JPH06178774A - Contact medium for ultrasonic diagnosis - Google Patents

Abstract

PURPOSE:To provide a contact medium for ultrasonic diagnosis that satisfies the characteristics required for the contact medium, and is excellent in safety, physical strength, and transparency, and also that is easy in handling. CONSTITUTION:A contact medium for ultrasonic diagnosis is such a solid contact medium that includes (a) matrix polymer obtained by copolymerizing polymerized vinyl monomer consisting of 1 to 25wt.% of a hydroxyalkyl (meta) acrylate, 1 to 25wt.% of an N-vinyllactam, and 1 to 25wt.% of an alkylene glycol (meth)acrylate, (b) 0.1 to 6wt.%. of an alignic acid salt, and (c) to 97wt.%. of water, and in which the alignic acid salt has been substituted by polyvalent metallic salt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact medium for ultrasonic diagnosis, and more particularly to a solid contact medium used by being interposed between a probe and an inspection surface (living tissue) during ultrasonic diagnosis. Is.

[0002]

2. Description of the Related Art In ultrasonic diagnosis, a probe is brought into contact with an inspection surface (living tissue), and ultrasonic waves are emitted from the probe in a direction perpendicular to the inspection surface or in an oblique angle direction to detect the inside of the living body. I'm observing the situation. In this case, if air exists between the probe and the inspection surface, the transmission of ultrasonic waves deteriorates. Therefore, conventionally, a contact medium such as jelly is applied to the inspection surface, and the space between the probe and the inspection surface is conventionally reduced. Had eliminated the air.

However, the jelly has drawbacks such that when it is used for a long time, water evaporates to deteriorate the ultrasonic wave transmission efficiency, and it is difficult to thicken the layer of the contact medium if necessary.

On the other hand, polyvinyl alcohol-based hydrogel (JP-A-62-298342) and crosslinked hydrogel of polyvinyl alcohol-polyvinylpyrrolidone copolymer (55th Japan Sonic Medicine Association, pp. 703) has been published, and JP-A-63-302834 discloses a water-retaining molded article obtained by crosslinking an acrylate with a water-soluble polyfunctional vinyl monomer. Proposed.

[0005]

The properties required of the contact medium are that the conduction efficiency of ultrasonic waves is high and does not affect the image (specifically, the acoustic impedance is the impedance of the living body).
Close to (1.5 × 106 kg / m ² · s) with low attenuation of ultrasonic waves), it is a dry solid that is hard to dry, has high stability against sweating and temperature, and causes skin allergies. However, it is highly safe and has no foul odor.

However, in the conventional contact medium,
There are drawbacks such as (a) stains on clothes because they are sticky, (b) it takes time to wipe them off, (c) viscosity changes due to body temperature, and drips (cold flow). It was

An object of the present invention is to provide a contact medium for ultrasonic diagnosis which satisfies the above-mentioned properties required for the contact medium, and in particular, is excellent in safety, and has excellent physical strength and transparency. Another object of the present invention is to provide a contact medium for ultrasonic diagnosis, which is an easy contact medium and has a small attenuation of ultrasonic waves, and thus can obtain good image characteristics in ultrasonic diagnosis.

[0008]

The ultrasonic diagnostic contact medium of the present invention which achieves the above object is (a) hydroxyalkyl (meth) acrylate 1 to 25% by weight, N-vinyllactam 1 to 25% by weight. And a matrix polymer obtained by copolymerizing a polymerizable vinyl monomer consisting of 1 to 25% by weight of alkylene glycol (meth) acrylate, (b) alginate: 0.1 to 6% by weight and (c) water: 60 to 97% by weight. It is a solid-state ultrasonic diagnostic contact medium characterized by containing.

[0009]

[Detailed Description of the Invention]

(A) Matrix Polymer In the contact medium of the present invention, the matrix polymer, which is the matrix of the contact medium and forms the connecting phase, is composed of three polymerizable vinyl monomers, namely hydroxyalkyl (meth) acrylate, N-vinyllactam and alkylene glycol ( It is a copolymer of (meth) acrylate. Each of these polymerizable vinyl monomers is a monomer having a CH ₂ = CR- group (wherein R represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms) in the molecule, and is obtained by addition polymerization. Form a polymer.

Here, "(meth) acrylic acid" and "(meth) acrylate" are "acrylic acid and methacrylic acid" and "acrylate and methacrylate", respectively.
Means any of the above.

The hydroxyalkyl (meth) acrylate preferably has 2 to 4 carbon atoms in the alkyl group.
And those having one hydroxyalkyl group are preferred. Specific examples thereof include hydroxyethyl ester and hydroxypropyl ester of (meth) acrylic acid.

Examples of the alkylene glycol (meth) acrylate include ethylene glycol (meth) acrylate, diethylene glycol (meth) acrylate, triethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate (average molecular weight of about 200 to 2,000), Dipropylene glycol (meth) acrylate, tripropylene glycol (meth)
Acrylate, polypropylene glycol (meth) acrylate (average molecular weight about 300 to 3,000), polyalkylene glycol (meth) acrylate (ethylene oxide / propylene oxide block copolymer, average molecular weight about 200 to 3,000), methoxypolyethylene glycol (meth) acrylate (Average molecular weight 200 to 3,000) Ethoxy polyethylene glycol (meth) acrylate (average molecular weight 200 to 2,000), propoxy polyethylene glycol (meth) acrylate (average molecular weight
200-2,000), phenoxy polyethylene glycol (meth) acrylate (average molecular weight 300-2,000), methoxy polypropylene glycol (meth) acrylate (average molecular weight 250-3,000), ethoxy polypropylene glycol (meth) acrylate (average molecular weight 250- About 3,000).

Examples of the N-vinyllactam include N-vinylpyrrolidone and N-vinylpiperidone.

The matrix polymer of the component (a) can be obtained by copolymerizing three kinds of such polymerizable vinyl monomers with a polymerization initiator. As the polymerization initiator, those usually used for the polymerization of vinyl monomers can be used, for example, benzoyl peroxide,
Such as cumene hydroperoxide, peroxides such as t-butylperoxy-2-ethylhexanoate, azo compounds such as 2,2-azobis (2-aminodinopropane) dihydrochloride, azobisisobutyronitrile Radical polymerization initiator, light (U
V) A polymerization initiator and the like can be mentioned. As the polymerization method, for example, a thermal polymerization method under an inert gas atmosphere or an ultraviolet irradiation method can be used.

(B) Alginate As the alginate, there can be mentioned alginic acid metal salts, alkaline earth metal salts, aluminum salts, transition metal salts, ammonium salts and the like. Specifically, sodium alginate, potassium alginate, magnesium alginate, ammonium alginate, calcium alginate, zinc alginate, aluminum alginate, copper alginate, manganese alginate, iron alginate, cobalt alginate, nickel alginate, platinum alginate, uranium alginate, chromium alginate, etc. And at least one or more of these are used.

The alginate is preferably a polyvalent metal salt of alginic acid in the finally obtained contact medium. By making the alginate a polyvalent metal salt, the physical strength of the obtained contact medium is improved. In that case, it is not necessary to convert all of the alginate salt into a polyvalent metal salt, and the flexibility of the contact medium obtained by adjusting the concentration of the polyvalent metal salt can be adjusted.

(C) Solvent As the solvent used in the present invention, water is used because it has excellent ultrasonic conduction characteristics.

(Blending ratio) The blending ratio of the matrix polymer of the component (a) is 3 to 40% by weight, preferably 5 to 30% by weight based on the total amount of the components (a), (b) and (c).
% By weight. If the matrix polymer exceeds 40% by weight, the water content of the contact medium may decrease, and the ultrasonic conduction efficiency may deteriorate, and if it is less than 3% by weight, the gel may have poor mechanical strength, causing a problem in handling. May be.

The hydroxyalkyl (meth) acrylate compounding ratio in the matrix polymer is as follows:
1 to 25 based on the total amount standard of the components (b) and (c)
% By weight, preferably 2 to 12% by weight, more preferably 3 to
10% by weight. The blending ratio of N-vinyllactam is 1 to the total amount of the components (a), (b) and (c).
25% by weight, preferably 2-16% by weight, more preferably 5
~ 14% by weight. The mixing ratio of the alkylene glycol (meth) acrylate is (a) component, (b) component and (c).
1 to 25% by weight, based on the total amount of components, preferably 2
.About.12% by weight, more preferably 3 to 8% by weight.

The mixing ratio of the alginate as the component (b) is
It is 0.1 to 6% by weight, preferably 0.3 to 2% by weight.
If the amount of alginate exceeds 6% by weight, the gel cross-linking density becomes high when the alginate is changed to a polyvalent metal salt, so the water content may decrease and the ultrasonic transmission efficiency may deteriorate. If it is less than wt%, the gel will have poor mechanical strength, and it may not be possible to obtain a contact medium that is easy to handle.

The compounding ratio of the solvent as the component (c) is 60 to 97% by weight, preferably 80 to 95% by weight.

By blending the components (a), (b) and (c) in this way, the ultrasonic wave transmission efficiency is high, the flexibility and flexibility are high, and the transparency and physical strength are high. It is possible to obtain a contact medium which is excellent in handling and easy to handle.

(Production of Ultrasonic Contact Medium) The ultrasonic contact medium of the present invention can be produced, for example, by polymerizing a polymerizable vinyl monomer in the presence of alginate and water.

That is, a water-soluble alginate is dissolved in water, a degassed uniform aqueous solution of alginate and a liquid in which a polymerizable vinyl monomer is dissolved are mixed, and a polymerization initiator is further added.

This uniform solution is formed into a film or the like by a casting method or a casting method, and the temperature is 50 to 80 ° C. in an inert gas atmosphere.
The polymerizable vinyl monomer is polymerized by heating or by irradiating light (for example, UV). Further, the polymer can be further immersed in an aqueous solution of a polyvalent metal salt to replace the alginate with the polyvalent metal salt of alginic acid.

The polymer using a water-soluble alginate is an extremely flexible contact medium and has an extremely high adhesiveness, but its physical strength is weak, and it is immersed in an aqueous solution of a water-soluble salt of a polyvalent metal to form alginic acid. By converting to a polyvalent metal salt, alginic acid can be gelated in the medium matrix to obtain a solid contact medium with improved physical strength.

As another production method, there is a method of previously polymerizing a polymerizable vinyl monomer in the presence of water to synthesize a solid matrix polymer, and then incorporating an alginate in the polymer.

Specifically, first, a polymerizable vinyl monomer is dissolved in water, and a uniform solution containing a radical polymerization initiator is formed into a film-like material by a casting method or a casting method,
In an inert gas atmosphere, heat at 50-80 ° C for 4-16 hours,
A solid polymer is synthesized.

Next, the solid polymer is dipped in an aqueous solution containing alginate to contain the alginate in the medium. Further, this can be immersed in a polyvalent metal salt aqueous solution to replace the alginate with a polyvalent metal salt of alginic acid.

[0030]

The following examples serve to further illustrate the invention. These examples do not limit the scope of the invention.

The physical properties in the following examples were measured by the following methods.

(1) Moisture content (%)

[Formula 1]

(2) Physical strength (2-1) Scratch resistance When the sample surface is reciprocated 100 times with a wet gauze with a load of 100 g / cm ³ , the sample is observed for abnormal appearance such as cracks. (2-2) A rod with a bending resistance of 8 mmφ is applied to the center line of the sample, and the appearance abnormality is observed when the rod is folded back 180 degrees around the center. The X mark in the evaluation is
In the scratch resistance test, the surface blisters with a few reciprocations of gauze,
In the flex resistance test, cracks were found.

(3) Transparency When observed by the naked eye, the one that was almost colorless and transparent was marked with ◯, and the one that formed a white gel and became cloudy was marked with x.

(4) Acoustic impedance: z (kg / m ² · s) Using the method of measuring the ultrasonic transmission / reception signal in water, the reception side signal of the ultrasonic wave (measuring frequency: 5 MHz) transmitted through the medium is measured. The sound velocity v (m / s) of the medium is measured from the change in arrival time (Δt) and the thickness of the sample, and this and the density ρ (g / cm ³ ) of the medium are measured.
From the following equation,

[Equation 2] The acoustic impedance was calculated using z = ρ · v.

(5) Ultrasonic attenuation rate: α (dB / cm) The same samples having different thicknesses were used, and the ultrasonic attenuation rate was determined from the gradient with the output sensitivity (dB).

Example 1 1.4 g of sodium alginate (manufactured by Kimitsu Chemical Industry Co., Ltd.) in pure water 15
It was dissolved in 8.9 g and degassed to obtain a uniform aqueous solution.

Separately, hydroxyethyl methacrylate (hereinafter abbreviated as HEMA) 11.9 g, N-vinyl-2-pyrrolidone (hereinafter abbreviated as NVP) 15.9 g, and methoxy polyethylene glycol methacrylate (Shin Nakamura Chemical Co., Ltd., NK Ester M-230G, abbreviated as MPEGM hereinafter) 11.
9 g of the monomer mixture was added and mixed to prepare a uniform monomer mixture solution, which was then added and mixed with the sodium alginate aqueous solution to form a uniform solution.

Next, 2,2-azobis (2-
Amidinopropane) dihydrochloride (manufactured by Wako Pure Chemical Industries, hereinafter, V-50
Abbreviated) was added and mixed to form a uniform solution.

A part of this solution, 150 g, was poured into a polypropylene container (internal dimensions: length 950 mm x width 62 mm x height 52 mm), and the polypropylene container was placed in a vacuum dryer, and the inside was filled with nitrogen gas. After substituting with, the polymerization was carried out at 55 ° C. for 8 hours while slightly flowing nitrogen gas to obtain a soft polymer.

Next, the medium was taken out from the polypropylene container and immersed in a 1.0 wt% calcium chloride aqueous solution for 48 hours to prepare an ultrasonic diagnostic contact medium in which the sodium salt of alginic acid was replaced with a calcium salt.

The obtained contact medium was transparent, elastic, flexible and rich in flexibility, had good adhesion to a living body, and was extremely easy to handle.

With respect to the obtained contact medium, various physical properties and ultrasonic conduction characteristics (sound velocity at a measurement frequency of 5 MHz, acoustic impedance, ultrasonic attenuation factor) were measured. The results are shown in Table 1.

Example 2 8.0 g of HEMA as a polymerizable vinyl monomer, 23.8 g of NVP,
An ultrasonic diagnostic contact medium was obtained in the same manner as in Example 1, except that 8.0 g of MPEGM was used. The obtained contact medium was transparent, elastic, flexible and rich in flexibility, had good adhesion to a living body, and was extremely easy to handle. Table 1 shows the measurement results of the physical properties of the obtained contact medium.

Example 3 An ultrasonic diagnostic contact medium was obtained in the same manner as in Example 1 except that HEMA 8.0 g, NVP 8.0 g, and MPEGM 23.8 g were used as the polymerizable vinyl monomer. The obtained contact medium was transparent, elastic, flexible and rich in flexibility, had good adhesion to a living body, and was extremely easy to handle. Table 1 shows the measurement results of the physical properties of the obtained contact medium.

Example 4 An ultrasonic diagnostic contact medium was obtained in the same manner as in Example 1 except that 31.8 g of HEMA, 4.0 g of NVP and 4.0 g of MPEGM were used as the polymerizable vinyl monomer. The obtained contact medium was transparent, elastic, flexible and rich in flexibility, had good adhesion to a living body, and was extremely easy to handle. Table 1 shows the measurement results of the physical properties of the obtained contact medium.

Example 5 An ultrasonic diagnostic contact medium was obtained in the same manner as in Example 1 except that 11.9 g of hydroxyethyl acrylate (HEA), 15.9 g of NVP and 11.9 g of MPEGM were used as the polymerizable vinyl monomer. The obtained contact medium was transparent, elastic, flexible and rich in flexibility, had good adhesion to a living body, and was extremely easy to handle. Table 1 shows the measurement results of the physical properties of the obtained contact medium.

Example 6 HEMA 11.9 g, NVP 15.9 g as a polymerizable vinyl monomer,
A contact medium for ultrasonic diagnosis was obtained in the same manner as in Example 1 except that 11.9 g of MPEGM (NK ester M-90G) was used. The obtained contact medium was transparent, elastic, flexible and rich in flexibility, had good adhesion to a living body, and was extremely easy to handle. Table 1 shows the measurement results of the physical properties of the obtained contact medium.

Comparative Examples 1 to 3 A contact medium was produced in the same manner as in Example 1 except that the polymerizable vinyl monomer was changed to the two-component drink shown in Table 1. As shown in Table 1, the obtained contact medium was inferior in physical strength and transparency.

[0050]

[Table 1]

[0051]

Since the contact medium of the present invention thus obtained is a solid medium in which an alginate is contained together with water in a non-crosslinking type matrix polymer, the following effects are exhibited.

Since the contact medium has a high ultrasonic wave conduction efficiency and a small attenuation of the ultrasonic wave, good image characteristics can be obtained in ultrasonic diagnosis, and it is particularly suitable as a contact medium for high frequency ultrasonic diagnosis. It is a smooth solid, fits well in the living body, and slides well with the probe. Since it has excellent physical strength and good shape retention, it is easy to handle and maintain. It is highly safe against living organisms and highly safe against sweating and temperature changes. Due to its excellent transparency, the condition of the surface to be inspected can be observed during diagnosis.

Claims (2)

[Claims] 1. (a) Hydroxyalkyl (meth) acrylate 1 to 25% by weight, N-vinyllactam 1 to 25% by weight
And alkylene glycol (meth) acrylate 1 to 25
A matrix polymer obtained by copolymerizing a polymerizable vinyl monomer in an amount of 1% by weight, (b) 0.1 to 6% by weight of alginate, and (c) 60 to 97% by weight of water. Contact medium for sonic diagnostics. 2. The ultrasonic contact medium according to claim 1, wherein the alginate is a polyvalent metal salt of alginic acid.