JPH0240578A - Measuring apparatus of biomagnetism - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a biomagnetism measurement device that measures minute magnetism inside a living body.

[Conventional technology]

When a stimulus is applied to a living body, the polarization formed across cell membranes breaks down, causing an active current force 'rM. Such action currents are seen in the brain, heart, skeletal muscles, retina, etc., and are called electroencephalograms, electrocardiograms, electromyograms, electroretinograms, etc., respectively. Records of magnetic fields caused by the flow of electric current are called magnetoencephalography, magnetocardiography, magnetomyography, magnetoretinography, etc., respectively. In recent years, SQU has been used as a device to measure magnetism in living organisms.
I D (Superconducting Quan)
tum Interface Device (Superconducting Quantum Interference Device) has been developed, and it has become easier to measure minute magnetic fields inside living organisms (1~Riga One Separate Volume p155-163. December 1987, Parity Separate Volume N
o, 1. p26-38.1986. Mezoica I Registm News vol. 1.9 No. 4 No. 100 p26
-27.1988). Measuring the magnetic field inside the living body in this way has the following advantages compared to measuring the electric potential. For example, when a subject is stimulated with electrical, auditory, or visual signals, the state when an active current is generated in the neurons of the brain is determined by electroencephalography based on the response evoked. It can also be observed by measuring the potential. However, since the cranium has a relatively high resistivity, the potential generated within the cranium spreads laterally along the cranium.
Voltage changes that are observed on the surface of the brain skin are averaged when recorded on the skull, and local characteristics are lost. Therefore, in such an electroencephalogram, it is difficult to position the current dipole as a signal source. On the other hand, since the magnetic permeability of living tissue is almost the same as in a vacuum, when measuring magnetic fields, it is less susceptible to the influence of the cranium, and local changes can be easily detected. The position of the child can be determined.

[Problem to be solved by the invention]

However, the conventional 5QU1. Since the D-type biomechanical measurement device cannot measure multiple points simultaneously, for example, an isomagnetic field diagram is created based on the magnetic fields measured at many measurement points around the skull, and the source of the magnetic field is approximately a current dipole. When estimating the location of a brain tumor or the cause of epilepsy using the fact that it can be expressed as , the problem is that the measurement device must be moved, making data collection extremely troublesome. This invention enables simultaneous measurement at multiple points, easily understands the detected magnetic signals in relation to the detection points, and extracts the magnitude of each magnetic signal at a desired timing.
The purpose of the present invention is to provide a UI D-type main body magnetic measurement device.

[Means to solve problems] In order to achieve the above object, the biomagnetic measuring device according to the present invention includes a large number of detection coils arranged at predetermined positions at the bottom of the cooling container, an input coil connected to each detection coil, and a plurality of input coils connected to each of the detection coils. A detection means comprising a large number of magnetically coupled SQUIDs, a storage means for storing the position of the detection coil, and a means for displaying the waveform of the detection signal from the detection means in correspondence with the position of each detection coil. , means for displaying a time cursor for each detection signal waveform, and means for extracting a detection signal at a time specified by the time cursor. [For production]

A number of detection coils are arranged at the bottom of one cooling vessel. These detection coils are each connected to a SQUID input coil, and constitute a superconducting magnetic flux transformer. Therefore, it is possible to measure biomagnetism at each position of the detection coil, allowing for multi-point synchronization! jll can do it. Since the position of the detection coil is stored in advance, the detection signal can be displayed at a position corresponding to this detection point. This makes it easier to understand the overall waveform. Furthermore, a time cursor is displayed corresponding to each detection signal waveform, and the detection signal at the time specified by the time cursor is extracted, so the uniform magnetic field is calculated from the amount of magnetic flux at multiple points at the desired timing. You can easily create diagrams, etc.

【Example】

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the detection section 1. As shown in this figure, the detection section 1 is connected to a detection coil 1b inside a dewar (a container cooled with liquid helium or liquid nitrogen) la. The detection coil 1b is configured by incorporating a large number of input coils 1c and SQUIDs 1d magnetically coupled to the input coil 1c.
a (which is circular in this embodiment) as shown in FIG. 3A or B (FIG. 3A).
, B, the cross mark indicates the position of the detection coil, that is, the detection point). The detection coil 1b is preferably a magnetic flux gradiometer. Also, as SQUIDId, Teha thin wAD C-S Q
The magnetic flux gradient detected at each position of the detection coil 1b appears as a voltage change at both ends of the SQUID 1d. The output voltage of this SQUID1d is as shown in Fig. 2.
It is input to the magnetic flux lock circuit 2. The magnetic flux lock circuit 2 operates as a zero detector and produces an output according to the magnetic flux gradient by feedback current to the SQU ID1d. The thus detected signal is input to the A/D converter 4 via the amplifier 3 and converted into a small digital signal. When performing magnetic detection at nine points as shown in FIG. 3A, nine sets of detection coil 1b, input coil 1c, SQUID 1d, magnetic flux lock circuit 2, amplifier 3, and A/D converter 4 are provided. The magnetic detection signals at multiple points thus obtained as digital signals are written in parallel to the memory 5. When data is collected for a certain period of time, the waveform of the detection signal at each detection point is obtained in the memory 5. The signal waveforms at each point are once written into the memory 7 via the data bus 6 and then sent to the monitor device 8. The computer 9 stores in advance the positional relationship of the detection coil 1b, and under the control of the computer 9, the above waveforms are displayed on the screen of the monitor device 8 in accordance with this positional relationship as shown in FIGS. 4A and 4B. It will be displayed like this. Furthermore, when an arbitrary cursor position is input for each waveform from the console 14, the cursor is displayed for each waveform as shown by the vertical dotted lines in FIGS. 4A and 4B under the control of the computer 9. This cursor specifies time, and by operating the data capture switch on the console 14, magnetic flux data at the timing specified by the cursor is sampled and displayed, and the data is sent to the data recorder via the interface circuit 10. It is recorded in 11. Furthermore, the computer 9 creates an equal magnetic field diagram from the magnetic flux data for each point at this predetermined timing. At this time,
Data (stored in advance) indicating the position of each measurement point is used. The created isomagnetic field diagram is once stored in the memory 12 and then displayed on the monitor device 13. When the Dewar-1a is aimed at the subject's brain and the brain magnetic field is determined at multiple points to create an isomagnetic field diagram of the brain, something like the one shown in Figure 5 is obtained, for example, and this is displayed on the monitor device 13. . In FIG. 5, the black dots represent measurement points, the solid lines represent isomagnetic field lines, and the arrows represent the position of the signal source assuming that the signal source is a current dipole. Since this isomagnetic field map is easier to see when displayed in color, it is desirable to use a color monitor device 13. The stimulation device 16 and the controller 15 are used to provide stimulation such as sound and light to the subject under the operation of the operation console 14 and the control of the computer 9, and are usually equipped in an electroencephalograph. things are used. This gives a stimulus to the subject, and changes in the magnetic field that occur as a response are measured as described above. When selecting a measurement point, an arbitrary one is specified from all the displayed measurement points by operating the console 14. Then, the computer 9 identifies the input measurement point and performs measurement. In addition, multiple types of detection units 1 may be prepared, and the arrangement of the detection coils 1b may be changed for each type (for example, Fig. 3A, B
), any one of them can be selected and connected to the magnetic flux lock circuit 2. In this case, if the computer 9 is made to know the positional relationship of the measurement points for each detection unit 1 in advance, no matter which detection unit 1 is selected and connected, the display corresponding to the positional relationship of the measurement points will be displayed. , it is possible to quickly create a magnetic field diagram. Furthermore, in the embodiment 1, the detection signal waveform data is measured at each point in time specified by the cursor, but two cursors are displayed at a time, and the data between the two points specified by them is extracted and the data is measured. Record on recorder 11,
If the computer 9 calculates the frequency spectrum of this time-series data and creates an isomagnetic field diagram based on the components of a specific frequency band, it can be used to investigate the source of slow waves such as alpha waves and beta waves. . [Effects of the Invention] According to the biomagnetometer ill, 11 device of the present invention, it is possible to simultaneously measure biomagnetism at multiple points, and it is easy to understand the relationship between the detection point arrangement of a large number of detected fS waveforms, Furthermore, the time cursor allows signal extraction at a desired timing, thereby making it possible to easily create an isomagnetic field diagram. Therefore, it is extremely effective for non-invasive functional diagnosis of the brain.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a detection unit of an embodiment of the present invention, FIG. 2 is a block diagram showing the whole, FIGS. 3A and 3B are diagrams showing the arrangement of detection points, and FIG. 4A. B is a diagram showing a display example, and FIG. 5 is a diagram showing an isomagnetic field diagram of the brain. 1...Detection section, 1a...Dewar-11b...Detection coil, IC...Input coil, 1d...SQUI
D, 2...Magnetic flux lock circuit, 3...Amplifier, 4...
・A/D converter, 5.7.12...Memory, 6...
Data bus, 8.13... Monitor device, 9... Computer, 10... Interface circuit, 11.
...Data recorder, 14...Operation console, 15...Controller, 16...Stimulator.

Claims (1)

[Claims] (1) A detection means comprising a number of detection coils arranged at predetermined positions at the bottom of the cooling container, an input coil connected to each detection coil, and a number of SQUIDs magnetically coupled to each of these input coils; storage means for storing the positions of the detection coils; means for displaying the waveform of the detection signal from the detection means in correspondence with each detection coil position; and means for displaying a time cursor for each detection signal waveform; A biomagnetic measuring device comprising means for extracting a detection signal at a time specified by the time cursor.