JPH10211182A - Biological magnetic measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biological magnetic measuring instrument executing biological magnetic measurement with high precision even at the time of using a complicated image as stimulation by induced brain magnet. SOLUTION: Based on the display instruction of a prescribed image given from a collection control part 4 in advance of measuring, a personal computer 7 displays an image on a screen 9 through a projector 8. At this time, the luminance variation of the screen 9 is detected by a light trigger part 10 and a data collection unit 2 starts collection of biological magnetic data of a subject M by setting a detection signal outputted from the part 10 as a trigger. An arithmetic part 3 add-averages collected biological magnetic data by each displayed picture and analyses a magnetic field through the use of the data to execute the estimating arithmetic of a biological activity current source, which can be supposed to be generated by an image display at the subject M, to display the arithmetic result on a monitor 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring biomagnetism generated by a bioactivity current source in a subject, displaying the measured data, and displaying the measured data in the subject based on the measured data. The present invention relates to a biomagnetism measurement device for obtaining a biological activity current source.

[0002]

2. Description of the Related Art With the development of superconducting device technology in recent years, SQUIDs (Superconducting Quantum Interferen
A biomagnetic measurement device using a high-sensitivity magnetometer called ce Device) is being put to practical use as one of medical diagnostic devices.

Such a biomagnetism measuring device detects a weak magnetic field generated due to an electric phenomenon occurring in a living body and, based on the measured magnetic field data, uses a magnetic flux meter as a reference by, for example, a least square method or a minimum norm method. It estimates the position, orientation, and size of the biological activity current source using a coordinate system that is considered to be useful for elucidating brain functions and diagnosing cardiovascular diseases (Jukka Sarvas "Basic mathematical
and electromagnetic concepts of the biomagnetic in
verse problem ", Phys. Med. Biol., 1987, vol.32, No.
1, 11-22, Printed by the UK).

At present, two types of magnetic measurement methods, evoked brain magnetism and spontaneous brain magnetism, are used for clinical purposes in biomagnetism measurement. Spontaneous brain magnetism is a state in which there is no external stimulation or the like.
A magnetic field spontaneously generated in the subject, and the induced brain magnetic field is a magnetic field generated by a biological activity current source induced by a stimulus such as sound, electricity, or an image applied to the subject.

[0005] The induced magnetoencephalogram can be reproduced by repeatedly applying the same stimulus to the subject. Therefore, S / S is obtained by repeatedly applying tens to hundreds of stimuli and averaging the magnetic field data induced by the stimulus. N ratio can be improved,
In this regard, measurement with higher precision than spontaneous brain magnetism is possible.

Here, in the case of the induced magnetoencephalogram, when an induced magnetic field is measured using a stimulus by an image, various methods have been proposed as image display methods as shown below. (1) Vertical pattern on oscilloscope (grating pattern)
And displaying it to the subject through a mirror and measuring the induced magnetic field ((a) Brenner D, WilliamsonSJ, Kaufm
an L: Visually evoked magnetic fields of the hu
man brain. Science 190: 480-482, 1975).

(2) ON-OFF checkerboard pattern
To display to the subject and measure the evoked magnetic field ((b) Richer F, Barth DS, Beatty J: Neuromagneti
c localization of two components of the transient
visual evoked responseto patterned stimulation.N
uoro Cimento 2: 420-428, 1983. (c) Kouijzer WJJ, Sto
k CJ, Reits D, et al: Neuromagnetic fields evoked
by a pattern on-off set stimulus. IEEE Trans Bi
omed Eng. BME-32: 455-459, 1985. (d) Stok CJ: The inv
erse problem in EEG and MEG with application to vi
sual evoked responses.Doctor THesis, Rijksunive
rsiteit Leiden. 1986.).

(3) Method using pattern reversal to invert the checkerboard ((e) Ilimoneimi R, Ha
ri R, Reinikainen K: A four-channel SQUID magn
etometer for brain reserach.Elevtroenceph Clin
Neurophysiol 58: 467-473, 1984. ).

(4) A method of displaying images of several types of kanji and random dot patterns in random order and measuring the induced magnetoencephalogram for kanji ((f) M Kawakatsu, T Imada, M Kotani: Br)
inmagnetic fields to Kanji. Proceedings of the 11th Annual Meeting of the Japanese Society of Biomagnetism 9: 24, 1996).

(5) A method of displaying a total of 15 images of ten kinds of face photographs, two kinds of bird images, white circles, leaves, and globes in random order, and measuring the induced magnetoencephalogram for the face photograph ((g) J Miyamo
to, MKawakatsu, T Imada, et al: Neuromagnetic
fields for face stimulus and others. Proc. of the 11th Annual Meeting of the Japanese Society of Biomagnetism 9: 180-183, 1996. ).

In providing a stimulus to such an image or the like, in the conventional apparatus, a trigger for instructing the start of stimulus application is input to each stimulus application unit, and it is assumed that the input of the trigger is a stimulus application, and the trigger is used to generate biomagnetic data. Was started, and this was repeated several tens to several hundred times, and the results were averaged to perform a magnetic field analysis.

[0012]

When a sound or electric stimulus is used, the time lag between the start of the stimulus instruction and the actual stimulus application can be controlled within 1 msec. Even if the measurement is started, highly accurate measurement is possible. However, in the case of giving a stimulus by a complicated image, in addition to complicated control and arithmetic processing, it is necessary to replace an image to be displayed in accordance with a test content. So
A large time lag occurs between the time when the image display instruction is given to the stimulus applying unit and the time when the image is actually displayed.

For example, FIG. 6 is a time chart showing a trigger for instructing the stimulus application section to display an image, the collection of biomagnetic data, and the timing of actual image display. The resulting time lag has non-negligible values as shown at t1 to t3. Further, the time lag that occurs every time is not always constant due to the limitation on hardware performance and the use of a complicated OS (operating software) that can access a plurality of storage media from the application side without being particularly aware.

For this reason, in a conventional apparatus which starts collecting biomagnetic data by a trigger instructing the application of a stimulus,
When a complex image is used as a stimulus, the timing at which stimulus is applied and the timing at which biomagnetic data measured repeatedly are collected fluctuate each time, and when the averaging is performed, the measured waveform becomes dull, so that accurate magnetic field analysis becomes impossible.

The present invention has been made in order to solve these problems.
It is an object of the present invention to provide a biomagnetism measurement device capable of performing highly accurate biomagnetism measurement even when a complicated image is used.

[0016]

In order to achieve the above-mentioned object, the present invention measures the biomagnetism generated by a bioactive current source in the skull of a subject, and based on the obtained biomagnetic data. A biomagnetism measuring apparatus for diagnosing the subject, wherein image stimulating means for stimulating the subject with an image, and optical trigger means for generating a trigger signal by converting a change in brightness of a display image into a voltage. A magnetometer for measuring a cerebral magnetic field induced in a subject by a display image, a data collection unit for collecting biomagnetic data from the magnetometer in synchronization with the trigger signal, and collecting the collected biomagnetic data. Computing means for performing averaging for each display image.

The image stimulating means includes a personal computer for outputting a video signal for image display, a projector for inputting the video signal and projecting a predetermined image, and a screen mounted on the entire surface of the subject and displaying a projected image. And characterized in that:

[0018] The light trigger means is disposed opposite to the screen, and detects the brightness of the screen.

[0019] The arithmetic means is further adapted to perform an estimation calculation of a biological activity current source using the averaged data.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a biomagnetism measuring apparatus according to an embodiment of the present invention. In FIG. 1, a sensor unit 1 stores a plurality of high-sensitivity magnetometers S1 to Sm each including a pickup coil and a SQUID sensor together with a refrigerant inside a dewar, and approaches a head of the subject M prior to biomagnetic measurement. Be deployed.

The data collection unit 2 includes magnetometers S1 to S
A / D conversion is performed on the biomagnetic data generated in the subject M measured at m in synchronization with the trigger signal from the optical trigger unit 10,
Output to the arithmetic control unit 5.

The arithmetic control unit 5 performs an averaging operation on the biomagnetic data output from the data collection unit 2 for each image repeatedly displayed on the screen 9 and performs data processing for estimating a biological activity current source. The image processing unit 3 includes an arithmetic unit 3 for performing the operation and an acquisition control unit 4 for instructing the image stimulating unit 6 to display an image on the subject M. The arithmetic unit 3 has a predetermined memory for averaging the biomagnetic data output from the data collection unit 2.

The acquisition control unit 4 and the personal computer 7 in the image stimulating unit 6 are connected by a serial communication cable such as RS-232C, and information such as which image is to be displayed is instructed via this cable. . Of course, not only serial connection but also parallel connection may be used to indicate the type of image to be displayed.

The instruction information for image display output from the acquisition control unit 4 to the image stimulating unit 6 is also output to the arithmetic unit 3 at the same time, and the arithmetic unit 3 obtains the obtained biomagnetic data. Understand the type of image that causes
A separate addition process is performed for each type of image, such as magnetic field data for a human face photograph, magnetic field data for a landscape image, and the like, and a living activity current source is estimated. This makes it possible to estimate a life activity current source for each type of image.

The image stimulating unit 6 manages an image based on an instruction from the acquisition control unit 4 and outputs a video, a projector 8 that projects a display image output from the personal computer 7 as a video, and a projector 8 that projects the image. Screen 9.

A light trigger unit 10 is provided on a part of the screen 9. The light trigger unit 10 detects a change in luminance of a part of the screen 9, sends a trigger signal to the data collection unit 2, and performs sampling. Give instructions to start.

The light trigger section 10 is composed of a photodiode PD and an amplifier circuit connected thereto, as shown in FIG. 2B. The photodiode PD is, as shown in FIG. And a scintillator 10a covered by a portion other than the light detecting portion.

As shown in FIG. 3, when the luminance of the screen 9 changes, the terminals 10c, 1 of the photodiode PD change.
An electromotive force is generated during 0d, amplified by the amplifier circuit, and a trigger signal is output from the terminal V0.

In FIG. 1, a monitor 11 displays the magnetic field data averaged and averaged by the arithmetic unit 3 in the arithmetic control unit 5 and the biological activity current source.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG. 4 showing the operation of the arithmetic and control unit.

First, prior to measurement, the collection control unit 4 externally inputs initial conditions for measurement such as the order of displaying a plurality of images and the total number of repetitions (S1). It should be noted that various images may be displayed for the subject M depending on the examination, such as various combinations of landscape images and various combinations of shape patterns.

When the initial conditions are input, the collection control unit 4
Instructs the image stimulating unit 6 to display a predetermined image (S
2).

Next, the operation unit 3 includes the data collection unit 2
(S3), and performs a predetermined weighted addition with the previous averaged data stored in a predetermined memory (cleared at the start of the measurement), thereby performing an averaging operation. Perform (S4). Since addition to the memory is performed on the biomagnetic data obtained for each displayed image, the obtained biomagnetic data is simply written to the memory as it is for the first time.

When the averaging process is completed, if there is an image to be displayed next, the above-mentioned operations S2 to S4 are repeated (S5).

When all the images to be displayed are completed, the arithmetic unit 3 calculates a biological activity current source by performing a known processing such as a least square method from the averaging data stored in the memory (S6). The calculation result is displayed on the monitor 11 (S7).

The display of the biological activity current source on the monitor 11 is usually made by superimposing it on an MRI image of the subject M or the like.

With the above operation, as shown in FIG. 5, the collected biomagnetic data has no time lag from the time when the image is actually displayed. Even if the measurement waveform does not become dull, accurate magnetic field analysis can be performed.

In this embodiment, the brightness of the display image itself is detected in order to generate a trigger signal in the light trigger section. However, the present invention is not limited to this, and the image portion displayed on the subject M is not limited to this. A high-luminance portion may be provided at a position distant from the above, and the high-luminance portion may be detected by the light trigger unit.

In the present embodiment, the acquisition control unit instructs the display of an image. However, the present invention is not limited to this. The acquisition control unit is eliminated, and the display order and the total number of repetitions are directly input to the personal computer in the image stimulating unit. In addition, the personal computer may be self-propelled.

Further, in this embodiment, an example has been described in which the biological activity current source is obtained from the magnetic field data after the averaging, but the magnetic field data after the averaging may be simply displayed on the monitor.

[0042]

According to the present invention, in the visual evoked magnetic field measurement using the image stimulating device, even when the image stimulating device having a slow temporal response is used, the image display instruction from the acquisition control device and the actual image are displayed. The time lag between the displays can be almost eliminated, and highly accurate induced magnetic field measurement can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a biomagnetism measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic view of a light trigger unit according to the present invention.

FIG. 3 is an explanatory diagram of an operation of the light trigger means according to the present invention.

FIG. 4 is a flowchart showing the operation of the present invention.

FIG. 5 is a timing chart of an image stimulating unit and data collection according to an embodiment of the present invention.

FIG. 6 is a timing chart of an image stimulating unit and data collection according to a conventional method.

[Explanation of symbols]

 M subject S1 to Sm magnetometer 1 sensor unit 2 data collection unit 3 calculation unit 4 collection control unit 5 calculation control unit 6 image stimulating unit 7 personal computer 8 projector 9 screen 10 light trigger unit 11 monitor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsukasa Tomita 1 Shiwazu Works Sanjo Plant, Nishinokyo Kuwaharacho, Nakagyo-ku, Kyoto-shi

Claims (1)

[Claims] 1. A biomagnetism measuring apparatus for measuring biomagnetism generated with a bioactivity current source in a skull of a subject and diagnosing the subject based on obtained biomagnetic data. Image stimulating means for stimulating a sample with an image, light trigger means for converting a change in brightness of a display image into a voltage to generate a trigger signal, and a magnetometer for measuring a brain magnetic field induced in the subject by the display image. Data collecting means for collecting biomagnetic data from the magnetometer in synchronization with the trigger signal; andcalculating means for averaging the collected biomagnetic data for each display image. Biomagnetic measurement device.