JP2022146860A - Biomagnetism measurement apparatus, biomagnetism measurement system, biomagnetism measurement method, and biomagnetism measurement program - Google Patents

Abstract

To correctly estimate the nerve activity current of a nerve outside a spinal canal together with the nerve activity current of a spinal cord.SOLUTION: A biomagnetism measurement apparatus includes: a region-of-interest setting section configured to set a curved surface as a region-of-interest based on a morphological image including a portion to be evaluated of a subject, the morphological image being acquired by an image acquisition section, and the curved surface being a surface on which an anterior-posterior position of the subject changes in a cranial-caudal direction and in a left-right direction along a position of a nerve to be evaluated; and an estimation section configured to estimate current distribution in the region-of-interest based on magnetic data, the magnetic data being acquired by measuring a magnetic field with a magnetic measurement section, and the magnetic field being generated by an electrical activity of a nerve in the portion to be evaluated.SELECTED DRAWING: Figure 1

Description

The present invention relates to a biomagnetic measuring device, a biomagnetic measuring system, a biomagnetic measuring method, and a biomagnetic measuring program.

A biomagnetism measuring device that measures magnetism generated from the neck, waist, or the like, for example, includes a sensor array including a plurality of magnetic sensors arranged vertically and horizontally, and a sensor array placed at a position close to the sensor array, through which X-rays do not pass. Hard-to-find markers. In the measurement of biomagnetism, the positional relationship between the sensor array and nerves to be measured is obtained by taking an X-ray image of the marker and the subject from the side of the sensor array (see Patent Document 1).

For example, a biomagnetism measuring device reconstructs currents generated in vivo using an estimation technique such as a spatial filtering method based on magnetic data acquired by a sensor array. Then, the neural function is evaluated by the current distribution acquired by the reconstruction. At this time, the signal strength of the magnetic data decreases as the distance between the magnetic source and the sensor increases. In order to suppress the decrease in signal strength, the positional relationship between the position of the nerve to be measured and the sensor is acquired before biomagnetism is measured, and the acquired positional information is given to an estimation method such as the spatial filtering method.

For example, the spinal cord extends cranio-caudally and varies in position in the front-back direction, but usually does not change in position in the lateral direction. For this reason, when estimating the nerve activity current in the spinal cord, the reconstruction area (virtual electrode) of the current specified by the spatial filtering method is on a plane that bends only in the front-back direction along the shape of the spinal canal through which the spinal cord passes. It should be set.

However, for example, the brachial plexus, which extends laterally to the spinal canal, diverges anteriorly from the spinal canal toward the shoulder. For this reason, when the reconstruction area for reconstructing the current is set on a plane along the shape of the spinal canal, a difference occurs between the actual position of the brachial plexus and the calculated position. As a result, it becomes difficult to accurately estimate the intensity of nerve activity current in the brachial plexus extending from the spinal canal.

The disclosed technology has been made in view of the above problems, and aims to correctly estimate the nerve activity current of nerves outside the spinal canal together with the nerve activity current of the spinal cord.

In order to solve the above technical problem, a biomagnetic measuring device according to one aspect of the present invention provides a morphological image including an evaluation target region of a subject acquired by an image acquisition unit, along the position of the evaluation target nerve. a region-of-interest setting unit for setting, as a region of interest, a curved surface in which the front-back position of the subject in the cranio-caudal direction and the front-back position of the subject in the left-right direction change; an estimating unit for estimating the current distribution in the region of interest based on magnetic data acquired by measuring magnetism generated with the electrical activity of the magnetism measuring unit.

Nerve activity currents of extraspinal nerves can be correctly estimated together with spinal nerve activity currents.

1 is a configuration diagram showing an example of a biomagnetism measuring system including a biomagnetism measuring device according to a first embodiment of the present invention; FIG. FIG. 2 is a flowchart showing an example of the operation of the biomagnetism measurement device of FIG. 1; 2 is a diagram showing an example of a morphological image of a subject acquired by the morphological image acquiring unit in FIG. 1; FIG. 2 is a diagram showing an example of a region of interest set by a region of interest setting unit in FIG. 1; FIG. 5 is a perspective view showing the reference ROI of FIG. 4 and the reset ROI; FIG. FIG. 4 is a diagram showing an example of a current distribution in a region of interest estimated based on magnetic data and changes in current waveforms in virtual electrodes set in the region of interest. 2 is a diagram showing another example of a morphological image of a subject acquired by the morphological image acquiring unit in FIG. 1; FIG. FIG. 10 is a diagram showing another example of a current distribution in a region of interest estimated based on magnetic data and changes in current waveforms in virtual electrodes set in the region of interest; FIG. 9 is a diagram showing an example of a virtual electrode installation method along the nerve positions in FIG. 6 or FIG. 8; FIG. 2 is a configuration diagram showing an example of a biomagnetic measurement system including a biomagnetic measurement device according to a second embodiment of the present invention; FIG. 11 is a flowchart showing an example of the operation of the biomagnetic measurement device of FIG. 10; FIG. 11 is a block diagram showing an example of the hardware configuration of the biomagnetism measuring device of FIGS. 1 and 10; FIG.

Hereinafter, embodiments will be described with reference to the drawings. In addition, in each drawing, the same code|symbol may be attached|subjected to the same component part, and the overlapping description may be abbreviate|omitted.

(First embodiment)
FIG. 1 is a configuration diagram showing an example of a biomagnetism measurement system including a biomagnetism measurement device according to a first embodiment of the present invention. For example, the biomagnetic measurement system 200 shown in FIG.

The biomagnetic measuring device 100 has an estimating section 30 , a region-of-interest setting section 40 and a user interface section 50 . The user interface section 50 has a display section 60 and an operation section 70 . The user interface unit 50 may be a tablet or the like. The estimating unit 30 and the region-of-interest setting unit 40 may be implemented by a processor such as a CPU (Central Processing Unit) mounted on the biomagnetic measuring device 100 executing a biomagnetic measuring program.

For example, the magnetic measurement unit 10 has a SQUID sensor array including a plurality of superconducting quantum interference devices (SQUIDs) and a signal processing device. The magnetic measurement unit 10 measures the magnetism generated by the electrical activity of nerves in an evaluation target region of a subject (living body) due to electrical stimulation by a nerve stimulator or the like. The magnetism measurement unit 10 outputs the measured magnetism to the estimation unit 30 as magnetic data. In this embodiment, the magnetometer 10 is used as a magnetospinograph (MSG).

For example, the morphological image acquisition unit 20 is included in an X-ray imaging apparatus, a CT (Computed Tomography) imaging apparatus, or a magnetic resonance tomography imaging apparatus. The magnetic resonance tomographic imaging apparatus is hereinafter also referred to as an MRI (Magnetic Resonance Imaging) apparatus.

The morphological image acquisition unit 20 acquires a morphological image including an evaluation target site of the subject. The morphological image acquisition unit 20 is an example of an image acquisition unit that acquires morphological images. A morphological image is an X-ray image, a CT image or an MRI image. The morphological image acquisition unit 20 outputs the acquired morphological image to the region-of-interest setting unit 40 as morphological image data. Note that the X-ray imaging apparatus including the morphological image acquisition unit 20 is arranged on the front side and the side side of the subject.

The estimation unit 30 estimates the current distribution in the region of interest set by the region-of-interest setting unit 40 based on the magnetic data received from the magnetism measurement unit 10, and outputs the estimated current distribution. For example, the current distribution estimated by the estimation unit 30 may be displayed on the display unit 60 together with the morphological image. The region of interest is the computational region of the estimation algorithms used in estimation techniques such as spatial filtering methods.

The estimating section 30 may use the estimated current distribution to acquire the current waveform estimated at the virtual electrodes set by the operating section 70 based on the operator's operation. The current waveform acquired by the estimation unit 30 is displayed on the display unit 60 . The estimator 30 is an example of a current waveform acquisition unit that acquires a current waveform estimated by a virtual electrode. Note that the current waveform acquisition unit may be provided outside the estimation unit 30 . In this case, the current waveform acquisition unit uses the current distribution estimated by the estimation unit 30 to acquire current waveforms at the virtual electrodes set by the operation unit 70 .

The region-of-interest setting section 40 outputs the morphological image data received from the morphological image acquiring section 20 to the user interface section 50 . The region-of-interest setting unit 40 receives anatomical feature position information from the user interface unit 50 .

When the evaluation target site for nerve activity is nerves around the cervical spine such as the brachial plexus, the anatomical feature position information includes, for example, position information on the inner side of the coracoid process and position information on the leading edge of the seventh cervical vertebra. If the evaluation target site for nerve activity is nerves around the lumbar spine such as the lumbar plexus, the anatomical feature position information includes the position information of the greater sciatic notch, the posterior edge of the first sacral vertebral body, and the inferior edge of the pedicle. contains the position information of the intersection of .

The region-of-interest setting unit 40 resets a preset reference region of interest based on the anatomical feature position information received from the user interface unit 50 . The region-of-interest setting unit 40 outputs information indicating the reset region-of-interest to the estimation unit 30 . The reference region of interest is indicated by a deflected shaped surface that varies in front-to-back position in the craniocaudal direction of the subject. The region of interest after resetting is indicated by a curved surface in which the front and rear positions of the subject in the cranio-caudal direction and the front and rear positions of the subject in the lateral direction change, respectively.

When the biomagnetic measuring device 100 estimates nerve activity currents of nerves around the cervical spinal cord and cervical spine (for example, brachial plexus), the region of interest setting unit 40 is positioned 2 cm to 4 cm from the medial side of the coracoid process, In addition, the curved surface including the depth position of the center of the anterior edge of the seventh cervical vertebra is reset as the region of interest. It should be noted that the operator designates in advance via the operation unit 70 which nerve's nerve activity current is to be estimated by the biomagnetic measurement device 100 .
Examples of a reference region of interest and a reconfigured region of interest for estimating nerve activity currents in the cervical spinal cord and brachial plexus are shown in FIGS. 4 and 5. FIG.

When the biomagnetic measuring device 100 estimates nerve activity currents of the lumbar spinal cord and nerves around the lumbar spine (for example, the lumbar plexus), the region-of-interest setting unit 40 sets the position of the greater sciatic notch and the first sacral notch. A curved surface including the depth position of the intersection of the vertebral body posterior edge and the pedicle inferior edge is reset to the region of interest.

The display unit 60 has a function of displaying the morphological image acquired by the morphological image acquisition unit 20 on the screen. The display unit 60 also has a function of displaying the current distribution estimated by the estimation unit 30 on the screen.

The operation unit 70 receives an anatomical feature position that serves as an index of the position of the nerve to be evaluated, which is input based on the morphological image displayed on the screen of the display unit 60 . For example, an operator viewing a morphological image displayed on the screen of the display unit 60 selects an anatomical feature position on the morphological image displayed on the screen. For example, when evaluating the nerve activity of the brachial plexus, the operator uses a mouse or the like connected to the user interface unit 50 to determine the position of the inner side of the coracoid process and the position of the anterior edge of the 7th cervical vertebra shown in the morphological image. specify.

The operation unit 70 detects coordinates on the screen of the anatomical feature position selected by the operator, and outputs the detected coordinates to the region-of-interest setting unit 40 as anatomical feature position information. Then, the region-of-interest setting unit 40 resets the region of interest based on the coordinate information of the morphological image indicated by the morphological image data and the anatomical feature position information (coordinates, etc.) received from the operation unit 70. do.

In addition, based on the operation by the operator, the operation unit 70 displays a virtual image on the position of the evaluation target nerve located in the region of interest represented in the three-dimensional space, which is displayed together with the morphological image on the display unit 60. An electrode (hereinafter also referred to as a virtual electrode) is installed. A technique for representing the region of interest on the three-dimensional space will be described later. The operation unit 70 is an example of a virtual electrode setting unit (virtual electrode setting unit) that sets virtual electrodes on positions of nerves to be evaluated along a three-dimensionally represented region of interest.

FIG. 2 is a flowchart showing an example of the operation of the biomagnetic measuring device 100 of FIG. For example, the flow shown in FIG. 2 is implemented by a processor such as a CPU installed in the biomagnetism measuring device 100 executing a biomagnetism measurement program. That is, FIG. 2 shows an example of a biomagnetism measuring method and a biomagnetism measuring program executed by the biomagnetism measuring device 100 .

First, in step S10, the region-of-interest setting unit 40 sets the region information of the region of interest, which is the calculation region of the estimation algorithm. The target region of interest set in step S10 is a reference target region of interest including a plane along the spinal canal, and as described above, has a bent shape in which the front and back positions of the subject change in the cranio-caudal direction. represented by faces.

Next, in step S12, the region-of-interest setting unit 40 indicates an anatomical feature position that serves as an index of the position of the nerve to be evaluated on the X-ray image, CT image, or MRI image displayed on the display unit 60. Anatomical feature position information is acquired via the operation unit 70 . For example, the operation unit 70 receives anatomical feature position information based on an operator's operation for viewing the morphological image. Note that steps S10 and S12 may be performed in the reverse order.

Nerves and muscles are invisible on X-ray and CT images and may be difficult to see on MRI images. On the other hand, the positions of bones (anatomical feature positions) such as the coracoid process, the 7th cervical vertebra or the greater sciatic notch can be determined from X-ray, CT and MRI images. Therefore, the region-of-interest setting unit 40 determines the positions of nerves such as the brachial plexus or the lumbar plexus that are not or hardly captured in the image based on the anatomical feature position information received from the operation unit 70. be able to.

Next, in step S14, the region-of-interest setting unit 40 resets the region of interest based on the acquired anatomical feature position information so that the evaluation target nerve outside the spinal canal is included in the region of interest. do. Thereby, the region-of-interest setting unit 40 can set the region of interest to a curved surface in which the front-back position of the subject in the cranio-caudal direction and the front-back position of the subject in the left-right direction change. As a result, the region of interest can be set to a curved surface including not only the spinal cord but also the brachial plexus or the lumbar plexus.

Next, in step S16, the estimating unit 30 applies the magnetic data representing the magnetism generated from the evaluation target nerve to an estimation algorithm to estimate the current distribution in the reset region of interest. At this time, the curved surface indicating the region of interest includes not only the position of the spinal cord but also the position of the brachial plexus or the lumbar plexus.

For this reason, the estimating unit 30 calculates the actual position of the brachial plexus or the lumbar plexus, which is another part to be evaluated, together with the nerve activity current of the cervical or lumbar spinal cord, which is one of the parts to be evaluated. Nerve activity currents can be calculated. As a result, the nerve activity current of the brachial plexus or the lumbar plexus, which moves away from the spinal canal in the longitudinal direction of the living body, can be correctly estimated together with the nerve activity current of the spinal cord.

FIG. 3 is a diagram showing an example of a morphological image of a subject acquired by the morphological image acquisition unit 20 of FIG. The morphological images shown in FIG. 3 all show the cervical vertebrae and their surroundings. The morphological image on the left side of FIG. 3 is obtained by photographing the subject from the front. The morphological image on the right side of FIG. 3 is obtained by photographing the subject from the right side.

The upper part of FIG. 3 shows an example of an X-ray image acquired by the morphological image acquisition unit 20 included in the X-ray imaging apparatus. The lower part of FIG. 3 shows an example of an MRI image acquired by the morphological image acquisition unit 20 included in the MRI apparatus. An operator who operates the operation unit 70 (FIG. 1) observes front-view and side-view X-ray images or MRI images displayed on the display unit 60 (FIG. 1) to determine whether the brachial plexus is present in the nerve to be measured. If included, designate the medial coracoid and the anterior margin of the 7th cervical vertebra on the screen. The position on the screen specified by the operator is output to the region-of-interest setting unit 40 as anatomical feature position information.

When the morphological image acquiring unit 20 is included in the CT imaging apparatus, the operator sequentially displays the cross-sectional images of the subject on the display unit 60 while changing the cross-sectional position to observe the CT images, and observes the CT images. Designate the anterior edge of the C7 vertebral body on the screen.

Based on the anatomical feature position information received from the user interface unit 50, the region-of-interest setting unit 40, when the nerves to be measured include the brachial plexus, the inside of the coracoid process (spinal canal side). The region of interest includes locations ranging from 2 cm to 4 cm midline from the location and the height center of the anterior margin of the 7th cervical vertebra. Here, the position of 2 cm to 4 cm from the inner side of the coracoid process to the spinal cord side is the starting point of the brachial plexus in the left-right direction considering individual differences of the subject, and the position of the center in the height direction of the anterior edge of the 7th cervical vertebra. is the anterior-posterior starting point of the brachial plexus.

The region-of-interest setting unit 40 also includes the position of the intervertebral foramen, which is the end point of the brachial plexus, in the region of interest. Furthermore, the region-of-interest setting unit 40 causes the region of interest to include a straight line connecting the starting point and the ending point of the brachial plexus.

Note that the region-of-interest setting unit 40 may set the line connecting the coracoid process side to the depth position in a curved shape instead of a straight line as long as it is within the range indicating the position of the brachial plexus. In addition, when acquiring anatomical feature positions from a CT image or an MRI image, the variation in the position of the upper vertebral body due to posture is greater than the variation in the position of the lower vertebral body due to posture. Therefore, the vertebral body, which is the reference anatomical feature position, is preferably on the lower side (for example, the lowest 7th cervical vertebra).

Then, the region-of-interest setting unit 40 resets the region of interest by deforming the curved plane representing the reference region of interest into a curved surface including the brachial plexus. As a result, it is possible to set a curved surface including both the nerve running of the spinal cord and the nerve running of the brachial plexus as the region of interest. A plurality of white lines connecting the starting point of the brachial plexus and the intervertebral foramen shown in the MRI image shown in FIG. 3 are added to image the brachial plexus and are not included in the actual MRI image. do not have.

FIG. 4 is a diagram showing an example of a region of interest set by the region of interest setting unit 40 of FIG. The left side of FIG. 4 shows an example of a reference region of interest set in step S10 of FIG. The right side of FIG. 4 shows an example of the region of interest reset by step S14 of FIG. In FIG. 4, the curved surface representing the region of interest is shown in mesh in the coronal plane view, sagittal plane view, and axial plane view.

A coronal view indicates a state in which the subject is viewed from the front. Thus, the left side of the figure corresponds to the right side of the subject, and the right side of the figure corresponds to the left side of the subject. The upper side of the drawing corresponds to the cranial side (upper side) of the subject, and the lower side of the drawing corresponds to the caudal side (lower side) of the subject.

A sagittal view shows the subject viewed from the right side. Therefore, the left side of the drawing corresponds to the dorsal side (rear side) of the subject, and the right side of the drawing corresponds to the ventral side (front side) of the subject. The upper side of the drawing corresponds to the cranial side of the subject, and the lower side of the drawing corresponds to the caudal side of the subject.

A longitudinal view indicates a state in which a subject lying on his or her back is viewed from the caudal side. Thus, the left side of the figure corresponds to the right side of the subject, and the right side of the figure corresponds to the left side of the subject. The upper side of the drawing corresponds to the ventral side of the subject, and the lower side of the drawing corresponds to the dorsal side of the subject.

The black dots shown in the circles in the figure indicate the origin of the brachial plexus (range of 2-4 cm) estimated from the coracoid process, which is the anatomical feature position shown by the morphological image. The brachial plexus extends medial to the coracoid process and below the anterior margin of the 7th cervical vertebra toward the intervertebral foramen in a direction toward the spinal canal, as shown in FIG.

Thus, the location of the brachial plexus is not included in the mesh showing the reference region of interest set in the flexed shape along the spinal canal. The reference region of interest has a uniform cross-sectional shape in the left-right direction, as shown on the body-axis plane, and a straight line with a uniform cross-sectional shape in the craniocaudal direction, as shown on the sagittal plane. are shown by similar curves.

On the other hand, since the mesh of the reset target region of interest is set to a curved shape along the spinal canal and the brachial plexus, the position of the brachial plexus is included in the mesh indicating the reset target region of interest. The reconfigured region of interest has a non-linear cross-sectional shape in the left-right direction, as shown in the axial plane, and a uniform cross-sectional shape in the craniocaudal direction, as shown in the sagittal plane. not a curve. The mesh of the reconfigured region of interest can be represented by a quadratic surface, which is a curved surface cut by a plane into a quadratic curve such as an ellipse, hyperbola, or parabola. A quadratic surface is represented by a ternary quadratic equation.

FIG. 5 is a perspective view showing the reference ROI of FIG. 4 and the reset ROI. As shown in FIG. 5, the reference region of interest is set to have a surface shape curved along the curved shape of the spinal canal. On the other hand, the reset region of interest has a shape along the curved shape of the spinal canal in the spinal canal portion and a shape along the running of the brachial plexus.

The estimation unit 30 shown in FIG. 1 assumes that virtual electrodes are placed on the reconfigured region of interest, and uses an estimation method such as a spatial filtering method to generate in vivo based on magnetic data. Reconfigure the current. Therefore, the neural activity current of the brachial plexus located on the region of interest can be correctly estimated together with the neural activity current of the spinal cord.

Conventionally, regarding the measurement of the brachial plexus, evaluation was difficult in the supine position, which is a position that places less burden on the subject. This is because although the brachial plexus varies greatly in the depth direction, it is difficult to accurately estimate the intensity because it does not appear in the X-ray image. Therefore, conventionally, measurement is performed in the prone position.

In the case of the prone position, pressing the brachial plexus against the sensor area reduces changes in the depth direction of nerve runs. Therefore, relatively accurate intensity estimation was possible. On the other hand, in the prone position, it is difficult to detect biomagnetic signals from the cervical spinal cord because the distance between the cervical spinal cord and the sensor is long. It was difficult to evaluate because it could not be asserted that it could be reflected.

Therefore, it has been difficult to consistently evaluate nerve function from the brachial plexus to the cervical spinal cord. Also, from the viewpoint of reducing the burden on the subject, there has been a demand for the development of a method that enables measurement in the supine position, which is generally a less burdensome position. In this embodiment, by inputting the anatomical positional relationship of the brachial plexus and setting the target region of interest along the brachial plexus, it is possible to measure the brachial plexus in the supine position. As a result, the brachial plexus and the neck can be measured in a series of steps without changing the body position.

FIG. 6 is a diagram showing an example of a current distribution in a region of interest estimated based on magnetic data and changes in current waveforms in virtual electrodes set in the region of interest. FIG. 6 shows the results of estimating current distribution when electrical stimulation is applied to the subject's right hand.

The left side of FIG. 6 is an image in which the morphological image (X-ray image) of the neck of the subject, the virtual electrodes, the path of the axonal current, and the current distribution in the region-of-interest setting unit 40 are superimposed. indicates The left image of FIG. 6 corresponds to the coronal view of FIG. Virtual electrodes are placed on the morphological image of the subject by the user specifying positions on the morphological image displayed on the display unit 60 using a mouse or the like connected to the user interface unit 50. It can be carried out. At this time, the virtual electrodes can be automatically set at preset intervals.

The middle and right sides of FIG. 6 show current waveforms estimated in a reference region of interest and a current waveform estimated in a reconfigured region of interest, respectively. The numbers shown on the intensity axis of the current waveform correspond to the virtual electrode numbers in the morphological image. In the case of electrical stimulation from the right hand, the waveform of the current flowing through a virtual electrode, indicated by an X, located on the left side, which is conventionally the contralateral side, is evaluated.

From the two current waveform diagrams, it can be seen that the current associated with the electrical stimulation propagates sequentially from the lower numbered virtual electrode to the higher numbered virtual electrode. However, in the current waveform on the left, there is a virtual electrode where the signal strength increases as it propagates, resulting in an estimation result that cannot be explained neurophysiologically.

In the current waveform on the right side, the intensity of nerve activity current flowing through the brachial plexus is greater than that in the current waveform on the left side. In addition, in the current waveform on the right side, the intensity of the nerve activity current decreases as it propagates, which is an estimation result that does not pose a neurophysiological problem. Thus, while setting the reference region of interest cannot correctly estimate the nerve activity current, the reset region of interest allows correct estimation of the nerve activity current. The same is true for the case of the lumbar plexus.

FIG. 7 is a diagram showing another example of the morphological image of the subject acquired by the morphological image acquiring unit in FIG. The morphological image shown in FIG. 7 shows the lumbar vertebrae and their surroundings. The morphological image on the left side of FIG. 7 is obtained by photographing the subject from the front. The morphological image on the right side of FIG. 7 is obtained by photographing the subject from the right side. FIG. 7 shows an example of an X-ray image acquired by the morphological image acquiring section 20 included in the X-ray imaging apparatus.

An operator who operates the operation unit 70 (FIG. 1) observes the front view and side view X-ray images displayed on the display unit 60 (FIG. 1). , the position of the anatomical feature that serves as an index for the position of the lumbar plexus is specified on the screen. The position on the screen specified by the operator is output to the region-of-interest setting unit 40 as anatomical feature position information.

The anatomical feature position that serves as an index for the position of the lumbar plexus is, for example, the position of the greater sciatic notch and the depth position of the intersection between the posterior edge of the first sacral vertebral body and the inferior edge of the pedicle. . Here, the position of the greater sciatic notch is the starting point of the lumbar plexus in the left-right direction, and the depth position of the intersection of the posterior edge of the first sacral vertebral body and the lower edge of the pedicle is the anteroposterior direction of the lumbar plexus. is the starting point of Like the brachial plexus, the lumbar plexus terminates at the intervertebral foramen. As a result, the lumbar spinal cord and nerves around the lumbar spine can be evaluated for nerve activity current.

When the morphological image acquisition unit 20 is included in the CT imaging apparatus, the operator sequentially displays the cross-sectional images of the subject on the display unit 60 while changing the cross-sectional position, thereby observing the CT images and observing the greater sciatic notch. and the depth position of the intersection of the posterior edge of the first sacral vertebral body and the lower edge of the pedicle on the screen.

Based on the anatomical feature position information received from the user interface unit 50, the region-of-interest setting unit 40 determines the position of the greater sciatic notch and the first The depth position of the intersection of the posterior edge of the sacral vertebral body and the inferior edge of the pedicle is included in the region of interest.

Further, the region-of-interest setting unit 40 causes the region of interest to include a straight line that connects the position of the greater sciatic notch and the depth of the intersection point between the posterior edge of the first sacral vertebral body and the lower edge of the pedicle. Note that the region-of-interest setting unit 40 determines the position of the greater sciatic notch and the depth of intersection between the posterior edge of the first sacral vertebral body and the lower edge of the pedicle within the range indicating the position of the lumbar plexus. The line connecting the two may be set in a curved shape instead of a straight line.

Then, the region-of-interest setting unit 40 sets the plane of the bent shape indicating the reference region of interest to the lumbar nerve, similarly to the resetting of the region-of-interest including the brachial plexus shown in FIGS. The region of interest is reset by transforming into a curved surface that includes the plexus. As a result, it is possible to set a curved surface including both the nerve runs of the spinal cord and the nerve runs of the lumbar plexus as the region of interest.

FIG. 8 is a diagram showing another example of the current distribution in the region of interest estimated based on the magnetic data and changes in current waveforms in virtual electrodes set in the region of interest. A detailed description of the same elements as in FIG. 6 is omitted. FIG. 8 shows the results of estimating current distribution when electrical stimulation is applied to the subject's right leg.

The left side of FIG. 8 shows an image in which a morphological image (X-ray image) of the waist of the subject, virtual electrodes, axonal current paths, and current distribution in the region of interest setting unit 40 are superimposed. show. The middle and right sides of FIG. 8 show current waveforms estimated in a reference region of interest and a current waveform estimated in a reconfigured region of interest, respectively. As in FIG. 6, the placement of the virtual electrodes on the morphological image of the subject is performed by the user using a mouse or the like connected to the user interface unit 50 on the morphological image displayed on the display unit 60. This can be done by specifying the position. At this time, the virtual electrodes can be automatically set at preset intervals.

From the two current waveform diagrams, it can be seen that the current associated with the electrical stimulation propagates sequentially from the lower numbered virtual electrode to the higher numbered virtual electrode. However, the left current waveform, like the left current waveform in FIG. 6, has a virtual electrode in which the signal strength increases as it propagates, resulting in an estimation result that cannot be explained neurophysiologically.
In the current waveform on the right side, similarly to the current waveform on the right side in FIG. 6, the intensity of the nerve activity current flowing through the lumbar plexus is greater than the intensity of the current waveform on the left side. In addition, in the current waveform on the right side, the intensity of the nerve activity current decreases as it propagates, which is an estimation result that does not pose a neurophysiological problem. Thus, even in the lumbar plexus, the nerve activity current cannot be estimated correctly with the setting of the reference region of interest, whereas the nerve activity current can be correctly estimated with the reset region of interest. .

As described above, in this embodiment, the biomagnetism measuring device 100 obtains anatomical feature position information via the operation unit 70, and thereby detects the brachial plexus, the lumbar plexus, or the like, which is not or is difficult to be captured in the image. Nerve locations can be determined. Then, the region-of-interest setting unit 40 can set a region of interest including the positions of nerves such as the brachial plexus or the lumbar plexus away from the spinal cord, based on the determined nerve positions. As a result, the biomagnetic measuring device 100 can correctly estimate the nerve activity current of the nerve outside the spinal canal together with the nerve activity current of the spinal cord.

Next, a method of installing virtual electrodes along the positions of nerves in a three-dimensional space will be described. FIG. 9 is a diagram showing an example of a virtual electrode placement method along the nerve positions in FIG. 6 or FIG. In FIG. 9, the meshed region indicates, for example, the reset region of interest shown in FIG. Black lines indicate the positions of nerves (paths of axonal currents), and black dots indicate virtual electrode installation positions. The region of interest and each axis shown in FIG. 9 are displayed on the display unit 60 as a perspective view, for example.

For example, the virtual electrodes in the three-dimensional space are obtained by superimposing the path of the axonal current and the virtual electrodes on the morphological image (such as an X-ray image) of the subject on the two-dimensional plane by the user interface unit 50. Later (Fig. 6 or left overlay image of Fig. 8), the path of the axonal current on the 2D plane and the virtual electrodes are placed by rearranging them in 3D space along the region of interest in Fig. 9. can do.

For example, superimposition of the axonal current path and virtual electrodes on a morphological image (such as an X-ray image) of a subject on a two-dimensional plane can be performed using a mouse or the like connected to the user interface unit 50. , by the user specifying a position on the morphological image displayed on the display unit 60 . At this time, the virtual electrodes can be automatically set at preset intervals.

Also, virtual electrodes in the three-dimensional space may be placed directly on the region of interest in FIG. 9 by the user interface unit 50 . In this case, for example, first, the morphological image of the subject and the region of interest in FIG. 9 corresponding to the morphological image are displayed on the display unit 60 . Next, using a mouse or the like connected to the user interface unit 50, the user draws at least one of axonal current paths and virtual electrodes on the region of interest displayed in mesh on the display unit 60. Deploy. When the user places only the virtual electrodes on the region of interest, the user interface unit 50 automatically sets the route passing through the virtual electrodes placed on the region of interest as the route of the axonal current. may If the user places only axonal current pathways over the region of interest, the user interface unit 50 may automatically place virtual electrodes over the region of interest at preset intervals.

The display angle of the region of interest in FIG. 9 is set to an appropriate angle so that the user can easily arrange the path of the axonal current or the virtual electrode on the region of interest. However, the display angle of the region of interest may be adjustable based on instructions from the user. This allows the user to fine-tune the axonal current path or virtual electrode position in the region of interest while changing the viewing angle. It can be set with high precision. At this time, if a morphological image such as an MRI image or a CT image can be stereoscopically displayed on the display unit 60, the user interface unit 50 adjusts the display angle of the morphological image in conjunction with the adjustment of the display angle of the region of interest. may be adjusted.

From the above, the virtual electrodes can be placed three-dimensionally according to the actual nerve positions in the three-dimensional space including the z-axis instead of the plane indicated by the x-axis and y-axis. . Then, by acquiring the estimated current waveform with the installed virtual electrodes, the user can evaluate the nerve function in which the nerve running position is correctly reflected. After setting the position of the nerve, the user can reset the region of interest via the user interface unit 50. After resetting, the nerve activity current is re-estimated and the virtual electrode position is determined. It is also possible to acquire a current waveform. When the region of interest is reconfigured, the axonal current paths and virtual electrode locations on the region of interest are also reconfigured.

(Second embodiment)
FIG. 10 is a configuration diagram showing an example of a biomagnetism measurement system including a biomagnetism measurement device according to the second embodiment of the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. For example, a biomagnetic measurement system 200A shown in FIG. 10 has a magnetic measurement unit 10, a morphological image acquisition unit 20, and a biomagnetic measurement device 100A.

The biomagnetic measuring device 100A has an estimating section 30, a region-of-interest setting section 40A, an extracting section 80A, and a user interface section 50. FIG. The estimation unit 30, the region-of-interest setting unit 40A, and the extraction unit 80A may be implemented by a processor such as a CPU installed in the biomagnetic measurement device 100A executing a biomagnetic measurement program.

The extraction unit 80A uses the morphological image data received from the morphological image acquisition unit 20 to extract anatomical feature positions (the medial coracoid process and the anterior edge of the seventh cervical vertebra, etc.) that serve as indicators of the position of the nerve to be evaluated. do. Then, the extraction unit 80A outputs anatomical feature position information indicating the extracted anatomical feature positions to the region-of-interest setting unit 40A. That is, in this embodiment, the biomagnetism measuring device 100A can automatically extract the anatomical feature position that serves as an index of the position of the evaluation target nerve without receiving an instruction from the operator.

The region-of-interest setting unit 40A has the same function as the region-of-interest setting unit 40 in FIG. have. Based on the anatomical feature positions extracted by the extraction unit 80A, the target-of-interest setting unit 40A deforms the curved surface indicating the reference target-of-interest region to reset the target-of-interest region.

FIG. 11 is a flowchart showing an example of the operation of the biomagnetism measuring device of FIG. A detailed description of the same operations as in FIG. 2 will be omitted. For example, the flow shown in FIG. 11 is realized by executing a biomagnetic measurement program by a processor such as a CPU installed in the biomagnetic measurement device 100A. That is, FIG. 11 shows an example of a biomagnetic measuring method and a biomagnetic measuring program executed by the biomagnetic measuring device 100A.

In steps S20 and S26, the same processes as steps S10 and S16 in FIG. 2 are performed. After step S20, in step S22, the extraction unit 80A extracts anatomical feature positions that serve as indicators of the positions of nerves running outside the spinal canal, based on the X-ray image data, CT image data, or MRI image data. do. For example, the extraction unit 80A extracts the inner side of the coracoid process, the anterior edge of the seventh cervical vertebra, etc. as anatomical feature positions. Note that steps S20 and S22 may be performed in the reverse order.

Next, in step S24, the region-of-interest setting unit 40A sets the region of interest based on the anatomical feature positions extracted by the extraction unit 80A so that the evaluation target nerve outside the spinal canal is included in the region of interest. reset. Then, in step S26, the estimation unit 30 estimates the current distribution in the reset region of interest based on the magnetic data.

As described above, also in this embodiment, it is possible to obtain the same effect as in the above-described embodiment. For example, the biomagnetism measuring device 100 detects nerves such as the brachial plexus or the lumbar plexus away from the spinal cord based on the position of the nerve such as the brachial plexus or the lumbar plexus determined based on the anatomical feature position information. A region of interest can be established that includes the location of the . As a result, the biomagnetic measuring device 100 can correctly estimate the nerve activity current of the nerve outside the spinal canal together with the nerve activity current of the spinal cord.

Furthermore, in this embodiment, the biomagnetic measuring device 100A can automatically extract anatomical feature positions that serve as indicators of the positions of nerves to be evaluated without receiving instructions from the operator. Then, the biomagnetic measuring device 100A determines the position of nerves such as the brachial plexus or the lumbar plexus based on the automatically extracted anatomical feature positions, thereby determining the region of interest including the evaluation target nerve. can be reset.

FIG. 12 is a block diagram showing an example of the hardware configuration of the biomagnetic measuring devices 100 and 100A of FIGS. 1 and 11. As shown in FIG. Since the hardware configurations of the biomagnetic measuring devices 100 and 100A are the same, the configuration of the biomagnetic measuring device 100 will be described below.

For example, the biomagnetic measuring device 100 has a CPU 110, a RAM (Random Access Memory) 120, a ROM (Read Only Memory) 130, an auxiliary storage device 140, an input/output interface 150, and a display device 160, which are interconnected via a bus BUS. It is connected to the. The input/output interface 150 corresponds to the operation unit 70 . A display device 160 corresponds to the display unit 60 .

CPU 110 is an example of a computer. The CPU 110 controls the overall operation of the biomagnetic measuring device 100 . CPU 110 implements the functions of estimating section 30 and region-of-interest setting section 40 by executing a biomagnetic measurement program stored in ROM 130 or auxiliary storage device 140 . In the biomagnetism measuring device 100A, the CPU 110 implements the functions of the estimation unit 30, the region-of-interest setting unit 40A, and the extraction unit 80A by executing the biomagnetism measurement program.

A RAM 120 is used as a work area for the CPU 110 and stores a biomagnetic measurement program and various parameters. ROM 130 stores a biomagnetic measurement program.

The auxiliary storage device 140 is an SSD (Solid State Drive), HDD (Hard Disk Drive), or the like. For example, the auxiliary storage device 140 stores a control program such as an OS (Operating System) for controlling the operation of the biomagnetic measuring device 100, various morphological image data, various parameters, and the like.

A mouse, a keyboard, and the like are connected to the input/output interface 150 . Input/output interface 150 may include a communication interface for communicating with other devices. The display device 160 has, for example, a screen displaying a window displaying the morphological image and the current waveform shown in FIG. 6 and an operation window.

Although the present invention has been described above based on each embodiment, the present invention is not limited to the requirements shown in the above embodiments. These points can be changed within the scope of the present invention, and can be determined appropriately according to the application form.

REFERENCE SIGNS LIST 10 magnetic measurement unit 20 morphological image acquisition unit 30 estimation unit 40, 40A region-of-interest setting unit 50 user interface unit 60 display unit 70 operation unit 80A extraction unit 100, 100A biomagnetic measurement device 140 auxiliary storage device 150 input/output interface 160 display Device 200, 200A Biomagnetic measurement system BUS bus

Japanese Patent No. 4834076

Claims (11)

Based on the morphological image including the evaluation target site of the subject acquired by the image acquisition unit, along the position of the evaluation target nerve, the front and rear positions of the subject in the craniocaudal direction and the lateral direction of the subject. a region-of-interest setting unit that sets a curved surface in which the position before and after changes as a region of interest;
an estimating unit for estimating the current distribution in the region of interest based on magnetic data acquired by measuring the magnetism generated by the electrical activity of nerves in the evaluation target site by the magnetic measurement unit;
A biomagnetic measuring device characterized by comprising: a display unit that displays the morphological image;
an operation unit that receives an anatomical feature position as an index of the position of the nerve to be evaluated, which is input based on the morphological image displayed on the display unit;
2. The biomagnetic measurement apparatus according to claim 1, wherein the region-of-interest setting unit sets the region of interest based on the position of the nerve to be evaluated received by the operation unit. an extraction unit that extracts an anatomical feature position that serves as an index of the position of the nerve to be evaluated from the morphological image;
2. The biomagnetic measurement apparatus according to claim 1, wherein the region-of-interest setting unit sets the region of interest based on the anatomical feature positions extracted by the extraction unit. The biomagnetic measurement apparatus according to any one of claims 1 to 3, wherein the nerves to be evaluated include the cervical spinal cord and nerves around the cervical spine. The anatomical feature position that serves as an index of the position of the nerve to be evaluated is a position 2 cm to 4 cm from the medial side of the coracoid process and a depth position at the center of the anterior edge of the 7th cervical vertebra. Item 5. The biomagnetic measuring device according to item 4. The biomagnetic measurement device according to any one of claims 1 to 3, wherein the nerves to be evaluated include the lumbar spinal cord and nerves around the lumbar spine. The anatomical feature position that serves as an index for the position of the nerve to be evaluated is the position of the greater sciatic notch and the depth position of the intersection of the posterior edge of the first sacral vertebral body and the inferior edge of the pedicle. 7. The biomagnetism measuring device according to claim 6. an image acquisition unit that acquires a morphological image including an evaluation target site of a subject;
a magnetic measurement unit that measures biomagnetism;
Based on the morphological image acquired by the image acquisition unit, the front and back position of the subject in the craniocaudal direction and the front and back position of the subject in the lateral direction along the position of the nerve to be evaluated. Based on the magnetic data acquired by measuring the magnetism generated by the electrical activity of the nerve of the evaluation target region by the region of interest setting unit that sets the changing curved surface as the region of interest by the magnetic measurement unit , an estimating unit for estimating the current distribution in the region of interest; and
A biomagnetic measurement system characterized by comprising: A virtual electrode for setting a virtual electrode in a three-dimensional space according to a change in the position of the nerve to be evaluated in the three-dimensional space based on a morphological image including the evaluation target site of the subject acquired by the image acquisition unit. a setting unit;
a biomagnetic measurement device including a current waveform acquisition unit that acquires a current waveform estimated by the virtual electrode set by the virtual electrode setting unit;
A biomagnetic measurement system characterized by comprising: Based on the morphological image including the evaluation target site of the subject acquired by the image acquisition unit, along the position of the evaluation target nerve, the front and rear positions of the subject in the craniocaudal direction and the lateral direction of the subject. Set a curved surface in which the position before and after changes as the region of interest,
A biomagnetism characterized by estimating a current distribution in the region of interest based on magnetic data obtained by measuring magnetism generated by electrical activity of nerves in the evaluation target region with a magnetic measurement unit. measurement method. Based on the morphological image including the evaluation target site of the subject acquired by the image acquisition unit, along the position of the evaluation target nerve, the front and rear positions of the subject in the craniocaudal direction and the lateral direction of the subject. Set a curved surface in which the position before and after changes as the region of interest,
causing a computer to execute a process of estimating a current distribution in the region of interest based on magnetic data obtained by measuring the magnetism generated by the electrical activity of nerves in the evaluation target region with a magnetic measurement unit; A biomagnetic measurement program characterized by

Images