JP3427811B2 - Biomagnetic field measurement device - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to an SQUID (Superconducting Q) for measuring a weak biomagnetic field generated from the heart, brain, etc. of an adult, a child, a fetus in a mother's body, etc.
QuantumInterference Device
e: Superconducting quantum interference device) The present invention relates to a biomagnetic field measuring apparatus using a magnetometer.

[0002]

2. Description of the Related Art Conventionally, in the determination of myocardial ischemia using an electrocardiogram measured by an electrocardiograph, a time zone (a myocardial refractory period) in which an ST wave (an electrocardiographic waveform between an S wave and a T wave) occurs. (In the time zone corresponding to), whether the electrocardiographic waveform is rising or falling from the baseline, and when the electrocardiographic waveform is rising or falling, the duration of rising or falling is long. Whether or not, the ischemic disease was determined. However, with these methods, the determination was difficult unless a change in the electrocardiographic waveform was observed during the time period when the ST wave was sufficiently generated. Therefore, in the case of angina, etc., perform an exercise load test S
I was measuring changes in the T wave.

On the other hand, a biomagnetic field measuring apparatus, especially a cardiac magnetic field measuring apparatus for measuring a weak magnetic field generated from the heart (hereinafter referred to as
The magnetocardiograph) is obtained by partially differentiating a magnetic field Bz (t) generated in the normal direction (z direction or a direction perpendicular to the plane of the living body) from the heart in x direction and y direction (Equation 1), ( A current vector I ′ (t) (I′x) where x is the x component and y is the equation 2)
It is known that (t), I'y (t)) can be used to display a current vector in two dimensions and obtain it as a distribution map (arrow map) of the current vector representing electrophysiological activity of heart muscle. .

[0004]

[Equation 1] I′x (t) = dBz (t) / dy (Equation 1)

[0005]

[Equation 2] I′y (t) = − dBz (t) / dx (Equation 2)

[0006]

In the biomedical field measuring apparatus of the prior art, there is no method for quantitatively evaluating the magnitude of the current vector obtained from the measured magnetic field waveform. Similar to the determination method based on the electrocardiogram measured by a meter, the determination was made only based on the changes in the measured magnetic field waveform. Therefore, an analysis method of the magnetic field waveform to obtain more effective information by diagnosis has been desired.

An object of the present invention is to analyze the magnetic field waveform measured by a biomagnetic field measuring apparatus (magnetocardiograph) for measuring a weak magnetic field generated from the heart of an adult, a child, a fetus in the mother's body, etc. The purpose of the present invention is to provide information useful for diagnosis by displaying a screen on which heart disease (myocardial infarction, angina, etc.) and cardiomyopathy can be easily identified.

[0008]

In the first configuration of the biomagnetic field measuring apparatus (magnetocardiograph) of the present invention, a plurality of SQUID magnetometers arranged two-dimensionally are used to generate a magnetic field from a heart of a living body ( Hereinafter, the magnetic field of the magnetocardiography) is measured (hereinafter, the measured magnetic field waveform is referred to as the magnetocardiographic waveform). The magnetocardiographic waveform is based on all measurement points (hereinafter, also referred to as channels) at a predetermined time point in the time period before the time period in which the P wave occurs and in the time period between the time periods in which the P wave and the Q wave occur. The lines are aligned and displayed on the display screen of the display device.

In the time zone between the generation of the S wave and the T wave, t = T
1 and the normal component of the magnetocardiographic field of the i-th channel (Bzi) measured at time t = T2 (however, T2> T1)
Using (T1), Bzi (T2)), the arithmetic processing unit, based on (Equation 3) and (Equation 4), at time T1, the x component (Ixi (T1)) of the current vector Ii, The y component (Iyi (T1)) of the current vector Ii is calculated based on (Equation 5) and (Equation 6) at time T2, and the x component (Ixi (T2)) of the current vector Ii and the current vector Ii The y component (Iyi (T2)) is calculated.

[0010]

[Equation 3] Ixi (T1) = dBzi (T1) / dy (Equation 3)

[0011]

[Equation 4] Iyi (T1) =-dBzi (T1) / dx (Equation 4)

[0012]

[Equation 5] Ixi (T2) = dBzi (T2) / dy (Equation 5)

[0013]

[Equation 6] Iyi (T2) = − dBzi (T2) / dx (Equation 6) Further, the arithmetic processing device is Ixi (T1), Iyi (T1)
Is calculated for all channels (the total number of channels is N), and based on (Equation 7) and (Equation 8), Ixi (T
1) and Iyi (T1) are added for all channels, and a combined current vector I1 having I1x and I1y as components
And Ixi (T2) and Iyi (T2) are calculated for all channels, and Ixi (T2) and Iyi (T2) are added for all channels based on (Equation 9) and (Equation 10). Then, a combined current vector I2 having I2x and I2y as components is calculated. Note that (Equation 7) to (Equation 1)
0), Σ indicates an addition symbol, and addition is i = 1,
2, ..., N.

[0014]

[Equation 7] I1x = ΣIxi (T1) (Equation 7)

[0015]

[Equation 8] I1y = ΣIyi (T1) (Equation 8)

[0016]

[Equation 9] I2x = ΣIxi (T2) (Equation 9)

[0017]

[Equation 10] I2y = ΣIyi (T2) (Equation 10) The combined current vector I1 obtained based on (Equation 7) and (Equation 8) is displayed on the display device with I1x as the horizontal axis and I1y as the vertical axis. Two-dimensional plot is made on the screen, and (Equation 9) and (Equation 1)
0), the resultant current vector I2 is I2
2 on the display screen of the display device with x as the horizontal axis and I2y as the vertical axis.
The dimension is plotted.

The arithmetic processing unit calculates the angle θ1 based on (Equation 11), and the combined current vector I1 is displayed on the display screen by a straight line or a numerical value where θ1 indicates the angle. The angle θ2 is calculated based on 12), and the combined current vector I2 is displayed on the display screen by a straight line or a numerical value indicating the angle θ2.

[0019]

[Equation 11] θ1 = arctan (I1y / I1x) (Equation 11)

[0020]

[Mathematical formula-see original document] θ2 = arctan (I2y / I2x) (Equation 12) Further, the arithmetic processing unit calculates the difference between the combined current vector I1 at the time point T1 and the combined current vector I2 at the time point T2. , ΔIx shown in (Equation 13) is the x component,
The differential combined current vector ΔI having ΔIy shown in (Equation 14) as the y component is calculated.

[0021]

[Equation 13] ΔIx = (I2x−I1x) (Equation 13)

[0022]

[Expression 14] ΔIy = (I2y−I1y) (Expression 14) The differential combined current vector ΔI obtained based on (Expression 13) and (Expression 14) is a display device with ΔIx as the horizontal axis and ΔIy as the vertical axis. 2D plot on the display screen of.

The arithmetic processing unit calculates the angle Δθ based on (Equation 15), and Δθ is displayed on the display screen of the differential combined current vector ΔI by a straight line or a numerical value indicating the angle.

[0024]

Δθ = arctan (ΔIy / ΔIx) (Equation 15) The display screen of the display device is the absolute value (scalar) of the combined current vectors I1 and I2 at time T1 or T2 | I1 The absolute value (scalar) of the differential combined current vector ΔI is | ΔI, with one of | and | I2 |
Is plotted two-dimensionally with | as the vertical axis, and on the display screen, the absolute value | ΔI | of the differential combined current vector and the absolute value of the combined current vector calculated by (Equation 16) to (Equation 19) The value γ1 to the ratio of either | I1 | or | I2 |
Calculate any of γ4 and display any of γ1 to γ4

[0025]

[Equation 16] γ1 = | I1 | / | ΔI | (Equation 16)

[0026]

[Equation 17] γ2 = | ΔI | / | I1 | (Equation 17)

[0027]

[Equation 18] γ3 = | I2 | / | ΔI | (Equation 18)

[0028]

Γ4 = | ΔI | / | I2 | (Equation 19) According to the first configuration of the present invention, the myocardium is caused by the electrophysiological activity that changes with ischemia or fibrosis of the myocardium. The magnitude and direction of the current flowing inside can be obtained by a simple analysis method, and can be displayed on the display screen as information useful for diagnosis.

In the second configuration of the biomagnetic field measuring apparatus (cardiac magnetic field measuring apparatus (magnetocardiograph)) of the present invention, the measured magnetocardiographic waveform is the time when the P wave is generated, as in the first configuration. Baseline alignment is performed for all channels and displayed on the display screen of the display device in at least one of the time zone before the band and the time zone during which the P and Q waves occur.

The current vector Ii for each channel of i = 1, 2, ..., N is measured i at each time point j in a predetermined time section Ts to Te of the time zone during which the QRS wave is generated.
The normal component of the magnetic field of the th channel (Bzi (tj),
Using Bzi (tj), the arithmetic processing unit
0) and (Equation 21), at time tj, the x component (Ixi (tj)) of the current vector Ii and the y component (Iyi (tj)) of the current vector Ii are calculated.

[0031]

[Equation 20] Ixi (tj) = dBzi (tj) / dy (Equation 20)

[0032]

Iyi (tj) =-dBzi (tj) / dx (Equation 21) Further, the arithmetic processing unit calculates | Ii | which is the absolute value of the current vector Ii of each channel based on (Equation 22). Then
| Ii | is integrated by (Equation 23) to calculate the integrated current amount Isi of the channel i. In equation (23) | Ii |
The time range for integrating is the above-mentioned predetermined time section Ts to Te.
Is.

[0033]

[Equation 22] | Ii | = √ {(Ixi) ² + (Iyi) ² )} (Equation 22)

[0034]

[Equation 23] Isi = ∫ | Ii | dt (Equation 23) Here, based on magnetocardiogram waveforms measured in two different states (state A and state B) of the same subject's heart ( Channel i (i = 1, 2,
,, N) are integrated currents Iai and Ibi. For example, state A is a state before exercise load and is at rest, and state B is a state after exercise load.

The arithmetic processing unit is calculated from the integrated current amount Iai in a predetermined time section of the channel i calculated from the magnetocardiographic waveform measured in the A state and the magnetocardiographic waveform measured in the B state. The integral current amount ratio δi with respect to the integral current amount Ibi in the predetermined time section of the channel i is calculated by (Equation 24) or (Equation 25).

[0036]

[Equation 24] δi = Iai / Ibi (Equation 24)

[0037]

Δi = Ibi / Iai (Equation 25) Further, the arithmetic processing unit adds the integrated current amount Iai and the integrated current amount Ibi for all channels based on (Equation 26) and (Equation 27). Then, the added current amount Ita,
Calculate Itb. In (Equation 26) to (Equation 27), Σ indicates an addition symbol, and addition is i = 1, 2, ..., N
Do about.

[0038]

[Equation 26] Ita = ΣIai (Equation 26)

[0039]

[Equation 27] Itb = ΣIbi (Equation 27) Further, the arithmetic processing device is configured such that the integrated current amount ratio δ of the channel i is
i, using the added current amounts Ita and Itb, (Equation 28)
Alternatively, based on (Equation 29), the current amount ratio εi of channel i
Are calculated for i = 1, 2, ..., N, points having the same current amount ratio are obtained by interpolation and extrapolation, and a current amount ratio distribution map (CRM) represented by contour lines connecting points having the same current amount ratio is calculated. :
Current Ratio Map). The obtained current amount ratio distribution map is displayed in black and white or in color on the display screen of the display device. In (Equation 28), δi shown in (Equation 24) is used, and in (Equation 29), (Equation 2)
Use 5).

[0040]

[Equation 28] εi = δi × (Itb / Ita) (Equation 28)

[0041]

[Equation 29] εi = δi × (Ita / Itb) (Equation 29) According to the second configuration of the present invention, from the weak current obtained before the exercise load of the weak current induced after the exercise load, Of the myocardial stenosis (or imaginary region) by displaying the current amount ratio distribution map, which shows the calculated amount of weak current change as contour lines, as useful information for diagnosis. It is possible to easily estimate the blood site).

In the present invention, the measured magnetic field waveform is analyzed by a simple analysis method, and a screen display capable of easily identifying ischemic heart disease (myocardial infarction, angina, etc.) and cardiomyopathy is displayed. Can be performed and can provide useful information for heart diagnosis.

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a diagram showing a configuration example of a biomagnetic field measuring apparatus (cardiac magnetic field measuring apparatus (magnetocardiograph)) of Embodiment 1 of the present invention. As shown in FIG. 1, inside the magnetically shielded room 1, the bed 7 on which the subject lies and the SQUA.
A cryostat 2 in which a refrigerant (liquid helium or liquid nitrogen) for holding the ID magnetometer in a superconducting state is stored
And a gantry 3 for mechanically holding the cryostat 2 is arranged. Bed 7 has X direction, Y direction and Z
It can move in any direction. S outside the shield room 1
The drive circuit 4 of the QUID magnetometer and an amplifier filter unit 5 for amplifying and filtering the output of the drive circuit 4
And an arithmetic processing unit (computer) 6 that takes in the output of the amplifier filter unit 5 as data and performs arithmetic processing of the taken-in data. The arithmetic processing unit (computer) 6 is provided with a display device, and the arithmetic processing result by the arithmetic processing unit is displayed on the display screen of the display unit. Further, the calculation processing result can be displayed on the display screen of the display device arranged separately from the calculation processing device.

FIG. 2 is a diagram showing an arrangement example of a plurality of SQUID magnetometers arranged near the bottom inside the cryostat 2 in the first embodiment. As shown in FIG. 2, 64 SQUID magnetometers 202 for measuring a weak magnetic field generated from the heart are two-dimensionally arranged at each lattice point of an 8 × 8 square lattice. Each SQUID magnetometer has a first-order differential type detection coil having a detection coil and a compensation coil, and detects a magnetic field in the normal direction (z direction, direction perpendicular to the body surface). In the first embodiment, the baseline of the first-order differential type detection coil is 50 mm, and the diameter of the detection coil is 18 m.
m.

The SQUID arranged above the xiphoid process of the subject at the lattice point (3, 7) of the 8 × 8 square lattice.
With the magnetometer 201 coming, the measurement range of the cardiac magnetic field by a plurality of SQUID magnetometers was set, and the lower surface of the cryostat and the heart of the subject were aligned.

FIG. 3 shows the cardiac magnetic field (Bz) at the time point T1 in the time zone in which the peaks of the R wave and the T wave and the ST wave of the healthy person obtained in the first embodiment of the present invention are obtained. FIG. 5 is a diagram showing an example of a screen display of a display device in which an isomagnetic field line diagram connecting points equal to each other, a distribution diagram of current vectors, and waveforms obtained by superimposing measured magnetocardiographic waveforms of 1 to 64 channels are displayed. As shown in FIG. 3, in the upper part of the display screen, the distribution diagram (arrow map) 301 of the current vector obtained at the time when the peak of the R wave of a healthy person occurs, the ST wave (between the S wave and the T wave). Distribution diagram (arrow map) 302, T of the current vector obtained at time T1 in the time zone in which the magnetocardiogram waveform) occurs
The distribution map (arrow map) 303 of the current vector obtained at the time when the wave peak occurs is displayed, respectively.
As shown in, the waveform 304 in which the magnetocardiographic waveforms of channels 1 to 64 are overwritten, and the line 305 indicating the start point of the Q wave are displayed at the bottom of the display screen.

The distribution of the current vector at each time point shown in FIG. 3 is created by using the measured magnetocardiographic field (Bz) in the normal direction (z direction) as I'from (Equation 1) and (Equation 2). x and I'y are calculated and created, and the distribution diagram of the current vector at each time point is displayed with the intensity standardized. Comparing the current vector distribution diagram 301 at the time when the R wave peak reflects the depolarization process of the heart and the current vector distribution diagram 303 at the time when the T wave peak occurs, the flowing current directions are almost the same. It turns out to be the direction.

Also, in the current vector distribution diagram 302 at the time point T1 of the time zone in which the cardiac muscle cells of the heart are in the refractory period (the time when they do not respond to the stimulation to the cells) and the ST wave is generated, the current vector It can be seen that the current flows in almost the same direction as the distribution diagrams 301 and 303 in FIG. Changes in the direction of current flow during the refractory period may sensitively reflect the state of myocardial fibrosis such as ischemic heart disease and cardiomyopathy. The first embodiment aims at quantitatively evaluating a heart disease by paying attention to minute changes in the direction and magnitude of the current flowing in the refractory period (time when ST wave occurs).

In order to quantitatively evaluate the change in the direction and magnitude of the current at a certain time t in the time zone in which the ST wave is generated, the magnetic field Bzi in the normal direction measured at the measurement point i (channel i) is measured.
The current vector sum I (t) (combined current vector), which is the vector sum of the current vector Ii (t) obtained from (t), is calculated from (Equation 30) to (Equation 32). (Equation 3
0) to (Equation 32), Σ indicates an addition symbol, and the addition is performed for i = 1, 2, ..., N (= 64). The component Ix (t) in the x direction and the component Iy (t) in the y direction of the combined current vector I are obtained by (Equation 31) and (Equation 32). The component Ixi (t) in the x direction and the component Iyi (t) in the y direction of the combined current vector Ii (t) are obtained from (Equation 33) and (Equation 34).

[0051]

[Equation 30] I (t) = ΣIi (t) (Equation 30)

[0052]

[Equation 31] Ix (t) = ΣIxi (t) = ΣdBzi (t) / dy (Equation 31)

[0053]

[Equation 32] Iy (t) = ΣIyi (t) = − ΣdBzi (t) / dx (Equation 32)

[0054]

[Expression 33] Ixi (t) = dBzi (t) / dy (Equation 33)

[0055]

(34) Iyi (t) =-dBzi (t) / dx (Equation 34) Combined current vector sum I obtained by (Equation 30)
(T) is the main current flowing through each part of the heart at time t (current flowing when myocardial cells are electrically active) spreads in the same direction to some extent. It is considered that the feedback current that flows through each part of the heart in a closed circuit and returns to the original part is canceled out, and the combined current vector mainly due to the main current can be easily estimated. The direction of the main current is calculated by the angle ζ shown in (Equation 35).

[0056]

Ζ = arctan {Iy (t) / Ix (t)} (Equation 35) FIG. 4 shows the same magnetic field (Bz) created by the single dipole model in the first embodiment of the present invention. It is a figure explaining the isomagnetic field diagram which connects a point, and the distribution diagram of a synthetic | combination electric current vector. FIG. 4 is a diagram showing a result of confirming a method for estimating a combined current vector by using (Equation 30) to (Equation 32) using a single dipole model. The dipole 401 has a dipole size of 1 (μA · mm) and a dipole position (X = 25 mm, Y = 25 mm, Z = −80 mm).
And it is assumed that it is fixed at an angle of 45 degrees to the lower right (the dipole 401 exists at the tip of the arrow shown in FIG. 4A). Therefore, (Equation 30) to (Equation 34)
Each side of is independent of time t. Assuming that the detection coil has a baseline of 50 mm, the magnetic field strength of the normal component (Bz) is measured, and the measurement surface 4 on which a plurality of SQUID magnetometers are arranged.
The measurement point i (channel i (i = 1, 2,
, And Bzi at N (= 64) was obtained.

In FIG. 4A, the normal line component (Bz) of the magnetic field generated by the single dipole 401 is connected to points having the same magnetic field (Bz) on the measurement surface 402 where a plurality of SQUID magnetometers are arranged. The magnetic field diagram and the distribution diagram of the current vector obtained by calculating the component Ixi in the x direction and the component Iyi in the y direction of the combined current vector Ii on the measurement plane 402 by (Equation 33) and (Equation 34) are shown.

FIG. 4B uses the results of the current vector distribution chart shown in FIG. 4A to obtain (Equation 31) and (Equation 32).
The combined current vector obtained by the addition of is plotted in a two-dimensional space in which the x-direction component of the combined current vector is the Ix axis and the y-direction component is the Iy axis. This is indicated by the point 404. Figure 4
In (b), the assumed direction 403 of the current dipole 401 is also shown in order to compare the calculated point 404 with the assumed dipole direction. Further, it can be seen that the angle ζ representing the direction of the main current is calculated by (Equation 35), and the angle ζ obtained by the calculation is estimated to substantially match 45 ° assuming the direction of the main current.

From the above results, the combined current vector sums (combined current vectors) I1 and I2 at time t = T1 and time t = T2 in the time zone in which the ST waveform occurs are calculated by
6) and (Equation 37). (Equation 36), (Equation 3)
In 7), Σ indicates an addition symbol and addition is i = 1,
2, ..., N (= 64). Ii (T1),
Ii (T2) is a combined current vector obtained from the magnetic fields Bzi (T1) and Bzi (T2) in the normal direction measured in the channel i.

[0060]

[Equation 36] I1 = ΣIi (T1) (Equation 36)

[0061]

[Equation 37] I2 = ΣIi (T2) (Equation 37) T1 and T2 are lines 3 indicating the time points when the Q wave shown in FIG. 3 starts.
Two different time points set with 05 as the starting point are shown, and the heart rate is taken into consideration to obtain from (Equation 38) and (Equation 39). The standard time point of T1 is a time point that is 180 ms, which is about twice the time of the time zone in which the QRS wave appears, from this starting point with the line 305 as the starting point.
The standard T2 time point is a point 30 ms away from the T1 time point.

[0062]

[Equation 38] T1 = 0.18 / √ (Trr) (Equation 38)

[0063]

T2 = 0.21 / √ (Trr) (Equation 39) In (Equation 38) and (Equation 39), Trr indicates the RR interval (interval), and Trr returns and appears. The time interval of the repetition of the R wave is shown among the repetitions of the PQRST wave. Since the RR interval changes depending on the individual and the disease, the time axis of the measured magnetocardiographic waveform is standardized using the RR interval (= Trr). Although Trr is expressed in units of seconds, the unit of Trr is made dimensionless and used in the calculations in (Equation 38) and (Equation 39). That is, in the standardized magnetocardiogram waveform, the RR interval is standardized to 1 second. T1 and T2 of (Equation 38) and (Equation 39) are Trr.
Is a value standardized by.

Furthermore, in order to detect a weak change in the current in the time zone in which the ST waveform occurs, the differential combined current vector ΔI is calculated based on (Equation 36) and (Equation 37) to (Equation 40).

[0065]

ΔI = I2-I1 (Equation 40) The x-direction component and the y-direction component of the differential combined current vector ΔI are calculated by (Equation 13) and (Equation 14). (Equation 40) In other words, at the time T1 of the time axis of the magnetocardiogram, the magnetocardiographic waveforms of all channels are baseline-corrected and the baselines are aligned, and the distribution of the current vector at time T2 of the magnetocardiographic waveform is calculated. It is equivalent to using (Equation 37) to calculate.

FIG. 5 shows an example of a display screen of the distribution diagram of the composite current vector obtained by measuring the magnetocardiogram waveform and analyzing the magnetocardiogram waveform for 29 healthy adults in the first embodiment of the present invention. FIG. FIG. 5 is a diagram for examining an index that characterizes the ST waveform. FIG. 5A is an example of a display screen of the distribution diagram of the combined current vector at the time point T1 obtained by (Equation 36), and FIG. 5B is the composition at the time point T2 obtained by (Equation 37). An example of the display screen of the distribution diagram of the current vector, and FIG. 5C shows an example of the display screen of the result of the differential combined current vector ΔI obtained by (Equation 40). FIG. 5 (d) shows the time variation of the ST waveform, for example, the absolute value | I1 | of the combined current vector I1 and the absolute value | ΔI | of the difference combined current vector ΔI for evaluating the flatness of the ST waveform. It is an example of a display screen showing a relationship.

From the results shown in FIGS. 5 (a) and 5 (b),
Due to the variation in the RR interval value (= Trr) used for normalizing the time axis of the magnetocardiographic waveform and the actual RR interval value of an adult healthy person, T1, which is standardized by Trr, is T
Although there are variations in the value of 2, the combined current vector that is almost downward to the left chest is detected. Furthermore, when the index of the electric axis used in the electrocardiogram is displayed at the same time as the combined current vector, it is the value of the index of the electric axis, which is said to be a normal value.
Between 30 ° and + 110 °, the combined current vectors for all 29 examples are plotted.

As shown in FIG. 5C, the plot of the x-direction component and the y-direction component of the differential combined current vector ΔI is compared with the plots shown in FIGS. 5A and 5B. The variation is suppressed, and the combined current vectors for all 29 cases are detected in the direction toward the lower left chest (from 0 ° to + 90 °). In FIG. 5C, the approximate straight line A is also displayed in order to clarify the directionality of the combined current vector. The approximate straight line A is represented by (Equation 41).

[0069]

(I2y−I1y) = − 0.46 (I2x−I1x) (Expression 41) As shown in FIG. 5 (d), a short period (T2-T1) in the time zone in which the ST waveform occurs. ) = 30 ms, the combined current vector I
It is understood that the relationship between the absolute value | I1 | of 1 and the absolute value | ΔI | of the differential combined current vector ΔI can be approximated by the approximation line B. The approximate straight line B is represented by (Equation 42). In addition,
The approximate straight line B is also shown in the examples of the display screens shown in FIGS. 7 and 8 for easy understanding of the features of the first embodiment.

[0070]

[Expression 42] | ΔI | = | I2-I1 | = 0.47 | I1 | +6.1 (Expression 42) Next, the distance between the heart of the subject and the measurement surface on which the plurality of SQUID magnetometers are arranged. In order to confirm how the distribution map of the composite current vector obtained in Example 1 changes, the magnetocardiographic waveform is measured by changing only the height direction of the bed on which the subject is mounted by 20 mm. I did.

FIG. 6 shows that in the first embodiment of the present invention, the distance between the heart of the subject and the measurement surface is sequentially increased by 20 mm.
Position of the place, 0mm (normal measurement condition), 20m
It is a figure which shows the example of the display screen of the distribution chart of the synthetic | combination electric current vector which measured the magnetocardiogram waveform about the healthy adult person in m, 40 mm, 60 mm, 80 mm, and 100 mm, and analyzed the magnetocardiogram waveform. .

FIG. 6A shows an example of the display screen of the distribution diagram of the combined current vector at the time point T1 obtained by (Equation 36), and FIG. 6B shows the time point T2 obtained by (Equation 37). Example of display screen of combined current vector distribution map in Japan, Fig. 6
(C) shows an example of a display screen of the result of the differential combined current vector ΔI obtained by (Equation 40).

In the data of 6 points plotted in FIGS. 6 (a) to 6 (d), the point where the combined current vector and the difference combined current vector are the largest is the state where the measurement surface is closest to the body surface. The data in (0 mm: normal measurement state) is shown, and as the combined current vector and the difference combined current vector become smaller, the data correspond to positions separated by 20 mm.

The directionality in any of the distribution diagrams of the combined current vectors of FIGS. 6A, 6B, and 6C may not depend on the distance between the heart of the subject and the measurement surface. I understand. Figure 6
As shown in (d), the absolute value | I1 | of the combined current vector I1 can be determined from the plot that reflects the change in the magnetocardiographic waveform that occurs in the short period (T2-T1) = 30 ms in the time zone in which the ST waveform occurs. And the absolute value of the differential combined current vector ΔI |
It can be seen that the relationship with ΔI | can be approximated by the approximation line C. The approximate straight line C is represented by (Equation 43).

[0075]

[Expression 43] | ΔI | = | I2-I1 | = 0.62 | I1 | +6.5 (Expression 43) The approximate straight line B ((Expression 42)) shown in FIG.
Comparing the approximate straight lines C ((43)) shown in (d), it can be seen that the approximate straight lines B and C have almost the same inclination. Therefore, it is considered that the change of each plot point along the approximate straight line B shown in FIG. 5D is caused by the variation in the distance between the source of the magnetic field and the measurement surface.
It is estimated that the variation of each plotted point in the right angle direction is a quantity (size) mainly reflecting individual differences in electrophysiological activity of the myocardium and differences in types of heart disease.

As described above, in the distribution diagram of the composite current vector obtained from the magnetocardiogram waveform of a healthy person, the magnetic field strength at the time T1 of the magnetocardiogram waveform and the magnetocardiogram waveform at the time T2 when 30 ms have elapsed from the time T1. The relationship between the magnetic field strength of and the amount of change is
The change in the distance between the heart and the measurement surface appears to change in the direction along the approximate straight line B, and the variation of the plot points in the direction perpendicular to the approximate straight line B reflects the individual difference and the difference in the type of heart disease. It was found that such a correlation exists. An example in which this correlation is applied to the analysis of the magnetocardiographic waveform of a patient with heart disease will be described below.

FIG. 7 shows patients with myocardial infarction (MI), which is myocardial ischemia, in Example 1 of the present invention.
P) It is a figure which shows the example of the display screen of the distribution map of the synthetic | combination electric current vector which measured the magnetocardiogram waveform about 10 patients and analyzed the magnetocardiogram waveform.

FIG. 8 shows patients with hypertrophic cardiomyopathy (HCM), which is a cardiomyopathy in Example 1 of the present invention, patients with dilated cardiomyopathy (DCM), and restricted cardiomyopathy (RCM). ) It is a figure which shows the example of the display screen of the distribution map of the synthetic | combination electric current vector which measured the magnetocardiogram waveform about one patient and analyzed the magnetocardiogram waveform. The vertical and horizontal axes shown in (a) to (d) of FIGS. 7 and 8 show the analysis results of the healthy person in FIGS. 5 and 6 (a).
Since the vertical axis and horizontal axis shown in (d) to (d) are the same, description thereof will be omitted.

In patients with myocardial infarction (MI), at the plot points of the distribution map of the composite current vector shown in FIGS. 7 (a) to 7 (c), the value of the electric axis index, which is said to be normal, is -30 °. Often does not fall within the range of + 110 °,
At the plot points of the distribution diagram of the combined current vector shown in FIG. 7D, | ΔI | = | I2-I1 | even though the value of the combined current vector at time T1 is large.
It can be seen that the value of may be small.

Here, a boundary line D parallel to the approximate straight line B shown in FIG. 5D is set as a boundary line between a patient with heart disease and a normal person, and an area on the left side of the boundary line D is Assuming that it is a normal region and plot points relating to a normal person are plotted in the normal region, it can be seen that two cases deviate from the normal region. The boundary line D is represented by (Equation 44).

[0081]

[Expression 44] | ΔI | = | I2-I1 | = 0.47 | I1 | -235 (Expression 44) On the other hand, in a patient with angina (AP), there is a part that is ischemic at rest. Since it is small, it is relatively similar to the plot points of the healthy person shown in FIG. In the distribution map of the synthetic current vector in patients with angina (AP), the synthetic current vector is
It can be seen that it has directionality and strength close to the synthetic current vector in the distribution diagram of the synthetic current vector of the healthy person shown in FIG. However, as shown in FIG.
In the example shown in FIGS. 7A and 7B, the magnitude of the combined current vector is small, but the direction of the combined current vector deviates from the normal value range (−30 ° to + 110 °) and the plot points are 5 points. I know there are examples.

In the example shown in FIG. 8, hypertrophic cardiomyopathy (HC
In all cases, M) 4 cases, dilated cardiomyopathy (DCM) 3 cases, and restricted cardiomyopathy (RCM) 1 case, there is a large variation in the magnitude of the synthetic current vector. Since the magnitude of the combined current vector varies, time T1
In FIG. 8D showing the relationship between the magnitude of the combined current vector at time point T1 and the amount of change in the magnitude of the combined current vector at time points T1 and T2, the boundary line D expressed by (Equation 44) is exceeded. An example case is detected, and the effect of using | ΔI | as an index is clearly seen.

From the results shown in FIGS. 5 to 8, the boundary between a patient with heart disease and a normal person will be considered as follows. In the distribution diagrams of the combined current vectors at the time points of T1 and T2 ((a) and (b) of FIGS. 5 to 8), the range of −30 ° to + 110 ° is the normal region. The first criterion (index) to be used and the normal range is a range in which the direction of the differential combined current vector in the distribution diagram of the differential combined current vector ((c) of FIGS. 5 to 8) is from 0 ° to + 90 °. In the case of representing the relationship between the criterion (index) of No. 2 and the magnitude of the combined current vector at the time point T1 and the change amount of the magnitude of the combined current vector at the time points T1 and T2 (FIGS. 7 to 8).
In (d)), the third criterion in which the region on the side of the approximation line B of the boundary line D represented by (Equation 44) (left side of the boundary line in FIGS. 7 to 8D) is the normal region (Index) and are set. A plot point that satisfies all the first to third criteria (index) is considered normal, and if any one of the first to third criteria (index) exceeds the normal range, it is regarded as positive. It was decided to judge.

FIG. 9 uses the first to third criteria (indexes) described above, and FIGS. 5 and 7 of the first embodiment of the present invention.
It is a figure which shows the number of positives considered to be positive (myocardial abnormality) from the result shown in FIG. As shown in FIG. 9, 29
0 positive cases, 8 positive cases for 10 myocardial infarctions, 5 positive cases for 10 angina, 4 positive cases for 4 hypertrophic cardiomyopathy, 3 dilated cardiomyopathy
Regarding the cases, 3 cases were positive and 1 case of restrictive cardiomyopathy was also positive. From the above results, when the myocardium is in an ischemic state and has a state close to necrosis, a fibrotic state, etc., it is possible to distinguish between a patient with a heart disease and a normal person by the analysis method of Example 1 described above. I found out.

However, with regard to myocardial infarction, all 10 patients could not be detected, and 1 out of the 2 cases not judged as positive was judged as old myocardial infarction, and the time after the occurrence of infarction occurred. It was thought that this might be due to the fact that changes in the magnetocardiogram waveform during the time period in which the ST waveform occurs decreased as time passed.

As described above, it has been found that it is possible to obtain useful information for determining myocardial ischemia by creating a distribution map of the synthetic current vector in the time zone in which the ST waveform occurs. The analysis method according to the first embodiment is not limited to the creation of the distribution map of the combined current vector in the time zone in which the ST waveform occurs, and, for example, P wave, Q wave, R wave,
It can be applied even in the time zone in which either S wave, T wave, etc. occur, and especially when abnormal Q wave (Q wave having amplitude higher than R wave) indicating myocardial infarction occurs. Therefore, the analysis using the distribution map of the combined current vector is considered useful.

(Embodiment 2) Next, embodiment 2 will be described, which mainly identifies angina (AP) by exercise load.
In Example 2 as well, using the biomagnetic field measuring apparatus (cardiac magnetic field measuring apparatus (magnetocardiograph)) shown in FIG. 1 as in Example 1, measurement of the magnetocardiographic waveform in the measurement range shown in FIG. Are doing.

In the second embodiment, the arithmetic processing unit detects the magnetic fields generated by the hearts of the subject in different states A and B in the space in which the external magnetic field is shielded, and the magnetic fields detected by the plurality of SQUID magnetometers. A process of collecting data representing waveforms and aligning the time axes of the magnetic field waveforms detected by the plurality of SQUID magnetometers at a first predetermined time point, and setting the baseline of the magnetic field waveforms to the second axis of the magnetic field waveform time axis. The process of matching at a predetermined time point and the magnetic field waveform (or the magnitude of the current vector obtained from the magnetic field waveform for each point) at each point where the magnetic field waveform is detected are different from the predetermined time point Ts and the predetermined time point Ts. A process of obtaining an integrated value by integrating in a time section with a predetermined time point Te is performed on the magnetic field waveform detected in each of the states A and B, and an integrated value SA corresponding to the state A is obtained. S from the integral value SB corresponding to the state B
A process for obtaining the first ratio defined by A / SB or SB / SA for each point, a process for obtaining the added value of the integrated value by adding the integrated values for each point, and the added value corresponding to the state A RA / RA from the added value RB corresponding to the state B to RA /
Of the process of obtaining a second ratio defined by RB or RB / RA, the process of obtaining the product of the first ratio and the second ratio for each point, and the process of obtaining the first ratio and the second ratio. A process of obtaining data representing a contour map connecting points having the same product is performed. The obtained contour map (current amount ratio distribution map (CRM: Current)
RatioMapping)) is displayed on the display screen of the display device.

Generally, angina is considered to be caused by a part of coronary artery causing stenosis. Exercise that consumes oxygen in the presence of stenosis in the coronary artery causes insufficient ischemia in the myocardium, resulting in an ischemic condition and subjective symptoms such as chest pain. The one in which the ischemic state is induced by exercise is called exertional angina, and the one in which the coronary arteries contract due to mental stress or the like to become ischemic is called spastic angina. Normal,
For exertional angina, it is common to wear a 12-lead electrocardiogram and observe changes in the electrocardiographic waveform during a time period in which an ST waveform before and after exercise occurs. However, in the method using the 12-lead electrocardiogram, it is necessary to apply a strong exercise load that causes a waveform change in the time zone in which the ST waveform occurs, which is a great burden to the patient. In addition, when the degree of stenosis is severe, it is often impossible to apply an exercise load that causes a change in the electrocardiographic waveform during the time period when the ST wave occurs. Example 2 proposes an analysis method for identifying exertion angina even in the case of an exercise load in which the magnetic field waveform and the electrocardiographic waveform do not change in the time zone in which the ST waveform occurs.

As described in the first embodiment, the change in the electrocardiographic waveform of the ST waveform before and after the exercise load has been often used as an indicator of the state of ischemia. However, since the change of the magnetocardiographic waveform in the time zone in which the ST waveform is generated is weak, as described in the first embodiment, the distribution map of the combined current vector obtained by time integration of the magnetocardiographic waveform is used. There was no choice but to improve S / N. The method of Example 1 is useful for distinguishing the presence or absence of ischemia when ischemia occurs even at rest, but the magnetocardiogram waveform is generated in the time zone in which the ST waveform is generated even when exercise load is applied. It is not suitable for identifying the presence or absence of ischemia when there is little change in

On the other hand, studies have also been conducted on the movement of the R wave of the electrocardiogram before and after exercise load. According to the experiment using body surface electrocardiogram, the change of the peak value of the R wave of the electrocardiogram before and after the exercise load is different between the healthy person and the angina patient, and the potential changes in the time zone of the R wave of the ischemic patient. Part to be done, ST
It has been reported that the region where the potential changes in the time period in which the waveform occurs is almost the same. In Example 2, an analysis method for identifying an ischemic state was devised by using a magnetic field waveform in the vicinity of a time zone in which an R wave having a strong magnetic field intensity of the magnetocardiographic waveform is generated.

FIG. 10 is a diagram for explaining an analysis method according to the second embodiment of the present invention. As shown in FIG.
The current obtained from the magnetocardiogram waveform at rest (Rest) at a measurement point i (channel i) at a certain time point (for example, the time point of the R wave peak (Tp)) is defined as Ii (Tp). At rest, it is assumed that both a healthy person and an ischemic patient have the same current Ii (Tp). After exercise (Exercise), the current changes to Ai (Tp) × Ii (Tp) in healthy subjects and Ai (Tp) × {Ii (Tp) + Bi (T) in ischemic patients.
p)}.

In order to show the change in FIG. 10 (a) more conspicuously, the ratio of the currents before and after the exercise load in channel i (referred to as the first ratio) αi (Tp) and βi (Tp) are
Calculation using (Equation 45) and (Equation 46) results in FIG.
Becomes The numerator is the current after exercise (Exercise), and the denominator is the current before exercise (Rest). By the ratio αi (Tp), the change amount of the current in a healthy person is
The amount of change in current in an ischemic patient can be calculated from i (Tp).

[0094]

[Equation 45] αi (Tp) = Ai (Tp) × Ii (Tp) / Ii (Tp) = Ai (Tp)                                                             … (Equation 45)

[0095]

Βi (Tp) = Ai (Tp) × {Ii (Tp) + Bi (Tp)} / Ii (Tp) = Ai (Tp) × {1+ (Bi (Tp) / Ii (Tp))} (Equation 46) Ratios αi (Tp) and βi (Tp) obtained in FIG.
The standardization shown in FIG. 10C is performed to eliminate the individual difference. As shown in (Formula 47) and (Formula 48), the normalization is performed by calculating the ratio (second ratio) of the added value obtained by adding the absolute values of the current amounts before and after the load shown in FIG. 10 (b) The ratios αi (Tp) and βi (Tp) obtained by reciprocal (the denominator is the sum of the absolute values of the current after loading, and the numerator is the sum of the absolute values of the current before loading) It is done by multiplying. In (Equation 47) and (Equation 48), Σ indicates an addition symbol, and addition is performed for i = 1, 2, ..., N (= 64).

Mapping connecting points of equal α0i (Tp) calculated by (Equation 47) and (Equation 48), β0i
A map obtained by mapping points having the same (Tp) is used as a current amount ratio distribution map (CRM: Current Ratio).
Mapping).

[0097]

[Equation 47] α0i (Tp) = αi (Tp) × {Σ | Ii (Tp) |} / {Σ | Ai (Tp) × Ii (Tp) |} (Equation 47)

[0098]

[Formula 48] β0i (Tp) = βi (Tp) × {Σ | Ii (Tp) |} / {Σ | Ai (Tp) × (Ii (Tp) + Bi (Tp)) |} (Formula 48) ( If normalization is performed using (47) and (48), if the value Ai (Tp) of the amount of change in current has a value close to a constant value in all channels in a healthy person, α0i (Tp) becomes ( Number 4
It is considered that the value will be close to 1 as shown in 9). On the other hand, in an ischemic patient, the value Bi (Tp) of the amount of change in the current that changes with ischemia is locally present, so Bi (Tp)
Is considered to be close to 0 for all channels, and in the ischemic patient, if the condition shown in (Equation 50) is satisfied, β0
i (Tp) is (Equation 51), and it is considered that only the amount of change due to ischemia can be detected.

[0099]

[Equation 49] α0i (Tp) ≈1 (Formula 49)

[0100]

[Equation 50] ΣBi (Tp) <ΣIi (Tp) (Equation 50)

[0101]

[Formula 51] β0i (Tp) ≈1 + {Bi (Tp) / Ii (Tp)} (Formula 51) For easy understanding in FIG.
The data at time t) is used as the denominator, and the load (Exercise)
Although the latter data is shown as a numerator, the actual calculation results shown in FIGS. 14 to 17 show that the magnetocardiogram waveform at rest has a larger amplitude than the magnetocardiogram waveform after loading (see FIGS. 12 and 13). ), The denominator is the post-load data, and the numerator is the rest data.

In the above description, the time point of the peak of the R wave (T
α0i (Tp) and β0i (Tp) were obtained in p), and the results shown in FIGS. 14 to 17 are (Expression 52), (Expression 53),
Based on (Equation 54), the magnetocardiogram waveform of the QRS wave is integrated in predetermined time sections Ts to Te, that is, the temporal change of the current obtained from the temporal change of the magnetocardiographic waveform, Ii (t), Ai ( t)
× Ii (t), Ai (t) × {Ii (t) + Bi
(T)} is integrated in a predetermined time section Ts to Te, and these integrated values are Ii (Tp) values in (Equation 44) to (Equation 48), Ai (Tp) × Ii ( Tp) and the value of Ai (Tp) × (Ii (Tp) + Bi (Tp)) are used to find the equal points of α0i (Tp) obtained based on (Equation 44) to (Equation 48). It is a figure which shows the result of having performed the mapping which connects, and the mapping which connects the points with equal (beta) 0i (Tp). The maps shown in FIGS. 14 to 17 are converted into current amount ratio distribution diagrams (CRM: Current Ratio).
o Mapping). 14 to 17, the current amount ratio distribution diagram is displayed with the outline position of the heart aligned with the contour diagram of the subject.

[0103]

[Equation 52] ∫ Ii (t) dt → Ii (Tp) (Equation 52)

[0104]

[Equation 53] ∫ {Ai (t) × Ii (t)} dt → Ai (Tp) × Ii (Tp) ... (Equation 53)

[0105]

∫ {Ai (t) × (Ii (t) + Bi (t))} dt → Ai (Tp) × (Ii (Tp) + Bi (Tp)) (Equation 54) FIG. 11 shows the present invention. FIG. 8 is a diagram showing an example of a procedure of measuring a magnetocardiographic waveform in Example 2. Measurement of 12-lead electrocardiogram and magnetocardiographic waveform in a resting state in a space in which the external magnetic field is shielded (for example, a space in a magnetically shielded room in which the bed is placed, or a space in which the external magnetic field is placed in which the bed is placed) Are measured at the same time. Next, Master '
Exercise load by stair walking called s 2 step method is performed. The Master's 2 step method is an inspection method that requires less load than methods such as treadmills.
It is a test method that is less burdensome for patients. The load varies with age and gender. During exercise load, the patient's condition is observed while monitoring with a 12-lead electrocardiogram, and when the patient becomes distressed, the exercise load is immediately stopped. After the load, the patient immediately enters the space in which the external magnetic field is shielded and simultaneously receives the magnetocardiographic waveform measurement and the 12-lead electrocardiographic measurement. Immediately after loading, the patient's heart is aligned with the lower surface of the cryostat to measure the magnetocardiographic waveform, and the magnetic field immediately after loading is measured about 45 seconds to 1 and a half minutes after the loading is completed. The magnetocardiographic waveform was measured at 1-minute intervals from about 5 minutes to 10 minutes after the end of the load until the patient sufficiently returned to the resting state. Since the data of the magnetocardiogram waveform before and after the load was used when the positional relationship between the patient's heart and the lower surface of the cryostat was not misaligned, the data after sufficient time from the load was used as the data at rest.

According to the procedure for measuring the magnetocardiographic waveform described with reference to FIG. 11 described above, the magnetocardiographic waveform was measured for 4 healthy subjects, 6 exertional angina pectoris, and 2 spastic angina pectoris. I did. In addition, in 2 out of 6 cases of exertional angina, magnetocardiographic waveforms were measured twice before and after balloon treatment (PTCA).

FIG. 12 is a diagram showing an example of a display screen for displaying magnetocardiographic waveforms measured by the 64-channel SQUID magnetometer before and after exercise of a healthy person in the second embodiment of the present invention. In FIG. 12A, magnetic field waveforms of 64 channels before and after the load of a healthy person are displayed side by side. Channel 121 R
The magnetocardiogram waveforms before and after the load were superimposed on the basis of the time point (Tp) of the wave peak. FIG. 12B shows channel 1
22 is an enlarged display of 22 magnetocardiographic waveforms. Resting magnetocardiogram 1
25 (solid line) and the magnetocardiographic waveform 124 (dotted line) immediately after the load are superimposed and displayed. 12 (a) and 12 (b)
From the waveform of the QRS wave shown in (1), it can be seen that there is almost no change in the healthy person before and after the load. In FIG. 12B, the integration section 123 (40 ms) of the magnetocardiographic waveform of the QRS wave in (Equation 51) to (Equation 53) and predetermined time sections Ts to Te are shown.
, Ts = (Tp-20) ms, Te = (Tp
+20) ms.

FIG. 13 is a diagram showing a display screen of magnetocardiographic waveforms measured by a 64-channel SQUID magnetometer before and after exercise load of an angina patient in Example 2 of the present invention. Figure 1
Similarly to FIG. 12, 3 shows the magnetocardiogram waveform of the QRS wave when the ST waveform changes before and after the exercise load. Also in FIG. 13A, the magnetocardiographic waveforms before and after the load are superimposed on the basis of the time point (Tp) of the R wave peak of the channel 131. FIG. 13B is an enlarged display of the magnetocardiogram waveform of the channel 132. The magnetocardiographic waveform 135 at rest (solid line) and the magnetocardiographic waveform 134 immediately after loading (dotted line) are superimposed and displayed. In FIG. 13B, Q in (Equation 51) to (Equation 53)
The integration section 133 (40 ms) of the magnetocardiographic waveform of the RS wave and a predetermined time section Ts to Te are shown, and Ts = (Tp-2
0) ms and Te = (Tp + 20) ms. As shown in FIG. 13, it can be seen that, before and after the load, a change in the magnetocardiographic waveform that is similar to the amount of change in the magnetocardiographic waveform in the ST waveform also occurs in the QRS wave. Since the magnetocardiogram waveform of the R wave changes as well as the magnetocardiogram waveform of the ST waveform, it is considered that the magnetocardiogram waveform in the vicinity of the R wave can be used to obtain the amount of change indicating the state of ischemia.

FIG. 14 is a diagram showing an example of a display screen in which a current amount ratio distribution chart which is an analysis result regarding four cases of exertional angina in the second embodiment of the present invention is superimposed on the contour of the patient. is there. Fig. 14 (a) shows the result of stenosis of the left circumflex of the left coronary artery, Fig. 14 (b) shows the result of stenosis of the right coronary artery, and Figs. 14 (c) and 14 (d) show the left. The result shows that the anterior descending coronary artery is stenotic. A change in the ST electrocardiographic waveform on the electrocardiogram appeared due to the exercise load, and the positive reaction occurred only in the case of Fig. 14 (d). In the other three cases, the positive reaction was induced by the exercise load. There wasn't. The peak 141 of the current amount ratio distribution chart shown in FIG. 14A is located in the upper left chest and appears corresponding to the site where the left circumflex branch exists. The peak 142 of the current amount ratio distribution chart shown in FIG. 14B is located above the right chest and appears corresponding to the existing site of the right coronary artery. 14 (c) and 14
The peaks 143 and 144 in the current amount ratio distribution chart shown in (d) appear corresponding to the existing site of the left anterior descending coronary artery.
As shown in FIGS. 14 (a) to 14 (c), even when the change in the magnetocardiographic waveform of the ST waveform is not induced by the exercise load, by using the current amount ratio distribution map, the stenotic site (or ischemic site) It is understood that can be estimated.

FIG. 15 is a diagram showing an example of a display screen in which a current amount ratio distribution chart, which is an analysis result of four healthy subjects in the second embodiment of the present invention, is superimposed on the contour of the patient. Figure 1
Peaks 151, 152, 153, and 154 are present in the current amount ratio distribution diagrams of the four examples shown in FIGS. 5 (a) to 15 (d), but the current amount ratios shown in FIGS. 14 (a) to 14 (d) are present. Compared with the distribution chart, it can be seen that the number of contour lines is small and the peak value is small. Further, in the two cases of spastic angina, stenosis was not induced by the load, and the current amount ratio distribution diagram was almost the same as that in FIG. 15, so the current amount ratio distribution diagram is not shown.

FIG. 16 shows an example of analysis of exertional angina pectoris with stenosis in the left anterior descending coronary artery in Example 2 of the present invention, before balloon treatment (PTCA) and one week after the treatment. FIG. 7 is a diagram showing an example of a display screen of a magnetocardiogram waveform and an example of a display screen in which a current amount ratio distribution chart is superimposed on the contour of the patient. Figure 1
In the case shown in 6, the ST waveform was predominantly changed in the magnetocardiographic waveform before and after PTCA. FIG. 16 (A) shows a magnetocardiogram waveform and current amount ratio distribution diagram before PTCA operation, and FIG. 16 (B) shows PT.
The magnetocardiogram waveform after CA operation and the current amount ratio distribution chart are shown. FIG.
(A) and (I) in FIG. 16 (B) show superposed waveforms of magnetocardiographic waveforms of 64 channels 1 minute after the exercise load. (II) in FIGS. 16 (A) and 16 (B) shows a superposed waveform of magnetocardiographic waveforms of 64 channels 5 minutes after the time of returning to the rest state. 16 (A) and 16 (B)
(III) in Fig. 3 shows a current amount ratio distribution chart. FIG.
It can be seen that in the magnetocardiographic waveform 161 shown in (A) and (I), the ST waveform greatly changes with time. 16 (A) (I
It can be seen that in the magnetocardiographic waveform 162 after 5 minutes shown in I), the large change in the ST waveform has disappeared. 16 (A) (I
II) is a current amount ratio distribution chart created using the magnetocardiographic waveform 161 and the magnetocardiographic waveform 162. 16 (A) (III)
The peak 163 in the current amount ratio distribution chart shown in FIG.
It can be seen that, similar to the peak 144 in the current amount ratio distribution charts shown in (c) and (d), it appears in the left anterior descending coronary artery region. Looking at the magnetocardiogram waveforms after one week after the PTCA treatment shown in FIG. 16B, it can be seen that there is almost no change in the ST wave between the magnetocardiogram waveform 164 immediately after the load and the magnetocardiogram waveform 165 at rest. . Fig. 1 despite no change in ST wave
6 (B) (III) shows the peak 1 in the current amount ratio distribution chart.
66 still appears big.

FIG. 17 shows an analysis example of exertional angina disease having a stenosis in the left anterior descending coronary artery in Example 2 of the present invention, before balloon treatment (PTCA) and one month after the treatment. FIG. 7 is a diagram showing an example of a display screen of a magnetocardiogram waveform and an example of a display screen in which a current amount ratio distribution chart is superimposed on the contour of the patient.

FIG. 17A shows a magnetocardiogram waveform before PTCA and a current amount ratio distribution diagram, and FIG. 17B shows a magnetocardiogram waveform after PTCA and a current amount ratio distribution diagram. 17 (A) (I),
Comparing the magnetocardiogram waveform 171 and the magnetocardiogram waveform 172 shown in (II), it can be seen that there is no change in the ST waveform between them. Although the ST waveform change does not appear significantly,
In the current amount ratio distribution chart shown in FIG.
It can be seen that 3 appears. It can be seen that the case shown in FIG. 17 (A) is left circumflex branch stenosis, and a pattern of the current amount ratio distribution map very similar to the case of left circumflex branch stenosis shown in FIG. 14 (a) is obtained. Figure 17 (B) shows 1 after PTCA
It is a magnetocardiogram waveform and the current amount ratio distribution map which were measured after a lapse of months. Magnetocardiographic waveform 17 shown in FIGS. 17 (B) (I) and (II)
4 is compared with the magnetocardiogram waveform 175, it can be seen that there is no change in the ST waveform as in the case of FIG. An abnormal Q wave always appeared in the magnetocardiogram waveform 174 and the magnetocardiogram waveform 175, and it was considered that myocardial infarction occurred in a part of myocardium after PTCA. Peak 17 in the current amount ratio distribution chart
Although 6 exists, the number of contour lines is small and is very similar to the pattern of the current amount ratio distribution map of the healthy person shown in FIG. 15, and the pattern of the current amount ratio distribution map has a small peak.

FIG. 18 is a diagram showing a result example in which the peak value of the current amount ratio distribution chart is shown in a bar graph in the second embodiment of the present invention. The six plots 181 on the left side shown in FIG. 18 show the peak value of exertional angina, the two plots 182 show the peak value of spastic angina, and the four plots of 183
The example shows the peak value of a healthy person. From the results shown in FIG. 18, it is considered that the boundary between a healthy person or a patient with spastic angina and a patient with exertional angina is around 0.5. In addition, two PTs treated with the PTCA treatment shown in FIGS.
A plot of the peak value of the current amount ratio distribution chart after CA is shown in a plot 184. # 1 of plot 181 and plot 18
# 1 in 4 corresponds to the same patient in the same case, and plot 18
# 2 of 1 and # 2 of plot 184 correspond to the same patient in the same case. The change in peak value before and after PTCA is 2
Although the number decreased in all cases, the value was high in case # 2 even after PTCA. It is considered that this may be due to the measurement of the magnetocardiographic waveform when only one week had passed after PTCA.

In the second embodiment described above, the processing is performed by focusing on the QRS wave, but the same analysis can be performed not only on the QRS wave but also on the P wave or the T wave. In particular, it is considered that P waves show abnormalities in the atrium, valves in the heart, and left ventricle.

In the first and second embodiments described above, 1
The example has been described in which the magnetic field component in the normal direction (z direction) of the cardiac magnetic field is detected by the SQUID magnetometer having the second-order differential type detection coil. In the first and second embodiments, the tangential direction of the cardiac magnetic field ( Magnetic field components in the x direction and the y direction) may be detected.

For the channel i, the tangential direction (x direction, y
When detecting the magnetic field components (Bxi, Byi) of the (direction), (Equation 3) to (Equation 6) representing the components of the combined current vector in the first embodiment described above are shown below (Equation 5).
5) to (Equation 58) to represent the components of the combined current vector in the second embodiment described above (Equation 20) to
(Equation 21) may be replaced with (Equation 59) to (Equation 60) shown below. As a result, tangential direction (x direction, y direction)
Also when detecting the magnetic field component of
The same result as in Example 2 can be obtained.

[0118]

[Equation 55] Ixi (T1) = Byi (T1) (Equation 55)

[0119]

[Equation 56] Iyi (T1) =-Bxi (T1) (Equation 56)

[0120]

[Equation 57] Ixi (T2) = Byi (T2) (Equation 57)

[0121]

[Equation 58] Iyi (T2) =-Bxi (T2) (Equation 58)

[0122]

[Equation 59] Ixi (tj) = Byi (tj) (Equation 59)

[0123]

Iyi (tj) = − Bxi (tj) (Equation 60) Further, in addition to the SQUID magnetometer having the first-order differential type detection coil, it is possible to use the SQUID magnetometer having the second-order differential type detection coil. Needless to say.

Furthermore, the analysis method of the present invention can be applied to adults, children,
It goes without saying that it can be effectively applied to the analysis of a weak magnetic field generated from the heart such as the fetus in the mother's body.

[0125]

According to the present invention, the measured magnetocardiographic waveform can be analyzed by a simple method to easily identify ischemic heart disease (myocardial infarction, angina, etc.) and cardiomyopathy. It can display various screens and can provide useful information for heart diagnosis. In addition, the changes in the state of the current flowing along with the electrophysiological activity of the myocardium of patients with ischemic heart disease or cardiomyopathy are compared with those of normal subjects. Since it can be easily monitored on the screen, it can provide useful information for diagnosis. Furthermore, even in an ischemic state induced by exercise load or the like, the degree of ischemia and the site where ischemia exists can be estimated, so that a useful index for diagnosis can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a biomagnetic field measuring apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an arrangement example of a plurality of SQUID magnetometers arranged near the bottom inside the cryostat according to the first embodiment of the present invention.

FIG. 3 is a diagram showing the isomagnetic field diagram at the time point T1 in the time zone in which the R wave and T wave peaks and the ST wave of the healthy person are obtained, which are obtained in the first embodiment of the present invention; Distribution map,
The figure which shows the example of the screen display in which the waveform which overwrites the measured magnetocardiogram waveform of 1 channel to 64 channels is displayed.

FIG. 4 is a diagram for explaining an isomagnetic field line diagram created by a single dipole model and a distribution diagram of a composite current vector in Example 1 of the present invention.

FIG. 5 is a diagram showing an example of a display screen of a distribution diagram of a composite current vector obtained by measuring magnetocardiographic waveforms and analyzing the magnetocardiographic waveforms in 29 healthy adults in Example 1 of the present invention.

[Fig. 6] Fig. 6 is a graph showing a magnetocardiogram waveform of an adult healthy person measured at six positions where the distance between the heart of the subject and the measurement surface is sequentially increased in Example 1 of the present invention, and the magnetocardiogram waveform is analyzed. The figure which shows the example of the display screen of the distribution map of the synthetic | combination electric current vector obtained by it.

FIG. 7: Obtained by measuring magnetocardiographic waveforms and analyzing magnetocardiographic waveforms in patients with myocardial infarction (MI) and angina (AP), which are myocardial ischemia, in Example 1 of the present invention. The figure which shows the example of the display screen of the distribution map of the synthetic | combination electric current vector.

FIG. 8 is a magnetocardiogram waveform of a hypertrophic cardiomyopathy (HCM) patient, a dilated cardiomyopathy (DCM) patient, and a restricted cardiomyopathy (RCM) patient in Example 1 of the present invention. The figure which shows the example of the display screen of the distribution map of the synthetic | combination electric current vector which measured and measured the magnetocardiogram waveform.

FIG. 9 is a diagram showing the number of positives considered to be positive (myocardial abnormality) from the results shown in FIGS. 5, 7 and 8 in Example 1 of the present invention.

FIG. 10 is a diagram illustrating an analysis method according to the second embodiment of the present invention.

FIG. 11 is a diagram showing an example of a procedure of measuring a magnetocardiographic waveform in Example 2 of the present invention.

FIG. 12 is a diagram showing an example of a display screen of magnetocardiographic waveforms measured by a 64-channel SQUID magnetometer before and after exercise of a healthy person in Example 2 of the present invention.

FIG. 13 is a diagram showing an example of a display screen of magnetocardiographic waveforms measured by a 64-channel SQUID magnetometer before and after an exercise load of an angina patient in Example 2 of the present invention.

FIG. 14 is a graph of exertional angina 4 according to Example 2 of the present invention.
The figure which shows the example of the display screen of the electric current amount ratio distribution chart which is the analysis result regarding an example.

FIG. 15 is a diagram showing an example of a display screen of a current amount ratio distribution diagram, which is an analysis result of four healthy subjects in Example 2 of the present invention.

FIG. 16 shows an example of analysis of exertional angina disease with stenosis in the left anterior descending coronary artery in Example 2 of the present invention, showing magnetocardiography before balloon treatment (PTCA) and one week after the treatment. The figure which shows the example of a display screen of a waveform, the example of a display screen of a current amount ratio distribution diagram.

FIG. 17 shows an analysis example of exertional angina disease having a stenosis in the left anterior descending coronary artery in Example 2 of the present invention, showing magnetocardiography before balloon treatment (PTCA) and one month after the treatment. The figure which shows the example of a display screen of a waveform, the example of a display screen of a current amount ratio distribution diagram.

FIG. 18 is a diagram showing a result example in which a peak value of a current amount ratio distribution chart is shown in a bar graph in Example 2 of the present invention.

[Explanation of symbols]

1 ... Magnetically shielded room, 2 ... Cryostat, 3 ...
Gantry, 4 ... Measuring circuit, 5 ... Amplifier filter unit, 6 ... Arithmetic processing device, 7 ... Bed, 201 ... Sword-like projection, 202 ... SQUID magnetometer, 301 ... Synthetic current vector at the time when peak of R wave occurs Distribution map, 302 ...
The distribution diagram of the combined current vector at the time of T1 in the time zone where the ST wave is generated, 303 ... The distribution map of the combined current vector at the time when the peak of the T wave is generated, 304 ... Magnetic field waveforms of 1 to 64 channels Overwritten waveform, 305
... line showing the time point when the Q wave starts, 401 ... current dipole, 402 ... measurement plane, 403 ... direction of dipole 401, 404 ... calculation point, 121, 131 ... time alignment of R wave of magnetocardiogram waveform before and after exercise load Occasionally reference channel magnetocardiographic waveforms, 122, 132 ... Channel magnetocardiographic waveforms showing typical changes, 123, 133 ... Magnetocardiographic waveform integration interval (40 ms), 124, 134 ... Magnetocardiogram after exercise load Waveform, 125, 135 ... Magnetocardiographic waveform before exercise load, 141,
142, 143, 144, 151, 152, 153, 1
54, 163, 166, 173, 176 ... Peak of current amount ratio distribution map, 161, 164, 171, 174 ... Magnetocardiographic waveform after 1 minute of exercise load, 162, 165, 172, 175
… Magnetocardiographic waveform after 5 minutes of exercise load.

Continuation of the front page (56) Reference JP 10-305019 (JP, A) JP 11-104095 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) A61B 5 / 05 G01R 33/035

Claims (5)

(57) [Claims] 1. A different state A in a space in which an external magnetic field is shielded
And the magnetic field generated from the heart of the subject in state B is detected.
Of the magnetic field waveforms detected by multiple SQUID magnetometers
An arithmetic processing unit that collects data and performs arithmetic processing on the data
Of the arithmetic processing obtained by the arithmetic device and the arithmetic processing device.
And a display device for displaying a result, the arithmetic processing device
Adjusts the time axis of the magnetic field waveform at the first predetermined time point.
Processing and the baseline of the magnetic field waveform to the magnetic field waveform
The process of adjusting at the second predetermined time point of the
A time point Ts and a predetermined time point Te different from the predetermined time point Ts
For each point where the magnetic field waveform was detected in the time interval of
Process for obtaining magnitude of current vector from the magnetic field waveform
And the magnitude of the current vector for each point
The product in the time section between the predetermined time Ts and the predetermined time Te
The above-mentioned state A, the above-mentioned state
Regarding the magnetic field waveform detected in each state of B
The integrated value SA corresponding to the state A and the state
SA / SB or S from the integrated value SB corresponding to the state B
Obtain the first ratio defined by B / SA for each of the points
Data representing a contour map connecting points having the same first ratio
And the contour map is displayed on the display device.
A biomagnetic field measuring device characterized by being displayed on. 2. The biomagnetic field measuring apparatus according to claim 1.
Then, the arithmetic processing unit determines the integrated value from
A process of adding points to obtain the added value of the integrated value
And the addition value RA corresponding to the state A and the state B
RA / RB or RB / from the added value RB corresponding to
The process of obtaining the second ratio defined by RA, and
A process for obtaining a product of the first ratio and the second ratio for
And the point where the product of the first ratio and the second ratio is equal
And the process of obtaining the data representing the connecting contour map,
The contour map is displayed on the display device.
Biomagnetic field measuring device. 3. A different state A in a space in which an external magnetic field is shielded
Detecting the magnetic field that occurs from a subject's heart in the state B
Of the magnetic field waveforms detected by multiple SQUID magnetometers
An arithmetic processing unit that collects data and performs arithmetic processing on the data
Of the arithmetic processing obtained by the arithmetic device and the arithmetic processing device.
And a display device for displaying a result, the arithmetic processing device
Adjusts the time axis of the magnetic field waveform at the first predetermined time point.
Processing and the baseline of the magnetic field waveform to the magnetic field waveform
The process of adjusting at the second predetermined time point on the time axis of
For each point where the field waveform was detected,
A time point Ts and a predetermined time point Te different from the predetermined time point Ts
The process of calculating the integrated value by integrating in the time interval of
The magnetic field detected in each of state A and state B
The integration corresponding to the state A is performed on the field waveform.
From the value SA and the integrated value SB corresponding to the state B, S
The first ratio defined by A / SB or SB / SA
The process of obtaining the point and the integrated value
A process of adding points to obtain the added value of the integrated value
And the addition value RA corresponding to the state A and the state B
RA / RB or RB / R from the added value RB corresponding to
The process of obtaining the second ratio defined by A
Processing for obtaining the product of the first ratio and the second ratio
And a point where the product of the first ratio and the second ratio is equal.
The process of obtaining the data representing the contour map is performed, and
A contour map is displayed on the display device.
Biomagnetic field measurement device. 4. The biomagnetic field measuring apparatus according to claim 3.
Then, the predetermined time points Ts and Te are the QR of the magnetic field waveform.
Raw characterized by being set to a time section in which S waves occur
Body magnetic field measuring device. 5. The biomagnetic field measuring apparatus according to claim 3.
Then, the predetermined time points Ts and Te are P waves of the magnetic field waveform.
Alternatively, it is set to a time section in which a T wave occurs.
Biomagnetic field measurement device.