Patent ID: 12239476

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments will be described with reference to the drawings. In each drawing, the same constituent elements may be denoted by the same reference numerals and duplicate explanations thereabout may be omitted.

First Embodiment

FIG.1is a block diagram illustrating an example of a biometric information measurement apparatus including a biometric information display apparatus according to the first embodiment of the present invention. For example, a biometric information measurement apparatus100illustrated inFIG.1includes a Superconducting QUantum Interference Device (SQUID) unit10, a signal acquisition unit20, a data processing apparatus30, an input apparatus80, and a display apparatus90. The data processing apparatus30is a computer such as a Personal Computer (PC), a server, and the like, and functions as a biometric information display apparatus.

The signal acquisition unit20includes a Flux Locked Loop (FLL) circuit21, an analog signal processing unit22, an Analog-to-Digital (AD) conversion unit23, and a Field-Programmable Gate Array (FPGA)24. For example, the SQUID unit10and the signal acquisition unit20are installed in a shield room shielding the magnetism; and the data processing apparatus30, the input apparatus80, and the display apparatus90are installed outside of the shield room.

The data processing apparatus30includes an input control unit40, a display control unit50, an operation control unit60, and a storage unit70. The operation control unit60includes a measurement control unit61, a current reconstruction unit62, a current waveform generation unit63, and an emphasis display determination unit64. For example, the functions of the input control unit40, the display control unit50, and the operation control unit60are implemented by causing a processor such as a Central Processing Unit (CPU) provided in the data processing apparatus30to execute a display program to carry out the biological information display method in cooperation with hardware.

The biometric information measurement apparatus100includes a magnetoencephalograph (MEG), a magnetocardiograph (MCG), a magnetospinograph (MSG), or the like. The biometric information measurement apparatus100may be used to measure magnetic fields of the spinal cord but also magnetic fields of nerves or magnetic fields of muscles (i.e., magnetic fields generated in the skeletal muscles, myocardium, smooth muscles, and the like).

The SQUID unit10measures the magnetic field generated by a subject on the basis of an instruction from the measurement control unit61, and outputs the measured magnetic field as voltage signals. For example, the SQUID unit10includes multiple SQUID sensors arranged to face the measurement portion of the magnetic field of the subject who lies on the bed. The FLL circuit21improves the dynamic range by linearizing the non-linear magnetic field-voltage characteristics measured by the multiple SQUID sensors.

For example, the SQUID sensor is a three-axis sensor with the X axis, the Y axis, and the Z axis, capable of measuring a magnetic field signal as a three-dimensional vector quantity. Alternatively, the SQUID sensor may be a two-axis sensor with the X axis and the Y axis, capable of measuring a magnetic field signal as a two-dimensional vector quantity, or may be a one-axis sensor with only the Z axis. In a case where the one-axis SQUID sensor with only the Z axis is used, a component in the X axis and a component in the Y axis (i.e., a two-dimensional vector quantity) are calculated from the measured biomagnetism signal. The three-axis SQUID sensor has a higher directional resolution than the one-axis SQUID sensor and the two-axis SQUID sensor, so that the three-axis SQUID sensor can improve the measurement accuracy of any given component in the X-Y direction to achieve more detailed evaluation.

The analog signal processing unit22amplifies a magnetic field signal (i.e., a voltage signal), which is a linearized analog signal output from the FLL circuit21, and performs filter processing and the like on the amplified voltage signal. The AD conversion unit23converts the filtered magnetic field signal (i.e., the voltage signal) into a digital value to generate magnetic field data. The FPGA24further performs filter processing, interleave processing, and the like on the magnetic field data digitalized by the AD conversion unit23, and transfers the processed magnetic field data to the data processing apparatus30. Note that at least a part of the processing performed by the FPGA24may be performed by the data processing apparatus30. The digitalized magnetic field data is an example of a biometric signal acquired from a subject (a living body).

The biometric information measurement apparatus100may include other magnetic sensors instead of the SQUID unit10. The biometric information measurement apparatus100may include a potential measurement unit for measuring the potential of the evaluation target area of the subject instead of the SQUID unit10and the signal acquisition unit20. For example, the potential measurement unit continuously measures the potential via multiple electrodes attached to the evaluation target area. For example, a current signal can be calculated as a two-dimensional vector quantity by causing the data processing apparatus30to process temporal changes in the measured potential signal.

In the data processing apparatus30, the input control unit40receives various kinds of information from an operator, who operates the data processing apparatus30, through an input apparatus80such as a mouse, a keyboard, and the like. Hereinafter, the operator of the data processing apparatus30may also be simply referred to as an operator. The operator may be an evaluator such as a doctor explained later. The display control unit50performs control to display, on a display apparatus90such as a liquid crystal display, an X-ray image, an MR image, current waveforms superimposed on the X-ray image or the MR image, and the like. In addition, the display control unit50performs control to display an image display window for displaying images and a user interface screen with which various kinds of conditions are input and displayed when current data are reconstructed from data of the measured magnetic field. The input apparatus80and the display apparatus90may be included in the data processing apparatus30. In addition, an output apparatus such as a printer may be connected to the data processing apparatus30.

In the operation control unit60, the measurement control unit61controls the operation of the SQUID unit10and the signal acquisition unit20. For example, when the biometric information measurement apparatus100functions as a magnetocardiograph, the measurement control unit61causes the SQUID unit10and the signal acquisition unit20to measure the magnetic field in accordance with a measurement start instruction received from the input apparatus80through the input control unit40.

When the biometric information measurement apparatus100functions as a magnetoencephalograph, a magnetospinograph, or a myomagnetometer, the measurement control unit61causes the SQUID unit10and the signal acquisition unit20to measure the magnetic field in accordance with a synchronized signal from a stimulation apparatus giving an electrical stimulation and the like to the subject. The measurement control unit61performs control to receive biomagnetism data generated by the signal acquisition unit20on the basis of the magnetic field measured by the SQUID unit10and stores the received biomagnetism data in the storage unit70. The stimulation given to the subject by the stimulation apparatus is not limited to an electrical stimulation, and the stimulation apparatus may give stimulation by magnetism, sound, or light, or may apply physical stimulation such as vibration and the like.

The current reconstruction unit62reconstructs current components (the orientation, strength, and the like) from the biomagnetism data stored in the storage unit70, and stores the reconstructed current components in the storage unit70. For example, the current components reconstructed from the biomagnetism data are three-dimensional vector data. For example, whereas the SQUID sensors are arranged with a distance of several centimeters between each other, the voxels which are calculation points of currents are arranged with a distance of several millimeters (for example, equal distances) between each other. Because the voxels which are calculation points of currents do not physically exist, the voxels are virtually arranged in programs reconstructing currents from the magnetic field data or in data used by such programs. In this case, the current reconstruction unit62reconstructs the current component in the direction indicated by the calculation direction of the current received from the input apparatus80with the input control unit40. The calculation direction of the current is explained later with reference toFIG.2. When the voxels are arranged with equal distances between each other, the current can be calculated from the magnetic field data by a simpler calculation method than in the case where the voxels are not arranged with equal intervals between each other.

The reconstruction of the current component by the current reconstruction unit62may be performed by using a linear interpolation method, or may be performed using a method with a Unit Gain REcursive Null Steering (UGRENS) filter studied by the inventors of the present application. The method using the UGRENS filter can perform calculation more accurately in a shorter period of time than the linear interpolation method. Note that the method of reconstructing currents from the magnetic field is not limited to the spatial filter method.

The current waveform generation unit63acquires current data that changes over the elapse of time for each voxel as a current waveform (i.e., a measurement result) on the basis of the current components calculated by the current reconstruction unit62and stored in the storage unit70. The current waveform generation unit63causes the acquired current waveform to be displayed on the display apparatus90with the display control unit50, and calculates the latency, which is the time when the current value attains the maximum level, on the basis of the acquired current waveform. In addition, the current waveform generation unit63calculates a maximum value of current data in a certain period of time for each voxel. The current waveform generation unit63is an example of a maximum value calculation unit.

The emphasis display determination unit64determines whether to display a current waveform with emphasis for each voxel at every measurement time, on the basis of a fractional value VT (explained later with reference toFIG.2) received from the input apparatus80with the input control unit40. When the emphasis display determination unit64determines to display a current waveform with emphasis on the basis of the determination result, the emphasis display determination unit64causes the current waveform to be displayed with emphasis on the display apparatus90with the display control unit50. The current waveform may be displayed with emphasis by changing the display color of the current waveform, by displaying a figure (emphasis mark) with the current waveform, or by displaying only a figure. Such displaying with emphasis is explained later with reference toFIG.2.

The storage unit70is implemented with a storage device such as, e.g., a hard disk drive (HDD), and includes areas for storing biomagnetism data71, morphological data72, and various kinds of setting values73. The biomagnetism data71includes magnetic field data measured by the SQUID unit10and processed by the signal acquisition unit20. The morphological data72includes X-ray image data captured by an X-ray image-capturing apparatus, not illustrated, or a magnetic resonance (MR) image data captured by a magnetic resonance imaging apparatus, and the like.

The morphological data72may include current waveform data generated for each voxel, emphasis mark data, and the like. The current waveform data and the emphasis mark data may be stored, as superimposing data which are displayed in a superimposed manner on a morphological image, in a separate area in the storage unit70. Hereinafter, an X-ray morphological image of a subject generated from the X-ray image data is referred to as an X-ray image, and a cross-sectional image of a subject generated from MR image data is referred to as an MR image.

The setting values73are used to store various kinds of information displayed in a user interface screen on the display apparatus90. Examples of the setting values73are explained later with reference toFIG.2. Parameters and the like of filters (e.g., a high pass filter and a low pass filter) provided in the signal acquisition unit20may be stored as the setting values73in the storage unit70.

FIG.2is an explanatory diagram illustrating an example of a user interface screen displayed on the display apparatus90ofFIG.1. For example, currents are reconstructed from the magnetic field data acquired by measuring the magnetic field generated by myocardial motions, and as illustrated inFIG.2, the waveforms of the reconstructed currents and the emphasis marks are displayed for respective voxels in a superimposed manner on the morphological image.

Hereinafter, in an image display window WIN displayed on the user interface screen, a point corresponding to a voxel is referred to as a voxel point. The display control unit50operating on the basis of an instruction given by the operation control unit60controls the display apparatus90to display the user interface screen as illustrated inFIG.2on the display screen of the display apparatus90. In the example as illustrated inFIG.2, a morphological image (MR image) of the heart of which the magnetic field is measured by the magnetocardiograph is displayed in the image display window WIN.

The user interface screen includes the image display window WIN in which a morphological image and the like can be displayed, area coordinate input fields Ymax, Ymin, Xmax, and Xmin, waveform display time input fields tWAVE, peak detection time input fields tPEAK, and a fractional value input field VT. The user interface screen includes a pitch input field PITCH and a current calculation direction input field DIR. Hereinafter, the setting values73, which are set using the respective input fields Ymax, Ymin, Xmax, Xmin, tWAVE, tPEAK, VT, PITCH, and DIR, will be hereinafter explained with reference to the names of the respective input fields.

Also, the user interface screen includes a slide bar SLIDE and a moving picture output button EXPM. When an operator slides the slide bar SLIDE, an evaluation time of current components displayed on the upper side of the image display window WIN is changed. When the operator presses the moving picture output button EXPM, an image displayed according to operation of the slide bar SLIDE is exported as moving picture data. The evaluation time is a relative time indicating a measurement time with respect to a reference time. The measurement time is a time at which the magnetic field signals used for calculating current components displayed on the morphological image in the image display window WIN were measured. For example, when the magnetic field generated by myocardial motions is measured, the reference time (0 ms) is a point in time when a heartbeat occurs. The evaluation time indicates the extent of time before the heart beat occurs. In this case, the evaluation time is of a negative value.

The entered area coordinates Ymax, Ymin, Xmax, and Xmin are used to set a rectangular area for calculating current waveforms in the image displayed in the image display window WIN. The rectangular area designated by the area coordinates Ymax, Ymin, Xmax, and Xmin is an example of area for calculating current waveforms. In the example as illustrated inFIG.2, the designated area coordinates Ymax, Ymin, Xmax, and Xmin are “Y1”, “−Y2”, “X1”, and “−X2”. The current waveforms displayed in the image display window WIN are biometric signal waveforms derived from muscles obtained by restructuring current values from magnetic field signals that occur according to currents flowing due to myocardial motions.

The waveform display time input field tWAVE is used to set a time range for displaying the current waveforms. In the example as illustrated inFIG.2, the time range for displaying the current waveforms is set to a range from “−200 ms” to “−50 ms”. Where a point in time at which a heartbeat occurs (reference time) is defined as 0 ms, the time range is of negative values, because the time range indicates a length of time before the heartbeat.

The peak detection time input field tPEAK is used to set a time range used for detection of the latency (in this example, a time when a peak current appears). The time range set by the peak detection time input field tPEAK is included in the range of the waveform display time tWAVE. In the example as illustrated inFIG.2, the peak detection time tPEAK is set to a range of “−135 ms” to “−120 ms”. The peak detection time tPEAK is an example of a certain period of time. With the peak detection time tPEAK being set, a wrong latency is prevented from being detected due to noise waveforms and the like outside of the range of the peak detection time tPEAK.

The fractional value input field VT is used to set a fractional value VT for determining whether a current value is to be displayed with emphasis at each voxel point. For example, the maximum value (peak value) of the current, i.e., the measurement result, is defined as 100%, and the fractional value input field VT is represented as a percentage of any given current value with respect to 100% such that when the magnitude of the current value is greater than or equal to a threshold value obtained by multiplying the peak current value by the percentage entered in the fractional value input field VT, the current value is displayed with emphasis. In the example as illustrated inFIG.2, when the current value at the evaluation time is greater than or equal to 99% of the peak current value, the current value is determined to be displayed with emphasis.

In this embodiment, the fractional value VT for determining whether to display any given current value with emphasis can be set with reference to the current value at the latency for each voxel point, so that, even in a measurement portion where an amount of current is relatively small, an evaluator such as a doctor can readily judge the latency from the image displayed in the user interface screen. With the fractional value VT being set, a current value is displayed with emphasis in a predetermined period of time around the latency, so that the visibility of the latency for an evaluator such as a doctor can be improved as compared with a case where the current value is displayed with emphasis only at the instance of the latency. InFIG.2, the fractional value VT is set commonly for all the voxels, but the fractional value VT may be set individually for each of the voxels.

In addition, for each voxel, a current waveform and a figure for emphasis are displayed in a superimposed manner on the measurement target area of the morphological image, so that an evaluator such as a doctor who evaluates the function of the subject by seeing the user interface screen can readily recognize the association between the current flowing through the evaluation target area and the corresponding portion of the morphological image. In contrast, when the fractional value VT is represented as a current value, a voxel point of which the amount of current is less than amounts of currents in other voxel points is not displayed with emphasis, which makes it difficult for an evaluator such as a doctor to visually determine the latency.

The pitch input field PITCH is used to set a pitch of voxels in which currents are reconstructed. In the example as illustrated inFIG.2, the pitch PITCH is set to “10 mm”. In the range defined by the area coordinates Ymax, Ymin, Xmax, and Xmin, multiple blocks are set, with a pitch PITCH, in association with the respective voxels.

In the current calculation direction input field DIR, the operator sets, in angle, a target component direction, i.e., a direction in which currents (measurement values) are calculated. For example, in the user interface screen, the right-hand side direction is defined as “0 degrees”, the lower side direction is defined as “90 degrees”, the lefthand side direction is defined as “180 degrees”, and the upper side direction is defined as “270 degrees”. In the example as illustrated inFIG.2, the current calculation direction DIR is set to “0 degrees (X direction)”.

Current waveforms are calculated by setting the current calculation direction DIR according to the evaluation target area (a direction in which muscle fibers or neural fibers), so that clinically useful muscle-derived or nerve-derived current waveforms can be obtained. For example, the cardiac muscles do not extend in a single direction but extend in various directions, and accordingly, it is preferable to allow the operator to set the current calculation direction DIR to any desired direction.

InFIG.2, the current calculation direction DIR is set commonly for all the voxels, but the current calculation direction DIR may be individually set for each of the voxels, or may be set for each of the voxel groups, each including a predetermined number of voxels. In this case, even in a case where muscles extend in various directions, the current calculation direction DIR may be set for each of the directions in which the muscles extend, so that clinically useful current waveforms can be obtained. In contrast, the potentials measured by what is termed as a catheter mapping using a catheter are scalar quantities. Therefore, with the catheter mapping, the current components calculated from the potentials cannot be divided into directions.

Note that the operation control unit60may set the current calculation direction DIR (i.e., the target component direction) on the basis of information received from the input control unit40with respect to operation performed by the operator on the input apparatus80with a mouse and the like. For example, an input mode for inputting the current calculation direction DIR may be prepared, and when the operator draws a straight line on the image display window WIN with the mouse, the operation control unit60may set the direction (angle) of the straight line drawn from a start point to an end point as the current calculation direction DIR.

In this embodiment, the current calculation direction DIR may be set to any given direction (greater than or equal to 0 degrees, and less than 360) in a plane including the X direction (i.e., the horizontal direction inFIG.2) and the Y direction (i.e., the vertical direction inFIG.2). Further, the current calculation direction DIR may be allowed to be set to any spherical direction which is a combination of not only the X and Y directions but also the Z direction. Also, the current calculation direction DIR may be set for each of the voxels, or may be set for each of the voxel groups, each including a predetermined number of voxels.

The operation control unit60controls the display control unit50to display the entered setting values Ymax, Ymin, Xmax, Xmin, tWAVE, tPEAK, VT, PITCH, and DIR on the user interface screen, and stores them as the setting values73in the storage unit70. The storage unit70may store the default values of the setting values Ymax, Ymin, Xmax, Xmin, tWAVE, tPEAK, VT, PITCH, and DIR, in advance. The current reconstruction unit62, the current waveform generation unit63, and the emphasis display determination unit64perform processing by using the default values of setting values73not having been input from among the setting values Ymax, Ymin, Xmax, Xmin, tWAVE, tPEAK, VT, PITCH, and DIR.

InFIG.2, current waveforms (temporal changes of current intensities) and indications for emphasis (black circles) at the evaluation time “−131.60 ms”, displayed on the upper side of the image display window WIN, are displayed in a superimposed manner on the morphological image in the image display window WIN. In other words, in the image display window WIN, the current waveforms of which the current values at the evaluation time are located on the Y axis are displayed. At each voxel point, when the current value on the Y axis at the evaluation time “−131.60 ms” is 99% or more with respect to the peak current value at the latency, a black circle is displayed as an emphasis.

The black circle is an example of a figure indicating that the measurement value has been determined to be greater than or equal to a threshold value obtained by multiplying the maximum value (i.e., the peak current value) by a predetermined fractional value defined in advance. A block (voxel area) in which a black circle is displayed is an example of a positively-determined block in which the measurement value has been determined to be greater than or equal to the threshold value obtained by multiplying the maximum value (i.e., the peak current value) by a predetermined fractional value defined in advance and in which the determination result has been reflected. A block (voxel area) in which a black circle is not displayed is an example of a negatively-determined block in which the measurement value has been determined to be less than the threshold value obtained by multiplying the maximum value (i.e., the peak current value) by the predetermined fractional value defined in advance. The shape of the figures displayed in the blocks corresponding to the voxels is not limited to the black circles, and the color of the figures is not limited to black. Instead of displaying the black circles, the thicknesses of the current forms may be increased for emphasis.

In the enlarged view of the voxel area illustrated on the upper side ofFIG.2, each voxel point is located at the intersection between the X axis representing the time and the Y axis representing the current intensity (amplitude). As described above, the current value of the current waveform intersecting the Y axis is the current value at the evaluation time “−131.60 ms” displayed in the user interface screen. The scales (defined by the maximum values and the minimum values in the X axis and the Y axis) of the current waveforms displayed in the image display window WIN are the same for all of the voxel points.

When the image including the current waveforms and the like displayed in the image display window WIN is changed by operating the slide bar SLIDE, the current waveforms are moved in the X axis direction so that the current values at the evaluation time that is set by operating the slide bar SLIDE intersect the Y axis. At each voxel point, when the current value intersecting the Y axis in the current waveform is greater than or equal to the threshold value obtained by multiplying the maximum value (i.e., the peak current value) at the latency by the fractional value VT, a black circle is displayed, and when the current value is less than the fractional value VT, a black circle is not displayed.

When images and the like are displayed in color in the image display window WIN, the current waveforms in the voxels corresponding to the black circles may be displayed in red and the like for emphasis, instead of being emphasized with the black circles. Also, a circular mark of which the size is changed in accordance with the magnitude of the peak current at the latency may be displayed. Specifically,FIG.13illustrates an example in which, where the magnitude of the maximum value of the peak currents in all of the blocks is denoted as A, a large circular mark is displayed in a block with a current value of A×0.9 or more, a medium circular mark is displayed in a block with a current value of A×0.7 or more and less than A×0.9, and a small circular mark is displayed in a block with a current value of less than A×0.7. It is to be understood that how greatly the size of the circular mark is changed may be in any manner, and the circular mark may not be necessarily changed to three levels in size. For example, the circular mark may be changed to two levels in size, or may be changed to four levels or more in size. Also, a circular mark may be displayed in a color corresponding to the magnitude of the peak current at the latency. In a case where the circular marks are displayed in corresponding colors, a legend including a color bar (like an intensity bar indicating the intensity as illustrated inFIG.6) indicating a correspondence between the magnitude of the current and the color may be displayed besides the image display window WIN. The shapes and the colors in the method for displaying the current values in the image display window WIN are not particularly limited as long as a voxel in which the current value is greater than or equal to the threshold value obtained by multiplying the maximum value (i.e., the peak current value) by the fractional value VT and a voxel in which the current value is less than the threshold value can be readily distinguished from each other.

FIG.3is a flowchart illustrating an example of operation of the data processing apparatus30as illustrated inFIG.1. First, in step S10, the measurement control unit61measures the biomagnetism of the subject by controlling the SQUID unit10and the signal acquisition unit20. For example, when the measurement control unit61measures the magnetic fields of nerves such as the brain and the spinal cord or measures the magnetic field of muscles, the measurement control unit61causes the SQUID unit10to measure the biomagnetism of the subject while an electrical stimulation is given to the peripheral nerves of the subject. The electrical stimulation is given to the subject by the stimulation apparatus connected to the signal acquisition unit20as illustrated inFIG.1.

The measurement control unit61may measure the biomagnetism in advance before the flow as illustrated inFIG.3is performed. In this case, the data processing apparatus30does not perform step S10, and instead, the data processing apparatus30performs processing in step S20and subsequent steps by using the biomagnetism data stored in the storage unit70.

In step S20, the current reconstruction unit62reconstructs the current components on the basis of the magnetic field data of all the measurement points. The current reconstruction unit62stores current information including the intensities and coordinates of the currents acquired from reconstruction as the morphological data72in the storage unit70. Note that when the storage unit70does not store setting values73such as VT, PITCH, DIR, and the like used in the processing in step S20and subsequent steps, the default values are used.

Next, in step S30, current waveforms in the designated current calculation direction DIR are generated for each voxel. By using the current information stored in the storage unit70, the current waveform generation unit63generates the current waveforms that change according to an elapse of the measurement time. Then, the operation control unit60controls the display control unit50to display current waveforms, corresponding to the evaluation time that is set with the slide bar SLIDE, in a superimposed manner on the morphological image such as an X-ray image, an MR image, and the like in the image display window WIN. The image on which the current waveforms are superimposed is not particularly limited as long as the evaluation target area of the subject can be seen in the image.

Next, in step S40, when current waveforms in respective voxels are desired to be displayed with emphasis according to current values at the evaluation time that has been set, the emphasis display determination unit64displays black circles and the like for emphasis in the image displayed in the image display window WIN.

Next, in step S50, the input control unit40receives inputs of various kinds of setting values73from the operator with the input apparatus80, and stores the received setting values73in the storage unit70. Hereinafter, the receiving of inputs of various kinds of setting value73is explained with reference toFIG.4. For example, when it is difficult for the operator to see how the currents change from the current waveforms displayed with the emphasis in step S40, step S50is performed to change the current calculation direction DIR and the fractional value VT on the basis of an operation performed by the operator.

Next, in step S60, when currents need to be reconstructed according to changed setting values73, the operation control unit60proceeds to step S20, and when currents do not need to be reconstructed, the operation control unit60proceeds to step S70. For example, when a voxel in which a current has not been reconstructed occurs due to a change in area coordinates Ymax, Ymin, Xmax, and Xmin, the currents need to be reconstructed.

In step S70, when current waveforms need to be reconstructed according to changed setting values73, the operation control unit60proceeds to step S30, and when current waveforms do not need to be reconstructed, the operation control unit60proceeds to step S40. For example, when at least one of the pitch PITCH and the current calculation direction DIR is changed, the currents need to be reconstructed. The processing in step S20to step S70is repeatedly performed until the biomagnetism is measured, until an operation is performed to close the user interface screen, or until the data processing apparatus30is turned off. When the slide bar SLIDE is operated, a current distribution (voxels displayed with emphasis) and the like corresponding to the evaluation time that is set by operating the slide bar SLIDE are displayed in the image display window WIN again.

FIG.4is a flowchart illustrating an example of step S50ofFIG.3. The order of execution of processing in step S501to step S512such as the pair of steps S501and S502, the pair of steps S503and S504, and the like is not limited to the order illustrated inFIG.4, and the setting of each pair may be performed successively.

When the input control unit40receives inputs of the area coordinates Ymax, Ymin, Xmax, and Xmin in step S501, the input control unit40stores the received area coordinates Ymax, Ymin, Xmax, and Xmin in the storage unit70in step S502to set the received area coordinates Ymax, Ymin, Xmax, and Xmin as setting values73.

When the input control unit40receives the pitch PITCH in step S503, the input control unit40stores the received pitch PITCH in the storage unit70in step S504to set the received pitch PITCH as a setting value73. When the input control unit40receives a waveform display time tWAVE in step S505, the input control unit40stores the received waveform display time tWAVE in the storage unit70in step S506to set the received waveform display time tWAVE as a setting value73.

When the input control unit40receives the peak detection time tPEAK in step S507, the input control unit40stores the received peak detection time tPEAK in the storage unit70in step S508to set the received peak detection time tPEAK as a setting value73. When the input control unit40receives the fractional value VT in step S509, the input control unit40stores the received fractional value VT in the storage unit70in step S510to set the received fractional value VT as a setting value73.

When the input control unit40receives the current calculation direction DIR in step S511, the input control unit40stores the received current calculation direction DIR in the storage unit70in step S512to set the received current calculation direction DIR as a setting value73. When the input control unit40determines that the inputs of all of the setting values73have been finished, the input control unit40terminates the processing in step S50. Whether the inputs have been finished may be determined on the basis of a termination instruction of reception entered by the operator with the input apparatus80.

The setting values73stored in the storage unit70in the processing of step S50as illustrated inFIG.4may be used when currents are reconstructed from other magnetic field data to display current waveforms and the like in the image display window WIN. In this case, in the processing of step S50, the determinations in steps S501, S503, S505, S507, S509, S511are made as “NO”, and thereafter, the determination in step S513is made as “NO”. Accordingly, the processing in step S50can be substantially omitted, and the time it takes to set the setting values73can be reduced. In addition, when the same setting values73are used, the current data reconstructed from magnetic field data different from each other can be compared easily. A series of setting values73that are set in step S50may be stored in the storage unit70with a group name, and the setting values73may be recalled and used by designating the group name.

FIG.5is an explanatory diagram illustrating an example of changes in images displayed on the display apparatus90ofFIG.1. LikeFIG.2, the image as illustrated inFIG.5includes a morphological image (MR image) of the heart of which the magnetic field is measured by magnetocardiograph. The method for displaying current waveforms and black circles for emphasis is the same as the method according to the flow as illustrated inFIG.3.FIG.5illustrates only the image displayed in the image display window WIN ofFIG.2, but the configuration of the user interface screen for displaying the image is the same as the configuration ofFIG.2.

When the operator operates the slide bar SLIDE, the image displayed in the image display window WIN is changed in the order as indicated by the arrows inFIG.5. A white solid circle inFIG.5indicates the position of the posterior wall of the left atrium, and is an area in which a relatively large magnetic field signal derived from the left atrium is measured. A white broken line circle illustrated inFIG.5indicates the position of a connection portion between the pulmonary vein and the heart, and is an area in which a relatively small magnetic field signal derived from the myocardium surrounding the pulmonary vein is measured. The white solid circles and the white broken line circles are attached for the sake of explanation, and are not actually displayed in the images.

When current information such as currents reconstructed from magnetic field data is displayed in a superimposed manner on a morphological image according to a conventional technique, the current information is displayed with a scale corresponding to a signal with a large current intensity. In this case, the current information about the myocardium connected to the pulmonary vein is difficult to recognize because it is buried in the current information about large currents derived from the left atrium, and it is difficult to evaluate the myocardium connected to the pulmonary vein.

For example, it has been reported that, in the heart, the myocardium signal connected to the pulmonary vein is the cause of atrial fibrillation. In this embodiment, black circles are not displayed with reference to the magnitudes of the currents, but are displayed with reference to the peak values of the currents in the respective voxels. Therefore, when the amplitudes of the currents are small, black circles can be displayed around an occurrence of a peak current, and conduction of a small current in the myocardium and the like can be visually recognized.

The fractional value VT is set for each voxel point, and therefore, even if a large magnetic field signal derived from the left atrium and a small magnetic field signal derived from the myocardium of the pulmonary vein are present at the same time, the current information about the myocardium of the pulmonary vein can be displayed with emphasis on the basis of a reference that is different from the current information about large currents derived from the left atrium.

Accordingly, as indicated by the white broken line circle, currents flowing in the right pulmonary vein at “−132.4 ms” and currents flowing in the left pulmonary vein at “−120.4 ms” can be displayed without being hidden by large currents derived from the left atrium. In other words, as compared with conventional methods, signals transmitted to the pulmonary vein can be displayed in a visually easy-to-understand manner.

For example, it is assumed that there are a first voxel of which the peak value of the current is “10” and a second voxel of which the peak value of the current is “100”, and it is assumed that the fractional value VT is set to 90%. In this case, a black circle is displayed in the first voxel if the current value is greater than or equal to “9”, and a black circle is displayed in the second voxel if the current value is greater than or equal to “90”. Therefore, just like a large current, even a small current of which the peak value is about one-tenth can be emphasized with a black circle and the like in the image at the evaluation time at around the peak current.

When the operator operates the slide bar SLIDE with the input apparatus80such as a mouse, the operation control unit60reads a morphological image and the like from the storage unit70on the basis of an operation content received with the input control unit40, and causes the display control unit50to display the morphological image.

Comparative Example

FIG.6is an explanatory diagram illustrating an example (Comparative Example) of changes in images displayed on a display apparatus of another biometric information measurement apparatus. In the image as illustrated inFIG.6, (the directions and the intensities) of the current components reconstructed in respective voxels from the measured magnetic field are displayed in a superimposed manner on the morphological image (MR image) of the heart of which the magnetic field is measured by magnetocardiograph. The morphological image inFIG.6is similar to the morphological image as illustrated inFIG.5. In the example as illustrated inFIG.6, the current values at all the voxel points are displayed as arrows with lengths corresponding to the current intensities with the same scale. Curved lines in a manner of contour lines are current intensity distribution lines that indicate the positions of equal current intensities, and although it is difficult to see, a line of a lighter color indicates a higher current, and a line of a darker color indicates a lower current. When images and the like are displayed in color in the image display window WIN, the current intensity distribution lines may be displayed in different colors corresponding to the current intensities.

Just likeFIG.5, a white solid circle inFIG.6indicates the position of the posterior wall of the left atrium, and a white broken line circle illustrated inFIG.6indicates the position of a connection portion between the pulmonary vein and the heart. The white solid circles and the white broken line circles are attached for the sake of explanation. In order to evaluate the currents derived from the myocardium surrounding the pulmonary vein, it is important to be able to easily recognize the currents flowing in the connection portion between the pulmonary vein and the heart. However, as illustrated inFIG.6, when information about the current intensity is displayed, the currents derived from the left atrium are relatively large and noticeable, whereas the currents derived from the myocardium surrounding the pulmonary vein are difficult to recognize and are difficult to evaluate.

FIG.7is an explanatory diagram illustrating an example of changes in images in another measurement portion displayed on the display apparatus90as illustrated inFIG.1. In the example as illustrated inFIG.7, the biometric information measurement apparatus100is caused to function as a magnetospinograph to measure the biomagnetism in the cervical spinal cord (nerves) of the subject in response to an electrical stimulation given by a stimulation apparatus, and a change in a current reconstructed from the magnetic field data is displayed for each voxel in a superimposed manner on an X-ray image of the subject. The current waveforms displayed in the image display window WIN are biometric signal waveforms derived from the nerves obtained by reconstructing current values from the magnetic field signals occurring according to the currents flowing due to the actions of the nerves. An evaluation time (for example, 7.0 ms) displayed on the upper side of the image display window WIN is a measurement time at which the magnetic field signals used for calculating the current components are measured, and indicates a length of time elapsed from a point in time (reference time=0 ms) of an electrical stimulation.

The method for displaying current waveforms and displaying black circles for emphasis is the same as the method according to the flow as illustrated inFIG.3.FIG.7illustrates only the image displayed in the image display window WIN ofFIG.2, but the configuration of the user interface screen for displaying the image is the same as the configuration ofFIG.2. A white broken line circle as illustrated inFIG.7indicates a position beside the direction in which the nerves of the cervical spinal cord extend, which is the evaluation target area, and indicates a position to evaluate the current component (inward currents of depolarized portions) perpendicular to the direction in which the nerves of the cervical spinal cord extend. In the nerves, it is important to evaluate inward currents of depolarized portions. The white broken line circles are attached for the sake of explanation, and are not actually displayed in the images.

InFIG.7, the current components (inward currents of depolarized portions) perpendicular to the direction in which the nerves of the cervical spinal cord extend, which are the valuation target area, are evaluated, and accordingly, the current calculation direction DIR is set to “0” degrees (the X direction, i.e., the horizontal direction ofFIG.5). Therefore, only the inward current components of depolarized portions can be displayed as black circles, and an evaluator such as a doctor can easily visually recognize conductions of inward currents of depolarized portions.

Comparative Example

FIG.8is an explanatory diagram illustrating an example (Comparative Example) of changes in images in another measurement portion displayed on a display apparatus of another biometric information measurement apparatus. In the image as illustrated inFIG.8, (the directions and the intensities) of the current components reconstructed in respective voxels from the measured magnetic field are displayed in a superimposed manner on the morphological image (X-ray image) of the cervical spinal cord (nerves) of which the magnetic field is measured by magnetocardiograph. The morphological image inFIG.8is similar to the MORPHOLOGICAL image as illustrated inFIG.7. LikeFIG.6, in the example as illustrated inFIG.8, the current values at all the voxel points are displayed as arrows with lengths corresponding to the current intensities with the same scale. LikeFIG.6, curved lines in a manner of contour lines are current intensity distribution lines that indicate the positions of equal current intensities.

When currents are displayed as arrows with lengths corresponding to the current intensities, not only currents in the white broken line circle, which is the evaluation target area, but also current components (intraaxonal currents) flowing, outside of the white broken line circle, in parallel with the direction in which the nerves of the cervical spinal cord extend, and current components (volume currents) flowing around the axons are displayed prominently. Therefore, with only the directions and the magnitudes of the arrows, it is difficult to evaluate current components (inward currents of depolarized portions) perpendicular to the direction in which the nerves of the cervical spinal cord extend.

Hereinabove, in the first embodiment, for each voxel, a current value is determined as to whether a peak value of a current waveform is greater than or equal to the threshold value obtained by multiplying the maximum value (i.e., the peak current value) by the fractional value VT, and a black circle and the like indicating that the current value is close to the peak value is displayed for emphasis with a block corresponding to a voxel in which the peak value is greater than or equal to the threshold value obtained by multiplying the maximum value (i.e., the peak current value) by the fractional value VT. In this case, according to the fractional value VT, a black circle and the like indicating a positively-determined block is displayed for emphasis with a positively-determined block that is determined to be around the peak current, and the black circle is not displayed with a negatively-determined block other than the positively-determined block. Therefore, a measurement result of a relatively small biometric signal can be displayed in the image display window WIN, without being buried in a measurement result of a relatively large biometric signal. As a result, the visibility of the measurement result of the relatively small biometric signal in the image display window WIN can be improved, and even when the biometric signal of the evaluation target is relatively small, an evaluator such as a doctor can easily evaluate the conductions of the biometric signals while seeing the user interface screen.

For each voxel, the current waveform and the figure for emphasis are displayed in an overlapping manner on the morphological image of the measurement target area, and therefore, an evaluator such as a doctor can easily recognize the relative positions between the currents in the evaluation target area and the corresponding portions in the morphological image.

In the first embodiment, a magnetic field signal, which is a vector quantity, or a current signal, which is a vector quantity, are used. Therefore, the current calculation direction DIR for calculating the current waveforms can be set according to the evaluation target area (the direction in which muscle fibers or nerves extend). Because the current calculation direction DIR is set according to the direction in which muscle fibers or nerves extend, clinically useful muscle-derived or nerve-derived current waveforms can be obtained. For example, although current components of desired X-Y direction components can be obtained with a high precision by using a three-axis SQUID sensor of a high directional resolution, components in the X axis and components in the Y axis can be obtained from magnetic field data measured with a one-axis (the Z axis) SQUID sensor.

Second Embodiment

FIG.9is an explanatory diagram illustrating an example of a display screen displayed on a display apparatus of a biometric information measurement apparatus according to the second embodiment of the present invention. Constituent elements similar toFIG.2are denoted with the same reference numerals, and detailed explanation thereabout is omitted.

The user interface screen as illustrated inFIG.9is displayed on the display apparatus90of the biometric information measurement apparatus100as illustrated inFIG.1. The morphological image, the current waveform, and the like displayed in the image display window WIN of the user interface screen are generated by the data processing apparatus30as illustrated inFIG.1. Therefore, the biometric information measurement apparatus100as illustrated inFIG.1is different from the second embodiment in some of the functions of the input control unit40and the functions of the operation control unit60. A morphological image (MR image) of the heart of which the magnetic field is measured by the magnetocardiograph is displayed in the image display window WIN ofFIG.9in a manner similar toFIG.2.

In this embodiment, multiple areas AREA can be set in the image display window WIN, and the pitch PITCH of voxels and the current calculation direction DIR can be set for each of the areas AREA. According to the pitch PITCH that has been set for each of the areas AREA, the voxels are arranged with equal distances.

In addition, a waveform display button DISP for switching ON or OFF the display of the current waveform for each voxel is added. InFIG.9, “waveform display ON” is selected, and accordingly, black circles and current waveforms are displayed in the image display window WIN. The waveform display time tWAVE, the peak detection time tPEAK, and the fractional value VT are commonly set for all of the areas AREA. The fractional value VT may be set for each of multiple areas AREA, or may be set for each of the voxels.

For example, the area AREA is set by inputting an area name (“A2” inFIG.9) to the area coordinate input field AREA and designating an area AREA (A2) in the image display window WIN. The area AREA may be designated by inputting a rectangular frame with the input apparatus80such as a mouse, or may be designated by inputting a closed curve of any shape (e.g., a polygon). Alternatively, the area AREA may be designated using the area coordinate input fields Ymax, Ymin, Xmax, and Xmin illustrated inFIG.2. As long as the area AREA is in such a range that current values can be reconstructed from measurement data of the magnetic field, the range of the area AREA may be set outside of an area of an image displayed in the image display window WIN.

For example, the areas AREA that have been set in the past may be selected from a pull-down list that is displayed when the area coordinate input field AREA is clicked, and the selected area AREA may be displayed with emphasis by a white frame FLM (A2) in the image display window WIN. The pitch input field PITCH and the current calculation direction input field DIR are used to input the current calculation direction DIR (component direction) with respect to the selected area AREA (=A2).

When multiple areas AREA that have been set overlap with each other in the image display window WIN, an area AREA that is set later becomes valid in the overlapping portion. In the example as illustrated inFIG.9, after the area AREA (=A1; Ymax=Y1, Ymin=−Y2, Xmax=X1, Xmin=−X2) similar toFIG.2is set, an area AREA (=A2) indicated by a white frame FLM (A2) is set to overlap with the area AREA (A1). The pitch PITCH of the area AREA indicated by the white frame FLM (A2) is set to “5 mm”, and the current calculation direction DIR is set to “0 degrees”. As explained with reference toFIG.2, the current calculation direction DIR may be allowed to be set with the Z direction, and/or may be allowed to be set for each of the voxels or for each of the voxel groups.

In this embodiment, a predetermined number of areas AREA each being of any given size and being at any given position can be set, and the pitch PITCH of voxels and the current calculation direction DIR can be set for each of the areas AREA. Accordingly, for each evaluation target area of the subject, an emphasis (a black circle and the like) can be displayed according to the pitch PITCH and the current calculation direction DIR of the evaluation target area. Therefore, even when the value of the current flowing through the evaluation target area is small, an evaluator such as a doctor can easily evaluate the conductions of the biometric signals while seeing the user interface screen.

FIG.10is an explanatory diagram illustrating another example of a display screen displayed on a display apparatus of a biometric information measurement apparatus including the biometric information display apparatus according to the second embodiment of the present invention. Constituent elements similar toFIG.9are denoted with the same reference numerals, and detailed explanation thereabout is omitted. The example as illustrated inFIG.10illustrates a user interface screen in which the area AREA (=A1) is selected. For example, the pitch PITCH of the area AREA indicated by the white frame FLM (A1) is set to 10 mm, and the current calculation direction DIR is set to 0 degrees.

FIG.11is an explanatory diagram illustrating still another example of a display screen displayed on a display apparatus of a biometric information measurement apparatus including the biometric information display apparatus according to the second embodiment of the present invention. Constituent elements similar toFIG.9are denoted with the same reference numerals, and detailed explanation thereabout is omitted. The example as illustrated inFIG.11illustrates a user interface screen in which an area AREA (=A3) is selected. For example, the pitch PITCH of the area AREA indicated by the white frame FLM (A3) is set to 5 mm, and the current calculation direction DIR is set to 0 degrees. InFIG.11, “waveform display OFF” is selected by the waveform display button DISP. As a result, the current waveforms corresponding to the voxels are not displayed in the white frame FLM (A3). For example, the details of the morphological image can be displayed in an easy-to-see manner by hiding the current waveforms, and an evaluator such as a doctor can easily recognize the relative positions between the currents in the evaluation target area and the corresponding portions in the morphological image.

Hereinabove, according to the second embodiment, effects similar to the first embodiment explained above can be obtained. For example, a measurement result of a relatively small biometric signal can be displayed in the image display window WIN, without being buried in a measurement result of a relatively large biometric signal. As a result, the visibility of the measurement result of the relatively small biometric signal in the image display window WIN can be improved, and even when the biometric signal of the evaluation target is relatively small, an evaluator such as a doctor can easily evaluate the conductions of the biometric signals while seeing the user interface screen.

Further, in the second embodiment, multiple areas AREA can be set, and the pitch PITCH of voxels and the current calculation direction DIR can be set independently in each of the multiple areas AREA. Accordingly, an emphasis (a black circle and the like) can be displayed according to the pitch PITCH for each evaluation target area of the subject. In this case, the magnetic field signal or the current signal, which is a vector quantity, is used, and therefore, according to the evaluation target area (a direction in which the muscle fibers or the nerves extend), the current calculation direction DIR can be set, and the current waveforms can be calculated. As a result, even when the value of the current flowing through the evaluation target area is small, an evaluator such as a doctor can obtain clinically useful muscle-derived or nerve-derived current waveforms, and can easily evaluate the conductions of the signals while seeing the user interface screen.

FIG.12is a block diagram illustrating an example of hardware configuration of a data processing apparatus30ofFIG.1. The data processing apparatus30includes a CPU301, ROM (Read Only Memory)302, RAM (Random Access Memory)303, and an external storage device304. Also, the data processing apparatus30includes an input interface unit305, an output interface unit306, an input and output interface unit307, and a communication interface unit308. For example, the CPU301, the ROM302, the RAM303, the external storage device304, the input interface unit305, the output interface unit306, the input and output interface unit307, and the communication interface unit308are connected to each other by a bus BUS.

The CPU301executes various kinds of programs such as an OS and applications to control the entire operation of the data processing apparatus30. The ROM302holds basic programs for executing various kinds of programs with the CPU301, various kinds of parameters, and the like. The RAM303stores various kinds of programs executed by the CPU301and data used by the programs. The external storage device304is an HDD (Hard Disk Drive), an SSD (Solid State Drive), or the like, and stores the various kinds of programs which are extracted to the RAM303. The various kinds of programs may include display programs for displaying current waveforms reconstructed from magnetic field data on the display apparatus90.

The input interface unit305is connected to the input apparatus80such as a keyboard, a mouse, and a tablet that receives inputs from an operator or the like who operates the data processing apparatus30. The output interface unit306is connected to an output apparatus92(for example, the display apparatus90ofFIG.1) such as a printer or a display apparatus for displaying a display screen and the like generated by various kinds of programs executed by the CPU301.

The input and output interface unit307is connected to a recording medium400such as USB (Universal Serial Bus) memory and the like. For example, the recording medium400stores various kinds of programs such as the display program and the like explained above for displaying current waveforms on the display apparatus90. In this case, the programs are transferred via the input and output interface unit307from the recording medium400to the RAM303. The recording medium400may be a CDROM, a Digital Versatile Disc (DVD, registered trademark), and the like. In this case, the input and output interface unit307includes an interface according to the connected recording medium400. The communication interface unit308connects the data processing apparatus30to a network and the like.

In the embodiment explained above, the example for displaying, on a screen, waveforms of currents reconstructed from biomagnetism data of the subject has been explained. However, for example, a magnetic field signal estimated for each voxel by using the biomagnetism data of the subject may be displayed on a screen. In other words, signals displayed on the screen may be other than currents, as long as the signals can be represented as vector quantities. For example, for each voxel, a magnetic field signal that is determined to be greater than or equal to a threshold value obtained by multiplying the maximum value (i.e., the peak current value) by a fractional value defined in advance with respect to a maximum value of the magnetic field signal is displayed with emphasis. When the magnetic field signals are displayed, the measured magnetic field signals can be used as they are, and therefore, complicated signal processing for reconstructing current signals is not needed. When magnetic field signals that can be expressed as vector quantities are used in a manner similar to the current signals, only the components of the magnetic field signals in the direction that is set by the operator can be displayed in a superimposed manner on the morphological image. Further, waveforms and the like of the magnetic field signals can be displayed in a selective manner according to the chronological order. Therefore, on the basis of a change in the magnetic field signals, an evaluator can verify where the signal source (current source) is located and in which direction the signals are flowing.

Alternatively, the potentials of the evaluation target area of the subject may be measured at multiple locations, a current signal may be calculated from a difference between the measured potentials, and the calculated current signal may be displayed on the screen. In this case, for each voxel, a current signal that is determined to be greater than or equal to a fractional value defined in advance with respect to a maximum value of the current signal is displayed with emphasis. The currents occur according to the actions in the living body, and therefore, when current signals are displayed in a superimposed manner on the morphological image, an evaluator can easily visually ascertain an evaluation as to in which portion and to what degree the signals occur. In this manner, the magnetic fields and the currents are useful for physiological evaluation because the components can be decomposed into desired directions.

Although the present invention has been hereinabove explained on the basis of the embodiments, the present invention is not limited to the features of the above embodiments. These features can be changed without deviating from the gist of the present invention, and can be appropriately determined according to the form of application.

REFERENCE SIGNS LIST

10SQUID unit20signal acquisition unit21FLL circuit22analog signal processing unit23AD conversion unit24FPGA30data processing apparatus40input control unit50display control unit60operation control unit61measurement control unit62current reconstruction unit63current waveform generation unit64emphasis display determination unit70storage unit71biomagnetism data72morphological data73setting value80input apparatus90display apparatus100biometric information measurement apparatus301CPU302ROM303RAM304external storage device305input interface unit306output interface unit307input and output interface unit308communication interface unit400recording mediumAREA areaDIR current calculation directionDISP waveform display buttonEXPM moving picture output buttonFLM white framePITCH intervalSLIDE slide bartPEAK peak detection timetWAVE waveform display timeVT fractional valueWXmax, Xmin, Ymax, Ymin area

The present application is based on and claims the benefit of priorities of Japanese Priority Application No. 2019-213566 filed on Nov. 26, 2019, and Japanese Priority Application No. 2020-074272 filed on Apr. 17, 2020, the contents of which are incorporated herein by reference.