JP3430256B2 - Animal head fixation device for magnetic resonance imaging - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to the use of MRI (Ma) for brain images of animal heads for research and development and veterinary diagnostic treatment.
(gnetic Resonance Imaging, Magnetic Resonance Imaging) The present invention relates to a device for fixing an animal head when photographing.

[0002]

2. Description of the Related Art The position of an area in the brain of an animal is described based on anatomical coordinates. The most practical and general anatomical coordinates can be determined from outside the body, and a representative example thereof is shown in FIG. A plane including a straight line y connecting the left and right ear canals 1R and 1L and the lower edges 3R and 3L of the orbit 2 (ear orbit lower edge plane U), and a plane orthogonal to the plane passing through the left and right centers of the head (median plane V), A plane that is orthogonal to both and includes the ear canals 1R and 1L (a coronal cross section W that includes the ear canals) is used as a reference plane. Therefore, the origin of the spatial coordinates is the left and right ear canals 1R, 1
It is the intersection O of the straight line y connecting L and the median plane V.

The position of the part in the brain is xmm from the origin of the coordinates.
If it is on the rostral side, it is expressed as Ax, and if it is on the xmm caudal side, it is expressed as Px (A
Stands for Anterior, P stands for Posterior), ymm from the median plane
If left and right are separated, it is represented as Ly (L is an abbreviation for lateral).
The coordinates on the horizontal plane of the brain can be expressed by the numerical values AP and L.
In order to represent the position on the coronal section, information in the height direction is necessary in addition to the value of L, but the height from the plane of the lower edge of the ear socket orbit is used (at this time, before the height value). To H (Horizont
abbreviation of al). ) There are animals that are supposed to be staggered, and animals that are supposed to be staggered in numbers (constant for each animal species).

The published brain charts are created based on the above anatomical coordinates. Also, stereotactic brain surgery will be performed according to the above anatomical coordinates using a head fixing device for surgery. Therefore, in order to utilize the captured MRI brain image, it is desired to match the obtained image with the anatomical coordinate system.

The principle of a method of fixing the head of an animal, for example, a monkey, will be described with reference to FIG. In the figure, 11 is an ear bar, 14 is an orbital lower edge fixing tool, and 8 is an upper jaw fixing tool. As the tip of the ear bar is inserted into the ear canal, the tip of the ear bar is conical and the center axis of the ear bar passes through the conical apex of the tip in order to match the center axis of the left and right ear canals with the center axis of the ear bar. . Note that the same reference numerals are used in the present specification to represent the same elements.

The plane U of the lower edge of the orbit is located in the left and right ear canals 1R, 1
Since it is determined by the axis passing through L and the lower edges 3R and 3L of the orbit, the head is fixed so that the left and right ear canals and the lower edge of the orbit are in the same plane. The procedure for immobilizing the animal's head is as follows. The left and right ear canals are fixed by a central axis of a rod (hereinafter, referred to as an ear bar) that sandwiches the left and right ear canals from the left and right, and the lower orbit lower edges 3R and 3L are pressed from above by the tip of the lower orbital edge fixing tool 14. Then, the upper jaw is pressed from below by the upper jaw fixing tool 8.

Crist Instrument Co., Inc. (MD, US
The animal head fixing device for MRI (hereinafter referred to as the head fixing device) sold by A) has a shaft-like hollow portion in the center axis of the ear bar, and is a substance (water, copper sulfate aqueous solution, which can be imaged by MRI). Oil, etc.) As a result, the positions of the ear canals 1R and 1L can be clearly seen even in the captured image. Figure 7
Schematic diagrams in which the brain is reconstructed based on the MRI image of the monkey brain fixed to this head fixing device and arranged on anatomical coordinates, (a) is a top view, (b) is the left side. The side view is shown. Since the hollow part of the ear bar 6 is photographed on the MRI image, the median plane V can be determined from the position information of the ear canal in the brain image and the morphology of the brain. The rotation information before and after the axis connecting the ear canals (see θ in FIG. 7B) is insufficient on the brain image.

Since there is no clue to determine the rotation information in the MRI image taken by using the head fixing device made by Crist Instrument Co., Inc., the brain image on the plane image passing through the central axis of the ear bar tip is taken. The plane U of the lower edge of the orbit of the ear canal was estimated from the conventional knowledge about the shape and the arrangement on the coordinates.

The cut surface U of the plane of the lower edge of the orbit of the ear canal shown in FIG.
The morphology of the brain on the MRI image at the cutting surface Ua in the vicinity of c and the vicinity thereof has very similar arrangements, and experience is required to select the correct arrangement from them. Also, even if there is a correct layout as a model, there is no guarantee that it is the correct layout for any individual. When the brain is arranged on the coordinates with the cut surface Ua in which the head is erroneously tilted backward as shown by the solid line in FIG. 7B as the plane of the lower edge of the orbit of the ear canal, there is an error from the correct arrangement (dotted line) in the periphery of the ear canal. Although it is small, it has a drawback that the error increases as the distance from it increases.

A method of fixing the head of the above conventional device will be described.
First, general anesthesia is applied to the animal to be imaged by MRI, and ear bar 6
Local anesthesia is applied in order to prevent pain and lowering of anesthesia level in the ear to be inserted. When fixing the head of the animal to the head fixing device, the two operators are located on the left and right of the crushed animal, the right operator holds the right auricle 4 with the left hand, and the right operator holds it with the right hand. Insert the tip of the ear bar 6 into the ear canal 1R.
The operator on the left holds the left auricle 4 with his right hand, and inserts the tip of the ear bar 6 into the ear canal 1L with his left hand. At this time, ear bar 6
In order to ensure the insertion of the ear, both ear operators insert the ear bar 6 into the ear canal from diagonally upper rear while pulling the pinna diagonally rearward. The operator attaches the ear bar to the ear bar fixing device of the head fixing device while fixing the head of the animal with the auricle and the ear bar.

The above method for attaching the ear bar 6 to the ear bar fixing device will be described with reference to FIG. In the figure, 9 is an ear bar fixing tool, 10 is a rail for fixing the ear bar fixing tool 9,
9b represents a fixing screw for fixing the ear bar fixing tool 9 to the rail 10. 6a is the tip of the ear bar 6, and 6c is an MRI-capable substance enclosed in a hollow portion provided so as to coincide with the central axis 6s of the ear bar tip. In this example, the ear bar fixing tool 9 is fixed below the left and right rails 10 (see FIG. 8C). To fix the ear bar 6 diagonally from below and rear, use the ear bar fixing tool 9
An opening 9a into which the member 6b of the ear bar is inserted is provided obliquely below and rearward.

The ear bar 6 is fixed obliquely from the lower rear side because the specifications of the surgical head fixing device in which various devices are mounted on the rail 9 are followed as they are. As a result, if a straight ear bar 6 is used, the head of the animal will be too low, so in order to prevent this, the shape of the ear bar 6 is made into a crank shape so that the portion (6a) entering the ear canal becomes higher. is there. (Fig. 6
(See (a))

[0013]

As a result, the conventional head fixing device for MRI has poor operability in two respects. First, since the ear bar has a crank shape, an unnatural force is required to pinch the pinna from the left and right. Second, in order to attach the ear bar diagonally from below and rear, the angle of the ear bar once inserted from diagonally above and rear must be changed. By combining these two points,
How to apply force for the surgeon's operation of the ear bar becomes very complicated. After temporarily fixing the ear bar to the fixture, adjust the left and right positions while pressing the ear bar against the animal to align the center line, but it is difficult to apply force also at this time. Even an operator who is skilled in using the surgical head fixing device needs more than a few minutes to fix it with the ear bar.

As described above, when the head of an animal is imaged by the MRI apparatus, a head fixing device for taking an image with reference to the plane of the lower edge of the orbit orbit, which is an anatomical reference plane, is commercially available. However, operability was poor due to the structure following the head fixing device for surgery, and the plane of the lower edge of the orbit orbit was not confirmed on the image.

[0015]

According to the present invention, the tip portion is left.
An animal head fixing device for magnetic resonance imaging for securely fixing the animal head to the plane of the lower edge of the orbit of the ear canal by means of the central axes of the left and right ear bars inserted into the right ear canal and the lower orbital margin fixing tool. , Eye
Fix the animal head by sandwiching the upper jaw with the inferior fossa rim fixture
This image and the image of the substance that can be photographed by the MRI device enclosed in the left and right ear bars by installing the substance that can be photographed by the MRI device on the upper jaw fixture and the plane of the lower edge of the orbit of the ear canal. In combination with and, the head fixing device is configured so that the plane of the lower edge of the orbit orbit on the image can be determined. This allows the captured MRI image to be reliably aligned with the anatomical coordinates.

Further, according to the present invention, the ear bar fixing device is fixed on the support, and the ear bar fixing device is provided with an opening obliquely rearward and upward, which is a direction for fixing the head of the animal, to fix the ear bar shaft. It is easy to insert and fix in a tool.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described with reference to the embodiments shown in FIGS. FIG. 1 shows a head fixing device of the present invention. In the figure, 11 is an ear bar, 12 is an ear bar fixture, 12b is a fixing screw for fixing the ear bar fixture to the rail 10, 13 is a screw for fixing the ear bar fixture 12 to the rail 9, and 14 is a lower orbital edge 3R, 3L. A lower orbital edge fixing tool fixed at a position where the tip ends face each other, 15 is an adjusting device that adjusts the lower orbital edge fixing tool corresponding to the lower orbital edge, and 16 is a tip of the lower orbital edge setting tool 14. An adjusting device for fixing the upper jaw fixing tool 8 at a position where the lower orbital edge 3 corresponds to the level, 1
Reference numeral 7 denotes an orbital fixing tool moving table that supports a lower orbital edge fixing tool and is movable in a direction perpendicular to the central axis 11s of the ear bar tip portion 11a, 18a is a head fixing apparatus main body supporting portion, and 18b is a head fixing apparatus main body horizontal. A plate, 19 is a fixing screw for movably fixing the orbital lower edge fixing tool moving table 17 to the fixing device supporting portion 18a, 20 is a reference object, 21 is a reference object fixing plate, 22 is a fixing screw, and 23 is a fixing device horizontal plate and support. It shows one of a plurality of horizontal level adjusting screws provided on the main body of the section.

Tip 11 of the conical tip of the two ear bars
The a is fixed on the same axis as the central axis 11s of the ear bar 11, and the plane including the central axis 11s and the tips 14a of the two lower orbital edge fixing devices 14 defines the lower surface of the orbital orbital edge U. The head leveling device main body horizontal plate 18b and the ear canal orbit lower edge plane U are set substantially horizontal to the gantry portion by the horizontal level adjusting screw 23. The head fixing device main body supporting portion 18a supports the rail 10, the lower orbital edge fixing device moving table 17, and the reference object fixing plate 21, and the lower corner portion is easily inserted into the cylindrical gantry portion of the MRI apparatus. It is rounded.

[0019] With the rostral head of the anesthetized animal facing the right side of Fig. 1 (in front of the head fixing device), two ear bars 11
11a are inserted into the left and right ear canals 11R and 11L, respectively, and sandwiched so that the central axis 11s and the straight line y passing through the left and right ear canals coincide. Shaft member 11b of ear bar 11
A graduation 11d is struck on this, and the median plane V of the head can be fixed to the vertical center of the head fixing device by matching the numerical values of the left and right graduations. Next, the adjusting device 15 is adjusted so that the lower edge of the orbit is in a position where the lower edge of the orbital edge is in contact with the tip portion 14a of the lower edge of the orbital fixing tool 14, the lower orbital edge fixing tool moving table 17 is moved, and the fixing screw 19 fixes To do. Finally,
The lower edge of the orbit is clamped from above by the lower orbital edge fixing tool 14, the upper jaw is clamped from below by the upper jaw fixing tool 8, and the upper jaw fixing tool 8 is fixed by the fixing screw 16, and the head is fixed. In this way, the head of the animal can be fixed to the head fixing device in accordance with the anatomical coordinates with respect to the plane of the lower edge of the ear socket orbit U.

A hollow portion 11c along the central axis 11s at the tip of the ear bar 11 is filled with a substance capable of capturing an MRI image. The reference object 20 is the central axis 1 of the tip 11a of the ear bar.
It is arranged so that it can be two-dimensionally moved within a plane U of the orbit lower edge of the ear canal, which is determined by Is and the tip 14a of the lower orbital edge fixing tool 14. The reference object 20 is a structure containing a substance that can be clearly photographed by an MRI apparatus enclosed in a hollow portion having a planar shape in a non-magnetic member. The outer shape of the reference object 20 and the two-dimensional shape of the hollow portion do not matter. In the example of FIG. 1, the hollow portion 2
Reference numeral 0a denotes a planar triangular structure included in the lower plane of the orbital orbit, but has a planar U-shaped structure and one or a plurality of planar small circular structures arranged in the planar U. In other words, when the encapsulated substance is photographed, the size of the plane figure of the hollow portion needs to be a size that allows MRI imaging, that is, a size that does not leak from MRI sampling.

FIG. 2 schematically shows a left side view of a brain arranged on anatomical coordinates based on an MRI image of a monkey head taken by using the head fixing device of the present invention. . The substance enclosed in the hollow portion (planar shape) 20a of the reference object 20 and the substance enclosed in the distal end hollow portions 11c of the left and right ear bars 11 are photographed together with the ear canal and the brain. The plane U of the lower edge of the ear socket orbit is reliably determined based on the two enclosed images. (Actually, as will be described later, a plane on which the left and right earbar images 31 and 32 and the hollow image 33 of the reference object are reflected is selected as shown in FIG. 4, and this plane is defined as a plane U of the orbit orbit lower edge.) , The brain image can be correctly arranged on the anatomical coordinates based on the plane U of the lower edge of the orbit.

The reference object 20 can be installed on the median line (intersection line with the median surface) x on the plane O of the orbit orbital lower edge, but basically it can be set to either the left or the right. Also has a side effect of being able to confirm the left and right sides of a symmetrical brain image on the image.

FIG. 3 is a diagram for explaining a method of fixing the ear bar 11 according to the present invention. The ear bar 11 has a linear shape (FIG. 3 (a)), and is structured to be fixed to the ear bar fixing tool 12 by an opening 12a obliquely above and rearward (FIG. 3).
Because of (c) and (d), the animal head can be easily fixed.

In the present invention, the ear bar fixing tool 12 is fixedly installed on the left and right rails 10 by, for example, fixing screws 12b (FIG. 3 (c)), and the shaft member 11b of the linear ear bar 11 is slanted from the upper rear side. An opening 12a for insertion is provided. The opening 12a connects the member 11b to the opening 1
When inserting and fixing to 2a (see FIG. 3), the tips 11a of the left and right ear bars are on the same shaft 11s.
It is configured so that 1 s is perpendicular to the rail. MR
Since no other device is attached to the rail in the I device, there is no problem. Reference numeral 11c is a substance that can be photographed by MRI and is enclosed in the hollow portion on the ear bar shaft 11s.

Since the ear bar 11 of the present invention has a linear shape (similar to that for surgery), it can be pushed straight in the axial direction to pinch the ear canal. Further, since the inserting direction of the ear bar 11 into the ear canal 1L, 1R of the animal and the attaching direction to the head fixing device are both obliquely from the upper rear side, the operator holds the pinna 4 and the ear bar The ear bar 11 can be temporarily fixed to the device by the continuous operation of inserting the ear bar 11. A scale 11d is struck in the axial direction (straight y direction) of the member 11b inserted into the ear bar fixing tool 12. By matching the scales of the left and right ear bars, the tip 11a of the ear bar is aligned.
The position of the intermediate point of can be the origin O of the coordinates. Since the ear bar 11 is linear, the left and right position adjustments are easy. The shaft member 11b of the ear bar 11 is fixed by pressing the fixing screw 13 (see FIG. 3D). Ear bar 1
The time required for animal immobilization with 1 is within 30 seconds. As described above, due to the improvement of the ear bar fixing method, the operability of the present invention is dramatically improved as compared with the existing device.

FIG. 4 shows an example of an MRI tomographic reconstructed image including the plane of the lower edge of the orbit of the ear canal, which is obtained by photographing the animal head using the head fixing apparatus of the present invention. Reference numerals 31 and 32 are images of the end hollow portion encapsulation material 11c of the left and right ear bars 11, and 33 is an image of the reference object hollow portion encapsulation material 20a. Image 31,
Since all 32 and 33 are included, the MRI image in FIG. 4 can be confirmed as an image including the plane O of the lower edge of the ear socket orbit. The straight line 34 passing through the central axes of the hollow-portion-encapsulating material images 31 and 32 at the tip of the ear bar is the anatomical coordinate line y (FIG. 5). A line 35 passing through the center of and perpendicular to the straight line 34 is the median line x. The intersection 36 of these lines is the origin O of the anatomical coordinates. Further, it can be seen from the direction of the triangle of the image 33 of the reference object 20 that the upper side of FIG. 4 is the rostral head and the left side is the left side of the head.

[0027]

EFFECTS OF THE INVENTION By allowing MRI to photograph a flat reference object placed on the center axis of the ear bar and the plane of the lower edge of the ear socket orbit, it is possible to confirm the lower edge plane of the ear hole orbit by MRI. The location in the brain can be confirmed by the position. The shape of the ear bar and the fixing direction to the main body are fixed in the direction of fixing the animal head to the head fixing device, and the operability is dramatically improved.

By using the device of the present invention, the plane of the lower edge of the orbit orbit can be confirmed on the image, so that the obtained image can be easily compared with the brain chart, and more accurate research and development and animal Can be treated.

The reference object can be placed on the median line (intersecting line with the median surface) on the plane of the lower edge of the orbit of the ear canal,
By shifting to the left or right, there is basically a side effect that the left and right of the symmetrical brain image can be confirmed on the image.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a head fixing device for MRI of the present invention.

FIG. 2 is a diagram for explaining the arrangement on the anatomical coordinates of the brain obtained based on the MRI image of the head captured by using the head fixing device of the present invention.

FIG. 3 is a diagram illustrating a method of fixing an ear bar according to the present invention.

FIG. 4 is an MRI tomographic reconstructed image including a plane U of the inferior orbit of the ear canal obtained by imaging the head of a monkey using the head fixing device of the present invention.

FIG. 5 is a diagram illustrating anatomical coordinates.

FIG. 6 is a diagram illustrating a principle of fixing an animal head according to anatomical coordinates.

FIG. 7 is a head M photographed using a conventional head fixing device.
It is a figure explaining arrangement | positioning on the anatomical coordinate of the brain calculated | required based on RI image.

FIG. 8 is a diagram illustrating a conventional ear bar fixing method.

[Explanation of symbols]

11 ear bars 11a Ear bar tip 11c hollow ear bar 11d Ear bar scale 12 Ear bar fixings 14 Infraorbital rim fixture 14a Lower orbital rim fixture tip 20 Standard 20a Reference part hollow part 31, 32 Image of the enclosed substance in the hollow part of the ear bar 33 Image of reference substance hollow part encapsulation material U Ear hole Orbital lower plane O Origin of anatomical coordinates

Front page continuation (56) References JP-A-8-150129 (JP, A) JP-A-60-58127 (JP, A) JP-B-4-50010 (JP, B2) (58) Fields investigated (Int .Cl. ⁷ , DB name) A61B 5/055 A61D 3/00

Claims (2)

(57) [Claims] 1. An animal head fixing device for magnetic resonance imaging for fixing the animal head to the plane of the lower orbital margin of the ear canal by means of the central axes of the left and right ear bars and the lower orbital edge fixing device for inserting the tip into the left and right ear canals. , Lower orbital rim fixture with upper jaw sandwiched between animals
An upper jaw fixing tool for fixing the head, a reference object installed in the same plane as the lower plane of the orbit orbit and the central axes of the left and right ear bars are provided with objects that can be imaged by nuclear magnetic resonance imaging. Animal head fixing device for magnetic resonance imaging. 2. A fixed on a support, comprising a ear bar fixture having an opening that opens upward obliquely in the direction of fixing the animal head unit, the oblique shaft member ear bar into the opening of the ear bar fixture A contract characterized by being inserted and fixed from above and behind
The animal head fixing device for magnetic resonance imaging according to claim 1 .