Diagnostic support device, diagnostic support method, and diagnostic support program

Abstract

To provide a diagnosis support device, a diagnosis support method and a diagnosis support program that can assist in diagnosis of a nervous disease.SOLUTION: A diagnosis support device includes a calculation unit for calculating a reduction ratio of current strength of an inward current which flows into a nerve tract on the basis of magnetic field data which is acquired by measurement of a magnetic field generated from an analyte.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a diagnostic support device, a diagnostic support method, and a diagnostic support program.

Background Art

[0002] For example, as a method for measuring a bio-magnetic field, a method is known in which an electrical stimulus is applied to a part of a subject to induce nerve activity in a site to be measured, and the magnetic field generated by the nerve activity is measured by a sensor. Further, a method is known in which nerve activity current is non-invasively evaluated by reconstructing the current generated in the living body using the magnetic field data obtained by measuring the bio-magnetic field with a sensor.

[0003] For example, the conduction velocity of the nerve activity current in the cauda equina can be non-invasively calculated by measuring the nerve magnetic field at the lumbar region when the peroneal nerve of the knee is stimulated and reconstructing the nerve activity current from the obtained magnetic field data. Further, by statistically analyzing the conduction velocity of the nerve activity current for a plurality of healthy subjects using the above method, the correlation between age and conduction velocity can be obtained (see, for example, Non-Patent Document 1).

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, a method for generating information capable of supporting the diagnosis of diseases such as lumbar vertebra from the nerve activity current calculated using the magnetic field data obtained by measuring the magnetic field generated from the subject has not been disclosed.

[0005] The disclosed technology has been made in view of the above problems, and an object thereof is to provide a diagnostic support device, a diagnostic support method, and a diagnostic support program capable of supporting the diagnosis of nerve diseases.

Means for Solving the Problems

[0006] To solve the above technical problems, a diagnostic support device according to one embodiment of the present invention includes a calculation unit that calculates a reduction rate of the current intensity of the inward current flowing into the nerve pathway based on magnetic field data obtained by measuring the magnetic field generated from a subject, and a display control unit that causes a display unit to display a comparison result obtained by comparing the reduction rate of the current intensity with a predetermined reference value. A reference change unit capable of changing the reference value based on information indicating a measurement site for calculating the current intensity, It is characterized by having the following.

Advantages of the Invention

[0007] It is possible to provide a diagnostic support device, a diagnostic support method, and a diagnostic support program capable of supporting the diagnosis of nerve diseases.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

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Figure 11

[0009] Hereinafter, embodiments will be described with reference to the drawings. In each drawing, the same reference numerals are given to the same components, and redundant descriptions may be omitted.

[0010] (First Embodiment) FIG. 1 is a configuration diagram showing an example of a biological information measurement system including a diagnostic support device according to the first embodiment of the present invention. For example, the biological information measurement system 100 shown in FIG. 1 includes a spinal cord evoked magnetic field measurement system that measures the magnetic field generated from nerves such as the spinal cord based on electrical stimulation.

[0011] The biological information measurement system 100 mainly includes a magnetic field measurement device 10, a cryostat 20, a nerve stimulation device 30, an X-ray imaging device 40, and a data processing device 50. The data processing device 50 is an example of a diagnostic support device. The nerve stimulation device 30 is a device that electrically stimulates the nerves from the body surface (skin) of the subject P. In FIG. 1, the X-ray imaging device 40 is arranged above the subject P, but it may be arranged on the side or both above and on the side.

[0012] The magnetic field measurement device 10 includes a SQUID sensor array 11 including a plurality of superconducting quantum interference devices (SQUIDs: Superconducting QUantum Interference Device) and a signal processing device 12. The magnetic field measurement device 10 can measure the magnetic field induced in the nerve to be measured of the subject P by the electrical stimulation of the nerve stimulation device 30.

[0013] In this embodiment, the magnetic field measurement device 10 is used as a magnetospinograph (MSG). Note that the magnetic field measurement device 10 can be used as a magnetoencephalograph (MEG) or a magnetocardiograph (MCG). Hereinafter, the superconducting quantum interference device is also referred to as SQUID.

[0014] The data processing device 50 has a function of controlling the timing of electrical stimulation of the living body by the nerve stimulation device 30 and a function of executing information processing of biological information such as the biomagnetic field measured by the magnetic field measurement device 10. Further, the data processing device 50 has a function of controlling the X-ray imaging of the subject P by the X-ray imaging device 40. The data processing device 50 has a function of receiving an input from input / output devices such as a mouse 50a and a keyboard 50b.

[0015] Furthermore, the data processing device 50 has a function of superimposing the direction of the current generated according to the magnetic field measured by the magnetic field measurement device 10 on the X-ray image and displaying it on the display device 50c. The data processing device 50 has a function of calculating the time change of the current value at a plurality of consecutive positions (virtual electrodes) indicated by an operator who operates the mouse 50a with respect to the image displayed on the display device 50c. For example, the operator indicates a plurality of positions along a nerve such as the spinal cord recognized by the X-ray image displayed on the display device 50c.

[0016] In addition, the data processing device 50 has a function of displaying the current waveform at each virtual electrode on the display device 50c. For example, when the decrease rate of the current intensity, which is the maximum amplitude of the current waveforms at adjacent virtual electrodes, is smaller than a preset reference value of the decrease rate, the data processing device 50 has a function of displaying text, a figure, or the like indicating that the decrease rate has become smaller at a position adjacent to the current waveform.

[0017] A part of the biological information measurement system 100 is disposed within a magnetic shield room 200 that shields magnetism. By using the magnetic shield room 200, a weak magnetic field (e.g., a spinal cord evoked magnetic field) generated from the subject P can be measured. The magnetic shield room 200 can be configured, for example, by laminating a plate material made of a high magnetic permeability material such as permalloy and a plate material made of a conductor such as copper or aluminum.

[0018] The magnetic shield room 200 has an internal space approximately 2.5 m in depth, 3.0 m in width, and 2.5 m in height, for example, and includes a door 210 that enables the conveyance of equipment and the entry and exit of people. The door 210 can be configured, like the other parts of the magnetic shield room 200, by laminating a plate material made of a high magnetic permeability material such as permalloy and a plate material made of a conductor such as copper or aluminum.

[0019] In this specification, the high magnetic permeability material refers to a material having a relative magnetic permeability greater than 1000. Examples of the high magnetic permeability material include, in addition to permalloy, single substances of iron, nickel, and cobalt, alloys thereof (including amorphous alloys, powders, and nanoparticles), and ferrites.

[0020] Hereinafter, the biological information measurement system 100 and its periphery will be described in more detail. A bed 300 is installed within the magnetic shield room 200. Also, a cryogenic container 20 is installed within the magnetic shield room 200, and a signal line 71 used for magnetic field measurement, control during measurement, etc. is connected to a SQUID sensor array 11 installed within a protruding portion 21 of the cryogenic container 20. The signal line 71 has a twisted cable structure to reduce magnetic field noise, and is drawn out of the magnetic shield room 200 through a hole penetrating the wall portion of the magnetic shield room 200 and connected to a signal processing device 12.

[0021] For example, the measurement of the spinal cord evoked magnetic field using the biological information measurement system 100 is performed with the subject P lying supine on the bed 300 in a resting state. By performing the measurement in a resting state, not only is the burden on the subject P reduced, but also the positional shift from the SQUID sensor array 11 due to the movement of the subject P can be reduced, and furthermore, magnetic field noise from muscles generated by muscle tension can be reduced.

[0022] The cryostat 20, also referred to as a Dewar, holds liquid helium necessary for operating the SQUID sensor array 11 that detects the magnetic field generated from the subject P at extremely low temperatures. The protruding portion 21 of the cryostat 20 has a shape suitable for the measurement of the spinal cord evoked magnetic field. For example, the measurement of the spinal cord evoked magnetic field is performed with the lumbar region of the supine subject P in contact with the protruding portion 21 and the lumbar region facing the tip of the SQUID sensor array 11.

[0023] When measuring the spinal cord evoked magnetic field, it is necessary to intentionally induce the nerve activity of the subject P by electrical stimulation. Therefore, electrical stimulation is applied using the nerve stimulator 30. For example, in this embodiment, electrical stimulation is alternately applied to the left tibial nerve and the right tibial nerve on the inner sides of both ankles, and the current conducted from upstream to downstream in the spinal cord is calculated based on each electrical stimulation. Here, upstream indicates a position relatively close to the stimulation position where the electrical stimulation is applied, and downstream indicates a position relatively far from the stimulation position. For this reason, the two electrode pairs connected to the nerve stimulator 30 via the two signal lines 72 having a twisted cable structure are respectively attached to the skin on the inner sides of both ankles.

[0024] Then, the electrical stimulation alternately applied to the subject P from the electrode pairs excites the tibial nerves of both feet of the subject P alternately, and the nerve activity due to the excitation is propagated to the central nervous system. Then, the magnetic field generated from the spinal cord and spinal nerves in the lumbar region is detected by the SQUID sensor array 11 facing the lumbar region of the subject P.

[0025] Incidentally, the two electrode pairs may be attached at positions on both feet where nerves other than the tibial nerve can be electrically stimulated. Also, the measurement site of the biomagnetic field based on the electrical stimulation from both feet may be the chest or neck. Further, when measuring the biomagnetic field of the neck, the two electrode pairs may be attached at positions where the nerves of both hands can be electrically stimulated.

[0026] By alternately applying electrical stimulation from the two electrode pairs and alternately measuring the biomagnetic field, it is possible to detect the difference in the current waveform conducted to the spinal cord via the left and right nerves. And based on the difference in the current waveform, information for specifying the lesion site can be provided to an evaluator such as a doctor.

[0027] For example, the data processing device 50 is a computer such as a PC (Personal Computer), and is connected to the signal processing device 12, the nerve stimulation device 30, and the X-ray imaging device 40 via signal lines. And the data processing device 50 controls the operations of the magnetic field measurement device 10, the nerve stimulation device 30, and the X-ray imaging device 40.

[0028] FIG. 2 is a perspective view showing an example of the SQUID sensor array 11 provided in the protruding portion 21 of the cryostat 20 in FIG. 1. For example, the SQUID sensor array 11 has a rod shape extending in the vertical direction and has a plurality of SQUID sensors 11a arranged in a staggered pattern in a top view. Each SQUID sensor 11a is arranged so that its upper end faces the measurement target site of the subject P lying on the bed 300. In this embodiment, the plurality of SQUID sensors 11a are arranged in the protruding portion 21 so that their upper ends are slightly curved in accordance with the curved shape when measuring the magnetic field of the waist of the subject P.

[0029] Each SQUID sensor 11a measures the magnetic field generated by the subject P based on an instruction from the signal processing device 12, and outputs the measured magnetic field to the signal processing device 12 as a voltage signal (magnetic field signal indicating the magnetic field). For example, each SQUID sensor 11a is a three-axis sensor having the X-axis, Y-axis, and Z-axis, and can measure the magnetic field signal as a three-dimensional vector quantity. Note that each SQUID sensor 11a may be a two-axis sensor having the X-axis and Y-axis that can measure the magnetic field signal as a two-dimensional vector quantity, or may be a one-axis sensor having only the Z-axis.

[0030] The signal processing device 12 shown in FIG. 1 estimates the nerve activity current at a specified measurement point based on the relationship between the position of the nerve of the subject P on the X-ray image and the position of each SQUID sensor 11a, and the magnetic field data obtained by measuring the magnetic field generated from the subject P by the plurality of SQUID sensors 11a. For example, an estimation algorithm such as a spatial filter method is used for the estimation of the nerve activity current. Thereby, a current waveform indicating the temporal change of the nerve activity current at an arbitrary position facing the SQUID sensor array 11 can be obtained. Note that in order to remove artifacts from the magnetic field data obtained by measuring the magnetic field, an artifact reduction method such as the DSSP (Dual Signal Sub-space Projection) method may be applied.

[0031] FIG. 3 is a diagram showing an example of the functional blocks of the data processing device 50 in FIG. 1. The data processing device 50 includes an input control unit 510, an arithmetic unit 520, a display control unit 530, and a storage unit 540. For example, the input control unit 510, the arithmetic unit 520, and the display control unit 530 are realized by a data processing program executed by a processor such as a CPU (Central Processing Unit) mounted on the data processing device 50.

[0032] The calculation of the reduction rate of the current intensity of the inward current by the input control unit 510, the calculation unit 520, and the display control unit 530 described below, and the display of the comparison result obtained by comparing the reduction rate of the current intensity with a predetermined reference value are realized by executing a diagnostic support program among data processing programs. Then, when a processor such as a CPU executes the diagnostic support program, a diagnostic support method is implemented.

[0033] Note that the input control unit 510, the calculation unit 520, and the display control unit 530 may be realized by hardware such as an FPGA, or may be realized by a combination of software and hardware. The calculation unit 520 is an example of a calculation unit that calculates the reduction rate of the current intensity of the inward current flowing into the nerve path based on the magnetic field data obtained by measuring the magnetic field generated from the subject P.

[0034] For example, the storage unit 540 is realized by at least any one of semiconductor storage devices such as DRAM (Dynamic Random Access Memory), SRAM (Static Random Access Memory), ROM (Read Only Memory), and flash memory. Note that the storage unit 540 may be realized by a combination of a semiconductor storage device and an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

[0035] The input control unit 510 includes a position input unit 511 and a waveform region specifying unit 512. The calculation unit 520 includes a path generation unit 521, a virtual electrode generation unit 522, a reconstruction analysis unit 523, a current component extraction unit 524, a current intensity calculation unit 525, a reduction rate determination unit 526, and a reference change unit 527. The display control unit 530 includes an image display unit 531, a waveform display unit 532, and a reduction rate abnormality display unit 533. Note that the display control unit 530 may be disposed outside the data processing device 50. A storage area for storing the biomagnetic field data 541, the morphological image data 542, the analysis setting value 543, and the reduction rate reference value 544 is allocated to the storage unit 540.

[0036] The input control unit 510 receives operations of a mouse 50a, a keyboard 50b, etc. by an operator of the magnetic field measurement device 10. The position input unit 511 receives the positions of control points for expressing a nerve pathway such as the spinal cord on a morphological image such as an X-ray image displayed on the display device 50c. The position information received by the position input unit 511 is stored in the storage unit 540 as analysis setting value 543. The waveform area designating unit 512 receives the time range for displaying the current waveform calculated by the virtual electrode on the display device 50c. The virtual electrodes set on a nerve pathway such as the spinal cord on the morphological image are an example of second virtual electrodes arranged at predetermined intervals along the nerve course.

[0037] The pathway generation unit 521 calculates the pathway of the active nerve based on the position information of a plurality of control points input from the position input unit 511. The set nerve pathway is referred to as a nerve course. Here, the calculated pathway is represented by a plurality of coordinate information or an expression indicating a curve, etc., and is stored in the storage unit 540 as analysis setting value 543.

[0038] The virtual electrode generation unit 522 generates a plurality of virtual electrodes A, for example, at equal intervals on the nerve course calculated by the pathway generation unit 521. Further, on the virtual electrode A on the nerve course, a virtual electrode B is generated at a point separated by an arbitrary distance in the normal direction of the nerve course. The interval between the virtual electrodes generated on the pathway, the distance in the normal direction, and the number are specified by the operator via an input device such as the mouse 50a or the keyboard 50b, and are stored in the storage unit 540 as analysis setting value 543 by the input control unit 510.

[0039] The reconstruction analysis unit 523 reconstructs the current components for each voxel arranged in a matrix at predetermined intervals using the magnetic field data of the subject P obtained by measuring the biomagnetic field by the magnetic field measurement device 10. The voxel is an example of a first virtual electrode installed in a predetermined region including the acquisition site of the magnetic field data.

[0040] The current component extraction unit 524 extracts the radio wave waveforms of each virtual electrode using the current components at the voxels calculated by the reconstruction analysis unit 523 based on the positional relationship between each virtual electrode and the voxel. For example, the current component extraction unit 524 extracts, as the intra-axonal current that conducts along the nerve axon in the nerve pathway, the current component at the virtual electrode A along the nerve pathway (with the direction from upstream to downstream being positive and the direction from downstream to upstream being negative) within the time range received by the waveform region specifying unit 512.

[0041] Also, the current component extraction unit 524 extracts, as the inward current, the current component in the normal direction to the nerve pathway on the virtual electrode B with the direction toward the nerve pathway being positive within the time range received by the waveform region specifying unit 512. Then, the current waveform of the inward current is generated based on the time change of the extracted inward current. Among the volume currents flowing outside the nerve axon, the inward current, which is the current component flowing into the depolarized part, is important for evaluating nerve function. The current waveform is generated, for example, by the waveform display unit 532 arranging the values of the inward current in chronological order as image data. The current component extraction unit 524 and the waveform display unit 532 are examples of a waveform generation unit that generates the waveform of the inward current at the virtual electrode.

[0042] The current intensity calculation unit 525 calculates the maximum value of the amplitude of the current waveform of the inward current for each virtual electrode calculated by the current component extraction unit 524 as the current intensity. For example, the current intensity calculation unit 525 calculates the amplitude of the positive value of the current waveform as the current intensity.

[0043] The decrease rate determination unit 526 calculates the decrease rate (%) of the current intensity of the inward current for each pair of adjacent virtual electrodes. For example, the decrease rate determination unit 526 calculates the decrease rate (%) of the current intensity according to Equation (1). In Equation (1), the symbol "*" indicates a product. Decrease rate of current intensity (%) = ((downstream current intensity CS2) / (upstream current intensity CS1)) * 100 ‥(1)

[0044] The decrease rate determination unit 526 compares the calculated decrease rate of the current intensity with a predetermined reference value (%) set in advance. For example, the decrease rate determination unit 526 determines whether the calculated decrease rate of the current intensity is smaller than the predetermined reference value. When the calculated decrease rate of the current intensity is smaller than the preset reference value of the decrease rate, the decrease rate determination unit 526 outputs the calculated decrease rate of the current intensity, as a comparison result, to the decrease rate abnormality display unit 533, for example, together with the position information of the virtual electrode downstream where the current intensity was calculated. Instead of outputting the comparison result, the calculated decrease rate of the current intensity and the predetermined reference value (the preset reference value of the decrease rate (%)) may be output and displayed on the display device 50c.

[0045] The reference change unit 527 changes the reference value of the decrease rate based on the information indicating the measurement site for calculating the current intensity of the inward current, which is input via an input device such as the mouse 50a or the keyboard 50b. For example, the reference value of the decrease rate for each measurement site is stored in the storage unit 540 as the decrease rate reference value 544. By making it possible to change the reference value of the decrease rate, an appropriate reference value can be set according to the measurement site, and the diagnosis of spinal cord diseases can be appropriately supported. Note that the reference change unit 527 may store the reference value of the decrease rate input from the keyboard 50b or the like in the storage unit 540 as the decrease rate reference value 544.

[0046] As shown in FIGS. 5 and 6, the image display unit 531 superimposes small white arrows representing the direction and intensity of the current at each voxel reconstructed by the reconstruction analysis unit 523 on the morphological image (X-ray image) and displays it on the display device 50c. Also, as shown in FIG. 7, the image display unit 531 superimposes the nerve path calculated by the path generation unit 521 and the virtual electrode generated by the virtual electrode generation unit 522 on the X-ray image and displays it on the display device 50c.

[0047] The waveform display unit 532 associates the current waveform for each virtual electrode calculated by the current component extraction unit 524 with the virtual electrode superimposed on the X-ray image and displays it on the display device 50c.

[0048] When the abnormal decrease rate display unit 533 receives the decrease rate of the current intensity and the position information of the virtual electrode from the decrease rate determination unit 526, it causes the display device 50c to display abnormal information indicating that the decrease rate of the current intensity is abnormal. For example, the abnormal information is displayed on or beside the current waveform of the virtual electrode indicated by the position information received from the decrease rate determination unit 526 as a value of the decrease rate, text such as "abnormal decrease rate", or a blinking figure.

[0049] In the storage area of the biomagnetic field data 541, the magnetic field data obtained by measuring the magnetic field generated from the subject P by the magnetic field measurement device 10 is stored. In the storage area of the morphological image data 542, the X-ray image data of the magnetic field measurement target part of the subject P taken by the X-ray imaging device 40 is stored.

[0050] In the storage area of the analysis setting value 543, various parameters necessary for measuring the biomagnetic field by the magnetic field measurement device 10 and various setting values such as filters (high-pass filter, low-pass filter) used for the magnetic field data obtained by measuring the biomagnetic field are stored in advance. Also, in the storage area of the analysis setting value 543, position information indicating the position of the voxel, which is the calculation point of the current on the image displayed on the display device 50c, and the position of the virtual electrode for acquiring the current waveform are stored in advance.

[0051] In the storage area of the decrease rate reference value 544, the reference value of the current intensity referred to by the decrease rate determination unit 526 is stored in advance. Although not particularly limited, for example, the reference value of the decrease rate in the lumbar spine is 70%. When the distance between the virtual electrodes is n (mm), the value of n to the power of 0.97 (percentage) may be defined as the reference value of the decrease rate, and the decrease rate of the current intensity may be set according to the distance between the virtual electrodes. By setting the reference value of the decrease rate of the current intensity when the distance between the virtual electrodes is several mm, it becomes possible to compare with the reference value with a spatial resolution of several mm.

[0052] FIG. 4 is a diagram showing an example of a model of neural activity current. FIG. 4 shows how current is generated by the activity of a nerve running linearly in the vertical direction of the figure. The lower side of FIG. 4 is the peripheral side, and the upper side of FIG. 4 is the central side. For example, by applying an electrical stimulus to the peripheral nerve, the stimulus is conducted as an electric current from the lower side to the upper side along the nerve axon.

[0053] At this time, an in-axon current flowing toward the upper side (forward direction) of FIG. 4 and an in-axon current flowing toward the lower side (reverse direction) of FIG. 4, and a volume current which is a current component flowing outside the nerve axon and returning to the depolarized point are generated. The in-axon current flowing toward the upper side of FIG. 4 is called the leading component, and the in-axon current flowing toward the lower side of the figure is called the trailing component.

[0054] In order to evaluate the nerve function in detail, it is preferable to extract an in-axon current flowing along the nerve axon, that is, a current component in the direction along the nerve course, and an inward current flowing into the depolarized point, that is, a current component in the direction from the normal direction with respect to the nerve course, and visually display them on the display device 50c.

[0055] FIGS. 5 and 6 are diagrams showing examples of the temporal change of the current distribution extracted based on the magnetic field data at the measurement target site (central nerve) acquired by the biological information measurement system 100 of FIG. 1. The images shown in FIGS. 5 and 6 are images in which the current components for each voxel reconstructed by the reconstruction analysis unit 523 are superimposed on the X-ray image by the image display unit 531 and are displayed on the screen of the display device 50c at once. Note that either the image of FIG. 5 or the image of FIG. 6 may be displayed on the screen of the display device 50c, or the image at the specified time may be enlarged and displayed.

[0056] The image shown in FIG. 5 shows the time change of the current distribution calculated from the magnetic field data obtained by measuring the biomagnetic field generated when an electrical stimulus is applied to the tibial nerve on the inner side of the right ankle of the subject P who may have a lumbar disc herniation, for example. The image shown in FIG. 6 shows the time change of the current distribution calculated from the magnetic field data obtained when an electrical stimulus is applied to the tibial nerve on the inner side of the left ankle of the same subject P. The images shown in FIGS. 5 and 6 have current components superimposed on the X-ray image taken from above of the subject P lying supine on the bed 300. For this reason, the left side of the image at each time corresponds to the right side of the subject P, and the right side of each image corresponds to the left side of the subject P.

[0057] The times such as "8.500 ms" shown above each image in FIGS. 5 and 6 indicate the elapsed time since the electrical stimulus was applied. The thick dotted line spanning the images arranged horizontally indicates the boundary (L4 / 5) between the fourth lumbar vertebra (L4) and the fifth lumbar vertebra (L5). Note that the arrows arranged between the images at each time are added for easy understanding of the passage of time and may not be displayed on the screen of the display device 50c.

[0058] In each image, a plurality of small white arrows indicate the direction of the current for each voxel extracted by reconstruction, and the length of the arrow indicates the current intensity. The end of the arrow opposite to the arrowhead is the position of the voxel that is the extraction unit of the current component. Also, the contour-like curve is a current intensity distribution line generated by connecting the positions where the current intensity is the same.

[0059] In the image at each time, the dotted arrow indicates the intra-axonal current, and the shaded arrow indicates the inward current. The dotted arrow and the shaded arrow are added for explanation and are not included in the image displayed on the display device 50c.

[0060] In order to obtain the magnetic field data used for calculating the current components shown in FIGS. 5 and 6, first, the subject P is placed in a supine position on the bed 300 of FIG. 1 so that the lumbar region of the subject P faces the SQUID sensor array 11. Next, a simple X-ray image of the lumbar region of the subject P is taken, and the data processing device 50 obtains the positional relationship between each SQUID sensor 11a and the lumbar vertebrae of the subject P.

[0061] Next, the electrodes of the nerve stimulator 30 are attached to the inner parts of the ankles of both feet, and electrical stimulation (a 5 Hz square wave pulse with a duration of 0.3 ms) is alternately applied to the left and right tibial nerves. Then, the nerve-induced magnetic field generated at the lumbar region in response to the electrical stimulation is measured by the magnetic field measurement device 10.

[0062] In FIG. 5 showing the time change of the current distribution when the right tibial nerve is electrically stimulated, as indicated by the dotted arrow, it is observed that the leading and trailing components of the axonal current that invaded from the L5 intervertebral foramen on the right side (left side in FIG. 5) of the subject P are conducted downstream. Also, as indicated by the shaded arrow, it is observed that an inward current is generated toward the nerve axon.

[0063] Also in FIG. 6 showing the time change of the current distribution when the left tibial nerve is electrically stimulated, as indicated by the dotted arrow, it is observed that the leading and trailing components of the axonal current that invaded from the L5 intervertebral foramen on the left side (right side in FIG. 6) of the subject P are conducted downstream. Also, as indicated by the shaded arrow, it is observed that an inward current is generated toward the nerve axon.

[0064] FIG. 7 is a diagram showing an example of the change in the current waveform when the inward current observed in FIGS. 5 and 6 is conducted from upstream to downstream. The current waveform shown in FIG. 7 is calculated on the virtual electrode by the current component extraction unit 524. In the waveform of the inward current corresponding to FIG. 5, a decrease in the current intensity is seen at the position of the L4 / 5 intervertebral disc. The arrow shown in the waveform of the inward current corresponding to FIG. 5 is added for easy explanation and indicates the amplitude amount (current intensity) of the positive value of the current waveform used for calculating the decrease rate.

[0065] In the two X-ray images shown in FIG. 7, virtual electrodes installed at positions shifted toward the center of the body with respect to the nerve path added for reference are superimposed and displayed. And in the X-ray image, an arrow pointing from the virtual electrode toward the nerve path indicates an inward current. In this way, virtual electrodes for extracting the inward current are set at intervals at positions separated from the nerve path by a predetermined distance. Also, virtual electrodes for extracting the inward current are set on the side opposite to the side to which the electrical stimulation is applied. For example, in the X-ray image corresponding to FIG. 5, since the tibial nerve of the right ankle (left side in FIG. 7) is electrically stimulated, virtual electrodes are set on the left side of the subject P (right side in FIG. 7) with respect to the nerve path.

[0066] The reduction rate determination unit 526 determines that the reduction rate of the current intensity at the position of the L4 / 5 intervertebral disc is lower than the reference value of the reduction rate, and outputs the reduction rate of the current intensity together with the position information of the virtual electrode corresponding to the position of the L4 / 5 intervertebral disc to the reduction rate abnormality display unit 533. Note that the reduction rate of the current intensity is calculated by the ratio of the current intensity at the virtual electrode of interest and the current intensity at one upstream virtual electrode (in this example, the position of the L5 / S1 intervertebral disc) as shown in Equation (1).

[0067] The reduction rate abnormality display unit 533 causes the display device 50c to display, as abnormal information, the information indicating the reduction rate of the current intensity received from the reduction rate determination unit 526 adjacent to the corresponding current waveform. In the example shown in FIG. 7, 63%, which is the reduction rate calculated by the reduction rate determination unit 526, is displayed on the display device 50c as the text "reduction rate 63%".

[0068] The text indicating the reduction rate may be a color that is more prominent than the color of the waveform, or it may blink. Also, the display of the reduction rate is not limited to text, and may also be a figure, a pop-up, etc. The position where the reduction rate is displayed is not limited to a position adjacent to the waveform, as long as it can correspond to the corresponding waveform. For example, the reduction rate may be displayed beside the virtual electrode superimposed on the X-ray image. Furthermore, as long as the display of the reduction rate can be associated with the waveform, it may be displayed at the upper part or the lower part, etc. of the image. In this case, the color of the virtual electrode corresponding to the reduction rate to be displayed may be made different from the colors of the other virtual electrodes, and furthermore, the figure of the corresponding virtual electrode may be made to blink.

[0069] On the other hand, in the waveform of the inward current corresponding to FIG. 6, no decrease in current intensity is observed at the position of the L4 / 5 intervertebral disc. Therefore, the reduction rate determination unit 526 does not output the reduction rate of the current intensity to the reduction rate abnormality display unit 533. Note that since the waveform indicated by No. 7 is a current waveform outside the diagnosis target, the reduction rate determination unit 526 does not determine the decrease in current intensity.

[0070] In the images corresponding to FIGS. 5 and 6, a plurality of reduction rates corresponding to each of all the virtual electrodes that generated the current waveforms may be displayed adjacent to the corresponding waveforms or the corresponding virtual electrodes. In this case, the color displayed on the screen may be changed according to whether the reduction rate of the current intensity is smaller than the reference value, or the size or type of the font may be changed. Thereby, the evaluator can recognize the transition of the reduction rate of the current intensity.

[0071] The MR (Magnetic Resonance) image shown on the left side of FIG. 7 is for reference and may not be displayed on the display device 50c. The display control unit 530 causes the display device 50c to display the X-ray image superimposed with the virtual electrodes corresponding to FIGS. 5 and 6 and the waveform of the inward current side by side. An evaluator such as a doctor observing the image shown in FIG. 7 can recognize the decrease in current intensity at the position of the L4 / 5 intervertebral disc due to the electrical stimulation of the right tibial nerve.

[0072] Then, for example, with reference to the image shown in FIG. 7, the evaluator observes separately captured MR images or the like to diagnose the presence or absence of L4 / 5 intervertebral disc herniation or the like. For example, an evaluator who has seen the image shown in FIG. 7 can recognize the image shown in FIG. 5 as an image of the healthy side without impairment and the image shown in FIG. 6 as an image of the affected side with impairment. As a result, the evaluator can, for example, diagnose an L4 / 5 intervertebral disc that protrudes predominantly to the right in the MR image as an intervertebral disc herniation. That is, the image shown in FIG. 7 generated by the data processing device 50 enables the diagnosis of spinal cord diseases to be supported.

[0073] Also, in the evaluation of the peripheral nerves, a reference value of the current intensity, which is referred to by the decrease rate determination unit 526, is stored in advance in the storage area of the decrease rate reference value 544. Although not particularly limited, for example, the reference value of the decrease rate in the carpal tunnel is 70%. When the distance between the virtual electrodes is n (mm), a value obtained by raising 0.97 to the power of n (percentage) may be defined as the reference value of the decrease rate, and the decrease rate of the current intensity may be set according to the distance between the virtual electrodes. By setting the reference value of the decrease rate of the current intensity at a distance of several millimeters between the virtual electrodes, it becomes possible to compare with the reference value with a spatial resolution of several millimeters.

[0074] FIG. 8 is a diagram showing another display example of the abnormality information indicating the decrease rate of the current intensity to be displayed on the decrease rate abnormality display unit 533 in FIG. 3. For example, the decrease rate determination unit 526 in FIG. 3 calculates the decrease rate (%) of the current intensity of the inward current for each pair of adjacent virtual electrodes. The decrease rate abnormality display unit 533 causes the display device 50c to display the value of the current intensity of each virtual electrode indicated by 0 to 8 calculated by the current intensity calculation unit 525 in FIG. 3. Further, the decrease rate abnormality display unit 533 causes the display device 50c to display the change rate (decrease rate) of the current intensity determined by the decrease rate determination unit 526 in association with the value of the current intensity of each virtual electrode. When the change rate of the current intensity is less than 100, it indicates that the current intensity is decreasing.

[0075] At this time, the decrease rate abnormality display unit 533 causes the display device 50c to display a decrease rate lower than the reference value pre-stored in the storage area of the decrease rate reference value 544 so as to be distinguishable from a decrease rate equal to or higher than the reference value. For example, the distinction of the decrease rate is made by highlighting such as changing the color or changing the typeface. Thereby, the evaluator can recognize the transition of the decrease rate of the current intensity while confirming the actual current intensity at each virtual electrode and the change rate of the current intensity between each pair of virtual electrodes.

[0076] Note that, as shown in FIG. 8, the decrease rate abnormality display unit 533 may cause the display device 50c to display the reference value together with the current intensity and the change rate. Further, the reference value may be displayed on the display device 50c so as to be changeable on the display screen by the user interface. In this case, when the reference value is changed, the decrease rate abnormality display unit 533 causes the display device 50c to highlight in real time a decrease rate lower than the changed reference value.

[0077] FIG. 9 is a diagram showing an example of the temporal change of the current distribution extracted based on the magnetic field data at the measurement target site (ulnar nerve) acquired by the biological information measurement system 100 of FIG. 1. Detailed descriptions of the same elements as those in FIGS. 5 and 6 are omitted. The image shown in FIG. 8 shows, for example, the temporal change of the current distribution calculated from the magnetic field data obtained by measuring the biomagnetic field generated when an electrical stimulus is applied to the left middle finger of the subject P who may have carpal tunnel syndrome.

[0078] FIG. 10 is a diagram showing an example of the change of the current waveform when the inward current observed in FIG. 9 conducts from upstream to downstream. The current waveform shown in FIG. 10 shows the current waveform at the virtual electrode arranged along the median nerve from the third metacarpal bone, and is extracted by the current component extraction unit 524 of FIG. 3. In FIG. 10, it can be recognized on the screen of the display device 50c that the amplitude attenuates to 36.9% between the waveform 8 and the waveform 7 (near the center of the third metacarpal bone) indicating the inward current. Note that in FIG. 10, the virtual electrode superimposed on the X-ray image, the arrow indicating the inward current, and the line indicating the nerve course are added for easy understanding of the explanation, and are the same as the superimposed image of FIG. 7.

[0079] FIG. 11 is a block diagram showing an example of the hardware configuration of the data processing device 50 in FIG. 3. The data processing device 50 includes a CPU 51, a ROM 52, a RAM 53, and an external storage device 54. The data processing device 50 also includes an input interface unit 55, an output interface unit 56, an input / output interface unit 57, and a communication interface unit 58. For example, the CPU 51, the ROM 52, the RAM 53, the external storage device 54, the input interface unit 55, the output interface unit 56, the input / output interface unit 57, and the communication interface unit 58 are mutually connected via a bus BUS.

[0080] The CPU 51 executes various programs such as an OS (Operating System) and applications, and controls the overall operation of the data processing device 50. The CPU 51 also implements the diagnostic support method by executing the above-described diagnostic support program. The ROM 52 holds various programs including the diagnostic support program executed by the CPU 51 and various parameters and the like. The RAM 53 stores various programs executed by the CPU 51 and data used in the programs. The external storage device 54 is an HDD or an SSD or the like, and stores various programs developed in the RAM 53.

[0081] An input device 60 for receiving an input from an operator or the like who operates the data processing device 50 is connected to the input interface unit 55. For example, the input device 60 is the mouse 50a, the keyboard 50b, or a tablet in FIG. 3. An output device 70 for outputting various images, texts, or graphics generated by the data processing device 50 is connected to the output interface unit 56. For example, the output device 70 is a display device 50c (FIG. 3) for displaying a display screen or the like generated by various programs executed by the CPU 51 or a printer.

[0082] A recording medium 80 such as a USB (Universal Serial Bus) memory is connected to the input / output interface unit 57. For example, various programs such as a diagnostic support program may be stored in the recording medium 80. In this case, the various programs are transferred from the recording medium 80 to the RAM 53 via the input / output interface unit 57. Note that the recording medium 80 may be a CD-ROM, a DVD (Digital Versatile Disc: registered trademark), or the like. In this case, the input / output interface unit 57 has an interface corresponding to the connected recording medium 80. The communication interface unit 58 connects the data processing device 50 to a network or the like.

[0083] As described above, in this embodiment, for example, by calculating the reduction rate of the current intensity of the inward current based on the magnetic field data obtained by measuring the magnetic field generated from the waist or neck, it is possible to assist in the diagnosis of spinal cord diseases such as intervertebral disc herniation.

[0084] By associating the reduction rate of the current intensity smaller than the reference value with the waveform of the inward current and displaying it on the display device 50c, the change in the current waveform and the value of the reduction rate can be provided to the evaluator as materials for diagnosis support. For example, by displaying the information indicating the reduction rate in association with the current waveform only when the reduction rate is smaller than the reference value, it is possible to make it easier to recognize the abnormal site compared to the case of displaying the information indicating all the calculated reduction rates.

[0085] In addition, based on the information indicating the measurement site for calculating the current intensity of the inward current, an appropriate reference reduction rate corresponding to the measurement site can be changed, so that the diagnosis of spinal cord diseases can be appropriately supported.

[0086] As described above, the present invention has been described based on each embodiment, but the present invention is not limited to the requirements shown in the above embodiments. Regarding these points, it can be changed without departing from the gist of the present invention, and can be appropriately determined according to the application form.

Description of Reference Numerals

[0087] 10 Magnetic field measurement device 11 SQUID sensor array 11a SQUID sensor 12 Signal processing device 20 Dewar 21 Protrusion 30 Nerve stimulation device 40 X-ray imaging device 50 Data processing device 50a Mouse 50b Keyboard 50c Display device 54 External storage device 55 Input interface section 56 Output interface section 57 Input / output interface section 58 Communication interface section 60 Input device 70 Output device 71, 72 Signal lines 80 Recording medium 100 Biological information measurement system 200 Magnetic shield room 210 Door 300 Bed 510 Input control section 511 Position input section 512 Waveform region specifying section 520 Arithmetic section 521 Path generation section 522 Virtual electrode generation section 523 Reconstruction analysis section 524 Current component extraction section 525 Current intensity calculation section 526 Decrease rate determination section 527 Reference change section 530 Display control section 531 Image display section 532 Waveform display section 533 Decrease rate abnormality display section 540 Memory section 541 Biomagnetic field data 542 Morphological image data 543 Analysis setting value 544 Low rate reference value BUS Bus CS1, CS2 Current intensity P Specimen

Prior art documents

Non-patent documents

[0088]

Non-patent document 1

Claims

1. A calculation unit that calculates a reduction rate of the current intensity of the inward current flowing into the nerve pathway based on magnetic field data obtained by measuring the magnetic field generated from a subject; A display control unit that causes a display unit to display a comparison result obtained by comparing the reduction rate of the current intensity with a predetermined reference value; A reference change unit capable of changing the reference value based on information indicating a measurement site for calculating the current intensity, wherein the diagnostic support device is characterized by comprising the reference change unit.

2. A calculation unit that calculates a reduction rate of the current intensity of the inward current flowing into the nerve pathway based on magnetic field data obtained by measuring the magnetic field generated from a subject; A display control unit that causes a display unit to display a comparison result obtained by comparing the reduction rate of the current intensity with a predetermined reference value; A reduction rate determination unit that determines whether the reduction rate of the current intensity calculated by the calculation unit is smaller than the reference value, wherein the display control unit causes the display unit to display, as the comparison result, information indicating the reduction rate of the current intensity determined by the reduction rate determination unit to be smaller than the reference value. A diagnostic support device characterized by the above.

3. The diagnostic support device according to claim 1 or claim 2, wherein the display control unit causes the display unit to display information for evaluating the reduction rate of the current intensity.

4. A reconstruction analysis unit that reconstructs current components at a plurality of first virtual electrodes installed in a predetermined region including an acquisition site of the magnetic field data based on the magnetic field data; A current component extraction unit that extracts current components at a plurality of second virtual electrodes arranged at predetermined intervals along the nerve pathway on the morphological image of the subject based on the current components reconstructed by the reconstruction analysis unit; A waveform generation unit that generates waveforms of the inward current at the plurality of second virtual electrodes based on the current components extracted by the current component extraction unit, wherein the display control unit causes the display unit to display the comparison result in association with the current waveform generated by the waveform generation unit. The diagnostic support device according to claim 2.

5. The diagnostic support device according to claim 4, wherein the display control unit causes the display unit to output information indicating the reduction rate of the current intensity determined by the reduction rate determination unit to be smaller than the reference value together with the corresponding current waveform.

6. The reduction rate of the current intensity is represented by a ratio CS2 / CS1 of the current intensity CS2 downstream of the nerve activity to the current intensity CS1 upstream of the nerve activity, and the diagnostic support device according to any one of claims 1 to 5 is characterized by the above.

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13. The calculation unit calculates the rate of decrease in the current intensity based on the magnetic field data obtained by measuring the magnetic field generated from the waist or neck of the subject. The diagnostic support device according to any one of claims 1 to 6, characterized in that.

8. The calculation unit calculates the rate of decrease in the current intensity based on the magnetic field data obtained by measuring the magnetic field generated in the peripheral nerves of the subject. The diagnostic support device according to any one of claims 1 to 6, characterized in that.

9. Based on the magnetic field data obtained by measuring the magnetic field generated from the subject, calculate the rate of decrease in the current intensity of the inward current flowing into the nerve path, Cause the display unit to display the comparison result of comparing the rate of decrease in the current intensity with a predetermined reference value, A diagnostic support method characterized by changing the reference value based on information indicating the measurement site for calculating the current intensity.

10. Based on the magnetic field data obtained by measuring the magnetic field generated from the subject, calculate the rate of decrease in the current intensity of the inward current flowing into the nerve path, Cause the display unit to display the comparison result of comparing the rate of decrease in the current intensity with a predetermined reference value, Determine whether the calculated rate of decrease in the current intensity is less than the reference value, A diagnostic support method characterized by causing the display unit to display, as the comparison result, information indicating the rate of decrease in the current intensity determined to be less than the reference value.

11. A process of calculating the rate of decrease in the current intensity of the inward current flowing into the nerve path based on the magnetic field data obtained by measuring the magnetic field generated from the subject, A process of causing the display unit to display the comparison result of comparing the rate of decrease in the current intensity with a predetermined reference value, A diagnostic support program characterized by causing a computer to execute a process of changing the reference value based on information indicating the measurement site for calculating the current intensity.

12. A process of calculating the rate of decrease in the current intensity of the inward current flowing into the nerve path based on the magnetic field data obtained by measuring the magnetic field generated from the subject, A process of causing the display unit to display the comparison result of comparing the rate of decrease in the current intensity with a predetermined reference value, A process of determining whether the calculated rate of decrease in the current intensity is less than the reference value, A diagnostic support program characterized by causing a computer to execute a process of causing the display unit to display, as the comparison result, information indicating the rate of decrease in the current intensity determined to be less than the reference value.

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