JP3726421B2 - Bioactive current source display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a life activity current source display device that displays the position, orientation, and size of a life activity current source, and more particularly to a life activity current source display device that can accurately display the position of a life activity current source. .
[0002]
[Prior art]
When a living body is stimulated, the polarization formed across the cell membrane breaks and a biological activity current flows. This bioactive current appears in the brain and heart and is recorded as an electroencephalogram or an electrocardiogram. The magnetic field generated by the bioactive current is recorded as a magnetoencephalogram or magnetocardiogram.
[0003]
In recent years, a multi-channel SQUID sensor using a SQUID (Superconducting Quantum Interference Device) has been developed as a device for measuring a minute magnetic field in a living body. This multi-channel SQUID sensor is placed outside the head, which is a region of interest of the subject, for example, and a micro magnetic field generated by a current dipole (hereinafter referred to as a “current source”) that is a bioactive current source generated in the brain. Non-invasive measurement can be performed with a multi-channel SQUID sensor. The position, orientation, and size of the current source of the region of interest of the subject are estimated from the measured magnetic field data. One of the current source estimation methods is a method using the minimum norm method (for example, WHKullmann, KDJandt, K. Rehm, HASchlitt, WJDallas and WESmith, Advances in Biomagnetism, pp.571-574, Plenum Pless, New York, 1989).
[0004]
The current source estimated by such a method is displayed on the tomographic image of the region of interest of the subject, which is a part of the three-dimensional shape information obtained by the MRI apparatus or the like, so that the region of interest of the subject is The position of the current source can be specified. Therefore, it is important to accurately grasp the positional relationship between the position of the current source in the three-dimensional coordinate system based on the multi-channel SQUID sensor and the three-dimensional form information obtained by the MRI apparatus or the like.
[0005]
Therefore, conventionally, the following method has been used as a method for obtaining the position on the tomographic image of the bioactive current source in the three-dimensional coordinate system based on the multi-channel SQUID sensor.
[0006]
First, a plurality of index points are determined on the region of interest of the subject. For example, in the diagnosis of the head, which is a region of interest of a subject, three index points are the center point of both eyebrows and the base of both ears. Here, the position of each index point in a three-dimensional coordinate system based on the multi-channel SQUID sensor is obtained. As shown in FIG. 6, conventionally, this position is specified by attaching a small coil, which is a marker, to each index point of a subject, and using a multi-channel SQUID sensor to generate a magnetic field generated by sequentially passing a current through each small coil. measure. From the measured magnetic field data, the position coordinates of each small coil in the three-dimensional coordinate system based on the multi-channel SQUID sensor, that is, the index point can be specified.
[0007]
Next, a procedure for grasping the position of the small coil on the conventional MRI image will be described with reference to FIGS. First, in a state where the small coils 3a, 3b, and 3c are attached to the site of interest of the subject M, the head that is the site of interest of the subject M is imaged by the MRI apparatus. The tomographic images 31, 32, and 33 including the small coils 3a to 3c obtained by this imaging are displayed on the divided screens 30a, 30b, and 30c of the monitor screen 30, respectively. In the divided screens 30a to 30c, the entire cross-sectional images 31 to 33 of the head that is the region of interest are displayed. The operator positions the small coils 3a to 3c on the divided screens 30a to 30c in the order in which the coordinate points on the small coils 3a to 3c are determined using an input device such as a mouse while viewing the monitor screen 30 ( For example, the first is the small coil 3a between the eyebrows, the second is the small coil 3b below the left ear, and the third is the small coil 3c below the right ear.
[0008]
When this designation is made, the mouse cursor 2 on the monitor screen 30 is operated and clicked at a position considered to be near the center of the small coils 3a to 3c (the operation of momentarily pressing a button mounted on the mouse is clicked. "). The clicked position is designated as the position of the small coils 3a to 3c, that is, the coordinate point in the three-dimensional form information obtained by the MRI apparatus or the like. The mouse cursor 2 freely moves on the monitor screen 30 in conjunction with a mouse operation (not shown).
[0009]
By superimposing the coordinate points of the small coils 3a to 3c and the position coordinates of the small coils of the three-dimensional coordinate system based on the previous multi-SQUID sensor, the position of the current source on the three-dimensional form information, That is, the position of the bioactive current source on the tomographic image of the region of interest of the subject M can be grasped.
[0010]
[Problems to be solved by the invention]
However, the conventional example having such a configuration has the following problems.
In the method of designating the index point by observing the screen on which the entire tomographic image of the region of interest of the subject is displayed, the image area of the displayed marker portion is small. That is, since the size of the mouse cursor is not suitable for the area of the displayed marker image portion, the mouse cursor cannot be accurately brought near the center of the marker. Here, if the size of the mouse cursor is reduced, it becomes difficult to operate the mouse cursor. Furthermore, even if the user clicks near the center of the marker, the position is greatly deviated from the vicinity of the center of the marker. For example, if the tomographic image of the head is displayed with a size of 1/10 of the actual tomographic image, if the clicked position is shifted by 1 mm on the screen from the vicinity of the center of the marker, the actual position is It will shift by 10 mm.
[0011]
Thus, when the position coordinate of the coordinate system based on the multi-channel SQUID sensor is superimposed on the coordinate point on the three-dimensional shape information designated at the shifted position, the position of the current source displayed on the tomographic image Is also displayed with a deviation from the original position of the current source.
[0012]
The present invention has been made in view of such circumstances, and provides a bioactive current source display device capable of accurately displaying the position of a bioactive current source on a tomographic image of a region of interest of a subject. The purpose is to do.
[0013]
[Means for Solving the Problems]
In order to achieve such an object, the present invention has the following configuration.
That is, according to the present invention, a marker is attached to a plurality of index points set in a region of interest of a subject, and a magnetic field generated from the marker is measured by a magnetic sensor disposed close to the region of interest of the subject. The position of the marker in a three-dimensional coordinate system with the magnetic sensor as a reference is specified, the minute magnetic field generated from the current source of the region of interest of the subject is measured, and the measurement magnetic field obtained by this measurement A tomographic image including each marker in the three-dimensional morphological information obtained by estimating a current source based on the data and imaging the region of interest of the subject to which the plurality of markers are attached with an image imaging device. The coordinate point in the three-dimensional morphological information on the marker image part included in the tomographic image is specified, and the specified coordinate point and the position coordinate of the specified marker are overlapped, thereby In the bioactive current source display device that displays the current source superimposed on the layer image, (a) storage means for storing the three-dimensional form information, and (b) three-dimensional information stored in the storage means A display device for displaying a plurality of tomographic images as morphological information; (c) an instruction means for specifying an arbitrary range and arbitrary coordinates on the image displayed on the display device; and (d) an instruction by the instruction means. Image processing means for enlarging and displaying the partial image including the marker image on the tomographic image, and specifying the coordinate point of each marker using the instruction means on the enlarged and displayed partial image. It is characterized by that.
[0014]
[Action]
The operation of the present invention is as follows.
A magnetic sensor generates a magnetic field generated from a plurality of markers in a region of interest of the subject, and specifies the position coordinates of the marker in a three-dimensional coordinate system with reference to the magnetic sensor. In a state where a plurality of markers are attached to the region of interest of the subject, three-dimensional shape information obtained by imaging using an image imaging device is stored in a storage means. A magnetic field from the current source of the region of interest of the subject is measured by the magnetic sensor, and the current source is estimated based on the measured magnetic field data. A tomographic image including each marker stored in the storage means is displayed on a display device. The image processing means enlarges and displays the partial image including the marker portion on the tomographic image designated by using the instruction means on the calling display device from the storage means. A coordinate point is designated near the center of the marker portion of the enlarged partial image using the instruction means. Then, the position of the current source on the tomographic image of the region of interest of the subject is grasped by superimposing the designated coordinate point and the position coordinate of the marker specified by the measurement of the magnetic field.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the schematic configuration and processing procedure of the bioactive current source estimation apparatus according to the embodiment will be described with reference to FIGS. In this embodiment, the current source is estimated with the region of interest of the subject as the head. In the figure, reference numeral 1 denotes a multi-channel SQUID sensor. The multi-channel SQUID sensor 1 is disposed outside the head of the subject M. The multi-channel SQUID sensor 1 is configured by storing a large number of magnetic sensors S _{1 to} S _{m (} not shown) immersed in a refrigerant in a dewar 1a. The multi-channel SQUID sensor 1 and the subject M are disposed in the magnetic shield room 15.
[0016]
Hereinafter, it will be described in detail with reference to the flowchart of FIG.
First, an index point is determined on the head of the subject M. In this embodiment, the center points of both eyebrows of the head and the bases of both ears are set as index points. Small markers 3a, 3b, and 3c (hereinafter referred to as “each small coil”) as markers are respectively attached to the index points. Although each small coil is shown in the drawing, it is sufficient if two or more coordinate systems are aligned, and the number of small coils is not limited to three.
[0017]
Each small coil is configured to be supplied with current individually from the current supply control unit 7. The current supply control unit 7 sequentially supplies currents one by one to each small coil, and the magnetic field generated from each small coil is measured by the multichannel SQUID sensor 1. The magnetic field measurement data from each small coil is converted into digital data by the data converter 4 and then sent to the data processor 9 via the data collector 5. (Step S1)
[0018]
On the other hand, an electrical stimulus (or sound, light stimulus, etc.) is given to the subject M from the stimulator 6. Due to this stimulation, a micro magnetic field generated by a bioactive current source generated in the brain of the subject M is also measured by the multichannel SQUID sensor 1. The measurement data is converted into digital data by the data conversion unit 4 and then collected in the data collection unit 5. Based on the measured magnetic field data of the current source collected in the data collection unit 5, the current source estimation unit 8 uses the method using a minimum norm method or the like to determine the position, orientation, and size of the current source of the region of interest of the subject M. Etc. This estimated current source is represented by a coordinate system based on the multi-channel SQUID sensor.
[0019]
The data processing unit 9 obtains the position coordinates of each small coil by the least square method or the like. For example, a case where there are n small coils will be described with reference to the flowchart of FIG. For example, the position of the k-th small coil (k is a natural number indicating the k-th of 1 to n small coils) first virtually determines the initial position of the small coil (step T2). Next, virtual virtual magnetic field data is calculated by calculation when it is assumed that the multichannel SQUID sensor has measured the magnetic field from the small coil at the virtually determined position (step T3). A square error between the data obtained by this calculation and the measured measurement data actually measured from the kth small coil by the multichannel SQUID sensor is obtained (step T4). The virtual position of the kth small coil is moved in the direction in which the square error is reduced (step T5). If the square error is equal to or less than the predetermined end determination value, the position is set as the position of the kth small coil. On the other hand, if the square error is larger than the end determination value, the processes in steps T3 to T5 are performed. Repeat (step T6). In this way, the position of the i-th small coil is obtained, and similarly, the positions of all the small coils are obtained (steps T1, T7, T8). The position of each small coil obtained in this way is a position coordinate in a three-dimensional coordinate system based on the multichannel SQUID sensor. (Step S2).
[0020]
Here, with the small coils attached, a magneto-optical disk which is a storage means for the three-dimensional form information of the region of interest obtained by imaging the region of interest of the subject M with the MRI apparatus which is an image capturing device 13 is stored. The storage means is not limited to a magneto-optical disk, and may be any medium that can store information. For example, a semiconductor memory or a magnetic tape may be used. This three-dimensional form information is composed of a plurality of tomographic images as indicated by a two-dot chain line in FIG. 6, and the images are represented by a three-dimensional coordinate system. The tomographic images 31, 32, and 33 in which the small coils 3a, 3b, and 3c are captured from the three-dimensional form information stored in the magneto-optical disk 13 are displayed on the color monitor 10 that is a display device. Reference numeral 20 shown in FIG. 4 indicates a monitor screen of the color monitor 10. On the monitor screen 20, tomographic images 31 to 33 and a mouse cursor 2 are displayed on the divided screens 20a to 20d. (Step S3)
[0021]
FIG. 5 is an enlarged view of the split screen 20 a of the monitor screen 20. In FIG. 5, the range including the small coil 3a is designated as follows. First, the operator operates the mouse cursor 2 on the monitor screen 20 that is linked to the operation of the mouse 12 as the instruction means while observing the monitor screen 20. For example, the range of the chain line portion 40 can be specified by moving the mouse cursor 2 along the diagonal line of the range to be specified while pressing a button arranged on the mouse 12. You can also specify a range by clicking on two diagonal points. Here, by clicking this button and pressing the button of the mouse 12 on the tomographic image, the coordinate point on the tomographic image is designated. The image processing means of the present invention calls the tomographic image corresponding to the designated range from the magneto-optical disk 13 and displays it on the divided screen 20d shown in FIG. The image displayed on the divided screen 20d is in a state in which the image is enlarged and displayed as compared with the divided screens other than the divided screen 20d. (Step S4)
[0022]
While looking at the divided screen 20d, the operator moves the mouse cursor 2 and clicks near the center of the small coil 3a. By this click, one coordinate point near the center of the small coil 3a is designated (step S5). Steps S4 to S5 are performed for all small coils. The small coil coordinate points are designated in a predetermined order. For example, the first designated coordinate point is determined as a small coil 3a between the eyebrows, the second is the small coil 3b with the left ear, and the third is the small coil 3c with the left ear. Are performed in this order. (Step S6)
[0023]
In the three-dimensional configuration information for all small coils, the coordinate points for the small coils 3a, 3b, and 3c are superimposed on the three-dimensional position coordinates based on the multi-channel SQUID sensor of the small coils 3a, 3b, and 3c previously identified. Match. Here, since the coordinate points of each small coil are specified in a predetermined order, they are superimposed on the corresponding position coordinates, so that the position of the current source on the three-dimensional form information is specified. A tomographic image including this current source is output to the color monitor 10 and the color printer 11. (Step S7)
[0024]
【The invention's effect】
As is apparent from the above description, according to the present invention, magnetic fields from a plurality of markers attached to a region of interest of a subject are measured in advance using a magnetic sensor. On the other hand, the magnetic field from the current source of the region of interest of the subject is measured. From these measurement magnetic field data, the position coordinates of the marker in the coordinate system based on the magnetic sensor and the current source of the region of interest of the subject are obtained. Next, an arbitrary range including a marker portion on the tomographic image of the region of interest of the subject is designated using an instruction unit. The image in the designated range is an enlarged image compared to the image before the designation. Since coordinate points based on three-dimensional morphological information are specified for the marker part on the enlarged image, the coordinate point closer to the center of the marker is specified than when the conventional image range is not specified. can do. By superimposing the marker coordinate point in the three-dimensional form information and the marker position coordinate specified from the previous measurement magnetic field data, the position of the current source with respect to the tomographic image of the region of interest of the subject can be accurately specified. it can.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an embodiment of a bioactive current source display device according to this embodiment.
FIG. 2 is a flowchart illustrating a processing procedure according to the embodiment.
FIG. 3 is a flowchart showing a process performed in step S2 of FIG.
FIG. 4 is a schematic diagram illustrating a monitor screen according to the embodiment.
5 is an enlarged view of a split screen of the monitor screen of FIG.
FIG. 6 is a schematic diagram illustrating three-dimensional form information according to the embodiment.
FIG. 7 is a schematic diagram showing a monitor screen screen of a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Multichannel SQUID sensor 2 ... Mouse cursor 9 ... Data processing part 10 ... Color monitor 12 ... Mouse 13 ... Magneto-optical disk 20 ... Monitor screens 31-33 ... Tomographic images 3a-3c ... Small coil

Claims (1)

A marker is attached to a plurality of index points set in a region of interest of the subject, and a magnetic field generated from the marker is measured by a magnetic sensor disposed in proximity to the region of interest of the subject. The position coordinate of the marker in the three-dimensional coordinate system is specified, the minute magnetic field generated from the current source of the region of interest of the subject is measured, and the current source is determined based on the measured magnetic field data obtained by this measurement. Using the tomographic image including each marker in the three-dimensional morphological information obtained by estimating and imaging the region of interest of the subject on which the plurality of markers are mounted by an image imaging device, the tomographic image The coordinate point in the three-dimensional morphological information on the marker image part included in is specified, and the specified coordinate point and the position coordinate of the specified marker are overlapped, thereby the current on the tomographic image of the region of interest. source In the bioactive current source display device that displays in a superimposed manner, (a) storage means for storing the three-dimensional shape information, and (b) a plurality of tomographic images that are three-dimensional shape information stored in the storage means (C) instruction means for designating an arbitrary range and arbitrary coordinates on the image displayed on the display apparatus, and (d) a marker on the tomographic image designated by the instruction means An image processing means for enlarging and displaying a partial image including an image, and the coordinate point of each marker is designated on the enlarged partial image using the instruction means Current source display device.

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