This allows the size (size of the circle area) of the first figure C1, which represents the subject's body movement during the acquisition period of the low-frequency region of k-space (compared to the acquisition period of the high-frequency region), to be displayed with greater sensitivity to body movement. By highlighting body movement during periods prone to artifacts, the subject can be encouraged to further suppress body movement during that period.

[0098] Furthermore, in the first embodiment of converting the magnitude of the subject's body movement into the size of the first figure, the magnitude of the subject's body movement is linearly or nonlinearly converted into the size of the first figure C1 as shown in the graphs of Figures 6 and 7, but it is preferable that the second embodiment of converting the magnitude of the subject's body movement into the size of the first figure be performed together with the first embodiment.

[0099] For example, in the case of the graph shown by the dotted line in Figure 6, a linear transformation is performed when converting the magnitude of the subject's body movement into the size of the first figure C1, but by weighting the parameters of this linear transformation according to the magnitude of the effect on imaging, the slope of the graph shown by the dotted line in Figure 6 can be changed, and this allows the size of the first figure C1 representing the subject's body movement to be changed more sensitively in response to the body movement.

[0100] [Set boundary values] The boundary values ​​allowed by the MRI apparatus 100 are preferably set according to imaging conditions such as the region to be imaged of the subject 102, the imaging sequence, and the k-space filling method by the MRI apparatus 100. The processor 210 acquires the imaging conditions from the MRI apparatus 100 and sets the boundary values ​​corresponding to the imaging conditions.

[0101] <First example of setting boundary values> For example, in a head DWI (Diffusion Imaging) or DTI (Diffusion Tensor Imaging) sequence, it is preferable to set the magnitude of the boundary value corresponding to the second graphic form C2 smaller than in other imaging sequences.

[0102] In head DWI or DTI sequences, movement of the imaging target region between a pair of MPG (Motion Probing Gradient) pulses can cause errors in the calculation of the diffusion coefficient, so it is desirable to minimize movement of the imaging target region during imaging. Therefore, by reducing the boundary value (by reducing the size of the circle in the second graphic C2 corresponding to the boundary value), the subject can be encouraged to minimize movement of the imaging target region. Furthermore, DWI or DTI sequences are generally often acquired after morphological imaging using other imaging sequences, such as T1W-based sequences or T2W-based sequences. In this case, by reducing the boundary value displayed during the other imaging sequence, the subject can be informed that it is desirable to minimize movement even more than in the previous imaging.

[0103] <Second example of boundary value setting> Even in high-resolution imaging in orthopedic areas such as knee joint examinations, it is desirable to keep the imaging target area as still as possible. Therefore, as in the first example above, by setting the boundary value smaller than that of other imaging sequences, the examinee can be informed that it is desirable to minimize the movement of the imaging target area.

[0104] <Third example of boundary value setting> For example, in an MRA (MR angiography) sequence, it is preferable to set the boundary value larger than in other imaging sequences.

[0105] MRA sequences generally require a long imaging time, and the need to keep the imaging target area still is not as great as when acquiring morphological images. Therefore, by increasing the boundary value, some movement is allowed. It also conveys to the subject that the tolerance for movement of the imaging target area is not strict.

[0106] Remaining motionless for a long period of time during imaging imposes a mental burden on the subject. Informing the subject of the period during which they can relax has the benefit of reducing the mental burden on the subject.

[0107] [Method of operating the body movement display device] FIG. 9 is a flowchart showing an embodiment of the operating method of the body movement display device according to the present invention, and shows the processing content and processing procedures by the processor 210 of the body movement display device 200 shown in FIG. 4 during an examination using the MRI device 100.

[0108] 9, once an examination is started by the MRI apparatus 100, the processor 210 repeatedly executes the processes from step S10 to step S70 until the examination is completed. Here, it is assumed that the processes from step S10 to step S70 are executed in accordance with the cycle of one frame of the camera image.

[0109] Processor 210 starts acquiring camera images from at least one of first camera 220A and second camera 220B that function as part of the body movement detection sensor (step S10).

[0110] Next, processor 210 calculates the magnitude of body movement of the subject's imaging target region using optical flow from the acquired camera image (step S20). Processor 210 acquires the body movement vector of the imaging target region between adjacent frames of the camera image, and detects the magnitude of the subject's body movement as the integral value (area) of the body movement vector over a certain period of time. Therefore, in step S20, once a certain period of time has passed since the start of acquisition of the camera image, the magnitude of body movement of the subject's imaging target region is detected (calculated) for each frame thereafter.

[0111] The processor 210 converts the magnitude of the detected body movement into the size of the object (first figure C1) (step S30). In this case, the processor 210 converts the magnitude of the body movement into the size of the first figure C1 according to preset parameters of linear or nonlinear transformation (see the graphs in FIGS. 6 and 7). Furthermore, during this conversion, it is preferable to perform the conversion with weighting according to imaging conditions such as the imaging target region, imaging sequence, and k-space filling method. This is because the influence of the subject's body movement on imaging by the MRI apparatus 100 differs depending on the imaging conditions.

[0112] Next, processor 210 generates a first graphic C1 corresponding to the size of the converted first graphic C1 (step S40). Since the first graphic C1 in this example has a circular outer shape, the size of the converted first graphic C1 corresponds to the diameter or area of ​​the circle.

[0113] The processor 210 causes the projector 230 to project (display) the generated first graphic C1 as an image inside the bore 120 (step S50). In this case, it is preferable that the processor 210 also simultaneously displays a second graphic C2 corresponding to a boundary value of the magnitude of the body movement of the subject 102. The second graphic C2 is a concentric circle having the same center as the first graphic C1 (see FIG. 5).

[0114] By observing the size of the first figure C1 contained in the image displayed within the bore 120, the subject can grasp the magnitude of his or her own body movement and can adjust (suppress) the body movement as necessary (step S60).

[0115] Next, the processor 210 determines whether the examination by the MRI apparatus 100 has ended (step S70). If it determines that the examination by the MRI apparatus 100 has not ended (examination is ongoing) (in the case of "No"), the process proceeds to step S10, and the processing from step S10 to step S70 is repeated. As described above, the processing from step S10 to step S70 is performed for each frame period, so that the image projected into the bore 120 displays the first figure C1 in real time according to the magnitude of the current body movement of the subject, and the subject can grasp the magnitude of his or her own body movement in real time by looking at the projected image.

[0116] On the other hand, if it is determined in step S70 that the examination by the MRI apparatus 100 has ended (in the case of "Yes"), the processor 210 ends the operation of the body movement display device 200. The processor 210 can determine whether imaging has ended based on communication with the control unit 150 of the MRI apparatus 100.

[0117] According to the operating method of the body movement display device of the present invention, the subject 102 can confirm the magnitude of his or her own body movement by viewing the image of the first figure C1, etc. projected into the bore 120. In particular, the size (diameter, area) of the first figure C1 changes depending on the magnitude of the body movement of the subject 102. However, because the first figure C1 has a circular shape with a fixed center, the subject 102 can view the first figure C1, etc., which changes in size, without moving his or her line of sight, thereby minimizing eye movement. This reduces head movement associated with eye movement and the induction of movements of parts other than the head.

[0118] <Second embodiment of body movement display device> Next, a second embodiment of the body movement display device according to the present invention will be described.

[0119] When examining the abdomen of a subject using the MRI apparatus 100, a respiratory-gated imaging method or a breath-holding imaging method is applied in order to reduce motion artifacts caused by the subject's breathing.

[0120] In respiratory gated imaging and the like, respiratory bands 222A and 222B shown in FIG. 3 are attached to the abdomen of the subject, and data is measured only when abdominal movement is small and stable (mainly during exhalation).

[0121] The second embodiment of the body movement display device differs from the first embodiment in that when respiratory-gated imaging or the like is performed by the MRI device 100, the display format of the image projected from the projector 230 is changed between during and during non-respiratory-gated measurement.

[0122] The following method is an example of changing the display format between images during respiratory synchronization measurement and images not during measurement.

[0123] (1) The brightness of the displayed figure or the entire image is changed. For example, the image is displayed brighter during data acquisition periods than during non-data acquisition periods, encouraging the subject 102 to suppress body movement. By changing the display brightness, the subject 102 is informed of whether respiratory-gated measurement is in progress or not, which can reduce the movement of the subject's line of sight compared to when the information is displayed in text.

[0124] (2) A few seconds before the start of the data acquisition period, the brightness is gradually changed (faded in) to the brightness of the data acquisition period. This allows the subject 102 to be notified in advance that data acquisition is about to begin.

[0125] (3) Change the color of the displayed figure. This includes changing the color display during respiratory synchronization measurement and black and white display during non-measurement.

[0126] According to the second embodiment, the subject 102 can be notified of the imaging period, and the subject 102 can suppress body movement (breathing) while watching the video during the imaging period.

[0127] <Third embodiment of body movement display device> The processor 210 of the third embodiment of the body movement display device differs from the first embodiment in that it generates a warning when the size of the first figure C1 approaches a boundary value corresponding to the magnitude of the subject's body movement that is acceptable to the MRI device 100 (approaches beyond a threshold value) or exceeds the boundary value.

[0128] The threshold value for determining whether the magnitude of the subject's body movement has approached the boundary value can be set to about 0.8 of the boundary value, but may be set appropriately.

[0129] The warning may be provided by one or more of an audible warning generator, a display, a lighting device within the gantry of the MRI apparatus 100, and a vibration generator.

[0130] The warning sound generator emits a beep or the like to notify the subject that the magnitude of the body movement is approaching the boundary value. The display including the projector 230 notifies the examiner that the magnitude of the body movement is approaching the boundary value, for example, by changing the graphic (by flashing the second graphic C2 corresponding to the boundary value). In addition, the lighting device in the gantry notifies the examiner that the magnitude of the body movement is approaching the boundary value by illuminating the light in the gantry.

[0131] The vibration generator may also vibrate a vibrator held by the subject to notify the examiner that the magnitude of the body movement is approaching a boundary value. In this case, the warning level can be changed by changing the frequency of the vibration, and the frequency can be increased as the boundary value is approached to call attention.

[0132] The above-mentioned warning sound generator, display device, lighting device in the gantry of the MRI apparatus 100, and vibration generator may be combined appropriately to generate a warning.

[0133] <Fourth embodiment of body movement display device> FIG. 10 is a diagram showing a part of the image projected by the projector 230, particularly showing the case where a mark for fixing the line of sight is displayed.

[0134] The processor 210 of the fourth embodiment of the body movement display device displays a mark M for gaze fixation at the center of the first figure C1 shown in Fig. 5. The mark M in this example is a cross mark, but is not limited to this.

[0135] Note that the first figure C1 shown in Fig. 5 is also displayed, but the first figure C1 is omitted in Fig. 10. Furthermore, even when the first figure C1 is displayed, it is preferable to combine the mark M, which has a different color and / or brightness from the first figure C1, on the first figure C1 so that the mark M is always visible.

[0136] According to the fourth embodiment, it is possible to further encourage the subject 102 to fix his / her gaze when visually recognizing the first figure C1 etc., and to prevent gaze movement that induces body movement including head movement.

[0137] [others] In this embodiment, the figure including the first figure C1 has a circular outer shape, but this is not limited to this and the figure may be a rotationally symmetric figure with a fixed center, for example, a regular polygon.

[0138] FIG. 11 is a diagram showing a figure projected by projector 230, and in particular a figure obtained by combining a first figure H1 that changes depending on the magnitude of body movement and a second figure H2 that corresponds to the magnitude of the boundary value.

[0139] The outer shape of the first figure H1 shown in Fig. 11 is a regular hexagon, and the second figure H2 is also a regular hexagon, and the centers of the first figure H1 and the second figure H2 are coincident. Note that the first figure H1 corresponds to the first figure C1 shown in Fig. 5, and the second figure H2 corresponds to the second figure C2 shown in Fig. 5, but the two figures have different outer shapes.

[0140] The first figure H1 corresponds to the first figure C1 shown in Figure 5, and the first figure H1 on the left side of Figure 11 indicates state A where body movement is sufficiently small, while the first figure H1 on the right side of Figure 11 indicates state B where body movement is large (approaching the boundary value second figure H2).

[0141] In addition, in this embodiment, the display that displays the first figure, etc. is a projector 230 that projects an image onto the bore 120 in the gantry 110 of the MRI device 100, but this is not limited to this, and examples include a head-up display, a head-mounted display, a monitor such as an LCD display or an organic EL display inside the bore 120, a monitor outside the bore 120, and a set of a mirror for viewing the monitor.

[0142] Furthermore, the diagnostic imaging device to which the body motion display device is applied is not limited to an MRI device, but may also be, for example, an X-ray CT device.

[0143] Furthermore, in this embodiment, each process is executed by any computer. Also, any computer may execute these processes by a processor, a program, or a combination thereof. Any computer may be a system such as a general-purpose computer, a specific-purpose computer, a workstation, or other hardware element capable of executing a program.

[0144] The processor may be composed of one or more pieces of hardware, and the type of hardware is not limited. For example, the processor may be composed of hardware such as a programmable logic device such as a CPU (Central Processing Unit), an MPU (Micro Processing Unit), or an FPGA (Field Programmable Gate Array), a dedicated circuit for executing specific processes such as an ASIC (Application Specific Integrated Circuit), a GPU (Graphic Processing Unit), or an NPU (Neural Processing Unit). The processor also has various units or means for executing various processes in the present embodiment. The type of hardware may also be a combination of different types of hardware. When multiple pieces of hardware are configured to execute one or more processes of a certain processor, the multiple pieces of hardware may exist in devices physically separated from each other or in the same device. In any of the embodiments, the order of the processes performed by the processor is not limited to the order described above and may be changed as appropriate. The hardware may be composed of an electric circuit or the like, which is a combination of circuit elements such as semiconductor devices.

[0145] Furthermore, the present embodiment may be implemented by hardware, software, firmware, microcode, or a combination thereof. Software, firmware, and microcode may be configured by a program. A program may also be, for example, a group of program modules, each function of which may be implemented by a processor configured to perform the respective function. The program may be program code or multiple code segments stored in one or more non-transitory computer-readable media (e.g., storage media or other storages). The program may be stored in multiple non-transitory computer-readable media that reside in physically separate devices. A program code or a code segment may represent a procedure, a function, a subprogram, a routine, a subroutine, a module, a software package, a class, or any combination of instructions, data structures, or program statements. A program code or a code segment may be connected to another code segment or a hardware circuit by sending or receiving information, data, arguments, parameters, or memory contents.

[0146] Furthermore, it goes without saying that the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0147] 100...MRI device 102...Subject 104...Static magnetic field generating magnet 106...Gradient magnetic field coil 108...Transmitting coil 110...Gantry 112...High frequency magnetic field generator 114...Receiver 116...Gradient magnetic field power supply 118...Signal processing unit 120…bore 130...Bed 130A...top plate 140...receiving coil 142...Signal cable 150...Control unit 160...Operation unit 170...Indicator 200...Body movement display device 210...processor 220A...1st camera 220B...Second camera 222A…Breathing band 230...Projector C1, H1...First figure C2, H2...Second figure Im…Video M...Mark S10 to S70: Steps for indicating the operation of the body movement display device

Claims

1. A body movement display device including a processor, a display device that displays an image in a manner that is visible to a subject during an examination of the subject by an imaging diagnostic device, and a body movement detection sensor that detects body movement of the subject, The processor: generating a rotationally symmetric first figure having a fixed center, the first figure changing in size depending on the magnitude of the body movement of the subject detected by the body movement detection sensor; displaying the generated first figure as the image on the display device; Body movement display device.

2. The processor: converting the magnitude of the body movement of the subject into the size of the first figure, and generating the first figure corresponding to the converted size of the first figure. The body movement display device according to claim 1 .

3. The transformation of the magnitude of the subject's body movement into the magnitude of the first figure is a linear transformation or a nonlinear transformation. The body movement display device according to claim 2 .

4. The conversion of the magnitude of the body movement of the subject into the size of the first figure is a conversion weighted according to the magnitude of the influence of the body movement of the subject on the imaging of the diagnostic imaging apparatus. The body movement display device according to claim 2 .

5. the magnitude of the influence of the body movement of the subject on the imaging of the diagnostic imaging apparatus varies depending on at least one of an imaging target region of the subject, an imaging sequence, and a k-space filling method of the diagnostic imaging apparatus; The body movement display device according to claim 4 .

6. a boundary value of the magnitude of the body movement of the subject that is allowed by the diagnostic imaging apparatus, the boundary value indicating a relationship with the size of the first figure, is set; the processor causes the display device to display a second figure having a size corresponding to the boundary value and having a similar outline to the first figure, with the center of the first figure being aligned with the center of the first figure; The body movement display device according to claim 1 .

7. the boundary value is set by at least one of an imaging target region of the subject, an imaging sequence, and a k-space filling method by the imaging diagnostic apparatus. The body movement display device according to claim 6 .

8. the processor causes the display device to display the first graphic and the second graphic with at least one of a color, a line type, and a brightness different from each other; The body movement display device according to claim 6 .

9. the processor generates a warning when the size of the first figure approaches or exceeds the boundary value by more than a threshold value. The body movement display device according to any one of claims 6 to 8.

10. the warning is issued by one or more of an alarm sound generator, the display, a lighting device in a gantry of the imaging diagnostic apparatus, and a vibration generator; The body movement display device according to claim 9 .

11. the body movement detection sensor includes a camera that captures an image of the subject and outputs an image of the subject, and an image processing unit that processes the image to detect body movement of the subject; The video processing unit includes: extracting a region of the subject to be imaged by the diagnostic imaging device included in the video; acquiring a motion of the extracted imaging target region between successive frames of the image as a body motion vector of the imaging target region; detecting a magnitude of the body movement of the subject from the body movement vector; The body movement display device according to any one of claims 1 to 8.

12. The first figure has an outer shape of a circle or a regular polygon. The body movement display device according to any one of claims 1 to 8.

13. the diagnostic imaging device; The body movement display device according to any one of claims 1 to 8, An imaging diagnostic system equipped with

14. The imaging diagnostic device includes a magnetic resonance imaging device or an X-ray CT device. The imaging diagnostic system according to claim 13.

15. 1. A method for operating a body movement display device including a processor, a display that displays an image in a manner that is visible to a subject during an examination of the subject using an imaging diagnostic device, and a body movement detection sensor that detects body movement of the subject, The processor acquires a magnitude of the body movement of the subject from the body movement detection sensor; generating a rotationally symmetric first figure with a fixed center, the first figure varying in size depending on the magnitude of the acquired body movement of the subject; a step of causing the processor to display the generated first figure as the image on the display; A method for operating a body movement display device, comprising:

Images