Patent Description:
For example, as a method of measuring a biomagnetic field, a method of applying electrical stimulation to a part of a subject to induce nerve activity in a part and measuring a magnetic field generated by nerve activity is known. In addition, there are known methods for non-invasively evaluating neural action currents by reconstructing currents generated in vivo using magnetic field data obtained by measuring the biomagnetic field by a sensor.

For example, the conduction velocity of the neural action current in a cauda equina can be computed non-invasively by measuring the neuromagnetic field in a lower back when the peroneal nerve in the knee is stimulated and reconstructing a neural action current from the obtained magnetic field data. In addition, a correlation between the age and the conduction velocity can be obtained by statistical analysis of the conduction velocity of the neural action current in a plurality of healthy subjects using the above-described method (see, for example, <NPL>).

<NPL> discloses a magnetospinography system with sensor positions in three orthogonal directions to record lumbar canal evolved magnetic fields in response to peripheral nerve simulation), and methods for localizing spinal lesions. <NPL> discloses a method for magnetospinography measurement after ulnar nerve stimulation.

However, no method is disclosed for generating information that can assist in diagnosing diseases such as the lumbar spine from the neural action current computed using the magnetic field data obtained by measuring the magnetic field generated by the subject.

The disclosed technique has been developed in view of the above problems and is aimed to provide the diagnostic support apparatus, diagnostic support method, and diagnostic support program that can assist in diagnosing neurological diseases.

In order to solve the above-described technical problem, an embodiment of the diagnostic support apparatus of the present invention comprises a computing unit for computing a decreasing rate in the current intensity of an inward current flowing into a nerve pathway, based on magnetic field data obtained by measuring the magnetic field generated from a subject, and a display controller for displaying a comparison result in which the decreasing rate in the current intensity is compared with a standard value, on a display unit, and further comprises a standard changing unit that is configured to change the predetermined standard value based on information indicating a measurement portion for which the current intensity is computed.

Thus, the diagnostic support apparatus, diagnostic support methods, and diagnostic support programs that can assist in diagnosing neurological diseases can be provided.

In each drawing, the same components are indicated by the same reference numerals and overlapping descriptions may be omitted.

<FIG> illustrates an example of a biometric measurement system including a diagnostic support apparatus according to a first embodiment of the present invention. For example, a biometric measurement system <NUM> illustrated in <FIG> includes a spinal cord evoked magnetic field measurement system that measures the magnetic field generated by the nerve, such as the spinal cord, based on electrical stimulation.

The biometric measurement system <NUM> includes a magnetic field measuring device <NUM>, a low temperature container <NUM>, a nerve stimulator <NUM>, an X-ray device <NUM>, and a data processor <NUM> as major components. The data processor <NUM> is an example of a diagnostic support apparatus. The nerve stimulator <NUM> is a device that electrically stimulates the nerve from the surface of the body (skin) of the subject P. In <FIG>, the X-ray device <NUM> is disposed on the top of the subject P, but may be disposed on the side and may be disposed on both the top and the side.

The magnetic field measuring device <NUM> includes a SQUID sensor array <NUM> including a plurality of superconducting quantum interference devices (SQUID) and a signal processor <NUM>. The magnetic field measuring device <NUM> can measure the magnetic field evoked by the nerve of the subject P to be measured upon electrical stimulation by the nerve stimulator <NUM>.

In this embodiment, the magnetic field measuring device <NUM> is used as a magnetospinograph (MSG). The magnetic field measuring device <NUM> may be used as a magnetoencephalography (MEG) or a magnetocardiograph (MCG). Hereinafter, the superconducting quantum interference device is also referred to as SQUID.

The data processor <NUM> has a function of controlling the timing of electrical stimulation to a biological body by the nerve stimulator <NUM>, and has a function of processing information processing of biological information such as a biomagnetic field measured by the magnetic field measuring device <NUM>. The data processor <NUM> also has a function for controlling the capture of an X-ray image of the subject P by the X-ray device <NUM>. The data processor <NUM> functions to receive inputs from input/output devices such as a mouse 50a and a keyboard 50b.

The data processor <NUM> has a function of superimposing the direction of the current generated in response to the magnetic field measured by the magnetic field measuring device <NUM> on an X-ray image and displaying it on the display 50c. The data processor <NUM> has the function of calculating the time change of the current value at a plurality of consecutive positions (virtual electrodes) instructed by an operator operating the mouse 50a with respect to an image displayed on the display 50c. For example, the operator may indicate a plurality of locations along a nerve, such as the spinal cord, which is recognized by an X-ray image displayed on the display 50c.

The data processor <NUM> also has a function to display the current waveform of each virtual electrode on the display 50c. The data processor <NUM> has a function of displaying a text or a graphic indicating that the decreasing rate of the current intensity, which is the maximum amplitude of the current waveform in adjacent virtual electrodes, is reduced when the decreasing rate is less than a predetermined standard value of the decreasing rate, or the like at a position adjacent to the current waveform.

A portion of the biometric measurement system <NUM> is disposed within magnetic shielding room <NUM> that shields the magnet. The magnetic shielding room <NUM> can be used to measure a weak magnetic field (e.g., spinal cord evoked magnetic field) generated by the subject P. The magnetic shielding room <NUM> may be formed by laminating, for example, a plate material made of permalloy or the like as a high magnetic permeability material and a plate material made of an electrically conductive material such as copper or aluminum.

The magnetic shielding room <NUM> has an internal space of, for example, about <NUM> depth, <NUM> width, and <NUM> height, and is provided with a door <NUM> for transporting devices and instruments and for allowing for entry and exit of persons. The door <NUM>, as well as other portions of the magnetic shielding room <NUM>, may be formed by laminating a plate material made with permalloy or the like as a high magnetic permeability material and a plate material made of an electrically conductive material such as copper or aluminum.

As used herein, a high magnetic permeability material refers to a material having a specific magnetic permeability greater than <NUM>. Examples of the high magnetic permeability material are iron, nickel, and cobalt alone, alloys thereof (including amorphous alloys, powders, and nanoparticles), ferrites, and the like, in addition to permalloys.

Hereinafter, the biometric measurement system <NUM> and its peripheral portions will be described in more detail. A bed <NUM> is provided within the magnetic shielding room <NUM>. The low temperature container <NUM> is installed in the magnetic shielding room <NUM>, and a signal cable <NUM> used for measuring the magnetic field and for controlling the measurement is coupled to the SQUID sensor array <NUM>, which is installed in the protruding unit <NUM> of the low temperature container <NUM>. The signal cable <NUM> has a twisted cable structure to reduce magnetic field noise and is drawn out of the magnetic shielding room <NUM> a through hole through the wall portion of the magnetic shielding room <NUM> and coupled to a signal processor <NUM>.

For example, spinal cord evoked magnetic field measurements using the biometric measurement system <NUM> are conducted while the subject P lies in the supine position on the bed <NUM> at rest. When the measurement at rest is performed, not only is the load on the subject P reduced, but the displacement of the subject P from the SQUID sensor array <NUM> due to the movement of the subject P can be reduced, and the magnetic field noise from the muscle caused by the muscle contraction and the like can be reduced.

The low temperature container <NUM>, also referred to as Dewar, holds the liquid helium necessary to operate the SQUID sensor array <NUM>, which detects a magnetic field generated from the subject P, at an extremely low temperature. The protruding unit <NUM> of the low temperature container <NUM> has a shape suitable for measuring spinal cord evoked magnetic fields. For example, the spinal cord evoked magnetic field is measured while the lower back of the subject P is made in contact with the protruding unit <NUM> and the lower back faces a head of the SQUID sensor array <NUM>.

When measuring the spinal cord evoked magnetic fields, it is necessary to deliberately evoke the neural activity of the subject P by electrical stimulation. Electrical stimulation is applied using the nerve stimulator <NUM>. For example, in this embodiment, electrical stimulation is applied alternately to the left tibial nerve and the right tibial nerve at the ankles, and the current conducted from an upstream to a downstream of the spinal cord is computed based on each electrical stimulation. Here, the term "upstream" refers to a position relatively close to the stimulation position to which the electrical stimulation is applied, and the term "downstream" refers to a position relatively distant from the stimulation position. Therefore, the two electrode pairs coupled to the nerve stimulator <NUM> via the two signal cables <NUM> of the twisted cable structure are applied to the skin inside the both ankles.

The tibial nerves of both of the legs of the subject P are alternately excited by electrical stimulation applied to the subject P alternately from an electrode pair, and nerve activity caused by the excitation is propagated to the central nervous system. The SQUID sensor array <NUM> opposite to the lumbar region of the subject P detects magnetic fields arising from the spinal cord and spinal nerves of the lumbar region.

In addition, the two electrode pairs may be applied to nerves other than the tibial nerves of both of the legs at an electrically stimulable position. Measurement positions of the biomagnetic fields based on electrical stimulation from both of the legs may be the thoracic or cervical region. In addition, when measuring the biomagnetic field in the cervical region, the two pairs of electrodes may be attached to positions capable of stimulating to nerves of both hands location.

By alternately applying electrical stimulation from the two electrode pairs and measuring the biomagnetic field alternately, differences in the current waveforms conducted through the left and right nerves to the spinal cord can be detected. Then, based on the difference in the current waveform, information for identifying a damaged area can be provided to an evaluator such as a physician.

For example, the data processor <NUM> is a computer, such as a PC (Personal Computer), connected via signal cables to the signal processor <NUM>, the nerve stimulator <NUM>, and the X-ray device <NUM>. The data processor <NUM> controls the operation of the magnetic field measuring device <NUM>, the nerve stimulator <NUM>, and the X-ray device <NUM>.

<FIG> is a perspective view illustrating an example of the SQUID sensor array <NUM> provided in protruding unit <NUM> of the low temperature container <NUM> illustrated in <FIG>. For example, the SQUID sensor array <NUM> has a plurality of SQUID sensors 11a having a vertically extending bar shape and staggered in a top view. The upper end of each SQUID sensor 11a is positioned so as to face a measurement target portion of the subject P lying on the bed <NUM>. In this embodiment, the plurality of SQUID sensors 11a are disposed within the protruding unit <NUM> such that the upper end is slightly curved in accordance with the shape of the curved shape of the lower back of the subject P during the magnetic field measurement.

Each SQUID sensor 11a measures the magnetic field generated by the subject P based on an instruction from the signal processor <NUM> and outputs the measured magnetic field as a voltage signal (the magnetic field signal indicating the magnetic field) to the signal processor <NUM>. For example, each SQUID sensor 11a is a three-axis sensor having an X-axis, a Y-axis, and a Z-axis, and the magnetic field signal can be measured as a three-dimensional vector quantity. Each SQUID sensor 11a may be a two-axis sensor having the X-axis and the Y-axis capable of measuring a magnetic field signal as a two-dimensional vector quantity, or may be a single-axis sensor having only the Z-axis.

The signal processor <NUM> illustrated in <FIG> estimates the neural action current at a specified point on the basis of the relationship between the position of the nerve of the subject P on the X-ray image and the position of each SQUID sensor 11a and the magnetic field data obtained by measuring the magnetic field generated from the subject P by the plurality of SQUID sensors 11a. For example, estimation algorithms such as a spatial filtering method are used to estimate the neural action current. This provides a current waveform indicative of the time change of the neural action current at any position facing the SQUID sensor array <NUM>. In order to remove artifacts from the magnetic field data obtained by measuring the magnetic field, the Dual Signal Subspace Projection (DSSP) method, which is an artifact reduction method, or the like may be applied.

<FIG> is a diagram illustrating an example of a functional block of the data processor <NUM> illustrated in <FIG>. The data processor <NUM> includes an input controller <NUM>, a computing unit <NUM>, a display controller <NUM>, and a memory unit <NUM>. For example, the input controller <NUM>, the computing unit <NUM>, and the display controller <NUM> are implemented by a data processing program executed by a processor such as a CPU (Central Processing Unit) installed in the data processor <NUM>.

The calculation of the decreasing rate of the inward current by the input controller <NUM>, the computing unit <NUM>, and the display controller <NUM>, which will be described later, and the display of a comparison result in which the decreasing rate of the current intensity is compared with the predetermined standard value are performed by executing the diagnostic assistance program from among the data processing programs. Then, when a processor such as the CPU executes the diagnostic support program, the diagnostic support method is executed.

The input controller <NUM>, the computing unit <NUM>, and the display controller <NUM> may be implemented by hardware, such as an FPGA, or may be implemented by a combination of software and hardware. The computing unit <NUM> is an example of the computing unit which computes the decreasing rate of the current intensity of the inward current flowing into the nerve pathway based on the magnetic field data obtained by measuring the magnetic field generated by the subject P.

For example, the memory unit <NUM> may be implemented by at least one of semiconductor memory devices such as a dynamic random access memory (DRAM), static random access memory (SRAM), read only memory (ROM), and flash memory. The memory unit <NUM> may be implemented by a semiconductor memory device and a hard disk drive (HDD) or a solid state drive (SSD).

The input controller <NUM> includes a position input unit <NUM> and a waveform area designating unit <NUM>. The computing unit <NUM> includes a path generator <NUM>, a virtual electrode generator <NUM>, a reconstruction analyzer <NUM>, a current component extractor <NUM>, a current intensity computing unit <NUM>, a decreasing rate determining unit <NUM>, and a standard changing unit <NUM>. The display controller <NUM> includes an image display unit <NUM>, a waveform display unit <NUM>, and a decreasing rate error display unit <NUM>. The display controller <NUM> may be disposed outside the data processor <NUM>. A memory area for storing the biomagnetic field data <NUM>, the morphological image data <NUM>, the analysis setting value <NUM>, and the decreasing rate standard value <NUM>. is allocated to the memory unit <NUM>.

The input controller <NUM> receives an operation such as a mouse 50a and a keyboard 50b, by an operator of the magnetic field measuring device <NUM>. The position input unit <NUM> receives the position of a control point for expressing a nerve path, such as the spinal cord, on a morphological image, such as an X-ray image displayed on the display 50c. The position information received by the position input unit <NUM> is stored in the memory unit <NUM> as the analysis setting value <NUM>. The waveform area designating unit <NUM> receives a time range in which the current waveform computed by the virtual electrode is displayed on the display 50c. A virtual electrode set on a nerve path, such as the spinal cord, on a morphological image is an example of a second virtual electrode that is positioned at predetermined intervals along the nerve route.

The path generator <NUM> computes the path of the active nerve based on position information of the plurality of control points input from the position input unit <NUM>. The set nerve path is called a nerve route. Here, the computed path is represented by a plurality of coordinate information or an expression representing a curve, and is stored in the memory unit <NUM> as an analysis setting value <NUM>.

The virtual electrode generator <NUM> generates a plurality of virtual electrodes A at equal intervals on the nerve route computed by the path generator <NUM>. Further, a virtual electrode B is generated on the virtual electrode A in the nerve running at a point at a predetermined distance in a direction normal to the nerve route. The distance and the number of the virtual electrodes generated in the path in the normal direction are specified by an operator through an input device such as a mouse 50a or a keyboard 50b, and stored in the memory unit <NUM> as an analysis setting value <NUM> by the input controller <NUM>.

The reconstruction analyzer <NUM> reconstructs the current components for each voxel arranged like a matrix at predetermined intervals using the magnetic field data of the subject P obtained by the measurement of the biomagnetic field by the magnetic field measuring device <NUM>. The voxel is an example of a first virtual electrode installed in a predetermined region that includes a magnetic field data acquisition site.

The current component extractor <NUM> extracts the electromagnetic waveform of each virtual electrode using the current component in the voxel computed by the reconstruction analyzer <NUM> based on the positional relationship between each virtual electrode and the voxel. For example, the current component extractor <NUM> extracts the current component (the direction from upstream to downstream is positive and the direction from downstream to upstream is negative) at the virtual electrode A along the nerve route in the time range received by the waveform area designating unit <NUM> as the current in the axon that conducts the nerve axon in the nerve route.

The current component extractor <NUM> extracts the current component in the normal direction relative to the nerve route on the virtual electrode B as the inward current within the time range received by the waveform area designating unit <NUM>. Here, the direction toward the nerve route is the positive direction. Then, a current waveform of the inward current is generated by a time change in the extracted inward current. Among volume currents flowing outside a nerve axon, the inward current, which is the current component entering a depolarizing region, is important in assessing nerve function. The current waveform is generated, for example, by the waveform display unit <NUM> arranging inward current values in chronological order to obtain image data. The current component extractor <NUM> and the waveform display unit <NUM> are examples of a waveform generator that generate waveforms of inward currents in the virtual electrode.

The current intensity computing unit <NUM> computes the maximum value of the amplitude of the current waveform of the inward current for each virtual electrode computed by the current component extractor <NUM> as the current intensity. For example, the current intensity computing unit <NUM> computes the amplitude of the positive value of the current waveform as the current intensity.

The decreasing rate determining unit <NUM> computes a percentage reduction in the current intensity of the inward current for each pair of adjacent virtual electrodes. For example, the decreasing rate determining unit <NUM> computes the decreasing rate (%) of the current intensity by using Eq. (<NUM>). In Eq. (<NUM>), the sign "*" denotes the operator of product. Decrease in current intensity (%) = ((Downstream current intensity CS2)/(Upstream current intensity CS1))*<NUM>.

The decreasing rate determining unit <NUM> compares the computed decreasing rate of the current intensity with a predetermined standard value (%). For example, the decreasing rate determining unit <NUM> determines whether the computed decreasing rate of the current intensity is less than a predetermined standard value. When the computed decreasing rate of the current intensity is less than a predetermined standard value (%) of the decreasing rate, the decreasing rate determining unit <NUM> outputs the computed decreasing rate of the computed current intensity to the decreasing rate error display unit <NUM> together with the position information of the virtual electrode located at the downstream where the current intensity is computed, for example, as a comparison result. In addition, instead of outputting the comparison result, a computed decreasing rate of the current intensity and a predetermined standard value (a standard value (%) of a predetermined decreasing rate) may be output and displayed on the display 50c.

The standard changing unit <NUM> modifies the standard value of the decreasing rate based on information representing a measurement portion for computing the current intensity of the inward current input through the input device such as the mouse 50a or the keyboard 50b. For example, the standard value of the decreasing rate for each measurement portion is stored in the memory unit <NUM> as the decreasing rate standard value <NUM>. Changing the standard value of the decreasing rate enables the standard value to be appropriately set depending on the measurement portion and the spinal disease diagnosis to be appropriately conducted. The standard changing unit <NUM> may store the standard value of the decreasing rate input from the keyboard 50b or the like as the decreasing rate standard value <NUM> in the memory unit <NUM>.

As illustrated in <FIG> and <FIG>, the image display unit <NUM> superimposes a small white arrow representing the direction and intensity of the current in each voxel reconstructed by the reconstruction analyzer <NUM> on a morphological image (X-ray image) and displays it on the display 50c. As illustrated in <FIG>, the image display unit <NUM> superimposes the nerve path computed by the path generator <NUM> and the virtual electrode generated by the virtual electrode generator <NUM> on the X-ray image and displays these on the display 50c.

The waveform display unit <NUM> displays the current waveform of each virtual electrode computed by the current component extractor <NUM> in accordance with the virtual electrode superimposed on the X-ray image on the display 50c.

Upon receiving the decreasing rate of the current intensity and the position information of the virtual electrode from the decreasing rate determining unit <NUM>, the decreasing rate error display unit <NUM> displays abnormal information indicating that the decreasing rate of the current intensity is erroneous on the display 50c. For example, the error information is displayed on the current waveform or beside the current waveform of the virtual electrode indicated by the position information received from the decreasing rate determining unit <NUM> as a value of the decreasing rate, a text such as an "erroneous decreasing rate" or the like, or a flickering graphic or the like.

The memory area of the biomagnetic field data <NUM> stores the magnetic field data obtained by measuring the magnetic field generated from the subject P by the magnetic field measuring device <NUM>. The memory area of the morphological image data <NUM> stores the X-ray image data of the magnetic field of the subject P captured by the X-ray device <NUM>.

In the memory area for the analysis setting value <NUM>, various parameters required for the measurement of the biomagnetic field by the magnetic field measuring device <NUM> and various set values such as filters (a high pass filter, low pass filter, and so on) used for the magnetic field data obtained by the measurement of the biomagnetic field are stored in advance. In the memory area of the analysis setting value <NUM>, the position information representing the position of the voxel which is the calculation point of the current in the image displayed on the display 50c and the position of the virtual electrode which acquires the current waveform is stored in advance.

The standard value of the current intensity to be referred by the decreasing rate determining unit <NUM> is stored in advance in the memory area for the decreasing rate standard value <NUM>. Although it is not limited, for example, the standard value of the decreasing rate in the lumbar is <NUM>%. Provided that the distance between the virtual electrodes is n (mm), the value of n-power (percentage) of <NUM> is defined as the standard value of the decreasing rate, and the decreasing rate of the current intensity may be set according to the distance between the virtual electrodes. By setting the standard value of the decreasing rate of the current intensity at the distance between the virtual electrodes of a few millimeters, comparison of the current with the standard value can be made at a spatial resolution of a few millimeters.

<FIG> is a diagram illustrating an example of a model of a neural action current. <FIG> illustrates how the current is generated, by the nerve activity, to linearly run in the up and down directions in the figure. The lower side of <FIG> is the distal side and the upper side of <FIG> is the proximal side. For example, by applying electrical stimulation to the peripheral nerve, the stimulation conducts through the nerve axon from the lower side to the upper side as an electrical current.

At this time, an intra-axonal current flowing toward the upper (forward) side of <FIG> and an intra-axonal current flowing toward the lower (reverse) side of <FIG> and a volume current, which is the current component flowing out of the nerve axon and returning to the depolarization point, are generated. The intra-axonal current flowing toward the upper side of <FIG> is referred to as a leading component, and the intra-axonal current flowing toward the lower side of <FIG> is referred to as a trailing component.

For a detailed assessment of nerve function, it is preferable to extract and visually display on display 50c an intra-axonal current flowing along the nerve axon, i.e., a current component in the direction along the nerve route, and the inward current flowing into the depolarization point, i.e., the current component in the direction toward the nerve route from the normal direction of the nerve route.

<FIG> and <FIG> are diagrams illustrating an example of the time change of the current distribution extracted based on the magnetic field data of the measurement target portion (central nervous system) acquired by the biometric measurement system <NUM> of <FIG>. The images illustrated in <FIG> and <FIG> are images in which the current components of each voxel reconstructed by the reconstruction analyzer <NUM> are superimposed on the X-ray image by the image display unit <NUM> and are displayed on the screen of the display 50c at one time. Any one from among the image of <FIG> and the image of <FIG> may be displayed on the screen of the display 50c, and the image for a specified time may be enlarged.

The image in <FIG> illustrates, for example, the time change of the current distribution computed from the magnetic field data obtained by measuring the biomagnetic field generated when the electrical stimulation is applied to the right tibial nerve at the ankle of the subject P, which may have a disc herniation. The image in <FIG> illustrates the time change of the current distribution computed from the magnetic field data obtained when the electrical stimulation is applied to the left tibial nerve at the ankle of the same subject P. In the images illustrated in <FIG> and <FIG>, the current components are superimposed on the X-ray image of the subject P lying on the bed <NUM> in the supine position when captured from above. For this reason, the left side of the image at each time corresponds to the right side of the subject P, and the right side of the image at each time corresponds to the left side of the subject P.

A time, such as "<NUM>" illustrated on the upper side of each image in <FIG> and <FIG>, indicates the elapsed time after applying the electrical stimulation. The thick dotted line arranged in the lateral direction of each image represents the junction (L4/<NUM>) of the fourth lumbar spine (L4) and the fifth lumbar spine (L5). The arrows arranged between the images for each time are added to make the passage of the time easy to understand, and are not required to be displayed on the screen of the display 50c.

In each image, a plurality of small white arrows indicates the direction of current per voxel extracted by reconstruction, and the length of the arrow indicates the current intensity. At the arrow, the end opposite to an arrow tail is the position of the voxel, which is an extraction unit of the current component. The contour-like curve is a current intensity distribution line produced by connecting positions where the current intensities are the same.

In the image at each time, dotted arrows indicate intra-axonal current and shaded arrows indicate the inward current. The dotted arrows and shaded arrows are provided for illustration purposes and are not included in the image displayed on the display 50c.

In order to obtain the magnetic field data used to calculate the current components illustrated in <FIG> and <FIG>, the subject P is laid in the supine position on the bed <NUM> of <FIG> so that the lower back of the subject P faces the SQUID sensor array <NUM>. Then, a plain X-ray image of the lower back of the subject P is captured, and the positional relationship between each SQUID sensor 11a and the lumbar of the subject P is acquired by the data processor <NUM>.

Next, an electrode of the nerve stimulator <NUM> is applied to the portions of the ankles of both legs, and the electrical stimulation (a <NUM> square wave pulse with a duration of <NUM>) is applied alternately to the left and right tibial nerves. The neuromagnetic field generated in the lower back in response to the electrical stimulation is then measured by the magnetic field measuring device <NUM>.

<FIG> illustrates the time change of the current distribution when the right tibial nerve is electrically stimulated. It is observed that the leading and trailing components of the intra-axonal current intruded through the L5 intervertebral foramen on the right side of the subject P (left in <FIG>) are conducted downstream, as indicated by the dotted arrows. As indicated by the shaded arrows, inward currents are observed to be directed toward the nerve axon.

Referring to <FIG> illustrating the time change of the current distribution when the left tibial nerve is electrically stimulated, as indicated by the dotted arrows, it is observed that the leading and trailing components of the intra-axonal current intruding through the L5 intervertebral foramen of the left side (the right side in <FIG>) of the subject P are conducted to the downstream. As indicated by the shaded arrows, the inward currents are observed to be generated toward the nerve axon.

<FIG> is a diagram illustrating an example of the change in the current waveform when the inward current observed in <FIG> and <FIG> is conducted from the upstream to the downstream. The current waveform illustrated in <FIG> is computed on the virtual electrode by the current component extractor <NUM>. The waveform of the inward current corresponding to <FIG> illustrates a decrease in the current intensity at the position of the L4/<NUM> intervertebral disk.

The arrows indicated in the waveform of the inward current corresponding to <FIG> are added for clarity of explanation. The arrows indicate the positive amount of the amplitude amount (current intensity) of the current waveform used for computing the decreasing rate.

In the two X-ray images illustrated in <FIG>, the virtual electrodes are displayed so as to be superimposed on the proximal side of the body with respect to the nerve route added for reference. In the X-ray images, the arrows pointing toward the nerve from the virtual electrode indicate the inward current. In this manner, the virtual electrodes for extracting the inward current are spaced apart by a predetermined distance from the nerve route. The virtual electrode for extracting the inward current is set to the side opposite to the side on which the electrical stimulation is applied. For example, in the X-ray image corresponding to <FIG>, the tibial nerve of the right ankle (left side in <FIG>) is electrically stimulated, so a virtual electrode is set on the left side of the subject P (right side in <FIG>) with respect the nerve route.

The decreasing rate determining unit <NUM> determines that the decreasing rate of the current intensity at the position of the L4/<NUM> intervertebral disc is lower than the standard value of the decreasing rate and outputs the decreasing rate of the current intensity to the decreasing rate error display unit <NUM> together with the position information of the virtual electrode corresponding to the location of the L4/<NUM> intervertebral disc. The decreasing rate of the current intensity is computed by the ratio of the current intensity at the virtual electrode of interest to the current intensity at one upstream virtual electrode (at the position of the L5/S1 intervertebral disc, in this example), as represented by Eq. (<NUM>).

The decreasing rate error display unit <NUM> displays information representing the decreasing rate of the current intensity received from the decreasing rate determining unit <NUM> as abnormal information on the display 50c adjacent to the corresponding current waveform. In the example illustrated in <FIG>, <NUM>%, which is the reduction rate computed by the decreasing rate determining unit <NUM>, is displayed on the display 50c as the text "decreasing rate <NUM>%".

Text indicating the decreasing rate may be more prominent or may be flashing than the color of the waveform.

Further, the display of the decreasing rate is not limited to text, and may be a graphic, a pop-up, or the like. The location where the decreasing rate is displayed is not limited to a position adjacent to the waveform, if this location can correspond to the waveform. For example, the decreasing rate may be displayed at the location that is beside the virtual electrode that is superimposed on the X-ray image. Further, the location where the decreasing rate is displayed may be on the upper or lower portion of the image, if the location can correspond to the waveform. In this case, the color of the virtual electrode corresponding to the decreasing rate to be displayed may be different from the color of another virtual electrode, and the graphic of the corresponding virtual electrode may blink.

On the other hand, the waveform of the inward current corresponding to <FIG> does not show a decrease in the current intensity at the position of the L4/<NUM> intervertebral disc. Therefore, the decreasing rate determining unit <NUM> does not output the decreasing rate of the current intensity to the decreasing rate error display unit <NUM>. Since the waveform illustrated in No. <NUM> is the current waveform not subject to diagnosis, the decreasing rate determining unit <NUM> does not determine the decrease in the current intensity.

In the image corresponding to <FIG> and <FIG>, a plurality of decreasing rates respectively corresponding to all the virtual electrodes that generate the current waveforms may be displayed adjacent to the corresponding waveform or corresponding virtual electrode. In this case, the color displayed on the screen may be changed, or the font size or font type may be changed, depending on whether the decreasing rate in the current intensity is less than the standard value. Thus, the evaluator can recognize the change in the decreasing rate of the current intensity.

The Magnetic Resonance (MR) image illustrated in the left side of <FIG> is for reference only and is not necessarily displayed on the display 50c. The display controller <NUM> displays a superimposed X-ray image and an inward current waveform corresponding to the virtual electrodes of <FIG> and <FIG> in the display 50c. The evaluator such as a physician observing the image illustrated in <FIG> is able to recognize that the electrical stimulation of the right tibial nerve decreases the current intensity at the position of the L4/<NUM> intervertebral disc.

The evaluator then examines the MR image, etc. separately captured with reference to the image illustrated in <FIG> to diagnose the presence or absence of herniation of L4/<NUM> intervertebral disc, etc. For example, the evaluator who viewed the image illustrated in <FIG> can recognize the image illustrated in <FIG> as an image on the unaffected side having a disorder, and can recognize the image illustrated in <FIG> as the image on the affected side without having a disorder. This allows the evaluator to diagnose, for example, the L4/<NUM> intervertebral disc protruding predominantly to the right side on MR images to be the disc herniation. That is, the image illustrated in <FIG> generated by data processor <NUM> can assist in diagnosing spinal disease.

In evaluating peripheral nerves, the standard value of the current intensity referred by the decreasing rate determining unit <NUM> is stored in advance in the memory area of the decreasing rate standard value <NUM>. For example, the standard value of the decreasing rate in the palmar area is <NUM>%, although it is not particularly limited. When the distance between the virtual electrodes is n (mm), the value of n-power (percentage) of <NUM> is defined as the standard value of the decreasing rate, and the decreasing rate of the current intensity may be set in response to the distance between the virtual electrodes. By setting the standard value of the decreasing rate of the current intensity at the distance between the virtual electrodes of a few millimeters, the comparison with the standard value can be made at a spatial resolution of a few millimeters.

<FIG> is a diagram illustrating another display example of abnormal information representing a decreasing rate of the current intensity displayed in the decreasing rate error display unit <NUM> illustrated in <FIG>. For example, the decreasing rate determining unit <NUM> in <FIG> computes a percentage reduction in the current intensity of the inward current for each pair of adjacent virtual electrodes. The decreasing rate error display unit <NUM> displays the value of the current intensity of each virtual electrode, which is computed by the current intensity computing unit <NUM> illustrated in <FIG> and is represented by <NUM> to <NUM>, on the display 50c. The decreasing rate error display unit <NUM> displays the rate of change (the decreasing rate) of the current intensity determined by the decreasing rate determining unit <NUM> in association with the value of the current intensity of each virtual electrode on the display 50c. When the change rate of the current intensity is less than <NUM>, it indicates that the current intensity is decreased.

At this time, the decreasing rate error display unit <NUM> displays the decreasing rate lower than the standard value previously stored in the memory area of the decreasing rate standard value <NUM> on the display 50c so as to distinguish it from the decreasing rate higher than or equal to the standard value. For example, the decreasing rate can be distinguished by highlighting, such as by separating colors or changing the character type. Thus, the evaluator can recognize the transition of the decreasing rate of the current intensity while checking the actual current intensity of each virtual electrode and the change rate of the current intensity between each virtual electrode pair.

As illustrated in <FIG>, the decreasing rate error display unit <NUM> may display the standard value on the display 50c together with the current intensity and the change rate. The standard value may also be displayed on the display 50c in a modifiable manner on a display screen by a user interface. In this case, when the standard value is changed, the decreasing rate error display unit <NUM> highlights a rate lower than the standard value after the change on the display 50c in real time.

<FIG> is a diagram illustrating an example of a time change of a current distribution extracted based on magnetic field data of a target portion (peripheral nerve) acquired by the biometric measurement system <NUM> of <FIG>.

For elements similar to <FIG> and <FIG>, the detailed description is omitted. <FIG> is the image illustrating the time change of the current distribution computed from the magnetic field data obtained by measuring the biomagnetic field generated when the electrical stimulation is applied to the left middle finger of the subject P, which may have carpal tunnel syndrome.

<FIG> is a diagram illustrating an example of a change in the current waveform when the inward current observed in <FIG> is conducted from the upstream to the downstream. The current waveform illustrate in <FIG> illustrates the current waveform at the virtual electrode disposed from the third metacarpal bone along the median nerve and extracted by the current component extractor <NUM> illustrated in <FIG>. In <FIG>, it is recognizable on the screen of the display 50c that the amplitude is attenuated to <NUM>% between the waveform <NUM> representing the inward current and the waveform <NUM> (near the center of the third metacarpal). In <FIG>, a virtual electrode superimposed on the X-ray image, the arrow indicating the inward current, and a line representing the nerve route are added to make the explanation easier to understand and are similar to the superimposed image in <FIG>.

<FIG> is a block diagram illustrating an example of a hardware configuration of the data processor <NUM> of <FIG>.

The data processor <NUM> includes a CPU <NUM>, a ROM <NUM>, a RAM <NUM>, and an external memory device <NUM>. The data processor <NUM> includes an input interface unit <NUM>, an output interface unit <NUM>, an input/output interface unit <NUM>, and a communication interface unit <NUM>. For example, the CPU <NUM>, the ROM <NUM>, the RAM <NUM>, the external memory device <NUM>, the input interface unit <NUM>, the output interface unit <NUM>, the input/output interface unit <NUM>, and the communication interface unit <NUM> are coupled to each other through the bus BUS.

The CPU <NUM> executes various programs such as an operating system (OS) and an application and controls the overall operation of the data processor <NUM>. The CPU <NUM> executes the diagnostic support method by executing the above-described diagnostic support program. The ROM <NUM> holds various programs and parameters including a diagnostic support program executed by the CPU <NUM>. The RAM <NUM> stores various programs executed by the CPU <NUM> and data used in the programs. The external memory device <NUM> is an HDD or an SSD or the like and stores various programs deployed in the RAM <NUM>.

The input interface unit <NUM> is coupled to the input device <NUM> that receives an input from an operator or the like operating the data processor <NUM>. For example, the input device <NUM> may be a mouse 50a, keyboard 50b, or tablet illustrated in <FIG>, or the like. An output device <NUM> for outputting various images, text or graphics generated by the data processor <NUM> is coupled to the output interface unit <NUM>. For example, the output device <NUM> may be a display 50c (<FIG>) or a printer for displaying a display screen or the like generated by various programs executed by the CPU <NUM>.

A recording medium <NUM>, such as a USB (Universal Serial Bus) memory, is coupled to the input/output interface unit <NUM>. For example, various programs, such as diagnostic support programs, may be stored in the recording medium <NUM>. In this case, various programs are transmitted from the recording medium <NUM> to the RAM <NUM> through the input/output interface unit <NUM>. The recording medium <NUM> may be a CD-ROM, a Digital Versatile Disc (DVD) ("Digital Versatile Disc" is a registered trademark), or the like. In this case, the input/output interface unit <NUM> includes an interface corresponding to the recording medium <NUM> to be coupled.

The communication interface unit <NUM> connects the data processor <NUM> to the network or the like.

Thus, in this embodiment, the decreasing rate of the current intensity of the inward current can be computed based, for example, on the magnetic field data obtained from measurements of the magnetic fields generated from the lower back or the cervical region. Therefore, the diagnosis of spinal disease, such as the disc herniation, can be assisted.

By displaying on the display 50c the decreasing rate of the current intensity smaller than the standard value corresponding to the inward current waveform, the change in the current waveform and the decreasing rate can be provided to the evaluator as a diagnostic aid. For example, when the decreasing rate is less than the standard value, the information representing the decreasing rate corresponding to the current waveform can be displayed on the display 50c, so that an abnormal site can be more easily recognized than when the information representing all computed decreasing rate is displayed.

In addition, it is possible to change the desirable standard decrease rate according to the measurement portion based on the information indicating the measurement portion where the current intensity of the inward current is computed. Therefore, it is possible to desirably support the diagnosis of spinal disease.

Although the invention has been described in accordance with the embodiments, the invention is not limited to the requirements described in the embodiments. In these respects, the subject matter of the present invention may be varied without prejudice and may be suitably defined according to its application.

Claim 1:
A diagnostic support apparatus comprising:
a computing unit (<NUM>) that computes a decreasing rate of a current intensity of an inward current flowing into a nerve pathway, based on magnetic field data obtained by measuring a magnetic field generated by a subject; and
a display controller (<NUM>) that displays a comparison result, in which the decreasing rate of the current intensity is compared with a predetermined standard value, on a display unit;
and characterized by further comprising:
a standard changing unit (<NUM>) that is configured to change the predetermined standard value based on information indicating a measurement portion for which the current intensity is computed.