JP2008200331A - Biological magnetic field measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biological magnetic field measuring apparatus easily identifying the current direction of a highly active part and its size. <P>SOLUTION: For a current arrow diagram, magnetic field vectors at spots where a plurality of SQUID magnetic sensors are arranged are measured and a current generating the magnetic field is displayed at each of the plurality of SQUID magnetic sensor positions. In the case of 64 pieces of the SQUID magnetic sensors, 64 current arrows are displayed. In current arrow emphatic display 1, the current arrow is displayed only when a current value is larger than surrounding 4 points or the same value among the 64 current arrows and the display of the current arrows is omitted in the other case. Thus, the displayed current arrow indicates the maximum point of the vicinity, and it can be considered as the local active part of the electrophysiological activity of the heart. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a biomagnetic field measuring apparatus for measuring a magnetic field of a living body caused by a current in the heart, such as myocardial activity of a living body heart.

  Using a superconducting quantum interference device (SQUID), which is a magnetic sensor, the distribution of a weak magnetic field generated from a living body is measured, the position of the active current inside the living body is estimated from the measurement result, and the distribution is imaged. Development of multi-channel biomagnetic imaging devices is in progress.

  The biomagnetic imaging apparatus described above is disclosed in, for example, Patent Document 1.

Japanese Patent No. 3228703

  By the way, in the conventional biomagnetic imaging apparatus, for example, a method called a current arrow diagram that reflects the current distribution in the heart is used.

  Here, the current arrow diagram is obtained by measuring a magnetic field vector at a point where the SQUID magnetic sensor is disposed, and displaying the current generating the magnetic field at the SQUID magnetic sensor position.

  This current arrow diagram displays the current arrow at the position where the SQUID magnetic sensor is arranged regardless of the strength of the magnetic field strength. For example, in the biomagnetic measuring device described in Patent Document 1, A current arrow will be displayed.

  In this case, it is difficult to identify the active site because each current arrow has to be displayed small. In addition, the activity of the myocardium at the position of the SQUID sensor with a small magnetic signal is low, and clinical significance is small.

  An object of the present invention is to realize a biomagnetic field measurement apparatus that can easily identify the current direction and the magnitude of a highly active site.

  The present invention provides a biomagnetic field measurement apparatus for measuring magnetic fields emitted from a plurality of positions in a living body of a subject, creating an isomagnetic field diagram from magnetic field signal information measured at the plurality of positions, and from the magnetic field signal information. From the magnetic field distribution at a specific time, calculate the maximum point of the magnetic field strength and its magnetic field strength, calculate the magnetic field vector indicating the direction and magnitude of the magnetic field at the magnetic field strength maximum point, and from the calculated magnetic field vector the direction and size of the current Is calculated. Then, the current arrow is displayed on the display on the isomagnetic field diagram.

  According to the present invention, it is possible to easily identify the current direction and the magnitude of a portion having high activity.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram of a biomagnetic measuring apparatus to which the present invention is applied. In FIG. 1, the biomagnetic measuring device is installed in a magnetic shield room 1 in order to remove the influence of environmental magnetic noise. The living subject 2 is placed on the bed 3 in a supine state, and measurement is performed. The biological surface of the subject 2 (a surface generally parallel to the chest wall in the case of the chest) is assumed to be substantially parallel to the surface of the bed 3, and this surface is the xy plane of the Cartesian coordinate system (x, y, z). It shall be parallel. The chest of the subject 2 is a curved surface and tilted, but in order to simplify the explanation, it is assumed to be substantially parallel.

  A deyuwa 4 filled with a liquid He, which is a refrigerant, is disposed above the chest of the subject 2, and this deyuwa 4 is connected to a superconducting quantum interference device (SQUID = Superducting Quantum Interference Device) and its SQUID. A plurality of magnetic sensors including a detection coil are accommodated. The dewar 4 is connected to the automatic supply device 5.

  The output of the magnetic sensor outputs a voltage having a specific relationship with the strength of the biomagnetic field (which can be considered as a magnetic flux density) generated from the subject 2 and detected by the detection coil, and the output is FLL (Flux). Locked loop) circuit 6 inputs. The FLL circuit 6 cancels the change of the biomagnetic field (biomagnetism) input to the SQUID via the feedback coil so as to keep the output of the SQUID constant (this is called magnetic field lock). By converting the current passed through the feedback coil into a voltage, a voltage output having a specific relationship with the change in the biomagnetic field signal can be obtained.

  As described above, since the detection is performed via the feedback coil, a weak magnetic field can be detected with high sensitivity.

  The output voltage is input to an amplifier / filter / amplifier (AFA) 7, and the output is sampled, A / D converted, and taken into a computer 8.

  The computer 8 is composed of a personal computer, 8-1 is a display unit thereof, 8-2 is a keyboard, and 8-3 is a mouse. The mouse 8-3 is used to select a processing target by moving the cursor on the screen. This operation can also be performed by operating the keyboard.

  The input gain (I gain) and output gain (O gain) of the AFA 7 can be adjusted. The AFA 7 is a low-pass filter (LPF) that passes a frequency signal below the first reference frequency, a high-pass filter (HPF) that passes a frequency signal above the second reference frequency that is lower than the first reference frequency, and a commercial power supply. A notch filter (BEF) for cutting the frequency is provided. The computer 8 can perform various types of processing, and the processing result is displayed on the display unit 8-1.

  For example, a direct current SQUID is used as the SQUID. When an external magnetic field is applied to the SQUID, a DC bias current (Ibias) is passed through the SQUID so that a corresponding voltage (V) is generated. When the external magnetic field is represented by a magnetic flux Φ, a characteristic curve of the voltage V with respect to the magnetic flux Φ, that is, a Φ-V characteristic curve is given by a periodic function.

  Prior to the measurement, an operation is performed to adjust the offset voltage (V OFF) of the FLL circuit 6 so that the DC voltage of the Φ-V characteristic curve becomes zero level. Further, when the input of the AFA 7 is zero, the offset voltage (A OFF) of the AFA 7 is adjusted so that the output becomes zero.

  FIG. 2 is a diagram showing an arrangement configuration of the magnetic sensor. The detection coil of the magnetic sensor has a coil for detecting a tangential component of the biomagnetic field (component substantially parallel to the biological surface, ie, the xy plane) and a normal component of the biomagnetic field (component orthogonal to the biological surface, ie, the xy plane). There is a coil to detect.

  As coils for detecting the tangential component of the biomagnetic field, two coils whose coil surfaces are directed in the x direction and the y direction, respectively, are used. Further, as a coil for detecting the normal component of the biomagnetic field, a coil whose coil surface is directed in the z direction is used.

  A plurality of magnetic sensors 20-1 to 20-8, 211-1 to 21-8, 222-1 to 22-8, 233-1 to 23-8, 24-1 to 24-8, 25-1 to 25 As shown in FIG. 2, −8, 26-1 to 26-8, and 27-1 to 27-9 are arranged in a matrix on a living body surface, that is, a surface substantially parallel to the xy plane.

  The number of magnetic sensors may be arbitrary, but in the example shown in FIG. 2, the matrix of magnetic sensors is composed of 8 rows and 8 columns, so the number of magnetic sensors is 8 × 8 = 64. As shown in FIG. 2, each magnetic sensor is arranged such that its longitudinal direction coincides with a direction (z direction) perpendicular to the biological surface, that is, the xy plane.

  In the illustrated example, the bed surface and the XY plane of the sensor are parallel to each other. However, in order to improve measurement accuracy, it is better to bring the sensor closer to the body of the subject 2 and tilt the sensor. It can also be. However, since the human body which is the subject 2 is constantly moving, if the human body is brought into close contact with the human body, this movement moves the detection unit, which makes it difficult to detect with high accuracy.

  (A) of FIG. 3 is a figure which shows the structure which detects the normal line component Bz of a biomagnetic field of a magnetic sensor. In FIG. 5A, a coil made of a superconducting wire (Ni—Ti wire) is arranged so that its coil surface faces the z direction. This coil is composed of a combination of two coils 10 and 11 that are opposite to each other. The coil 10 closer to the subject 2 is a detection coil, and the far coil 11 is a compensation coil that detects external magnetic field noise. The

  The external magnetic field noise is generated from a signal source farther than the subject 2, and the noise signal is detected by both the detection coil 10 and the compensation coil 11. On the other hand, the magnetic field signal from the subject 2 is weak, and the biomagnetic field signal is detected by the detection coil 10, but the compensation coil 11 is hardly sensitive to the biomagnetic field signal.

  For this reason, the detection coil 10 detects the biomagnetic field signal and the external magnetic field noise signal, and the compensation coil 11 detects the external magnetic field noise signal. Therefore, by taking the difference between the signals detected by the two coils, the S / N ratio is obtained. A high biomagnetic field can be measured.

  These coils 10 and 11 are connected to the input coil of the SQUID 12 via the superconducting wire of the mounting board on which the SQUID 12 is mounted, and thereby the normal component Bz of the detected biomagnetic field signal is transmitted to the SQUID 12. The

  As shown in FIG. 3B, the tangential components Bx and By of biomagnetism can be detected by directing the detection coil surface and the compensation coil surface in the x direction or the y direction. A signal having a strong correlation with the actual tangential components Bx and By can be obtained by partial differentiation of the normal component Bz obtained by the magnetic sensor shown in a) with respect to x and y. Therefore, a value obtained by partial differentiation of the normal component Bz with respect to x and y may be used as the tangential component.

  In this case, it is possible to detect and measure both the tangential components Bx and By and the normal component Bz with a single magnetic sensor.

  FIG. 4 is a diagram showing a positional relationship between the magnetic sensor and the chest 30 which is a measurement part of the subject 2. The points shown in FIG. 4 represent the intersections between the rows and columns on the matrix shown in FIG. 2, that is, the measurement points of the subject 2, that is, the measurement positions. Each of these measurement positions is also called a channel. As can be seen from FIG. 4, in this example, the height direction of the subject 2 is the y direction, and the lateral direction of the subject 2 is the x direction.

  FIG. 5 shows the magnetocardiographic waveform of the normal component Bz for a healthy person.

  Like the electrocardiogram waveform, the magnetocardiogram waveform consists of a P wave due to atrial excitement, a QRS wave due to a ventricular excitement process, and a T wave due to a recovery process of ventricular excitement. Between the P wave and the Q wave, and between the S wave and the T wave, the signal due to the excitation of the heart is considered to be substantially 0 (zero), and the signal level between these is called the baseline.

As shown in FIG. 5, time periods T ₁ when the heart ventricles of the heart are depolarized, that is, times of respective waveform peaks in the QRS wave in the systole are shown as t _Q , t _R and t _S , respectively. Furthermore, the time zone of the T-wave is repolarization of the heart (diastole) is shown as T _2.

  Since the time waveform as shown in FIG. 5 is simultaneously measured by 64 sensors, an isomagnetic field diagram in which the measurement signal (that is, the magnetic field strength) of each sensor at a certain time point is expressed in two dimensions is created. Thus, the magnetic field distribution at that time can be obtained. A current arrow diagram is a combination of current vectors on a constant magnetic field diagram when current is present at a sensor position and a measured magnetic field vector is generated.

  In the current arrow diagram, an arrow is shown at a position corresponding to each sensor position, and the direction of this arrow indicates the direction of the current for generating the magnetic field. The magnetic field direction is obtained from the pseudo tangential magnetic field data obtained by partial differentiation of the measured tangential magnetic field data or normal magnetic field data in the X and Y directions, and this is reflected for the sake of simplicity. By rotating 90 degrees clockwise, the direction of the current for generating the magnetic field is made coincident.

  The length of the arrow in the current arrow diagram represents the magnetic field strength. Thus, a current arrow diagram in which an arrow is combined with an isomagnetic field diagram in the tangential direction represents the distribution of the magnetic field by the color density and the size of the arrow, and the current direction by the direction of the arrow.

  One embodiment of the present invention is operated, for example, by the flowchart shown in FIG.

  In FIG. 6, when the computer 8 is first turned on, a system program such as an operating system is automatically started (step S-1). Subsequently, the system program of the biomagnetic measurement system is activated (step S-2).

  A series of operations from registration of a subject to measurement of the registered subject's data and analysis of the measured data is performed while viewing the display screen displayed on the display 8-1. Is called. Therefore, before explaining the series of operations, the layout of the display screen will be described first.

  FIG. 7 shows a basic layout of a display screen displayed on the display 8-1 in FIG. In FIG. 7, the upper portion of the display screen is occupied by a title bar portion 801, a menu bar portion 802, and a toolbar portion 803 where icons 808-1 to 808-14 are arranged in order from the top. Each of the above parts can be considered as a display area or an area.

  These arrangements are also displayed in common on the display screen for other processing purposes, for example, registration and reading of a subject, measurement of a magnetic field, and processing for analysis of measurement data. This increases the ease of use and shortens the time for measurement and processing.

  The center part of the display screen is a subject information part 804-1 arranged in order from left to right, a data information part 804-2 for analysis data, and analysis data in which analysis data such as diagrams and waveforms is displayed. The part 805-1, the reference waveform part 805-2, and the operation area part 806 are occupied.

  When the subject list screen (shown in FIG. 9) is displayed in the subject information section 804-1, the subject on which the cursor 91 (FIG. 9) is placed in the subject list on that screen Is always displayed.

  Further, when analysis data such as a diagram or waveform is displayed in the analysis data section (shown in FIGS. 12 and 13), the information of the subject from whom the displayed analysis data is obtained is always displayed. Is displayed. This makes it possible to clearly know the relationship between the displayed analysis data and the subject from whom the analysis data was obtained.

  Similarly, when a subject list screen (shown in FIG. 9) is displayed in the data information section 804-2, a data list for the subject selected on the screen is displayed. In the data list, data information on which the cursor 92 (FIG. 9) is placed is displayed. Further, when analysis data such as a diagram or waveform is displayed in the analysis data portion (FIGS. 12 and 13), the information of the displayed analysis data is always displayed, so that it is displayed. It is possible to clearly know information such as measurement time and measurement conditions regarding analysis data.

  In this way, on the display screen of this system, like the menu bar unit 802, the subject information unit 804-1 and the data information unit 804-2 are always displayed at the fixed position (left side) of the display screen. Therefore, the user does not need to search the subject information area every time the display screen changes, and can always know by looking at a predetermined position (left side) of the display screen.

  In the title bar section 801 shown in FIG. 7, the name of the frame, specifically, the name “Multichannel MCG System” is displayed.

  FIG. 8 shows an operation menu. In FIG. 8, the menu bar portion is a portion for selecting an operation menu, and each menu of “file (F)”, “subject list (L)”, “data measurement (Q)”, and “analysis (A)”. Can be used.

  The contents of the operation menu shown in FIG. 8 are displayed as pull-down menus by clicking the corresponding menu button. For this reason, when the operation menu is not required, only the keywords for calling each menu are displayed compactly on the menu bar, so the display area required for each operation such as the analysis data section and the operation area section is widened. Can be set.

  When an operation menu is required, keywords arranged according to the operation procedure can be selected and displayed by selecting from the menu bar portion. At this time, since the keywords are arranged in accordance with the arrangement of characters (from left to right), the operation can be instructed in a natural manner.

The pull-down menu of “File (F)” includes an item “End of magnetocardiographic system (X)” for ending the Multichannel MCG System.
The pull-down menu of “subject list (L)” includes “open subject list (O)”, “subject registration (R)”, “subject deletion (D)”, “data deletion ( E) ".

  When “Open subject list (O)” is selected, the screen displayed on the display device 8-1 is switched to the subject list screen (FIG. 9). When “Subject Registration (R)” is selected, a subject registration dialog (not shown) is displayed, and the subject ID, name, date of birth, height, weight, gender, comment, etc. Accept the input.

  When “Delete subject (D)” is selected, the subject information in which the subject cursor 91 is placed in the subject list (FIG. 9) and all data related to the subject are deleted, When “Delete Data (E)” is selected, the data on which the data cursor 92 is placed on the data list on the subject list screen (FIG. 9) is deleted.

  The pull-down menu of “Data measurement (Q)” includes items of “Open measurement monitor screen (O)” and “Start measurement (M)”. When “Open measurement monitor screen (O)” is clicked, the screen display on the display device 8-1 is switched to a measurement monitor screen (not shown).

  When “Measurement start (M)” is clicked, the sensor state is automatically adjusted, the magnetic fields of all the SQUID sensors are locked, and the data is taken in under the designated conditions.

  When the measurement is completed, the measurement data is stored in the magnetocardiographic database. At the same time, the characteristic parameters are extracted from the measurement data, the Mahalanobis distance is calculated, and the measured data is stored in the magnetocardiographic database.

  The pull-down menu of “Analysis (A)” is “Time waveform display (W)”, “Magnetic diagram (B)”, “Current arrow diagram (C)”, “Current arrow emphasis display 1 (1)”, “Current arrow”. Emphasis display 2 (2) "is included.

  When “time waveform display (W)” is clicked, a grid map waveform display screen (FIG. 12) is displayed. In addition, when “isomagnetic diagram (B)”, “current arrow diagram (C)”, “current arrow emphasis display 1 (1)”, and “current arrow emphasis display 2 (2)” are clicked, the isomagnetism diagrams respectively. A screen (FIG. 13), a current arrow diagram (not shown), a current arrow emphasis display 1 (not shown), a current arrow emphasis display 2 (not shown) are displayed, and a check mark is placed on the left side of the clicked menu item. Is displayed.

  This is because the isomagnetic diagram, current arrow diagram, current arrow emphasis display 1 and current arrow emphasis display 2 share the same display screen, and the display contents are switched as shown in FIGS. .

  In the toolbar portion 803 of FIG. 7, icon buttons 808-1 to 808-14 associated with the frequently used items among the pull-down menu items of the operation menu are arranged.

  Next, a series of operations from registration of a subject to measurement of the registered subject's data and analysis of the measured data will be described with reference to FIGS. .

  In FIG. 6, as described above, when the power of the computer 8 is turned on (step S-1), the operating system is started up and a start icon of a program that can be used by the computer is displayed on the display unit 8-1. (Step S-2).

  When the Multichannel MCG System program icon is clicked from among the icons, the subject list shown in FIG. 9 is displayed as an initial screen for system startup (step S-3).

  In the subject list screen shown in FIG. 9, the upper left portion is occupied by the subject information portion 804 and the lower left portion is occupied by the data information portion 805. In addition, a subject list is displayed at the upper part of the entire right side, and a data list is displayed at the lower part. In the subject information section, information on the subject on which the cursor 91 is placed on the subject list is displayed, and when the cursor 91 is moved, the display content is updated accordingly.

  Items in the subject list include ID (subject ID number), name, date of registration (date of data registration), date of birth, age, height, weight, comment (comment on the subject), etc. including. The subject list can be scrolled with a vertical scroll bar, and the subject list items can be scrolled with a horizontal (horizontal) scroll bar. The row of the selected subject is highlighted.

  A measurement data list is displayed in the lower half of the subject list screen of FIG. 9, and data attributes such as data ID and measurement date are displayed. Similarly, information for creating an isomagnetic diagram from the measurement data is displayed in the isomagnetic diagram list.

  Returning to the overall flow of FIG. In step S-4, a desired subject row is selected from the subject list on the subject list screen. The subsequent flow is branched into four by the menu (step S-5).

  One of the branches is a case where a sub-menu “End of magnetocardiographic system (X)” in the menu “File (F)” is selected. In this case, an end process such as closing a window is performed (step S-8), thereby shutting down the system (step S-9). Thereafter, the power source of the computer 8 is turned off (step S-10), and all the processes are completed.

  In the other branch, data measurement (step S-6) or data analysis (step S-7) is performed. The branch to data measurement can be executed by selecting a submenu “Open measurement monitor screen (O)” in the menu “Data measurement (Q)”.

  In addition, branching to the data analysis includes “magnetic analysis (B)”, “current arrow diagram (C)”, “current arrow enhancement 1 (1)”, “current arrow enhancement 2” in the menu “data analysis (A)”. This can be executed by selecting one of the submenus (2).

  When step S-6 and step S-7 are completed, the process returns to step S-3 to display the subject list selection screen.

  The details of the flow of the subject list selection in step S-4, the data measurement in step S-6, and the data analysis in step S-7 will be described in more detail below with reference to FIGS. 10 and 11, respectively. Is done.

  FIG. 10 is a diagram showing a detailed flow of data measurement in step S-6 of FIG. In FIG. 10, first, a time waveform (not shown) based on a grid map is displayed as an initial state of the measurement screen (step S-15-1), and the waveform monitor is activated (step S-15-2).

  The channel consists of 64 channels of 8x8, and all channels can be selected and displayed by clicking the “Select All Channels” button or by dragging the channel matrix diagonally from end to end. it can.

  The waveform monitor captures and displays data at a preset cycle time (for example, 1 second), and repeats this until the measurement button is pressed. In setting / changing measurement condition parameters (step S-15-3), measurement conditions such as sampling time and sampling interval are set and changed, and measurement is started by pressing the “measurement” button in the operation area (step S). -15-4).

  For the sampling time (measurement time) and interval, click the corresponding text box with an inverted triangle in FIG. 12 to open a pull-down menu of selectable values. Select the desired number from the list. Can do. The selectable numbers are, for example, 1 sec, 5 sec, 10 sec, 30 sec, 1 min, and 2 min for the time, and for the interval, for example, 0.1 msec, 0.5 msec, 1.0 msec, 2.0 msec, 4 msec, 0.0 msec, 5.0 msec and 10.0 msec.

  The time may be selected from about 1 sec to about 24 h as necessary. “Time” in the “Scale” box in FIG. 13 means a time scale in units of msec, that is, a horizontal scale. For these, as with the selection of sampling time and interval, a desired numerical value is selected from a pull-down menu that is opened by clicking the corresponding text box.

  When a measurement start command is issued to the FLL control circuit 6 and the amplifier / filter 7, they collect data until the designated measurement is completed, and when completed, interrupt the computer 8-1 to notify the data collection. . In this way, the data measurement control waits for the end of data collection (step S-15-5).

  FIG. 11 is a diagram showing a data analysis flow in step S-7 in FIG. Data analysis is to display various types of waveforms and diagrams to obtain information necessary for diagnosis. By selecting the menu shown in Fig. 8, various types of waveforms and diagrams are displayed. Can be selectively displayed.

  That is, if “analysis (A)” “time waveform display (W)” is selected, a grid map waveform screen shown in FIG. 12 is displayed in step S-14-4. If “anamagnetic diagram (B)” of “analysis (A)” is selected, the isomagnetic diagram time waveform screen shown in FIG. 13 is displayed in step S-14-5.

  If “current arrow diagram (C)”, “current arrow emphasis display 1 (1)”, and “current arrow emphasis display 2 (2)” are selected, these are all performed in the same manner as in the isomagnetic field diagram. At -14-5, the same screen as the isomagnetic field diagram shown in FIG. 13 is displayed. However, what is displayed as an analysis diagram is a current arrow diagram (FIG. 15), a current arrow emphasis display 1 (FIG. 16), and a current arrow emphasis display 2 (FIG. 17), respectively. Note that the current arrow emphasis display 2 shown in FIG. 17 shows a circle proportional to the magnitude of the current value, centered on the maximum point of the current value, in order to make it easier to grasp the activity of the electrophysiological active site. It is displayed. That is, a circle proportional to the magnitude of the current value is displayed around the current arrow shown in FIG.

  Further, if “End of magnetocardiographic system (X)” of “File (F)” in the menu item is selected, the system is terminated.

  In each screen, if an icon button (808-1 to 808-14) on the toolbar is clicked, the waveform or diagram screen designated by the click is displayed instead. In the flowchart shown in FIG. 11, the branch portion is not “branch by menu” but “branch by menu or icon button” (step S-14-1).

  Therefore, according to this embodiment, various analysis data can be obtained by simply clicking on the radio button in the operation area without selecting the menu of FIG. It is possible to reduce operability and improve operability.

  In this embodiment, an update button 135 and a cancel button 134 are provided for screens for data analysis (FIGS. 12 and 13). That is, when the data analysis parameter is changed and the correspondence between the content indicated by the data analysis parameter and the content displayed in the analysis data portion 805-1 is lost, the update button 135 and the cancel button 134 are activated, When the operator presses the update button 135, recalculation is performed according to the updated data analysis parameter, and the display of the analysis data portion 805-1 is updated.

  When the cancel button 134 is pressed, the change of the data analysis parameter is returned to the original so that the content of the data analysis parameter matches the content of the analysis data section 805-1. That is, the update button 135 and the cancel button 134 are in an inactive state while the correspondence between the contents of the data analysis parameter and the display contents of the analysis data portion is maintained, and is activated when the correspondence is lost.

  As a result, when the data analysis parameter does not correspond to the display content of the analysis data portion 805-1, the analysis data can be misinterpreted because it can be clearly distinguished by the state of the update button 135 and the cancel button 134. Can be reduced.

  In the isomagnetic diagram of FIG. 13, an elongated magnetic field strength indicator box 310 is arranged vertically at the right end of the analysis data portion 805-1. The magnetic field strength index box is divided into sections of different colors. In this method, the visual (color) recognizability is improved by distinguishing the intensity range of the magnetic field indicated by each stripe pattern on the isomagnetic diagram screen by the type of color.

  That is, the center position 311 in the longitudinal direction of the magnetic field strength index box 310 is a position where the magnetic field strength is zero, and the sections above the center position are referred to as the first to sixth sections in the order closer to the center position. For example, the first section is in a magnetic field strength range of 0 to 2 pT, the second section is in a magnetic field strength range of 2 to 4 pT, the third section is in a magnetic field strength range of 4 to 6 pT, and the fourth section is 6 The fifth section corresponds to a magnetic field strength range of ˜8 pT, the fifth section corresponds to a magnetic field strength range of 8 to 10 pT, and the sixth section corresponds to a magnetic field strength range of 10 to 12 pT.

  The same applies to the section below the center position. However, the section above the center position represents the magnetic field intensity in the plus direction, and the section below the field represents the magnetic field intensity in the minus direction.

  In FIG. 13, “number of maps” in the “reconstruction parameter” box indicates the number of displayed isomagnetic diagrams, and “maximum value” indicates both ends of the magnetic field strength indicator box 310. The corresponding magnetic field strength “interval” means a magnetic field range corresponding to the length of each section in the magnetic field strength indicator box 310. The value can be selected by clicking the triangle or inverted triangle button in the corresponding text box.

  At the bottom of the analysis data portion, 16 cursor lines 140 corresponding to the reference channel waveform and 16 isomagnetic diagrams set as the number of maps are displayed. The intervals of the cursor lines 140 are set to be equal intervals at a predetermined time, but means for setting the intervals may be provided on the screen, and the cursor lines corresponding to a plurality of isomagnetic field diagrams are not displayed. Means for setting one by one at equal intervals may be provided.

  The position of the cursor line 140 is moved by dragging with the mouse to the left or right, but the time for creating the first isomagnetic diagram from the text box may be designated. In the example shown in FIG. 13, the number of displayed isomagnetic diagrams is 16, but these diagrams are diagrams at the time when the cursor line on the waveform is located. The time is also displayed so that it can be seen when the map is current.

  Accordingly, as described with reference to FIG. 13, the operator indicates how much the map currently displayed in the analysis data portion 805-1 occupies in the analysis time (reference waveform width). It is possible to grasp at a glance what range the map shows in the analysis time. Therefore, visibility can be improved.

  In addition, since the range indicated by the map can be set by simply moving two cursors with a mouse, the operation is easy. Furthermore, if the interval between the dividing lines is set freely, various analysis environments can be provided to the operator, such as making the part in question dense and making the other part sparse.

  Although the isomagnetic field map display has been described with reference to FIG. 13, the same effect can be obtained also in the current arrow diagram (FIG. 15), the current arrow emphasis display 1 (FIG. 16), and the current arrow emphasis display 2 (FIG. 17). Can do.

  With respect to the current arrow diagram shown in FIG. 15, as already described, the magnetic field vector at the point where the plurality of SQUID magnetic sensors are arranged is measured, and the current generating the magnetic field is represented by the plurality of SQUID magnetic sensors. It is displayed at each position.

  In the illustrated example, since 64 SQUID magnetic sensors are used, 64 current arrows are displayed.

  On the other hand, current arrow emphasis display 1 (FIG. 16) displays a current arrow only when the current value is larger than or equal to the surrounding four points among the 64 current arrows. is there. For example, the current values in the SQUID magnetic sensor arranged in n rows and m columns, that is, (n, m) are (n + 1, m), (n, m + 1), (n-1, m), (n, m). The current arrow is displayed only when the current value in the SQUID magnetic sensor arranged in -1) is greater than or equal to the current value. In other cases, the current arrow is not displayed.

  This causes the displayed current arrow to represent a local maximum near it, which can be thought of as a local active site of the electrophysiological activity of the heart. For this reason, clinical lesion detection can be easily performed.

  In addition, since the current direction and magnitude of the part with high activity can be easily determined, it is easy to compare with the current arrow emphasis display detected before that, and it is also easy to determine abnormality over time.

  As a method for obtaining the maximum point of the current value, in addition to the method of calculating the current value at the SQUID magnetic sensor position by comparing it with the current value at the adjacent SQUID magnetic sensor, the current value at the SQUID sensor position can be calculated on the measurement surface. The current distribution J (x, y) may be approximated as a function of x and y, and the maximum point may be calculated analytically or numerically.

For example, by a method such as multivariate analysis, [(x, y) = ax ² + bxy + cy ² + dx + ey + f] (where a, b, c, d, e, and f are constants) are approximated by a quadratic surface. In this case, if the x partial derivative of J (x, y) is J _x (x, y) and the y-order derivative is J _y (x, y), then J _x (x, y) = J _y (x, y) ) = 0 (x, y) gives a maximum point, and a current arrow may be displayed there.

  In the current arrow emphasis display 1, the current arrow to be displayed is not the current arrow in the SQUID magnetic sensor having the maximum current value because there may be a plurality of electrophysiological active sites. In order to capture the electrophysiological activity of the heart by displaying the current value and direction in each active site.

  In addition, the clinical meaning of displaying a current arrow at a site where the current value is small is small, and in general, there is a high possibility that a maximum point will occur due to the influence of noise. For this reason, the minimum current value displayed as a maximum value can be set as a threshold value, and only the current arrow at the maximum point having a current value higher than that can be displayed.

  For example, the highlight setting dialog shown in FIG. 18 may be provided, and after the setting value is input, the setting value is stored when the OK button is pressed, and the setting is not performed when the cancel button is pressed.

  In addition, in the region near the maximum point, for the region where the magnetic field strength exceeds a predetermined threshold value, the size of the magnetic field vector is calculated based on the value obtained by dividing the magnetic field strength into an area, and according to the calculated magnetic field vector size It is also possible to set the magnitude of the current arrow.

It is a schematic block diagram of the biomagnetic field measuring device with which this invention is applied. It is an arrangement configuration perspective view of a plurality of magnetic sensors used for a biomagnetic field measuring device. It is a perspective view of the magnetic sensor single-piece | unit which detects the normal component and tangent component of a magnetic field used in a biomagnetic field measuring apparatus. It is a figure which shows the positional relationship of the magnetic sensor in a biomagnetic field measuring device, and a subject's chest. It is a figure which shows the time waveform of the tangential component of the specific 1-channel magnetocardiogram measured about the healthy subject in the biomagnetic field measuring device. It is a flowchart of the whole operation in the biomagnetic field measuring device which is one Embodiment of this invention. It is a layout figure of a data information display field among basic layouts of a display screen displayed on a display part of a biomagnetic field measuring device which is one embodiment of the present invention. In the biomagnetic field measurement apparatus which is one Embodiment of this invention, it is a figure which shows the operation menu in the menu bar part of the display screen displayed on a display part in privileged user mode. It is a figure which shows the subject list screen displayed on the display part of the biomagnetic field measuring device which is one Embodiment of this invention. It is a figure which shows the flow of the data measurement in the data measurement step in the operation flowchart of FIG. It is a figure which shows the flow of the data analysis in the data analysis step in the operation flow of FIG. It is a figure which shows the grid map waveform display measurement screen displayed on the display part of the biomagnetic field measuring device which is one Embodiment of this invention. It is a figure which shows the isomagnetic diagram display screen displayed on the display part of the biomagnetic field measuring device which is one Embodiment of this invention. It is a figure which shows the isomagnetic field diagram displayed on an isomagnetic diagram display screen. It is a figure which shows the current arrow diagram displayed on an isomagnetic diagram display screen. It is a figure which shows the current arrow emphasis display 1 displayed on the isomagnetic diagram display screen in one Embodiment of this invention. It is a figure which shows the current arrow emphasis display 2 displayed on the isomagnetic diagram display screen in one Embodiment of this invention. It is a figure which shows the setting dialog for setting the lower limit of the maximum value which should be displayed in the current arrow emphasis display 1,2.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Magnetic shield room, 2 ... Test subject, 3 ... Bed, 4 ... Deyuwa, 5 ... Automatic replenishment apparatus, 6 ... FLL circuit, 7 ... AFA (amplifier) Filter / Amplifier), 8 ... Computer, 8-1 ... Display, 8-2 ... Keyboard, 8-3 ... Mouse, 10, 10 ', 10 "... Detection coil 11, 11 ′, 11 ″... Compensation coil, 12, 12 ′, 12 ″... SQUID, 13, 14... Sensor, 20-1 to 20-8, 21-1 to 21-8, 22-1 to 22-8, 23-1 to 23-8, 24-1 to 24-8, 25-1 to 25-8, 26-1 to 26-8, 27-1 to 27-8, ... Magnetic sensor 30 ... Chest, 90 ... Subject information sorting button, 91 ... Subject information cursor, 92 ... Data Information cursor, 93 ... Data list selection tab, 134 ... Display update cancel button, 135 ... Display update button, 136 ... Channel selection button, 140 ... First magnetic field diagram, etc. Magnetic field time cursor, 142 ... sensor position, 801 ... title bar part, 802 ... menu bar part, 803 ... toolbar part, 804 ... subject information part, 805 ... Data information part, 805-1 ... analysis data part, 805-2 ... reference waveform part, 806 ... operation area part, 808-1 to 808-14 ... icon

Claims (5)

In a biomagnetic field measurement apparatus that measures magnetic fields emitted from a plurality of positions in a subject's living body,
Storage means for storing magnetic field signal information measured at the plurality of positions;
Arithmetic means for creating an isomagnetic field diagram from magnetic field signal information stored in the storage means;
From the magnetic field signal information, the maximum point of the magnetic field strength and the magnetic field strength are calculated from the magnetic field distribution at a specific time, and the magnetic field vector indicating the direction and magnitude of the magnetic field at the magnetic field strength maximum point is calculated. Means for calculating a current arrow indicating direction and magnitude;
Display means for displaying the current arrow on the isomagnetic field diagram;
A biomagnetic field measurement apparatus comprising: The biomagnetic field measurement apparatus according to claim 1,
A biomagnetic field measuring apparatus which displays an isomagnetic field diagram at a plurality of times and a current arrow at a magnetic field intensity maximum point in one screen. The biomagnetic field measurement apparatus according to claim 1 or 2,
A biomagnetic field measuring apparatus for displaying a current arrow based on a magnetic field vector having a magnetic field strength larger than a predetermined threshold value on the isomagnetic field diagram. The biomagnetic field measurement apparatus according to claim 3, wherein
In the region near the calculated magnetic field strength maximum point, the size of the magnetic field vector is calculated based on the value obtained by dividing the magnetic field strength for the region where the magnetic field strength exceeds a predetermined threshold value. A biomagnetic field measuring apparatus characterized by setting the size of a current arrow according to the size. In the biomagnetic field measurement apparatus according to claim 1 or 3,
A biomagnetic field measurement apparatus characterized by calculating a circle proportional to the size of the calculated current arrow and displaying the circle on the isomagnetic field diagram so as to surround the current arrow.

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