JP7479032B2 - Biomagnetic measurement device and biomagnetic measurement system - Google Patents

Description

The present invention relates to a biomagnetic measurement device and a biomagnetic measurement system.

As a method for testing the function of the spinal cord, peripheral nerves, or muscles, a technique for measuring the magnetic field generated by a living body based on their activity is known. For example, in a biomagnetic measurement device that measures the magnetic field generated from the neck or lumbar region, the tip of each sensor in a sensor array is positioned along the curved shape of the measurement site. Then, an X-ray image is taken from the side of the subject to obtain the positional relationship between the sensor array and the nerves (see Patent Document 1).

In another biomagnetic measurement device, an ultrasound probe of an ultrasound diagnostic device is placed in a shielded room in which the biomagnetic measurement device is placed. A sensor array that measures the magnetic field generated by the heart using ultrasonic tomographic images of the heart is then placed at an appropriate measurement position on the subject, and the biomagnetic field is measured (see Patent Document 2).

In a biomagnetic measurement device, by making it possible to change the relative position between the detection target part of the subject supported by the support part and the biomagnetic measurement part, it becomes possible to place the radiation detection part between the support part and the biomagnetic measurement part. This makes it possible to obtain position information of the detection target part by the radiation detection part in the same posture as the subject is in when measuring the biomagnetic field (see Patent Document 3).

By placing the lower leg in a boot-shaped synthetic resin tank filled with hot water and applying an ultrasound probe to the outer wall of the tank, cross-sectional images of the lower leg can be obtained while minimizing changes to the shape of the lower leg caused by pressure from the ultrasound probe. For example, the ultrasound probe is applied to the outer wall of the tank corresponding to a position marked directly on the subject's body surface (see Non-Patent Document 1).

In biomagnetic measurement systems such as magnetospinal systems, for example, neural function is evaluated by estimating the current distribution inside the body using estimation methods such as the spatial filter method from magnetic field data obtained by a sensor array. Because magnetic field data signals change rapidly depending on the distance between the magnetic field source and the sensor, it is necessary to obtain nerve position information in advance and provide the obtained position information to an estimation method such as the spatial filter method.

For example, when trying to estimate the nerve activity current of the spinal cord, since the spinal cord is located in the spinal canal inside the spine, it is possible to obtain the positional relationship between the spinal cord and the sensor array from the spinal canal shown in an X-ray image. However, when trying to estimate the activity of nerves such as peripheral nerves, where the positional relationship between the bone and the nerve is not uniquely determined, it is difficult to obtain the positional relationship between the nerve and the sensor array from an X-ray image, making it difficult to accurately estimate the nerve activity current.

Ultrasound measuring devices can acquire ultrasound images that include images of nerves. However, there is no established method for accurately detecting the position of the subject to which the ultrasound probe is applied. For this reason, in the past, for example, the position to which the ultrasound probe will be applied was directly marked on the subject's body surface. Furthermore, when the ultrasound probe is pressed against the subject's body surface, there is a risk that the position of the nerve in the ultrasound image will shift from the position of the nerve when the biomagnetic field was acquired.

The disclosed technology was developed in consideration of the above-mentioned problems, and aims to estimate current distribution from biomagnetic field data by using ultrasound images to enable identification of the positional relationship between the nerve position and the magnetic sensor at the time of magnetic field measurement.

In order to solve the above technical problems, one form of the biomagnetic measuring device of the present invention has a sensor storage section in which a magnetic sensor is stored, a transparent plate member that is movable on an opposing surface facing the detection unit of the magnetic sensor in the sensor storage section , and a current estimation section that estimates the current distribution in the measurement target area from biomagnetic field data of the measurement target area measured by the magnetic sensor based on the positional relationship between the nerve and the magnetic sensor, and is characterized in that the positional relationship between the nerve and the magnetic sensor is obtained from positional information of the nerve in the measurement target area that can be obtained by an ultrasonic probe that is placed on the plate member with which the measurement target area is in contact while the plate member is separated from the opposing surface , and an image including the ultrasonic probe and the plate member at the time of acquiring the positional information of the nerve.

Using ultrasound images makes it possible to identify the relative position of the nerve and the magnetic sensor when measuring the magnetic field, making it possible to estimate the current distribution from biomagnetic field data.

1 is a block diagram showing an example of a biomagnetic measurement system according to a first embodiment of the present invention. FIG. 2 is a block diagram showing an example of changing the position of a camera in the biomagnetic measurement system of FIG. 1 . 2 is a perspective view showing an example of a sliding structure of a movable plate provided on a protruding portion of the dewar in FIG. 1. 1. FIG. 4 is a perspective view showing another example of a movable plate provided on the protruding portion of the dewar of FIG. FIG. 2 is a block diagram showing an example of the functions of the biomagnetic measurement system of FIG. 1 . FIG. 3 is a flow chart showing an example of the operation of the biomagnetic measurement system of FIGS. 1 and 2 . FIG. 3 is an explanatory diagram showing an example of an ultrasonic image acquired by the ultrasonic measuring device of FIGS. 1 and 2 . 6 is an explanatory diagram showing an example of acquiring the positional relationship between a nerve and a magnetic sensor of a sensor array by the positional relationship acquiring unit of FIG. 5 . 3 is an explanatory diagram showing an example of a current waveform (time change in current intensity) estimated by a current estimation unit based on magnetic field data measured by the magnetic measurement device of FIGS. 1 and 2 ; FIG. FIG. 10 is an explanatory diagram showing peak intensities of the current waveforms shown in FIG. 9 in order of waveform numbers. FIG. 11 is a block diagram showing an example of a biomagnetic measurement system according to a second embodiment of the present invention. FIG. 11 is a perspective view showing an example of a movable plate provided on a protruding portion of a Dewar in a biomagnetic measurement system according to a third embodiment of the present invention. 13A to 13C are explanatory diagrams showing examples of evaluation results when ultrasonic images of a measurement target site are acquired through the sensor facing regions of FIG. 12 formed of various materials. 14 is a diagram showing an example of an ultrasonic image of a measurement target portion acquired through a sensor facing region formed of the material of FIG. 13 . 14 is a diagram showing an example of an ultrasonic image of a measurement target portion acquired through a sensor facing region formed of the material of FIG. 13 . 14 is a diagram showing an example of an ultrasonic image of a measurement target portion acquired through a sensor facing region formed of the material of FIG. 13 . 14 is a diagram showing an example of an ultrasonic image of a measurement target portion acquired through a sensor facing region formed of the material of FIG. 13 . 14 is a diagram showing an example of an ultrasonic image of a measurement target portion acquired through a sensor facing region formed of the material of FIG. 13 . 14 is a diagram showing an example of an ultrasonic image of a measurement target portion acquired through a sensor facing region formed of the material of FIG. 13 . FIG. 12 is a block diagram showing an example of a hardware configuration of the data processing device of FIGS. 1, 2 and 11.

The following describes the embodiments with reference to the drawings. Note that in each drawing, the same components are given the same reference numerals, and duplicate descriptions may be omitted.

First Embodiment
Fig. 1 is a system configuration diagram showing an example of a biomagnetic measurement system according to a first embodiment of the present invention. The biomagnetic measurement system 100 shown in Fig. 1 includes a magnetic measurement device 10, a Dewar 20, a nerve stimulation device 30, an ultrasonic measurement device 40, and a data processing device 50. The magnetic measurement device 10 is an example of a biomagnetic measurement device.

The magnetic measurement device 10 has a sensor array 11 including multiple superconducting quantum interference devices (SQUIDs) and a signal processing device 12. The magnetic measurement device 10 is connected to a data processing device 50, and its operation is controlled by the data processing device 50. The data processing device 50 is a computer such as a server or a PC (Personal Computer), and can perform various data processing by executing programs.

The sensor array 11 is stored inside a protruding portion 21 that protrudes from the dewar 20. For example, the upper surface of the protruding portion 21 has a curved cross section. The magnetic detection portion on the tip side of each magnetic sensor (SQUID sensor) of the sensor array 11 is arranged facing the inner surface along the inner surface of the curved shape of the protruding portion 21. The protruding portion 21 is an example of a sensor storage portion in which the magnetic sensors of the sensor array 11 are stored.

A guide rail 70 is fixed on the protrusion 21, and is arranged along the protrusion direction of the protrusion 21. The guide rail 70 is an example of a guide member. A movable plate 60 is attached to the guide rail 70 so as to be slidable in the protrusion direction of the protrusion 21 (toward the lower right in the figure, perpendicular to the cross section). For example, the movable plate 60 has a curved shape that corresponds to the curved shape of the upper surface of the protrusion 21, and can move on the guide rail 70 so as to slide along the upper surface of the protrusion 21. The movable plate 60 is an example of a plate member, and the upper surface of the protrusion 21 is an example of an opposing surface that faces the magnetic sensor.

For example, the movable plate 60 is a resin plate such as polyethylene terephthalate, and a plate material that is transparent to visible light and allows a magnetic field to pass through is used. The movable plate 60 is preferably colorless and transparent. The material of the movable plate 60 is preferably a non-magnetic substance with an acoustic impedance close to that of the human body. The movable plate 60 may be polycarbonate other than polyethylene terephthalate. The movable plate 60 is set to a thickness (for example, about 1 mm to 5 mm, preferably about 1 mm to 2 mm) that does not bend when the ultrasonic probe is pressed. The movable plate 60 may also be thicker at the periphery (guide rail 70 side) where strength is required compared to the central portion.

By attaching the guide rail 70 to the protrusion 21, a mechanism for moving the movable plate 60 can be constructed more easily than if a mechanism for moving the movable plate 60 together with a chair or bed were provided. This allows the guide rail to be easily attached to a magnetic measurement device 10 that is already in operation, minimizing costs and enabling the magnetic measurement device 10 to be modified to acquire ultrasound images.

The nerve stimulation device 30 applies electrical stimulation to the subject via electrodes attached to the subject's body surface, inducing neural activity in the subject. The nerve stimulation device 30 is connected to a data processing device 50, and its operation is controlled by the data processing device 50. In FIG. 1, the cables connected to the nerve stimulation device 30 and the electrodes that apply electrical stimulation to the subject are omitted. The data processing device 50 can operate the nerve stimulation device 30 and the magnetic measurement device 10 in synchronization with each other.

The ultrasonic measurement device 40 acquires an ultrasonic image of the measurement target area before measuring the biomagnetic field from the subject with the magnetic measurement device 10. As explained in FIG. 7, the ultrasonic image shows nerves, so the position of the nerves can be determined. The ultrasonic measurement device 40 is connected to a data processing device 50, and the ultrasonic image acquired by the ultrasonic measurement device 40 is transferred to the data processing device 50 and can be displayed on the display device 50a of the data processing device 50.

The dewar 20 including the protrusion 21 and the ultrasonic measuring device 40 are placed in a magnetically shielded room 200 that shields against magnetism. The magnetically shielded room 200 has an internal space with a width and height of, for example, about 2.5 m and a length of about 3 m, and has a door 210 for transporting the dewar 20 and the like and for people to enter and exit.

A chair 80 on which the subject sits may be placed near the protruding portion 21 within the magnetically shielded room 200. In this embodiment, the subject sits on the chair 80 and places his or her forearm on the upper surface of the movable plate 60, bringing the front surface of the elbow (palm surface) into contact with the movable plate 60, and facing the upper surface of the protruding portion 21 via the movable plate 60. At this time, the movable plate 60 is retracted toward the Dewar 20.

A camera 300 is installed above the movable plate 60 on the ceiling of the magnetically shielded room 200. The camera 300 may be a video camera capable of capturing moving images, or a digital still camera capable of capturing still images. When an ultrasound image of the subject is acquired by the ultrasound measurement device 40, the camera 300 captures the measurement target part (forearm) of the subject placed on the movable plate 60 pulled out along the guide rail 70, and the ultrasound probe (not shown) visible through the movable plate 60.

The camera 300 is connected to the data processing device 50. Images acquired by the camera 300 can be transferred to the data processing device 50 and displayed on the display device 50a. In addition, when the camera 300 is a digital still camera, the operator who operates the ultrasound probe may release the camera 300. This allows the digital still camera to acquire an image at any timing intended by the operator (a timing at which an appropriate ultrasound image can be acquired).

Figure 2 is a block diagram showing an example of changing the position of the camera 300 in the biomagnetic measurement system of Figure 1. In Figure 2, the camera 300 is installed on the floor below the protrusion 21, rather than on the ceiling of the magnetically shielded room 200. By installing the camera 300 on the floor, it is possible to capture an image of the measurement site (measurement position) of the subject to which the ultrasound probe is placed, through the transparent movable plate 60.

Figure 3 is a perspective view showing an example of a sliding structure of the movable plate 60 provided on the protruding portion 21 of the dewar 20 in Figure 1. The subject (forearm) is not shown in Figure 3. The movable plate 60 is retracted into the dewar 20 when the biomagnetic field is measured by the magnetic measuring device 10 (Figure 1) and before ultrasonic measurement by the ultrasonic measuring device 40 (Figure 1).

With the movable plate 60 retracted into the Dewar 20, the subject sits on the chair 80 (Figure 1), places the forearm on the protruding portion 21 (on the movable plate 60), and places the front of the elbow (palm surface) on the movable plate 60. This is the state when the biomagnetic field is measured by the magnetic measurement device 10.

Then, while the front surface of the elbow (palm surface) is kept in contact with the movable plate 60, the movable plate 60 slides along the guide rail 70 and is pulled out to the side opposite the dewar 20. In this way, the movable plate 60 can be separated from the upper surface of the protruding portion 21. The movable plate 60 is moved until it hits a stopper 72 attached to the tip of the guide rail 70. For example, when the tip of the movable plate 60 hits the stopper 72, it is fixed to the stopper 72 by a locking mechanism such as a clasp (latch) (not shown).

Since the movable plate 60 only moves with the arm placed on it, when the movable plate 60 is fixed to the stopper 72, the contact state of the front surface of the elbow (palm surface) with the movable plate 60 is the same as when the movable plate 60 is retracted into the Dewar 20. In other words, the contact state of the front surface of the elbow (palm surface) with the movable plate 60 is the same as when the biomagnetic field is measured by the magnetic measurement device 10. Then, when the movable plate 60 is fixed to the stopper 72, the ultrasound probe of the ultrasound measurement device 40 is placed against the back surface (lower side) of the movable plate 60, and ultrasound images are obtained at multiple locations of the subject's measurement target area via the movable plate 60.

At this time, the pressing force from the tip of the ultrasound probe is applied to the back surface of the movable plate 60, but the movable plate 60 does not bend due to its rigidity, and the contact state of the front surface of the elbow (palm surface) with the movable plate 60 does not change. Therefore, the shape of the subject's measurement target area can be maintained in the same state as when the biomagnetic field was measured by the magnetic measurement device 10, and an ultrasound image can be acquired.

Here, the shape of the part of the subject being measured is the same means that the position of the nerve in the part being measured is the same when the ultrasound image is acquired and when the biomagnetic field is measured. The position of the nerve in the part being measured includes the position on the surface facing the movable plate 60 and the position in the depth direction from the movable plate 60. Hereinafter, the position on the surface facing the movable plate 60 is also referred to as the XY position, and the depth from the movable plate 60 (skin) is also referred to as the Z position.

Because the movable plate 60 is transparent, the operator of the ultrasonic probe can easily grasp the position of the ultrasonic probe without looking into the back side of the movable plate 60. In addition, because the movable plate 60 is transparent, when the movable plate 60 is pulled out, the position of the ultrasonic probe can be photographed by the camera 300 installed on the ceiling of the magnetically shielded room 200, and can be recognized from the image captured by the camera 300.

After an ultrasound image is acquired and position information indicating the position of the nerve in the measurement target area of the subject is acquired, the movable plate 60 and the stopper 72 are unlocked. The acquisition of the nerve position information is described in FIG. 8. The ultrasound image acquired by the ultrasound measurement device 40 and the image captured by the camera 300 are transferred to the data processing device 50.

Then, while the front surface of the elbow (palm surface) is kept in contact with the movable plate 60, the movable plate 60 is pulled back on the guide rail 70 toward the dewar 20, resulting in the state shown on the left in FIG. 3. At this time, the movable plate 60 may be fixed to the outer wall surface of the dewar 20 by, for example, a locking mechanism.

In this state, electrical stimulation is applied to the subject from the nerve stimulation device 30 (Figure 1), and the magnetic field generated from the nerve in the elbow, which is the measurement target, is measured by the magnetic measurement device 10. The magnetic measurement device 10 transfers biomagnetic field data indicating the measured magnetic field to the data processing device 50. Note that the electrodes that apply electrical stimulation to the subject are preferably attached to the subject in advance before acquiring an ultrasound image.

The data processing device 50 estimates the nerve activity current based on nerve position information obtained from the ultrasound image and the image captured by the camera 300, position information of the magnetic sensor, and biomagnetic field data measured by the magnetic measurement device 10. The data processing device 50 then displays a current waveform or the like indicating the estimated current on the display device 50a. The process of estimating the nerve activity current by the data processing device 50 is described in FIG. 5.

1 and 3, an example has been described in which the movable plate 60 is moved horizontally along the guide rail 70 attached to the protrusion 21, creating a space below the movable plate 60 for an ultrasonic probe to fit in, and an ultrasonic image is acquired. However, a guide rail extending vertically may be attached to the dewar 20, and the movable plate 60 may be moved vertically along the guide rail. In this case, the movable plate 60 is moved upward until a space is created below the movable plate 60 for the ultrasonic probe to fit in, and then an ultrasonic image is acquired.

When the movable plate 60 is attached to the Dewar 20 so that it can be moved vertically, the acquisition of ultrasound images and the measurement of the biomagnetic field may be performed with the subject standing without placing a chair in the magnetically shielded room 200. Note that a chair that moves vertically in conjunction with the vertical movement of the movable plate 60 may be placed in the magnetically shielded room 200. In this case, the movable plate 60 may be attached together with the chair to a moving mechanism that moves vertically and moved together with the chair. Then, the acquisition of ultrasound images and the measurement of the biomagnetic field are performed with the subject sitting in the chair.

In addition, in FIG. 1, the chair 80 may be fixed to a moving mechanism that can move horizontally in conjunction with the horizontal movement of the movable plate 60, and the chair 80 may be moved together with the movement of the movable plate 60. In this case, the shape (nerve position) of the front surface of the elbow (palmar surface) in contact with the movable plate 60 can be made even less likely to change. The movable plate 60, or the moving mechanism that can move horizontally or vertically and includes the movable plate 60, may be moved electrically rather than manually.

As shown in FIG. 4, a marker coil 62 that emits a magnetic field may be installed on the movable plate 60, and at least one magnetic sensor may be installed on the ultrasonic probe (not shown). The magnetic field generated from the marker coil 62 may be detected by the magnetic sensor of the ultrasonic probe, and the positional relationship between the ultrasonic probe and the movable plate 60 may be calculated based on the detected magnetic field data. In this case, the current distribution in the measurement target area can be estimated from the biomagnetic field data of the measurement target area measured by the sensor array 11 based on the ultrasonic image (nerve image) obtained by the ultrasonic probe and the positional relationship between the measurement target nerve and the sensor array 11 obtained from the positional relationship between the ultrasonic probe and the movable plate 60, without installing the camera 300 shown in FIG. 1 and FIG. 2.

Figure 5 is a block diagram showing an example of the functions of the biomagnetic measurement system 100 of Figure 1. As described above, the ultrasonic measurement device 40 acquires an ultrasonic image of the measurement area of the subject P using the ultrasonic probe 42 inserted into the space below the movable plate 60 (left side in Figure 5) when the movable plate 60 is moved to the outside of the protrusion 21. The ultrasonic measurement device 40 then outputs the acquired ultrasonic image to the data processing device 50 as a morphological image (including a neurological image) of the measurement target area of the biomagnetic field.

When acquiring an ultrasound image, the camera 300 captures an image of the movable plate 60 and its surroundings, and acquires an image showing the part to be measured of the subject P (e.g., the forearm), the movable plate 60, and the ultrasound probe seen through the movable plate 60. The camera 300 then outputs the acquired image to the data processing device 50 as probe position information indicating the position of the ultrasound probe. The camera 300 may be installed on the floor of the magnetically shielded room 200, as shown in FIG. 2.

The nerve stimulation device 30 receives application timing information indicating the timing of application of the electrical stimulation from the data processing device 50 and generates the electrical stimulation. The magnetic measurement device 10 measures the magnetic field induced in the nerve of the measurement target part of the subject P by the electrical stimulation from the nerve stimulation device 30. The magnetic measurement device 10 outputs the measured magnetic field to the data processing device 50 as magnetic field data.

The data processing device 50 has a position information acquisition unit 52, a positional relationship acquisition unit 54, and a current estimation unit 56. For example, the position information acquisition unit 52, the positional relationship acquisition unit 54, and the current estimation unit 56 function as a biocurrent estimation device that estimates neural activity currents based on magnetic field data measured by the magnetic measurement device 10, etc. The position information acquisition unit 52, the positional relationship acquisition unit 54, and the current estimation unit 56 may be realized by a biocurrent estimation program executed by a CPU (Central Processing Unit) mounted on the data processing device 50.

The position information acquisition unit 52 receives a morphological image (ultrasound image) of the measurement target area including a nerve image received from the ultrasound measurement device 40, and probe position information including an image showing the XY position of the ultrasound probe 42 captured by the camera 300 when the morphological image was acquired. The probe position information includes time information. Then, the position information acquisition unit 52 acquires nerve position information (e.g., XY positions and Z positions at multiple points on the nerve's course) based on the morphological image and the probe position information.

As shown in FIG. 4, when a marker coil 62 is installed on the movable plate 60 and a magnetic sensor is installed on the ultrasound probe, the position information acquisition unit 52 acquires probe position information based on magnetic field data detected by the magnetic sensor of the ultrasound probe instead of probe position information from the camera 300. The position information acquisition unit 52 then acquires nerve position information based on the ultrasound image including the nerve image received from the ultrasound measurement device 40 and the probe position information.

The positional relationship acquisition unit 54 calculates positional relationship information indicating the positional relationship between the position of the nerve and the position of each magnetic sensor based on the position information of the nerve acquired by the positional information acquisition unit 52 and the position information of each magnetic sensor of the sensor array 11. For example, the positional relationship acquisition unit 54 calculates positional relationship information between the multiple points on the nerve and each magnetic sensor based on the positions (XY positions and Z positions) of the multiple points on the nerve in the three-dimensional coordinate system and the positions (XY positions and Z positions) of each magnetic sensor in the three-dimensional coordinate system.

The position information of each magnetic sensor is acquired in advance using design data of the magnetic measurement device 10, etc. For example, the Z position of the nerve and the Z position of each magnetic sensor indicate the Z coordinate value when the most protruding Z position of the tip of each magnetic sensor facing the inner surface of the curved shape of the protrusion 21 is set to "0" (reference point), and indicate the signed distance from the reference point.

The current estimation unit 56 estimates the nerve activity current at the specified measurement point in the measurement target region using an estimation algorithm such as a spatial filter method based on the positional relationship information between the multiple points of the nerve and each magnetic sensor acquired by the positional relationship acquisition unit 54. The current estimation unit 56 then outputs current information (current distribution) indicating the estimated nerve activity current.

The measurement points specified within the measurement target area may be points on a nerve, or multiple points within a specified range within the measurement target area. The estimated nerve activity current is displayed on the display device 50a of the data processing device 50 as a current waveform showing changes over time, for example as shown in FIG. 9 described below. When multiple points within a specified range within the measurement target area are specified, it is possible to display on the display device 50a the direction and intensity of the current flowing through the nerve and around the nerve, as well as their changes over time.

Figure 6 is a flow diagram showing an example of the operation of the biomagnetic measurement system 100 of Figures 1 and 2. Steps S12, S16, and S18 of Figure 6 show an example of a biocurrent estimation method for estimating neural activity currents generated in association with neural activity of the subject P based on the magnetic field data of the subject P obtained by measuring the biomagnetic field using the sensor array 11 and the neural image of the subject P. Steps S12, S16, and S18 of Figure 6 show an example of a biocurrent estimation program for estimating neural activity currents generated in association with neural activity of the subject P based on the magnetic field data of the subject P obtained by measuring the biomagnetic field using the sensor array 11 and the neural image of the subject P.

Before starting the operation of FIG. 6, the part of the subject P to be measured is placed on the movable plate 60, which is retracted into the protruding portion 21 side of the Dewar 20. For example, the part to be measured is the elbow. Then, while the front surface of the elbow (palm surface) is kept in contact with the movable plate 60, the movable plate 60 is slid to the outside of the protruding portion 21.

In this state, in step S10, the ultrasonic probe 42 is applied to the inner surface of the movable plate 60, and an ultrasonic image of the measurement target area of the subject P is acquired through the movable plate 60. In addition, an image showing the positional relationship between the ultrasonic probe 42 and the movable plate 60 at the time the ultrasonic image is acquired is captured by the camera 300.

Acquisition of the ultrasound image in step S10 is performed by the data processing device 50 controlling the ultrasound measurement device 40. Acquisition of the position information of the ultrasound probe 42 in step S10 is performed by the data processing device 50 controlling the camera 300. The data processing device 50 associates the position information of the ultrasound probe 42 with the ultrasound image based on the time information output from the camera 300 together with the image and the time information included in the ultrasound image data.

When a marker coil 62 is installed on the movable plate 60 and a magnetic sensor is installed on the ultrasonic probe 42, instead of taking an image using the camera 300, the magnetic sensor of the ultrasonic probe 42 detects the magnetic field generated by the marker coil 62 installed on the movable plate 60. Then, the acquisition of position information of the ultrasonic probe 42 in step S10 is performed based on the magnetic field detected by the magnetic sensor of the ultrasonic probe 42. The data processing device 50 associates the position information of the ultrasonic probe 42 with respect to the movable plate 60 and the ultrasonic image based on the time information included in the ultrasonic image data output from the ultrasonic measurement device 40.

Next, in step S12, the position information acquisition unit 52 acquires the Z position and the XY position of the nerve at multiple locations. The method of acquiring the Z position of the nerve is described in FIG. 7. The position information acquisition unit 52 acquires the XY position of the nerve based on the ultrasound image and the probe position information associated with each other by time information. The Z position and the XY position are position information of multiple locations specified when the ultrasound image was acquired.

After step S12, the movable plate 60 on which the measurement target area is placed is returned onto the protruding portion 21. Note that step S12 may be performed after the movable plate 60 is returned onto the protruding portion 21, or may be performed while the movable plate 60 is being returned onto the protruding portion 21. Also, step S12 may be performed after step S14 and before performing step S16.

Next, in step S14, the magnetic measurement device 10 measures the neuromagnetic field of the measurement target area of the subject P. Next, in step S16, the positional relationship acquisition unit 54 acquires continuous positional information (distance information) by, for example, n-th order function approximation based on the positional information of the nerve and the sensor array 11 acquired discretely within the measurement target area. For example, the positional relationship acquisition unit 54 receives the Z position and XY position of the nerve acquired by the positional information acquisition unit 52 and the positional information of each magnetic sensor of the sensor array 11 acquired in advance. Then, the positional relationship acquisition unit 54 acquires positional relationship information indicating the positional relationship between the positions of multiple points of the nerve and the positions of each magnetic sensor of the sensor array 11 based on the received Z position and XY position and the positional information of each magnetic sensor.

Next, in step S18, the current estimation unit 56 estimates the nerve activity current at the specified measurement point using, for example, a spatial filter method, based on the positional relationship information between the positions of the multiple nerve locations and the positions of each magnetic sensor acquired by the positional relationship acquisition unit 54. The estimated nerve activity current is displayed on the display device 50a of the data processing device 50, for example, as a current waveform or a current intensity map.

Figure 7 is an explanatory diagram showing an example of an ultrasound image acquired by the ultrasound measurement device 40 of Figures 1 and 2. The left side of Figure 7 shows an ultrasound image acquired through the movable plate 60 by placing the ultrasound probe 42 against the inner surface of the movable plate 60 (the upper side in Figure 7). The right side of Figure 7 shows an ultrasound image (comparative example) acquired by placing the ultrasound probe 42 directly against the measurement target area (skin) without using the movable plate 60.

The ultrasound image shown in Figure 7 was taken at a certain position on the forearm of subject P, which is the area to be measured, and the upper side of Figure 7 shows the surface of the skin on the front (palmar surface) of the elbow. In this embodiment, to calculate the time change in the estimated active current of the nerve and the conduction velocity of the electrical signal within the nerve, for example, around five ultrasound images are taken, and Figure 7 shows one of them. Since the ultrasound image shows subcutaneous tissue such as nerves, blood vessels, and muscles, it is possible to obtain the positional relationship of these tissues and their distance from the surface of the skin.

For example, in an ultrasound image, the distance (depth) from the surface of the skin to a nerve can be measured by specifying two positions on the ultrasound image using the distance measurement function of the ultrasound measuring device 40. The position of the nerve on the ultrasound image has a clear positional relationship to the blood vessels and to the skin for each measurement target area (forearm, etc.). In addition, the cross-sectional shape of the nerve in the ultrasound image is unique for each measurement target area.

However, when the ultrasonic probe 42 is pressed against the skin to obtain an ultrasonic image, the distance of the nerve from the skin surface changes depending on the magnitude of the pressure on the skin, etc. Furthermore, when the ultrasonic probe 42 is pressed against the skin, the positional relationship between the nerve and the blood vessel changes. By pressing the ultrasonic probe 42 against the skin surface via the movable plate 60, the distance from the skin surface to the nerve, the position of the nerve, and the positional relationship between the nerve and the blood vessel can be made the same as when measuring the biomagnetic field. For this reason, for example, by performing image analysis on the ultrasonic image and determining the position of the skin surface and the position of the nerve, it is possible to determine the distance (depth) from the skin surface to the nerve. At this time, a machine learning method such as deep learning may be used.

While an ultrasound image is being acquired by the ultrasound probe 42, the location of the ultrasound probe 42 in the measurement target area can be determined by analyzing the image acquired by the camera 300 with the data processing device 50. In other words, the image acquired by the camera 300 can be used to acquire probe position information (the XY position of the ultrasound probe 42).

In addition, a hook mark indicating the center position of the ultrasound probe 42 is displayed in the upper center of the ultrasound image. Therefore, based on the probe position information and the ultrasound image, the data processing device 50 can obtain the XY position of the nerve in the measurement target area.

Note that FIG. 7 shows an example in which an ultrasound image including a nerve image is obtained by placing the ultrasound probe 42 via a movable plate 60 against the skin surface on the front side (palmar surface) of the elbow of the subject P. However, an ultrasound image including a nerve image may also be obtained by placing the ultrasound probe 42 via a movable plate 60 against the skin surface on the back side (dorsal surface) of the elbow.

Figure 8 is an explanatory diagram showing an example of acquiring the positional relationship between the nerve and each magnetic sensor of the sensor array 11 by the positional relationship acquisition unit 54 of Figure 5. The image on the left side of Figure 8 shows a morphological image including the measurement target area A in a state where the elbow of the subject P is placed on the protruding portion 21 of the magnetic measurement device 10. In the image, the elbow side of the forearm is visible, the upper side of the image is the upper arm side, and the lower side of the image is the wrist side. The image on the left side of Figure 8 is an image in which the measurement target area A, the XY position of the nerve, and the XY position of each magnetic sensor of the sensor array 11 are superimposed on an image taken by the camera 300. Note that when the marker coil 62 is installed on the movable plate 60 and the magnetic sensor is installed on the ultrasound probe 42, the image on the left side of Figure 8 is an image in which the measurement target area A, the XY position of the nerve, and the XY position of each magnetic sensor of the sensor array 11 are superimposed.

The small circles distributed in a staggered pattern indicate the XY position of each magnetic sensor in the sensor array 11. The multiple double circles indicate the XY position of the nerve, and are acquired by the position information acquisition unit 52. The positions of the double circles are included in the positions where the ultrasound images are acquired by the ultrasound probe 42.

In the measurement target area A, multiple markers MC are placed on the left and right outside of the placement area of the sensor array 11. The markers MC are coils that are imaged together with the subject P to associate a morphological image such as an X-ray image with the measurement position of the magnetic field data by the sensor array 11, and a predetermined current is passed through them.

The positional relationship between the position of the marker MC and each magnetic sensor of the sensor array 11 is acquired in advance. Therefore, by identifying the position of the marker MC using each magnetic sensor, it is possible to detect that each magnetic sensor is located at a small circle in the figure. In addition, the dashed dotted line extending horizontally from the image on the left side of Figure 8 to the graph on the right side indicates the position where the ultrasound image was acquired by the ultrasound measurement device 40 in Figure 1.

The graph on the right side of Figure 8 shows the Z position (depth) of the nerve from the surface of the front (palm surface) of the elbow of subject P in the measurement target area A and its surroundings, corresponding to the image on the left. The small circle on the right side indicates the Z position (depth) of the tip of the magnetic sensor. The curve obtained by connecting the small circles on the right side indicates the position of the surface of the protrusion 21 and the inner surface of the movable plate 60. In the graph on the right side, the distance between the Z position of the curve obtained by connecting the circles and the Z position of the nerve indicates the distance from the magnetic sensor to the nerve.

The Z position of the nerve obtained from the ultrasound image acquired through the movable plate 60 is the same as the Z position of the nerve when the biomagnetic field is measured. Therefore, by acquiring an ultrasound image through the movable plate 60, the relationship between the Z position of the nerve shown on the right side of Figure 8 and the Z position of each magnetic sensor can be obtained. In other words, the relationship between the actual Z position of the nerve when the biomagnetic field is measured and the Z position of each magnetic sensor can be obtained.

The surface connecting the movable plate 60 and the tips of the magnetic sensors has a curved cross section, so the Z position of the nerve is calculated based on the Z position of the tips of the magnetic sensors, not on the "0" point of the Z coordinate. The current estimation unit 56 estimates the nerve activity current at the specified measurement point (the double circle shown on the left in the example of FIG. 8) based on the XY position of the nerve and the XY positions of each magnetic sensor shown on the left side of FIG. 8, and the Z position of the nerve and the Z positions of each magnetic sensor shown on the right side of FIG. 8.

Figure 9 is an explanatory diagram showing an example of a current waveform (time change in current intensity) estimated by the current estimation unit 56 based on the magnetic field data measured by the magnetic measurement device 10 of Figures 1 and 2. The left side of Figure 9 shows an image in which the direction of nerve flow is superimposed on an X-ray image of the subject P's forearm for ease of explanation, and is not used to estimate the nerve activity current by the current estimation unit 56. The lower side of the X-ray image is the wrist side.

The solid current waveform on the right side of Figure 9 shows the change over time in current intensity estimated taking into account the Z position (distance (depth) from the skin) of the nerve acquired by the position information acquisition unit 52. The dashed current waveform on the right side of Figure 9 shows the change over time in current intensity estimated assuming that the Z position of the nerve is constant (comparative example).

The time change in current intensity shown in Figure 9 is estimated from the biomagnetic field generated by the current flowing through the nerve axon in response to electrical stimulation when electrical stimulation is applied to the wrist side of the forearm by a nerve stimulation device. The current is transmitted through the nerve axon from the distal side (lower side of Figure 9) to the proximal side (upper side of Figure 9). For this reason, for both the solid current waveform and the dashed current waveform, the time at which the peak current intensity appears is delayed the closer to the nerve is to the proximal side. The current waveforms are numbered from 1 to 4 from the distal side to the proximal side.

Also, from a neurophysiological perspective, the peak intensity of the current waveform is roughly constant or becomes weaker the further proximal it is from the application position of the electrical stimulation. However, the peak intensity of the current waveform indicated by the dashed line becomes smaller the more distal it is, and the current intensity cannot be estimated correctly. This is because when estimating the current intensity assuming that the Z position of the nerve is constant, an error occurs with respect to the actual depth of the nerve, and this error appears as an error when estimating the current intensity from the magnetic field data.

On the other hand, the peak intensity of the solid current waveform estimated based on the actual Z position of the nerve has hardly changed, and it can be determined that the current intensity has been correctly estimated. As explained in FIG. 8, by acquiring an ultrasound image via the movable plate 60, the relationship between the actual Z position of the nerve at the time of measuring the biomagnetic field and the Z position of each magnetic sensor can be obtained. Therefore, the current estimation unit 56 can estimate the correct current intensity based on the correct Z position of the nerve, and obtain the current waveform shown by the solid line.

Figure 10 is an explanatory diagram showing the peak intensities of the current waveforms shown in Figure 9 in the order of waveform numbers. The solid line shows the characteristics of the current intensity estimated taking into account the Z position of the nerve acquired by the position information acquisition unit 52. The dashed line shows the characteristics of the current intensity estimated assuming that the Z position of the nerve is constant (comparative example). In the characteristics of the solid line, the rate of change of the current intensity due to the waveform number indicating the position of the nerve is small. In contrast, in the characteristics of the dashed line, the rate of change of the current intensity due to the waveform number is large. In other words, in the biomagnetic measurement system 100 shown in Figure 1, by using the movable plate 60, the same nerve position (Z position) as when measuring the biomagnetic field can be obtained from the ultrasound image, and the estimation accuracy of the current intensity can be improved as shown by the solid line.

In addition, when multiple points for estimating the current intensity are provided on the measurement target area A and the direction of the current flowing through the nerve and around the nerve or the current intensity distribution is estimated, the current intensity can be accurately estimated in the same manner as described in Figures 9 and 10.

As described above, in this embodiment, by using a transparent movable plate 60, for example, an operator of the ultrasonic probe 42 can grasp the position of the ultrasonic probe 42 without looking into the back surface of the movable plate 60. In addition, the ultrasonic probe 42 can be photographed through the movable plate 60 by a camera 300 installed on the ceiling or floor of the magnetically shielded room 200. Then, from the image obtained by photographing, the XY position of the ultrasonic probe 42 relative to the movable plate 60 at the time the ultrasonic image was acquired can be detected.

This makes it possible to detect the Z and XY positions of the nerve when the biomagnetic field is measured, based on the ultrasound image and the image acquired by the camera 300. The relationship between the position of the movable plate 60 and the position of each magnetic sensor in the sensor array 11 when the biomagnetic field is measured is acquired in advance. Therefore, the positional relationship between the position of the nerve (Z position and XY position) and the position of each magnetic sensor (Z position and XY position) can be detected, and the current distribution in the measurement target area can be estimated from the biomagnetic field data based on the positional relationship. In other words, the current distribution in the living body can be estimated from the biomagnetic field data of the peripheral nerves by utilizing the ultrasound image including the nerve image.

By positioning the movable plate 60 so that it can be separated from the protrusion 21, the measurement target area can be maintained in the same state as when the biomagnetic field was measured, and an ultrasound image of the measurement target area can be acquired. As a result, even if the measurement target area is moved to a location different from when the biomagnetic field was measured, the position information acquisition unit 52 can detect the same nerve position as when the biomagnetic field was measured. Therefore, the positional relationship acquisition unit 54 can accurately detect the positional relationship between the nerve position and the positions of each magnetic sensor, and the current distribution in the living body can be estimated with little error from the biomagnetic field data of the peripheral nerves.

By attaching the guide rail 70 to the protrusion 21, a mechanism for moving the movable plate 60 can be constructed more easily than if a mechanism for moving the movable plate 60 together with a chair or bed were provided. This allows the guide rail to be easily attached to a magnetic measurement device 10 that is already in operation, minimizing costs and enabling the magnetic measurement device 10 to be modified to acquire ultrasound images.

Second Embodiment
Fig. 11 is a block diagram showing an example of a biomagnetic measurement system according to a second embodiment of the present invention. The same elements as those in Figs. 1 and 2 are given the same reference numerals, and detailed description thereof will be omitted. The biomagnetic measurement system 102 shown in Fig. 11 has a similar configuration to the biomagnetic measurement system 100 in Fig. 1, except that it has a bed 90 and a pedestal 92 instead of the chair 80 in Fig. 1, and has a guide groove 96 instead of the guide rail 70. Note that in the biomagnetic measurement system 102, a camera 300 may be installed below a protrusion 21 on the floor surface of a magnetically shielded room 200, as in Fig. 2.

A subject (not shown) lies on the bed 90, for example, supine, with the head at the lower left side of FIG. 11. The subject lies supine on the bed 90 and places the knee on the movable plate 60. That is, in this embodiment, the biomagnetic field generated from the nerves in the knee is measured, and the neural activity current in the knee is estimated based on the measured magnetic field data. The shape, structure, and relative positions of the protrusion 21 and the movable plate 60 are the same as those in FIGS. 1 and 3.

However, in this embodiment, both sides in the width direction of the curved cross section of the movable plate 60 (attachment portions to the guide rail 70 in FIG. 1) are fixed to the bed 90 via plate-shaped fixing members 94. The base 92 has a guide groove 96 into which a protrusion provided on the underside of the bed 90 is fitted. The guide groove 96 is formed along the protruding direction of the protruding portion 21, and the bed 90 is movable in the protruding direction of the protruding portion 21. The guide groove 96 is an example of a guide member. The movable plate 60 moves together with the bed 90, so that the movable plate 60 can move in the same manner as in FIG. 1.

An ultrasound image of the knee is acquired by the ultrasound measuring device 40 after the bed 90 has been moved to the side opposite the Dewar 20 and the movable plate 60 has been moved to the outside of the protruding portion 21. At this time, as in the above-described embodiment, an image showing the positional relationship between the ultrasound probe and the movable plate 60 is taken by the camera 300. After this, the bed 90 is moved toward the Dewar 20 until the movable plate 60 is positioned above the protruding portion 21 (above the sensor array 11), and the biomagnetic field of the knee is measured by the magnetic measuring device 10.

The function of the biomagnetic measurement system 102 is the same as that of FIG. 5, except that the movable plate 60 of FIG. 5 moves in conjunction with the bed 90. In addition, the operation of the biomagnetic measurement system 102 and the images and waveforms acquired are the same as those described in FIGS. 6 to 10.

As described above, in this embodiment, the same effects as those of the above-mentioned embodiment can be obtained. Furthermore, in this embodiment, by providing a mechanism for moving the movable plate 60 together with the bed 90, the relationship between the position of the subject's knee nerve and the position of the sensor array 11 can be obtained more accurately using ultrasound images than when the movable plate 60 is not used. As a result, the active current of the knee nerve can be estimated more accurately based on the measurement of the biomagnetic field generated from the knee nerve than when the movable plate 60 is not used.

In FIG. 11, an example has been described in which the movable plate 60 can be moved horizontally together with the bed 90. However, a mechanism for moving the bed 90 vertically may be provided on the base 92, so that the movable plate 60 can be moved vertically together with the bed 90. In this case, the movable plate 60 is moved upward until a space is created below the movable plate 60 in which the ultrasound probe can be inserted, and then an ultrasound image of the lower part of the knee is acquired.

Third Embodiment
12 is a perspective view showing an example of a movable plate provided on a protruding portion of a Dewar in a biomagnetic measurement system according to a third embodiment of the present invention. Elements similar to those in the above-mentioned embodiments are given the same reference numerals, and detailed descriptions thereof will be omitted.

The movable plate 60A shown in FIG. 12 is slidably attached to the guide rail 70 in place of the movable plate 60 shown in FIG. 1, FIG. 2, and FIG. 11. The biomagnetic measurement system of this embodiment is similar to the biomagnetic measurement systems 100 and 102 shown in FIG. 1, FIG. 2, and FIG. 11, except for the structure of the movable plate 60A. Note that, as in FIG. 4, a marker coil 62 may be installed on the movable plate 60A.

The structure of the sensor facing area 61A located in the center of the movable plate 60A differs from the structure of the sensor facing area of the movable plate 60 shown in FIG. 3 and other figures. The sensor facing area 61A is provided in a position facing the tip side of the sensor array 11 when the movable plate 60A is retracted toward the Dewar 20.

The sensor facing area 61A is an area where the ultrasonic probe 42 of the ultrasonic measuring device 40 (FIG. 5) is applied from the back side (lower side) when the movable plate 60A is pulled out along the guide rail 70. The sensor facing area 61A only needs to be provided in the area where the ultrasonic probe 42 is applied, and may be smaller than the area of the facing part of the sensor array 11.

The sensor facing region 61A of the movable plate 60A is formed of a material or with a shape that makes it easy to obtain an ultrasonic image using the ultrasonic probe 42. For example, it is preferable that the thickness of the sensor facing region 61A of the movable plate 60A is thinner than the thickness of the periphery of the sensor facing region 61A on the movable plate 60A. Examples of materials and thicknesses of the sensor facing region 61A are shown in FIG. 13.

The material and thickness of the surroundings of the sensor facing area 61A on the movable plate 60A may be made of a material different from that of the sensor facing area 61A, so long as the material and thickness are rigid enough not to deform under the weight of the measurement target part of the subject P placed on the movable plate 60A. In this case, it is preferable that the material of the surroundings of the sensor facing area 61A on the movable plate 60A is transparent to visible light.

Figure 13 is an explanatory diagram showing an example of an evaluation result when an ultrasound image of a measurement target area is acquired through the sensor facing area 61A of Figure 12 formed from various materials. Figure 13 shows an example of acquiring an ultrasound image of the median nerve at the wrist and elbow, and an ultrasound image of the sural nerve at a position 8 cm and 12 cm away from the ankle joint, respectively. Note that the median nerve is thicker than the sural nerve.

12 MHz and 22 MHz indicate the frequency of the ultrasonic probe 42. The lower the frequency of the ultrasonic probe 42, the lower the resolution, but the easier it is to reach deeper into the body. Ultrasound images are acquired by placing the part of the upper or lower limb to be measured on the movable plate 60A, and with the movable plate 60A pulled out, placing the ultrasonic probe 42 against the part to be measured from below the movable plate 60A via the sensor facing area 61A.

In Figure 13, a circle indicates that the image quality (visibility) of the ultrasound image is good, a triangle indicates that the image quality of the ultrasound image is somewhat good, an X indicates that the image quality of the ultrasound image is poor, and a "-" indicates that the image has not been evaluated.

The evaluation shown in Figure 13 confirmed that the materials with good visibility of the median nerve and sural nerve in ultrasound images were 1 mm thick ABS (Acrylonitrile Butadiene Styrene) resin, polystyrene, and polycarbonate. It was also confirmed that the visibility of the median nerve and sural nerve in ultrasound images was good even with a thickness of 2 mm in the case of ABS resin.

The movable plate 60A is not limited to the above-mentioned structure, and may be any structure capable of acquiring an ultrasound image of the measurement target area of the subject P placed on the movable plate 60A. For example, slits or holes may be provided at a predetermined interval in the sensor facing area 61A of the movable plate 60A. Furthermore, if the area of the measurement target area is small, openings may be provided in the sensor facing area 61A to match the measurement target area.

Furthermore, if the area of the measurement target portion is small and the strength of the sensor facing area 61A is not required, the sensor facing area 61A may be formed from a material having an acoustic impedance close to that of the human body (e.g., a gel material, etc.) rather than a solid material such as resin.

Figures 14 to 19 are diagrams showing examples of ultrasound images of the measurement target area acquired through the sensor facing area 61A formed from the material in Figure 13. A hook mark indicating the center position of the ultrasound probe 42 is displayed in the upper center of each ultrasound image.

As explained in FIG. 5, the ultrasound images of the measurement target area of the subject P are acquired by the ultrasound probe 42, which is inserted into the space below the sensor facing area 61A of the movable plate 60A when the movable plate 60A is moved to the outside of the protrusion 21. In each ultrasound image, a nerve is present at the position indicated by the white dashed circle.

Figure 14 is an ultrasound image acquired through a sensor facing region 61A formed from 1 mm thick ABS resin. Figure 15 is an ultrasound image acquired through a sensor facing region 61A formed from 2 mm thick ABS resin. Figure 16 is an ultrasound image acquired through a sensor facing region 61A formed from 1 mm thick polystyrene.

Figure 17 is an ultrasound image acquired through a sensor facing region 61A made of 1 mm thick polycarbonate. Figure 18 is an ultrasound image acquired by opening the portion of the sensor facing region 61A that corresponds to the area to be measured. Figure 19 is an ultrasound image acquired through a sensor facing region 61A made of 1 mm thick acrylic resin.

Figures 14 to 17 are ultrasound images in which the evaluation results in Figure 13 were good (circle), and the nerves indicated by the dashed white circles are clearly visible. In the ultrasound image acquired by forming an opening in the sensor facing region 61A in Figure 18, the ultrasound probe 42 is directly applied to the measurement target area, so that a clear image of the nerve can be acquired. On the other hand, in the ultrasound image acquired through, for example, 1 mm thick acrylic resin as shown in Figure 19, the nerves indicated by the dashed white circles are barely discernible.

As described above, in this embodiment, the same effects as those of the above-mentioned embodiment can be obtained. Furthermore, in this embodiment, it is possible to obtain an ultrasound image of the measurement target area with good image quality (visibility) while maintaining the strength (rigidity) of the movable plate 60A. As a result, the positional relationship between the position of the nerve and the position of each magnetic sensor can be reliably detected based on the ultrasound image and the image obtained by the camera 300 shown in FIG. 1, etc., and the current distribution of the measurement target area can be estimated from the biomagnetic field data based on the positional relationship. In other words, the current distribution in the living body can be estimated from the biomagnetic field data of the peripheral nerves using the ultrasound image including the nerve image.

Figure 20 is a block diagram showing an example of the hardware configuration of the data processing device 50 of Figures 1, 2, and 11. For example, the data processing device 50 has a CPU 501, a RAM 502, a ROM 503, an auxiliary storage device 504, an input/output interface 505, and a display device 50a, which are interconnected by a bus 507.

The CPU 501 controls the overall operation of the data processing device 50. The CPU 501 executes a bioelectric current estimation program stored in the ROM 503 or the auxiliary storage device 504 to realize the functions of the position information acquisition unit 52, the positional relationship acquisition unit 54, and the current estimation unit 56. The CPU 501 may also control the operation of the biomagnetic measurement system 100, such as the magnetic measurement device 10 and the ultrasonic measurement device 40.

RAM 502 is used as a work area for CPU 501, and stores the bioelectric current estimation program and various parameters such as Z position, XY position, etc. ROM 503 stores the bioelectric current estimation program.

The auxiliary storage device 504 is a storage device such as an SSD (Solid State Drive) or an HDD (Hard Disk Drive). For example, the auxiliary storage device 504 stores control programs such as an OS (Operating System) that controls the operation of the data processing device 50, ultrasound images, morphological image data, various parameters, etc.

The input/output interface 505 is connected to a mouse, a keyboard, and the like. The input/output interface 505 may include a communication interface for communicating with other devices. The display device 50a displays a window displaying the current waveform shown in FIG. 9 and an operation window. The display device 50a may also display the ultrasound image shown on the left side of FIG. 7 or a diagram showing the positional relationship between the nerve and the sensor array 11 shown in FIG. 8.

The present invention has been described above based on each embodiment, but the present invention is not limited to the requirements shown in the above embodiments. These points can be changed without departing from the spirit of the present invention, and can be appropriately determined according to the application form.

10 Magnetic measurement device 11 Sensor array 12 Signal processing device 20 Dewar 21 Protruding portion 30 Nerve stimulation device 40 Ultrasonic measurement device 42 Ultrasonic probe 50 Data processing device 50a Display device 52 Position information acquisition unit 54 Positional relationship acquisition unit 56 Current estimation unit 60, 60A Movable plate 61A Sensor facing area 62 Marker coil 70 Guide rail 72 Stopper 80 Chair 90 Bed 92 Pedestal 94 Fixing member 96 Guide groove 100, 102 Biomagnetic measurement system 200 Magnetically shielded room 210 Door 300 Camera 501 CPU
502 RAM
503 ROM
504 Auxiliary storage device 505 Input/output interface 507 Bus A Measurement target area MC Marker P Subject

Japanese Patent No. 4834076 Patent No. 3094988 JP 2019-98156 A

Seiichi Hisamoto, Masatoshi Higuchi, Study on a method for observing the cross-section of limbs using ultrasonic echography combined with a water tank, Journal of the Society of Biomechanisms, vol. 34, No. 1 (2010)

Claims (7)

a sensor storage section in which the magnetic sensor is stored;
a transparent plate member disposed on a surface of the sensor housing portion facing the detection portion of the magnetic sensor so as to be separable from the surface of the sensor housing portion;
a current estimation unit that estimates a current distribution in a measurement target portion from biomagnetic field data of the measurement target portion measured by the magnetic sensor based on a positional relationship between a nerve and the magnetic sensor;
having
The positional relationship between the nerve and the magnetic sensor is as follows:
position information of the nerve of the measurement target portion that can be obtained by an ultrasonic probe applied to the plate member with which the measurement target portion is in contact while the plate member is separated from the opposing surface ; and
an image including the ultrasonic probe and the plate member when acquiring the position information of the nerve;
What you can learn from
A biomagnetic measuring device characterized by the above. 2. The biomagnetic measuring device according to claim 1, further comprising a guide member attached to the sensor housing portion for guiding the plate member as it moves along the opposing surface. a position information acquisition unit that acquires position information indicating the position of the nerve on the opposing surface and the depth of the nerve from the opposing surface when the plate member in contact with the measurement target portion is placed opposite the opposing surface, based on a nerve image included in the morphological image of the measurement target portion acquired by the ultrasonic probe and an image including the ultrasonic probe and the plate member captured from above or below the opposing surface when the morphological image is acquired;
a positional relationship acquisition unit that acquires a positional relationship between a nerve and the magnetic sensor based on position information of the nerve acquired by the positional information acquisition unit and position information of the magnetic sensor with respect to the plate member facing the facing surface,
3. The biomagnetic measurement device according to claim 1, wherein the current estimation unit estimates a nerve activity current based on the positional relationship acquired by the positional relationship acquisition unit and the biomagnetic field data. a sensor storage section in which the magnetic sensor is stored;
a transparent plate member provided with a plurality of marker coils and disposed on a surface of the sensor housing portion facing the detection portion of the magnetic sensor so as to be separable from the transparent plate member;
a current estimation unit that estimates a current distribution in a measurement target portion from biomagnetic field data of the measurement target portion measured by the magnetic sensor based on a positional relationship between a nerve and the magnetic sensor;
having
The positional relationship between the nerve and the magnetic sensor is as follows:
position information of the nerve of the measurement target portion that can be obtained by an ultrasonic probe that is applied to the plate member that is in contact with the measurement target portion while the plate member is separated from the opposing surface ; and
a positional relationship between the ultrasonic probe and the plate member that is acquired based on a magnetic field generated from the marker coil and measured by a magnetic sensor provided in the ultrasonic probe;
What you can learn from
A biomagnetic measuring device characterized by the above. The biomagnetic measurement device according to any one of claims 1 to 4, characterized in that at least a portion of the plate member is made of a material that allows the ultrasonic probe to obtain position information of the subject's nerves. The biomagnetic measurement device according to any one of claims 1 to 4, characterized in that at least a part of the plate member has an opening in an area where position information of the subject's nerves is to be obtained by the ultrasonic probe. A biomagnetic measurement system including a biomagnetic measurement device having a dewar including a sensor storage section in which a magnetic sensor is stored, an ultrasonic measurement device including an ultrasonic probe, and a camera installed above or below the sensor storage section,
The biomagnetic measuring device comprises:
a transparent plate member disposed on a surface of the sensor housing portion facing the detection portion of the magnetic sensor so as to be separable from the surface of the sensor housing portion;
a current estimation unit that estimates a current distribution in a measurement target portion from biomagnetic field data of the measurement target portion measured by the magnetic sensor based on a positional relationship between a nerve and the magnetic sensor;
having
The positional relationship between the nerve and the magnetic sensor is as follows:
position information of the nerve of the measurement target portion that can be obtained by an ultrasonic probe that is applied to the plate member that is in contact with the measurement target portion while the plate member is separated from the opposing surface ; and
an image including the ultrasonic probe and the plate member when acquiring the position information of the nerve;
What you can learn from
A biomagnetic measurement system comprising :

Images