RU2299011C2 - Method and device for estimating density and non-uniformity of biological tissue - Google Patents

Abstract

FIELD: medicine; medical equipment.

SUBSTANCE: method and device can be used for pathologic-anatomical testing of biological tissue. Method and device for estimating density and non-uniformity of biological tissue is the following: specimen of biological tissue is subject to influence of tactile detector, which has contact are made in form of many elastic air-proof chambers. Changes in pressure in chambers are measured for specific period of time. Changes in movement of contact area are also measured as well as total force of influence onto specimen. Recorded data is processed to get objective integral estimations of density and non-uniformity of tissue. Device for realization of the method has servo drive. Output shaft of servo drive is connected with movable end of level via connecting rod-crank transmission. Lever is fastened by hinges onto base. Movable end is tightly connected with strain-gauge single-component force measuring transducer and with contacting member by means of which member the specimen is subject to mechanical influence. Contacting member has to be tactile detector. Detector has many air-proof chambers filled with pressure-perceiving medium. Space among chambers is filled with elastic material which forms flat contacting area. Chambers are connected with pressure transducers. Readings of transducers together with readings of fore and shift detectors are registered by control computer system. Age, pathological and physiological changes can be diagnosed in remote parts of tissues or directly during process of surgical operations.

EFFECT: objective estimation of mechanical properties of tissues; widened area of application.

4 cl, 7 dwg, 3 att

Description

The present invention relates to medicine and medical technology, in particular to the practice and technique of postmortem examination of biological tissue.

An important criterion for assessing age-related, physiological, and pathological changes in biological tissues is a change in their mechanical properties as compared to normal. Currently, the most common method for assessing the mechanical properties of tissues is their palpation study (A.V. Strutynsky, A.P. Baranov, G.E. Roytberg, Yu.P. Gaponenkov. Fundamentals of semiotics of diseases of internal organs. - Russian State Medical University, 1997. - 224 p.). Palpation is carried out both when performing surgical operations, and when examining the extracted samples. At the same time, the subjective sensations of a particular researcher are recorded, and the conclusions are very general in nature such as “rigid tissue”, “dense soft muscle plate with a fold”, etc. The lack of objective measurements of tissue properties makes it difficult to systematize the results of studies, as a result of which the correct diagnosis is often determined by the subjective experience of a particular specialist.

The present invention allows to obtain objective assessments of the mechanical properties of tissues and will find effective application in pathological studies and for the rapid diagnosis of age-related, physiological and pathological changes in remote tissue sites or directly during surgery.

Known methods for recognizing tissue pathology, based on the analysis of their reflective and fluorescent properties, in particular, patents of the Russian Federation No. 2152162, No. 2088156. The method described in the patent of the Russian Federation No. 2002128728 (A) "Method and system for determining parameters and mapping of tissue lesions", suggests the introduction of a pathology recognition agent into the tissue, irradiation of the tissue with broadband continuous optical radiation and measurement of the dynamic optical property of this tissue, carried out after the interaction of the tissue with the specified recognition agent pathology. These methods use a change in the optical rather than mechanical properties of tissues.

The patent of the Russian Federation No. 2003108731 (A) describes an optical tactile sensor comprising a tactile part and image forming means, the tactile part comprising a transparent flexible body in which a plurality of colored markers are enclosed, the movement of which is detected by the image forming means when the flexible body is brought into contact with the object. The disadvantage of this device is the complexity of manufacturing, configuration and image processing.

The RF patent No. 93008580 (A) describes a device for determining the mechanical properties of biological tissues, in which the measuring rod is embedded in the tissue and the force and depth of penetration of the measuring rod are measured by means of ultrasonic vibration displacement meters, and the force is determined by the deformation of the calibrated spring. A similar solution was applied in RF patent No. 2082312 (C1) with the difference that the device contains a force sensor. The disadvantages of both devices is the inability to assess the heterogeneity of the tissue.

Closest to the claimed invention is a method and a device for examining breast tissue described in US patent US 006091981. The device contains many sensors located on the surface in contact with the test tissue, each of which measures the local pressure acting on it from the side tissue in response to the force with which the doctor presses the device against the tissue being examined. Depending on the structure of the underlying tissue, the pressure distribution between the sensors changes, which allows, after appropriate signal processing, to identify zones with altered physical properties. The disadvantage of this method and device is the lack of measurement of the movement of the contact surface in the direction of the tissue and the total force of action on the tissue, which does not allow to evaluate the averaged elastic-plastic properties of biological tissue. Another drawback is that the contact surface is made of a poorly deformed material, which, when examining tissue samples with pronounced local changes, such as pulmonary vesicles during pneumonia or the presence of calcification sites, can lead to rapid irreversible changes in the structure of the tissue and distortion of objective information.

The technical result of the claimed invention is the expansion of the possibilities of obtaining objective data on the mechanical properties of biological tissue when it is examined for uniformity and density.

The specified result is achieved by the fact that a sample of biological tissue of a given size is affected by a tactile sensor, the contact surface of which is made in the form of a plurality of elastic sealed chambers, changes in time of pressure in the chambers, movement of the contact surface and the total force of impact on the sample are recorded and the recorded information is processed for Obtaining objective integral estimates of tissue density and heterogeneity.

The technical essence of the device that implements the inventive method is illustrated by figures 1-3. Figures 4-6 illustrate examples of studies conducted using the patented method and device. Figure 7 presents a photograph of the implemented device.

Figure 1 presents a diagram of the mechanical part of the device for implementing the patented method. The output shaft of the servo drive 1 through a crank gear 2 is connected to the movable right end of the lever 3, the left end of which is pivotally connected to a fixed base. A strain gauge one-component force measuring sensor 4 and a tactile sensor 5, comprising a plurality of pressurized chambers connected by tubes to pressure sensors 6, are rigidly attached to the right end of the lever. digital converter controller used in the system. A test sample of biological tissue 8 is placed between the contact surface of the tactile sensor and the supporting surface. The device also contains a potentiometer 9 used to control the position of the output shaft of the servo drive.

Figure 2 shows two embodiments of a tactile sensor. The upper figures represent a section perpendicular to the plane of FIG. 1; bottom figures - bottom view. The sensor shown in Fig. 2a has a one-dimensional sensitive structure in which the air cavities 10 are made of soft polymer tubes sealed on one side and stiffer tubes 13 of smaller diameter are connected on the other side for connection with pressure sensors. This design is justified when samples of standard sizes of elongated shape are examined. The sensor shown in FIG. 2b has a two-dimensional sensitive structure in which the air cavities 10 are spherical in shape. This design allows you to explore samples of arbitrary geometric shape. For both options, air cavities are fixed on a support plate 11 having a threaded portion 12 for connection with a power sensor. The space between the cavities is filled with elastic material, which forms a flat sensitive surface 14. The dimensions of the air cavities are selected so as to provide the desired resolution of the sensor.

Figure 3 shows the structure of the control system of the device. Its central element is the controller 15, which provides communication with the equipment and a personal computer (PC) 16. The controller has an analog-to-digital converter 17, to which the outputs of the pressure sensors 5, force 4 and the setting potentiometer 9, and a pulse-width modulator 18 are connected to the output of which is the driving signal for the servomotor 1.

The controller’s program of work is downloaded from a personal computer and provides cyclic execution of the following operations with a specified period: 1) analog-to-digital conversion of signals from a potentiometer, power sensor, and pressure sensors; 2) sending the received information to a PC; 3) the formation of a control signal to the engine in accordance with the position of the potentiometer. The PC data recording and visualization program provides the following functions: 1) current output of digital information from sensors to verify their functioning and settings; 2) registration of information for a time sufficient for the study and its recording in a file; 3) a graphical representation of the recorded information in the form of a time-sweep of the signals from all the sensors mentioned, their processing and the derivation of numerical estimates of the density and heterogeneity of the tested sample.

A patented method for assessing the density and heterogeneity of biological tissue is carried out using the developed device as follows. The test sample is placed between the supporting surface and the contact surface of the tactile sensor, after which the output shaft of the servo drive is rotated according to the specified program or by the researcher using the setting potentiometer. The length of the lever is large compared to the size of the crank, the lever is near the horizontal position, therefore close to the vertical movement of its right (working) end and the tactile sensor through which the sample is mechanically deformed. The pressure in the sensor cavities is determined by their deformation, which, in turn, depends on the structure of the object of study. In particular, if an elastic object contains a solid inclusion of a size commensurate with the size of the cavity, then when the object is deformed in the cavities in contact with this inclusion, a greater change in pressure occurs than in the others. Upon reaching the desired value of the force applied to the sample, the mechanism returns to its original state. Moreover, throughout the study, pressure is recorded in the cavities of the tactile sensor and the vertical component of the force applied to the object. After the recorded information is presented in the form of graphs, it is saved in a file for subsequent analysis and statistical processing.

One of the options for processing the recorded information is that in the time interval when the tactile sensor is in contact with the object of study, the ratio of the magnitude of the arising force to the vertical movement of the tactile sensor is calculated and then this ratio is averaged over time. This criterion allows one to obtain an averaged estimate of the density of a sample. A similar averaging over time of the dispersion of the readings of pressure sensors gives an estimate of the heterogeneity of the tissue.

The claimed method and device are illustrated by specific examples of tissue samples. In this study, a comparison was made of the objective data recorded by the patented device with the subjective data obtained by touch by the researcher. The recorded data is shown in Figs. 4-6 in the form of a time scan of the angle of rotation of the servo shaft, the readings of the force sensor (at the top of the graphs) and five pressure sensors (at the bottom of the graphs). In the above examples, density and heterogeneity estimates obtained as a result of processing the obtained data are also given. Figure 7 shows a photograph of the device by which these studies were carried out. In this case, the tactile sensor is implemented in accordance with figa.

Example 1

The right, left lobe and the isthmus of the thyroid gland are removed according to Nikolaev.

A portion of the gland is palpated by the researcher. The case is identified as a uniform lobular structure. A portion of the gland is placed in a patented device, measurement No. 1 is carried out, presented on the graph (figa). The areas located under the two cavities of the tactile sensor are more dense. These graphs indicate the average stiffness and heterogeneity of the material (density 18, heterogeneity 29).

The area of the gland with the adenoma present in it is palpated by the researcher. The case was identified as a dense knot with a diameter of 4 mm against a lobed structure. A portion of the gland is placed in a patented device, measurement No. 2 is carried out. On the graph (Fig. 4b) below the horizontal line, it can be seen that the lines diverge significantly from each other, which indicates the inclusion of a significant size in the sample (density 34, heterogeneity 39).

Example 2

Sections of the aorta are extracted from the body in an acute manner.

The unchanged site of the aorta is palpated by the researcher. The case is identified as a dense elastic plate with areas of soft seal with a diameter of 1-2 mm. The site of the aorta is placed in a patented device, measurement No. 3 is carried out. On the graph (Fig. 5a) below the horizontal line, it can be seen that the lines do not diverge significantly from each other, which indicates the uniformity of the object. The material of the object has moderate stiffness (density 20, heterogeneity 21).

The site of the aorta with a small area of calcification is palpated by the researcher. The case has been identified as a dense elastic plate with hard seal sections 1-2 mm in diameter. The site of the aorta is placed in a patented device, measurement No. 4 is carried out. On the graph (FIG. 5b) below the horizontal line, it can be seen that the lines diverge significantly, which indicates the inclusion of a small object with a high density in the sample. The material of the object has a stiffness close to the previous one, but differs in a greater heterogeneity (density 22, heterogeneity 66).

Example 3

Sections of the lung are extracted from the body in an acute way.

The unchanged area of the lung is palpated by the researcher. The case is identified as a soft, uniformly smeared gelatinous plastic structure. The sample is placed in a patented device, measurement No. 5 is carried out. On the presented graph (figa) below the horizontal line it is seen that the lines do not diverge significantly from each other, which indicates the uniformity of the object. The material of the object is soft (density 19, heterogeneity 31).

The lung site with signs of pneumonia is palpated by the researcher. The case is identified as an unevenly compacted, smeared gelatinous plastic structure. The sample is placed in a patented device, measurement No. 6 is carried out. On the graph (Fig.6b) below the horizontal line you can see the difference in the readings of the pressure sensors at the initial stage of measurement, due to the presence of bubble formation, which later collapsed. Estimates of tissue properties obtained at the initial stage show a difference from the previous case (density 31, heterogeneity 57).

Studies have shown the possibility of obtaining the effect of touch of biological tissue by assessing its uniformity and density with the creation of an objective ("digital") portrait. At the same time, the proposed system is relatively simple, capable of further improvement and combination with various biological and medical techniques.

Claims (3)

1. A method for assessing the density and heterogeneity of biological tissue, consisting in the mechanical action of a contacting element on a tissue sample, determining by pressure sensors the change in pressure of the tissue of the sample over time due to its deformation, recording the movement of the contacting element and processing the recorded information, characterized in that as the contacting the element uses a tactile sensor with many sealed chambers, when registering, the readings of pressure sensors about pressure changes in the cavity are taken into account x cameras of the tactile sensor in time and the total force of influence on the sample, and when processing information, the ratio of the total force of influence to the displacement of the tactile sensor is calculated, the time-averaged value of the calculated ratio is estimated as the average value of the density of the biological tissue of the sample, and the time-averaged value the dispersion of the readings of the pressure sensors evaluate the heterogeneity of the tissue. 2. A device for assessing the density and heterogeneity of biological tissue, including a contacting element configured to move it, pressure sensors and an information processing device, characterized in that a fixed base for accommodating a tissue sample, a strain gauge force measuring sensor, an amplifier, a control system are introduced into it , a servo drive for moving the contacting element, and the contacting element is made in the form of a tactile sensor containing many sealed chambers, filled with pressure-sensitive medium, the space between which is filled with elastic material, the tactile sensor chambers are connected to pressure sensors, while the output shaft of the servo drive is connected via a crank gear to the movable end of the lever, the other end of which is pivotally connected to the fixed base, to the movable end of the lever a strain gauge load cell and a tactile sensor are attached, and pressure sensors and strain gauge load cells through the amplifier and the system topic management associated with the information processing device. 3. The device according to claim 2, characterized in that it contains a potentiometer configured to control the position of the output shaft of the servo drive connected to the control system.

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