JPH04354945A - Transmission medium for ultrasonic diagnosis and its manufacture - Google Patents

Abstract

PURPOSE:To provide a high-moisture transmission medium for ultrasonic diagno sis excellent in physical quality of self-flexibility, plasticity, softness and sticki ness while having excellent ultrasonic transmission. CONSTITUTION:A defoamed matter of a high water content hydrogel mainly composed of PVA having an excellent performance as transmission medium for ultrasonic diagnosis can be produced by a method wherein a high water content hydrogel composition with a total water content of >=40wt.% which, in short, is blended with 1-50wt.% of other additives is dissolved by heating into an aqueous solution of a polyvinyl alcohol having a saponification ratio of 95mol.% or more and an average polymerization degree of 1,500 or more, and is defoamed naturally or defoamed completely in vacuum, and then, injected into an optical container to be frozen below -10 deg.C. The other additives herein used are 1-10wt.% of polyvalent alcohol having 2-6 carbons, or saccharide such as sugar, carboxymethyl cellulose, sodium alginate, a viscosity imparting agent such as carrageenan or polysaccharide, for example, agar and a pigment is further contained therein.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to the head, thyroid gland, breast,
It relates to a transmission medium used as a medium for ultrasonic diagnosis of lymph nodes, digestive organs, etc.

0002

[Prior art] ■ Background Ultrasonic diagnostic technology in the medical field has already been developed since 1942.
It has been used for diagnostic purposes for about half a century since its development by USSIK, but in principle, it utilizes the difference in acoustic impedance inside the body, so the ultrasonic probe and the subject. If there is an air layer between the
Accurate inspection is not possible because strong reflected waves are generated at the interface with the air layer. For this reason, when carrying out ultrasonic examinations of breasts, necks, etc., which have particularly uneven surfaces on the subject's surface, it is necessary to compensate for the uneven surfaces and flatten them. Therefore, in conventional ultrasonic diagnosis, a water bag filled with degassed water is used as a transmission medium to couple the probe and the specimen surface.

[0003] Problems with the Prior Art However, the use of water bags has the disadvantage that the preparation of deaerated water is extremely complicated. Therefore, an ultrasonic transmission medium based on hydrocarbon paraffin that is easier to handle has been developed, and although it is now in a state of practical use.
There are problems in that a high temperature reaction is required during production, there are difficulties in mass production, and the price is high.

[0004] Furthermore, in Japanese Patent Publication No. 3-10371,
A transmission medium for ultrasound diagnosis has been described in which an aqueous solution of polyvinyl alcohol (hereinafter also referred to as "PVA") is frozen, molded, and dehydrated without melting, but this medium is opaque because it contains air bubbles, and Due to its high strength,
For example, it is unsuitable for applications that require greater plasticity, flexibility, etc., such as ultrasound diagnosis of the heart.

[0005]

[Problems to be Solved by the Invention] Therefore, the problem to be solved by the present invention is to have a material that has excellent ultrasonic transparency and is suitable for uses that require physical properties such as flexibility, plasticity, pliability, and adhesiveness. An object of the present invention is to provide a suitable high-moisture ultrasonic diagnostic transmission medium.

[0006]

[Means for Solving the Problems] ■ Overview In order to solve the above problems, the present invention provides a polyvinyl alcohol aqueous solution with a total water content of 40 mol % or more and a saponification rate of 95 mol % or more and an average polymerization degree of 1,500 or more. A transmission medium for ultrasonic diagnosis characterized by being a defoamed product of a hydrogel with a high water content of % by weight or more, and a polyvinyl alcohol aqueous solution having a saponification rate of 95 mol% or more and an average degree of polymerization of 1,500 or more, if necessary. A high water content hydrogel composition with a total water content of 40% by weight or more containing 1 to 50% by weight of a polyhydric alcohol having 2 to 6 carbon atoms or a saccharide such as sucrose is dissolved by heating and naturally defoamed while kept warm, or The gist of the present invention is a method for producing a transmission medium for ultrasonic diagnosis, which is characterized by completely defoaming under vacuum, then injecting into any container and freezing at -10°C or lower. The various elements constituting the invention will be explained below.

■ Polyvinyl alcohol (PVA) The degree of saponification (mol %) of PVA, which is the main component of the medium of the present invention, is
The average degree of polymerization is preferably 95% or more, preferably 97 to 99%, and the average degree of polymerization is 1,500 or more, preferably 1,700.
That's all.

[0008] Other additives In addition to the main component PVA, the medium of the present invention contains 1 to 50% by weight of a polyhydric alcohol having 2 to 6 carbon atoms, a sugar such as sucrose, or carboxymethyl cellulose, as a viscosity imparting agent.
Polysaccharides such as sodium alginate, carrageenan or agar can be included. Examples of suitable polyhydric alcohols include glycol, glycerin, propylene glycol, sorbitol, mannitol, and the like. Examples of sugars include sucrose, maltose, fructose, glucose, and lactose.

[0009] The above medium further contains 10 paraben compounds, such as methyl paraoxybenzoate, butyl paraoxybenzoate, propyl paraoxybenzoate, etc., which are approved by food additive and cosmetic raw material standards, as preservatives.
It is also possible to add about 0 ppm. Note that food coloring, flavoring, etc. may be added to increase the commercial value.

[0010] The medium of the present invention has approximately the same 80~
In order to obtain a hydrogel with a high water content of 90%, there is a certain limit to the total amount of the hydrogel, which further enhances the ultrasonic transmission characteristics.

[0011] Production To produce the medium of the present invention, 1 to 50% by weight of the other additives listed above are blended into an aqueous polyvinyl alcohol solution having a saponification rate of 95 mol% or more and an average degree of polymerization of 1,500 or more. The high water content hydrogel medium having a total water content of 40% by weight or more is heated and dissolved at around 80°C. After this solution is naturally defoamed while keeping warm or completely defoamed under vacuum, it is poured into any container and frozen at -10°C or below for 4 hours or more to form a gel with the desired elasticity. . At this time, even if the defoaming process is omitted, a somewhat elastic gel can be obtained, but
Even if the gel does not have any visible air bubbles, the tiny air bubbles within the gel strongly reflect the ultrasound beam during ultrasound diagnosis, resulting in an extremely unclear image. Therefore, defoaming is extremely important in achieving the purpose of the invention. For defoaming, refer to the above P.
This can be done naturally by simply heating and dissolving the VA-rich water-containing medium and keeping it warm at 70°C or higher for 3 hours or more, but the elastic gel body obtained by forced defoaming under vacuum and freezing and solidifying it It has extremely good permeability to sound waves and provides clear images.

[0012] The PVA content in the medium should be within a range where the water content is 40% by weight or more, and should be determined by appropriate adhesion to the skin, the size of the probe directly connected to the ultrasound diagnostic device, the target area of the subject, etc. It should be determined appropriately depending on the
When flexibility (flexibility) is required, a 7% by weight aqueous solution or more is optimal.

[0013]

[Function] The medium of the present invention has appropriate elasticity and plasticity, and can be closely attached to a target part of the body that has complex irregularities, and has excellent transparency to ultrasonic waves. Provides a clear measurement image regardless of the

[0014]

[Examples] Hereinafter, the embodiments and effects of the invention will be illustrated by Examples and Comparative Examples, but the examples are merely for illustration and do not mean any limitation or restriction on the idea of the invention.

Example 1 Commercially available PVA (saponification degree 98.5 mol%, average polymerization degree 175
0) in 2,000 g of water at a ratio of 7% by weight was heated to 80°C, kept warm at the same temperature for 1 hour, left to stand, and degassed. The gel-like material obtained by placing the container in a stainless steel container with a lid and freezing at -15°C for 10 hours to solidify was used as a transmission medium for ultrasonic diagnosis using Simarinic SDL310 manufactured by Shimadzu Corporation.
(Linear Convex Electronic Scanning Ultrasound Diagnostic System) The patient's abdomen was examined and a clear image was obtained.

Example 2 Commercially available PVA (saponification degree 99.0 mol%, average polymerization degree 2.0
00) powder 200g (10% by weight), glycerin 1
00g (5% by weight), methyl paraoxybenzoate 1g (
0.05wt%), and Blue No. 1 (food coloring) 0.00
After mixing 2g (0.0001wt%), 1,699% of water
g was added to make the total amount 2,000 g. After heating and dissolving this at 80°C, it was degassed using a vacuum pump, poured into a square plastic container with sides of 100 mm and thickness of 40 mm, covered with a lid, and frozen at -15°C for 10 hours. The test subject's neck was examined using the same ultrasonic diagnostic device as in Example 1, and the resulting gel-like substance was returned to room temperature. A great image was obtained.

Example 3 Commercially available PVA (saponification degree 99.0 mol%, average polymerization degree 2.0
00 ) powder 200g (10% by weight), 100g sucrose
(5% by weight), 1g of propyl paraoxybenzoate (0.
05% by weight) and Blue No. 1 0.002g (0.0001
% by weight), then add 1,660 g of water to make a total volume of about 2,000 g.
000g. This was heated to 80°C while stirring to completely dissolve it, and then degassed using a vacuum pump.
The mixture was poured into a plastic container with a diameter of 160 mm and a thickness of 10 mm, the lid was closed, and the mixture was frozen at -15°C for 10 hours. A clear image of the examiner's heart was obtained.

Example 4 Commercially available PVA (saponification degree 98.0 mol%, average polymerization degree 1.7
00 ) powder 450g (15% by weight), 150g sucrose
(5% by weight), 1.5g of propyl paraoxybenzoate (
0.05% by weight) dissolved in propylene glycol 60
g (2% by weight) and Blue No. 1 0.003g (0.00
After mixing 2,340 g of water to bring the total amount to 3,000 g, this was heated to 80°C while stirring to dissolve it, and then defoamed with a vacuum pump while still in the heated state. Next, the length is 170 mm, the width is 150 mm, and the depth is 150 mm.
Pour into a stainless steel container, close the lid, and heat at -15℃ for 15 minutes.
After freezing for a period of time, the resulting gel-like material was returned to room temperature, and the breast of the subject was examined using the same ultrasound diagnostic apparatus as in Example 1. As a result, a clear image was obtained.

Example 5 Commercially available PVA (saponification degree 99.0 mol%, average polymerization degree 1.7
00) powder, 60 g (3% by weight) of propylene glycol in which 1 g (0.05% by weight) of methyl paraoxybenzoate was dissolved, and Blue No. 1 0.
After mixing 002 g (0.0001% by weight), 1.74 g of water
Add 0g to bring the total amount to about 2,000g, and add 8.0g while stirring.
It was heated to 0°C to completely dissolve it. The resulting clear liquid was
After degassing with a vacuum pump, the diameter is 120 mm.
After pouring into a 15mm thick plastic container and closing the lid,
After freezing at -15°C for 15 hours and returning the frozen material to room temperature, the resulting gel-like substance was used to examine the subject's abdomen using the same ultrasound diagnostic device as in Example 1. As a result, a clear image was obtained. It was done.

Comparative Example 1 The same commercially available PVA as in Example 1 (saponification degree 98.5 mol%,
(average degree of polymerization 1,750) was dissolved in 2,000 g of water at a ratio of 7% by weight by heating to 80°C, and after being left at room temperature,
After freezing and solidifying at -15°C for 10 hours, the resulting gel-like substance was returned to room temperature.The abdomen of the subject was examined using the same ultrasound diagnostic equipment as in Example 1. As a result, the entire abdomen was cloudy. No images were obtained. The reason for this seems to be that the ultrasonic beam was reflected by microscopic bubbles in the gel-like substance.

Comparative Example 2 Commercially available PVA (saponification degree 97.0 mol%, average polymerization degree 2.0
00 ) powder to 200g (10% by weight) of water 1,800g (10% by weight)
After heating and dissolving at 80°C, 500g of the solution was placed in a polyethylene vat and frozen at -15°C for 10 hours. The frozen product was vacuum-dried for 5 hours to form a gel. 400 g of thawed product (dehydration rate: 20% by weight) was obtained.

Example 1 Using this gel-like substance as a transmission medium
As a result of breast examination using a similar ultrasound diagnostic device,
Because the air was not completely degassed, the overall image was unclear, making accurate inspection impossible.

Comparative Example 3 Commercially available PVA (saponification degree 88.0 mol%, average polymerization degree 1.7
Add 1,860 g of water to 140 g of powder of 50) to make a total amount of 2,000 g, heat to 80°C, dissolve and dissolve at -15°C.
When the gel substance was frozen for 10 hours and returned to room temperature, the resulting gel substance was too weak to withstand use.

Comparative Example 4 Commercially available PVA (saponification degree 98.5 mol%, average polymerization degree 1.0
00) powder was added with 1,800 g of water to make a total amount of 2,000 g, heated and dissolved in the same manner as in Comparative Example 3, frozen at -15°C for 10 hours, and then returned to room temperature. , it was not recognized as a gel-like substance and was not suitable for use.

[0025]

Effects of the Invention As explained above, the present invention provides a high-moisture ultraviolet material that has excellent ultrasonic transparency and is suitable for applications requiring physical properties such as flexibility, plasticity, pliability, and adhesiveness. By providing a transmission medium for ultrasound diagnostics, we can contribute to the improvement and rationalization of ultrasound diagnostic technology.

Claims (3)

[Claims] [Claim 1] Saponification rate of 95 mol% or more, average degree of polymerization 1
A transmission medium for ultrasonic diagnosis, characterized in that it is a defoamed product of a high water content hydrogel having a total water content of 40% by weight or more, the main component of which is an aqueous polyvinyl alcohol solution of 500 or more. 2. The polyvinyl alcohol aqueous solution contains 1 to 50% by weight of a polyhydric alcohol having 2 to 6 carbon atoms, a sugar such as sucrose, a polysaccharide such as carboxymethyl cellulose, sodium alginate, carrageenan, agar, etc. as a viscosity imparting agent. 2. The medium of claim 1, comprising an additive of. [Claim 3] Saponification rate of 95 mol% or more, average degree of polymerization 1
A high water content hydrogel composition with a total water content of 40% by weight or more, which is made by blending 1 to 50% by weight of other additives, if necessary, in a polyvinyl alcohol aqueous solution of 500 or more is dissolved by heating, and naturally defoamed while keeping it warm. A method for producing a transmission medium for ultrasonic diagnosis, which comprises completely degassing the medium under vacuum, then injecting the medium into an arbitrary container, and freezing at -10°C or lower.