JP2002308802A - Ultrasonic scattering material, method for manufacturing the same and contrast medium for ultrasonic diagnosis - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an ultrasonic scattering material having a narrow particle size distribution and high signal intensity. SOLUTION: In the method for manufacturing the ultrasonic scattering material, air is introduced into a shell material-containing liquid to perform air-liquid mixing by a micromixer to prepare air-containing particles with a mean particle size of 0.01-10 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an ultrasonic scatterer and a method for manufacturing the same. In particular, the present invention relates to an ultrasonic scatterer useful as a contrast agent for ultrasonic diagnosis and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, ultrasonic diagnosis has remarkably developed in the diagnosis of the thoracic region and the abdominal region due to its characteristic of obtaining blood flow information. In particular, ultrasonic imaging using a contrast agent has been developed, and more accurate blood flow information has been obtained. In these ultrasonic contrasts, a microbubble contrast agent in which a number of microbubbles having a diameter of 1 μm to several μm are mixed in a liquid is used. Microbubbles are harmless gases for living organisms,
It is enclosed in a shell made of a substance harmless to the living body. In addition, the use of Doppler signals and harmonic signals has advanced in the ultrasonic imaging apparatus, and it has become possible to acquire more tissue and blood flow information. In particular, blood flow dynamics have been more accurately evaluated in combination with ultrasonic imaging.

[0003] Many contrast agents for ultrasonic diagnostics are on the market or in clinical trials. For example, Echovist
^R , Levovist ^R (Shering AG), Imagent ^R (Alliancs Phar
^{mceutical Corp.), Optison TM (} Molecular Biosystems,
^{Inc.), EchoGen TM (SONUS} Pharmaceutical, Inc.), Sonaz
oid ^TM (Nucomed Amersham plc), Definity ^TM (DuPont Ph
^{armaceutical Co.), SonoVue TM (} Bracco Diagnostics In
c.), Quantison ^™ (Quadrant Healthcare plc) and the like. These contrast agents are microbubbles in which air or perfluorocarbon gas is wrapped around a surfactant or a polymer compound to stabilize bubbles having a particle size of several μm.

[0004] Also, there are many articles on ultrasonic contrast agents (E. Leen, medicalmudi, 43 (3), 17p (1999); Nico de
Jong and Folkert J. Ten Cate, Ultrasonics, 34, 587p
(1996); PJAFrinking et al, J. Acoust. Soc, 105
(3), 1989p (1999), PJAFrinking and Nico de Jon
g, J. Acoust. Soc, 105 (3), 1989p (1999), PADayton
et al, IEE Trans. Ultrason., 46 (1), 220p (1999),
A. Bouakaz and KK Shung, 1999 IEEE Ultrasonics Sympo
sium, 1963p) and patents (US Patent 5,855,86)
No. 5, No. 6,080,386, No. 5, 9
No. 48,387, Japanese Patent Application Laid-Open No. 10-505900, Japanese Patent Application Laid-Open No. 2000-501745, and Japanese Patent Application Laid-Open No. 2000-501745.
No. 52047, JP-T-2000-506122, etc.).

[0005] It is known that the ultrasonic scattering intensity of the ultrasonic contrast agent increases as the particle size increases, but if the particle size is too large, the risk of blocking capillaries such as the lungs increases. For this reason, it is a practical method to increase the signal intensity if the diameter is large enough not to occlude the capillaries and the particle size is monodisperse. However, there is a problem that the particle diameter distribution cannot be narrowed because the gas-liquid cannot be uniformly mixed by the conventional method.

[0006]

SUMMARY OF THE INVENTION In view of these problems of the prior art, an object of the present invention is to provide an ultrasonic scatterer having a narrow particle size distribution and a high signal intensity, and a method of manufacturing the same. . Another object of the present invention is to provide an ultrasonic scatterer having a narrow particle size distribution and a high signal intensity and a contrast agent for ultrasonic diagnosis.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a gas is introduced into a liquid containing a shell material and mixed by a micromixer to obtain an average particle diameter of 0.01 μm to 10 μm. It has been found that according to the production method of the present invention for preparing gas-containing particles of the present invention, it is possible to provide an ultrasonic scatterer exhibiting expected effects. In the production method of the present invention,
It is preferable to use a phospholipid dispersion as the shell material-containing liquid, and it is particularly preferable to use a phospholipid dispersion having an average particle size of 0.01 μm to 5 μm. Further, such a phospholipid dispersion is preferably prepared by dispersing with a high-pressure homogenizer.

In the present invention, the average particle size is from 0.01 μm to
An ultrasonic scatterer having a thickness of 10 μm and a degree of dispersion of 50% or less is also provided. Furthermore, there is provided a contrast agent for ultrasonic diagnosis, which comprises the ultrasonic scatterer of the present invention.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an ultrasonic scatterer of the present invention, a method for producing the same, and a contrast agent for ultrasonic diagnosis will be described in detail. In this specification, “to” means a range including the numerical values described before and after it as a minimum value and a maximum value, respectively.

In the method for producing an ultrasonic scatterer of the present invention, gas-liquid mixing is performed by a micromixer while introducing a gas into a liquid containing a shell material, and the average particle diameter is 0.01 μm to 1 μm.
This is to produce an ultrasonic scatterer composed of 0 μm gas-containing particles.

The gases used in the production method of the present invention include:
Hydrogen; nitrous oxide; inert gas (such as helium, argon, xenon or krypton); sulfur fluoride (sulfur hexafluoride, disulfur defluoride, trifluoromethylsulfur pentane) Selenium hexafluoride; optionally halogenated silanes (such as tetramethylsilane); low molecular weight hydrocarbons, such as alkanes containing up to 7 carbon atoms (methane, ethane, propane, butane, pentane, etc.) ), Cycloalkanes (eg, cyclobutane, cyclopentane), alkenes (eg, propene, butene), or alkynes (eg, acetylene); ethers; ketones; esters; Or a mixture of any of the above compounds. Advantageously, at least some of the halogen atoms of the halogenated gas are fluorine atoms. Thus, biocompatible halogenated hydrocarbon gases include, for example, bromochlorodifluoromethane, chlorodifluoromethane, dichlorodifluoromethane, bromotrifluoromethane, chlorotrifluoromethane, chloropentafluoroethane,
Dichlorotetrafluoroethane and perfluorocarbons such as perfluoroalkanes (perfluoro-n- which is a mixture with perfluoromethane, perfluoroethane, perfluoropropane, perfluorobutane and optionally other isomers such as perfluoroisobutane)
Butane, perfluoropentane, perfluorohexane, perfluoroheptane, etc.); perfluoroalkene (perfluoropropene, perfluorobutene (eg, perfluorobutane-2-ene), perfluorobutadiene, etc.); perfluoroalkyne (perfluoro Butan-2-yne and the like; and perfluorocycloalkanes (perfluorocyclobutane, perfluoromethylcyclobutane, perfluorodimethylcyclobutane, perfluorotrimethylcyclobutane, perfluorocyclopentane, perfluoromethylcyclopentane, perfluorodimethylcyclopentane, Perfluorocyclohexane, perfluoromethylcyclohexane, perfluorocycloheptane, etc.). Other halogenated gases include fluorinated, eg, perfluorinated ketones (eg, perfluoroacetone), and fluorinated, eg, perfluorinated ethers (eg, perfluorodiethyl ether). Particularly preferably, the gas is a perfluoroalkane, especially perfluoropropane, perfluorobutane, perfluoropentane or perfluorohexane.

The shell material used in the production method of the present invention is preferably used for stabilizing gas. The shell material that can be used in the present invention may be any of a surfactant, a natural or synthetic polymer compound, an amphiphilic substance, and the like. The one that does not coagulate blood by contact is more preferable, and the one that is biodegradable is particularly preferable.

The following are specific examples of the shell material, but the shell material that can be used in the present invention is not limited to these. Phospholipids (lecithin, dipalmitoylphosphatidylcholine,
Sodium dipalmitoyl phosphatidylate, dipalmitoyl phosphatidylethanolamine polyethylene glycol ether), higher carboxylic acids (lauric acid, sodium laurate, palmitic acid, potassium palmitate, stearic acid, arachidic acid, behenic acid, etc.), Higher alcohols (such as stearyl alcohol and palmitoyl alcohol) and higher amines (such as stearylamine) are exemplified. High molecular compounds include natural high molecular compounds (gelatin, collagen, albumin, chitosan, agar, silk fibroin, starch, cellulose, dextran, etc.), chemically modified natural high polymers (acetylated gelatin, phthalated gelatin, enzyme-degraded low molecular gelatin) , Hydroxypropylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, etc.), synthetic polymer compounds (polylactic acid, polylactic acid butyric acid copolymer, polyvinyl alcohol, polyethylene glycol, polyethylene glycol propylene glycol copolymer, urea resin, nylon, polyacrylic) Acid polyethylene glycol ester), anionic surfactant (sodium dodecyl sulfonate, diisobutyl sulfosuccinate, sodium dodecylbenzene sulfonate) Etc.), nonionic surfactant (low molecular weight polyethylene glycol, nonylphenol polyethylene glycol,
Low molecular weight polyethylene glycol propylene glycol copolymer, alkyl-modified saccharides, etc.), cationic surfactants, fluorinated surfactants and the like. These may be used alone or in combination of two or more. In the present invention, the shell material is preferably stabilized by crosslinking, denaturation, or the like, and the method may be any means such as chemical reaction, heat, ultraviolet irradiation, and radiation irradiation.

The kind of the dispersion medium (solvent) of the shell material-containing liquid is not particularly limited as long as it can disperse or dissolve the shell material and form particles containing the gas when the gas is introduced. Not restricted. About the concentration of the shell material in the shell material-containing liquid and the means for introducing gas,
It can be appropriately determined according to a commonly used method for producing an ultrasonic scatterer.

In the production method of the present invention, gas-liquid mixing is performed by a micromixer while introducing gas into the liquid containing the shell material. Hereinafter, the mixing principle of the micro mixer according to the present invention will be described. Most micromixers use a laminar mixing method because the flow path is small,
Many of them do not promote mixing by a stirring flow. The mixing method of the micro mixer is classified as follows.
1) contact of two sub-streams (T-type arrangement); 2) creation of a large contact area formed by collision and spraying of two sub-streams having high energy; 3) generation of a large number of small sub-streams composed of one component. Injection into the main stream composed of other components, 4) Injection of many substreams composed of two-component system, 5) Reduction of diffusion distance in the direction perpendicular to the flow direction due to increase in flow velocity, 6) Multi-branch splitting and re-flow Coupling, 7) mass transfer forced by external force, 8) periodic injection of microfluidic segments, 9) mixed type of 1-8). The mixing method and specific technical contents of these micromixers are described in "Microreactor" (W. Ehrfeld, V. Hessel, H. et al.
Lowe, 1Ed. (2000), WILEY-VCH).

The micromixer used in the present invention comprises:
This is an apparatus having a channel having an equivalent diameter of 1 mm or less. In the present invention, equivalent diameter (equivalent diameter)
r) is also called the equivalent (straight) diameter, and is a term used in the field of mechanical engineering. When an equivalent circular pipe is assumed for a pipe having an arbitrary cross-sectional shape (a flow path in the present invention), the diameter of the equivalent circular pipe is referred to as an equivalent diameter, A: sectional area of the pipe, p: wet length of the pipe. Eq = 4A / p using (perimeter)
Is defined as When applied to a pipe, this equivalent diameter corresponds to the pipe diameter. The equivalent diameter is used to estimate the flow or heat transfer characteristics of the pipe based on the data of the equivalent circular pipe, and represents the spatial scale (representative length) of the phenomenon. The equivalent diameter is eq = 4a for a square tube with one side a.
² / 4a = a, for an equilateral triangular tube with side a

(Equation 1) In the flow between the parallel flat plates having a road height h, eq = 2h (refer to “Encyclopedia of Mechanical Engineering” edited by The Japan Society of Mechanical Engineers, 199).
7 years, Maruzen Co., Ltd.).

In the present invention, the flow path is formed on a solid substrate by a fine processing technique. Examples of materials used include metals, silicon, Teflon, glass,
Ceramics or plastics. When heat resistance, pressure resistance and solvent resistance are required, preferred materials are metals,
Silicon, Teflon, glass or ceramics, and particularly preferably metal. To give an example of metal,
Nickel, aluminum, silver, gold, platinum, tantalum, stainless steel, hastelloy (Ni-Fe alloy) or titanium is preferable, and stainless steel, hastelloy or titanium having high corrosion resistance is preferable.

In a conventional batch type reaction apparatus, an apparatus in which a metal (such as stainless steel) is lined with glass is used when handling an acidic substance or the like. However, a glass coating may be performed on the metal surface with a microreactor. Depending on the purpose, not limited to glass, a metal may be coated with another metal or another material, or a material other than metal (for example, ceramic) may be coated with metal or glass.

A typical example of a fine processing technique for producing a flow path is L using X-ray lithography.
IGA technology, high aspect ratio photolithography using EPON SU-8, micro electric discharge machining (μ-E
DM), Deep RIE silicon high aspect ratio processing, Hot Emboss processing, stereolithography,
There are laser processing, ion beam processing, and mechanical micro-cutting using a micro tool made of a hard material such as diamond. These techniques may be used alone or in combination. A preferred microfabrication technique is LI using X-ray lithography.
GA technology, high aspect ratio photolithography using EPON SU-8, micro electric discharge machining (μ-ED
M), and a mechanical micro-cutting method.

When assembling a micromixer, a joining technique is often used. Conventional joining techniques can be broadly divided into solid-phase joining and liquid-phase joining. Commonly used joining methods are pressure welding and diffusion joining as solid-phase joining, welding, eutectic joining, soldering as liquid-phase joining. Adhesion and the like are typical joining methods. Furthermore, when assembling, it is desirable to use a high-precision bonding method that maintains dimensional accuracy without destruction of microstructures such as flow paths due to material deterioration or large deformation due to high-temperature heating. Examples include anodic bonding, surface activation bonding, direct bonding using hydrogen bonding, bonding using an HF aqueous solution, Au-Si eutectic bonding, and void-free bonding.

The channel of the micromixer may be subjected to a surface treatment according to the purpose. In particular, when an aqueous solution is operated, surface treatment is important because adsorption of a sample to glass or silicon may be a problem. For fluid control in micro-sized channels, it is desirable to achieve this without incorporating moving parts that require complex fabrication processes. For example, it becomes possible to create a hydrophilic region and a hydrophobic region in a flow path by surface treatment, and to operate a fluid by utilizing a surface tension difference acting on the boundary.

The equivalent diameter of the flow path used in the present invention is 1 m
m, preferably 10 μm to 500 μm, particularly preferably 20 μm to 300 μm. The length of the flow path is not particularly limited, but is preferably 1 mm to
1000 mm, particularly preferably 10 mm to 500 mm
mm. It is not necessary that the number of channels used in the present invention is only one, but any number of channels may be parallelized (numbering-up) as needed to increase the number of processing channels. In the present invention, the reaction is performed while flowing in the flow channel, that is, in a flow.

A fluid control function is required for introducing and mixing a reagent, a sample, and the like into a micro-sized channel of a micromixer. In particular, the behavior of the fluid in the micro area has different properties from the macro scale,
A control method suitable for the micro-scale must be considered. The fluid control method is classified into a continuous flow method and a liquid drop (liquid plug) method when classified into forms, and is classified into an electric drive method and a pressure drive method when classified into a driving force.

These methods will be described in detail below. The most widely used form of handling fluid is the continuous flow method. In the continuous flow type fluid control, it is general that the entire flow path of the microreactor is filled with fluid, and the entire fluid is driven by a pressure source such as a syringe pump provided outside. In this case, one advantage is that a control system can be realized with a relatively simple setup. However, operation involving multiple steps of reaction and sample exchange is difficult, and the degree of freedom of the system configuration is small. Since the medium is the solution itself, there is a problem in that the dead volume is large. As a method different from the continuous flow method, there is a droplet (liquid plug) method. In this method, droplets separated by air are moved inside the reactor and in the flow path leading to the reactor,
Each droplet is driven by air pressure. At this time, a vent structure that allows the air between the droplet and the channel wall or between the droplets to escape to the outside as needed, and a valve structure that keeps the pressure in the branched channel independent of other parts Etc.
It must be provided inside the reactor system. Also,
In order to operate the droplet by controlling the pressure difference, it is necessary to construct a pressure control system including a pressure source and a switching valve outside. As described above, in the droplet method, the device configuration and the structure of the reactor are slightly complicated, but a multi-step operation such as performing a plurality of reactions sequentially by operating a plurality of droplets is possible. The degree of freedom of the configuration increases.

As a driving method for performing fluid control, an electric driving method for generating an electroosmotic flow by applying a high voltage to both ends of a flow path (channel) and thereby moving the fluid, and a pressure source externally are prepared. In general, a pressure driving method of applying pressure to a fluid to move the fluid is widely used. The difference between the two is, for example, that the flow velocity profile in the cross section of the flow path is flat when the electric drive method is used, whereas the flow path profile is hyperbolic in the pressure drive method and the flow path center is It is known that the distribution is fast and the wall portion has a slow distribution. The electric drive method is more suitable for the purpose of moving the sample plug or the like while maintaining the shape. In the case of performing the electric drive method, since the inside of the flow path needs to be filled with the fluid, it is inevitable to take the form of the continuous flow method, but the fluid can be operated by electric control. Therefore, for example, a relatively complicated process such as creating a temporal concentration gradient by continuously changing the mixing ratio of two types of solutions has also been realized.
In the case of the pressure drive system, there is almost no influence on the substrate because it can be controlled regardless of the electrical properties of the fluid and there is no need to consider secondary effects such as heat generation and electrolysis. , Its applicability is wide. On the other hand,
It is necessary to automate complicated processes, such as the need to provide an external pressure source and the change in response characteristics of the operation depending on the size of the dead volume of the pressure system.
The method used as the fluid control method is appropriately selected depending on the purpose, but is preferably a continuous flow type pressure drive method.

The temperature of the micromixer may be controlled by placing the entire apparatus in a temperature-controlled container, or by forming a heater structure such as a metal resistance wire or polysilicon in the apparatus and controlling the heating. Uses this,
As for cooling, a thermal cycle may be performed by natural cooling. For temperature sensing, another resistance wire same as the heater is formed in the metal resistance wire, the temperature is detected based on the change in the resistance value, and the polysilicon is detected using a thermocouple. Heating and cooling may be performed from the outside by bringing the Peltier element into contact with the reactor. Which method is used is selected according to the use and the material of the reactor body.

In the manufacturing method of the present invention, the ultrasonic scatterer is manufactured so that the particle diameter of the ultrasonic scatterer is 0.01 μm to 10 μm as the average value of the circle equivalent diameter. In particular, in order to use the scatterer as a contrast agent for ultrasonic diagnosis, the thickness is preferably 0.1 μm to 10 μm.

Usually, the contrast agent for ultrasonic diagnosis is injected into a human body by intravenous injection and diagnosed at the timing of reaching the affected part. Here, if the ultrasonic scatterer as the contrast agent is too large, there is a risk of causing occlusion of peripheral blood vessels.If the ultrasonic scatterer is too small, the signal intensity of the ultrasonic scatterer such as blood cells and the in vivo ultrasonic scatterer can be reduced to obtain an echo signal. Analysis becomes difficult. Therefore, it is important to control the particle size within the above range.

In the present specification, the particle diameter of the gas-containing particles indicates a value measured by the method described below. That is, a dispersion of gas-containing particles is spread on a slide glass, a cover glass is placed thereon so as to have a clearance of 10 μm to 100 μm, and measurement is performed by observation with an optical microscope or a digital microscope. The number for measuring the particle size of each particle is preferably 200 or more, and more preferably 600 or more, in order to reduce statistical errors.

In the present invention, it is preferable to use a phospholipid dispersion as the shell material-containing liquid. At this time, the phospholipid dispersion preferably has an average particle size of 0.01 μm to 5 μm. Such a phospholipid dispersion is preferably prepared by dispersing with a high-pressure homogenizer. If a high-pressure homogenizer is used, the particle size is small,
A uniform phospholipid dispersion without aggregation can be obtained.
That is, in order to effectively obtain such a phospholipid dispersion, it is preferable to convert the aqueous dispersion into a high-speed stream and then apply a large force uniformly by reducing the pressure.

The high-pressure homogenizer has a shear force when passing through a narrow gap with a high-speed flow, an impact force due to collision between liquid and liquid or between liquid and a wall surface, and a dispersion force due to cavitation. In the present invention, among these, the dispersion efficiency can be increased and the quality can be stabilized particularly by cavitation. Therefore, in the present invention, when the aqueous solution containing the organic silver salt is subjected to the dispersion treatment, the air mixing amount is set so that a large amount of bubble nuclei are not generated when the pressure drops under the treatment pressure. The shear force generated when the processing liquid is passed through at a high flow rate and the impact force generated when (2) liquid-liquid collision or wall collision occurs in a narrow space with high pressure remain unchanged (3) The subsequent pressure drop Cavitation force is further strengthened to promote uniform and efficient dispersion.

In the present invention, if a large amount of bubble nuclei are present during the dispersion of the treatment liquid containing phospholipids, the transmission of force becomes insufficient during high-pressure treatment, and the bubble nuclei act as a cushion when the pressure drops, thereby causing cavitation. As the force is weakened and the dispersion is delayed, the calorific value increases, the photographic performance and the dispersibility are deteriorated, and the dispersing equipment such as the sealing material of the dispersing machine is damaged. If the number of bubble nuclei is too small, cavitation hardly occurs at the time of pressure drop, and the dispersion efficiency is lowered. Therefore, in the present invention, the air mixing amount is preferably 0.2% to 1%, more preferably 0.4% of the dissolved saturation concentration under atmospheric pressure.
0.8%.

In the present invention, in dispersing the treatment liquid containing the phospholipid, it is preferable to immediately suppress an increase in the liquid temperature which occurs when the pressure drops under the treatment pressure, and to reduce heat-induced particle aggregation. The liquid temperature causes aggregation as the temperature increases. As described above, the dispersing force of the high-pressure homogenizer includes cavitation force due to a pressure drop. At this time, a temperature drop of about 2.4 ° C. is caused by a pressure drop of 100 kg / cm ² . Therefore, when the pressure is increased to increase the dispersing power, the temperature of the dispersion is raised. In order to increase the dispersion efficiency, it is necessary to cool the dispersion liquid and the dispersing apparatus to lower the temperature immediately after the dispersion. The allowable time for rapid cooling after dispersion must be 10 seconds or less, and the average residence time is preferably 5 seconds or less, more preferably 1 second or less.

In the present invention, a dispersing chamber having any mechanism can be used.
It is more preferable to use a spherical chamber using a spherical check valve described in Japanese Patent Application Laid-Open No. 2 (1994) because maintenance is easy.

In the dispersion chamber used for the pressure homogenizer, expensive diamonds and the like are generally used as a countermeasure because the wall of the dispersion chamber due to the collision of a high-pressure liquid or the like is intense. I will be. On the other hand, in a spherical chamber, since only the ball can be replaced at the time of wear, maintenance is easy, quality can be stabilized, and equipment cost can be reduced.

In dispersing the phospholipid in the present invention, it is possible to disperse the phospholipid to a desired particle size by adjusting the flow rate, the differential pressure at the time of pressure drop, and the number of treatments. / sec ～600M / sec, preferably in the range differential pressure of 900kg / cm ² ~3000kg / cm ² during the pressure drop, flow rate 300 meters / sec ～600M / sec, the pressure difference at the pressure drop 1500 kg / cm ² ~ 3000kg /
More preferably, it is in the range of cm ² . The number of times of the dispersion processing can be selected as needed, but is usually set to 1 to 10 times, and is set to about 1 to 3 times from the viewpoint of productivity.

In the present invention, the phospholipid is generally mixed with water and sent as a slurry to a dispersing machine. However, the phospholipid may be subjected to a heat treatment or a solvent treatment in advance to form an organic silver salt powder or a wet cake. The pH may be controlled by a suitable pH adjuster before, during or after dispersion.
In addition to mechanically dispersing, by coarsely dispersing in a solvent by controlling the pH, the pH is then adjusted in the presence of a dispersing aid.
May be changed to fine particles. At this time, an organic solvent may be used as a solvent used for the coarse dispersion, and the organic solvent is usually removed after the completion of the fine particle formation.

Prior to the dispersion operation, the raw material liquid is preferably preliminarily dispersed. As means for preliminary dispersion, known dispersion means (for example, high-speed mixer, homogenizer,
High-speed impact mills, Banbury mixers, homomixers, kneaders, ball mills, vibrating ball mills, planetary ball mills, attritors, sand mills, bead mills, colloid mills, jet mills, roller mills, tron mills, high-speed stone mills) can be used. Instead of mechanically dispersing, fine particles may be formed by coarsely dispersing in a solvent by controlling the pH and then changing the pH in the presence of a dispersing aid. At this time, an organic solvent may be used as a solvent used for the coarse dispersion, and the organic solvent is usually removed after the completion of the fine particle formation.

According to the production method of the present invention, an ultrasonic scatterer having a preferable particle size and a small degree of dispersion can be easily produced. In particular, when the average particle size is 0.01
It is possible to produce a preferred ultrasonic scatterer having a diameter of 10 μm to 10 μm and a degree of dispersion of 50% or less. The degree of dispersion is more preferably 40% or less, and further preferably 30% or less. The definition of the degree of dispersion is as described in Examples described later.

The ultrasonic scatterer of the present invention having an average particle diameter of 0.01 μm to 10 μm and a degree of dispersion of 50% or less may be produced by a method other than the production method of the present invention. The material of the ultrasonic scatterer may be any material as long as it has a different acoustic impedance from the liquid into which the ultrasonic scatterer is injected, such as a dispersion medium or water or blood. Particles that evaporate at the temperature of the liquid to be injected, particles that evaporate by ultrasonic irradiation, and the like can be used.

When the ultrasonic scatterer of the present invention is used as a dispersion, any dispersion medium may be used as long as the ultrasonic scatterer is not denatured with time. The ultrasonic scatterer of the present invention can be particularly preferably used as a contrast agent for ultrasonic diagnosis which is injected into a liquid portion and used for confirming a flow state. When used as a contrast agent for ultrasonic diagnostics, the dispersion medium preferably contains physiological saline as a main component. In addition, the dispersion medium includes a polyhydric alcohol (glycerin, propylene glycol, ethylene glycol), a saccharide (such as glucose or fructose), a polysaccharide (such as dextran), or a water-soluble polymer (polyvinyl) for the purpose of adjusting viscosity. Alcohol, gelatin, albumin, etc.).

[0042]

The features of the present invention will be described more specifically with reference to the following examples. Material, amount used in the following examples,
The ratio, processing content, processing procedure, and the like can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples described below.

Example 1 (C ₃ with albumin shell)
F ₈ bubbles preparation of) human serum albumin (ALB) 5 g saline 100
It was dissolved ml, and by implanting C ₃ F ₈ gas from a nozzle having a diameter of 20μm at a linear velocity of 20 m / sec, to prepare ultrasound scatterers CA01. An ultrasonic scatterer CA02 was prepared in the same manner as CA01, except that 0.1 g of glutaraldehyde (GA) was further added to a physiological saline solution of human serum albumin. When preparing CA01 and CA02, the injected C ₃ F ₈ gas is mixed with a micromixer (Single Mixer (Nickel) Channel width, manufactured by IMM).
(25 μm) while mixing to obtain ultrasonic scatterers CA11 and CA12.

The obtained particles are injected into a Sekisui spectroscopic plate manufactured by Sekisui Chemical Co., Ltd., and the zoom lens V is mounted on a digital HD microscope VH-700 manufactured by KEYENCE CORPORATION.
The average particle size and the standard deviation were obtained by performing image analysis of an image photographed by using the H-Z450 under an automatic circular separation condition of Win ROOF manufactured by Mitani Corporation. Further, in order to evaluate the particle size distribution, a value (dispersion degree) obtained by dividing the standard deviation by the average particle size was calculated. Table 1 shows the results.

Example 2 (C ₃ F ₈ bubbles with phospholipids
Preparation) dipalmitoyl phosphatidylcholine 24.9 mg,
2.8m Sodium dipalmitoyl phosphatidylate
g, 2.3 mg of dipalmitoylphosphatidylethanolamine were dispersed in 6 ml of physiological saline with a high-speed mixer to obtain PR03. Then, PR03 was converted to Whatman ^™
Coarse particles are removed with a cyclopore membrane (hydrophilic polycarbonate membrane type, pore diameter 10 μm) made of P
R04 was prepared. Further, PR03 is cooled to 4 ° C.
DeBE made by BEE International (Israel)
The treatment liquid cooling heat exchanger was cooled to 4 ° C. in E2000, dispersed at a dispersion pressure of 60 kbar and a back pressure of 2 kbar, and the obtained dispersion was dispersed twice under the same conditions to obtain PR05.

The obtained particles were rapidly frozen in sherbet-like solid nitrogen prepared by reducing the pressure of liquid nitrogen with a vacuum pump. The frozen sample was photographed with a transmission electron microscope equipped with a cryostage. The photographed photograph was read by a scanner, and image analysis was performed under an automatic circular separation condition of Win ROOF manufactured by Mitani Corporation to obtain an average particle size (volume load). The results were 10 μm for PR01, 4 μm for PR02, and 0.1 μm for PR03.

Next, C ₃ F ₈ gas was injected into PR03-05 at a linear velocity of 20 m / sec from a nozzle having a diameter of 20 μm. The bubbles with the shell thus obtained were designated as CA03-05. In preparing CA03～05, the implanted C ₃ F ₈ gas micromixer (IMM Co., Single Mixer (Ni
ckel) Channel Width 25 μm) and the mixture was prepared as ultrasonic scatterers CA13 to CA15.

The obtained bubble particles were injected into a Sekisui Chemical Co., Ltd. Sekisui Microscope plate, and an image photographed by a digital HD microscope VH-700 manufactured by KEYENCE CORPORATION using a zoom lens VH-Z450 was used as a Mitani image. The average particle size and the standard deviation were determined by image analysis under automatic circular separation conditions of Win ROOF manufactured by Shoji Co., Ltd. Further, in order to evaluate the particle size distribution, a value (dispersion degree) obtained by dividing the standard deviation by the average particle size was calculated. Table 1 shows the results.

[0049]

[Table 1]

Example 3 (Measurement of Ultrasonic Scattering) The ultrasonic scatterer of the present invention was measured by the ultrasonic scattering measuring apparatus shown in FIG. In the ultrasonic scattering measurement apparatus shown in FIG. 1, pure water 102 is placed in a water tank 101, and a transducer 121, a hydrophone 123, and a cell 111, which is a container made of agar, are submerged in the pure water. An ultrasonic scatterer dispersion liquid 113 is injected into the agar cell 111. A signal is sent from the arbitrary waveform generator 122 to the transducer 121, and a transmission ultrasonic wave oscillates. Arbitrary waveform generator 1
At 22, a trigger signal is transmitted to the oscilloscope 124 at the same time as transmitting a signal to the transducer 121. The oscilloscope 124 captures a signal received by the hydrophone 123 in response to a trigger signal transmitted from the arbitrary waveform generator 122. The computer 125 is connected to the oscilloscope 124 and analyzes the received waveform of the hydrophone. Here, the transducer 121
Was measured with a 3.5 MHz wideband unfocused type A381S manufactured by Panametrics Japan, AWG2021 manufactured by Tektronix, an arbitrary waveform generator 122, a large-diameter PVDF hydrophone manufactured by Toray Techno, and an oscilloscope 124 measured by Bringo manufactured by Iwatsu. did. As the agar cell 111, a dentoid middle BLUE (8 mmφ) manufactured by Dentonics and having a 2.5 mmφ hole was used. From the ultrasonic scatterer of the present invention prepared in Examples 1 and 2, a good scattered signal was obtained in the intensity of the nonlinear signal.

[0051]

As described above in detail, according to the manufacturing method of the present invention, it is possible to provide an ultrasonic scatterer which is uniform and has strong ultrasonic scattering. The ultrasonic scatterer of the present invention is particularly effectively used as a contrast agent for ultrasonic diagnosis.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an apparatus for measuring an ultrasonic scatterer of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Water tank 102 Pure water 111 Agar cell 113 Ultrasonic scatterer dispersion liquid 121 Transducer 122 Arbitrary waveform generator 123 5 Hydrophone 124 Oscilloscope 125 Computer

Continuation of the front page F term (reference) 4C085 HH09 JJ03 KA40 KB20 KB30 KB60 LL07 4C301 DD01 DD02 EE06

Claims (7)

[Claims] 1. An ultrasonic scatterer comprising: introducing a gas into a liquid containing a shell material; and mixing the gas and liquid with a micromixer to prepare gas-containing particles having an average particle diameter of 0.01 μm to 10 μm. Manufacturing method. 2. The method for producing an ultrasonic scatterer according to claim 1, wherein said liquid containing a shell material is a phospholipid dispersion. 3. The phospholipid dispersion having an average particle size of 0.0
The method for producing an ultrasonic scatterer according to claim 2, wherein the thickness is 1 m to 5 m. 4. The method for producing an ultrasonic scatterer according to claim 3, wherein the phospholipid dispersion is prepared by dispersing the phospholipid dispersion using a high-pressure homogenizer. 5. An ultrasonic scatterer produced by the production method according to claim 1. 6. An ultrasonic scatterer having an average particle size of 0.01 μm to 10 μm and a dispersity of 50% or less. 7. A contrast agent for ultrasonic diagnostics, comprising the ultrasonic scatterer according to claim 5 or 6.