Elastograph head cap insert, elastography measurement kit and kit application

Abstract

The first object of the invention is an insert for an elastograph head cap, characterized that it includes a circular plate with a top surface configured to be in contact with the measuring head and a bottom surface configured to receive the measuring cap, with a circular projection extending from the bottom surface to fix the measuring cap, and the insert includes a through hole configured to receive the measuring head transducer. The invention also relates to an elastographic measurement kit, comprising an elastographic measurement cap and an insert. Another Subject of the invention also relates to the use of a kit as defined for elastographic measurements.

Description

[0001] Elastograph head cap insert, elastography measurement kit and kit application

[0002] The object of the invention is an insert for an elastograph head cap. The invention also includes a kit for elastography measurements, comprising an insert and a cap for elastography measurements. The invention is used in patient examinations conducted using an elastograph.

[0003] International PCT patent application W02020058188 describes a transient elastography probe comprising, a probe body, an ultrasonic transducer configured to generate an ultrasonic beam along an axis, the ultrasonic beam being generated from the face of the ultrasonic transducer, a vibrator located inside the probe body. Designed to induce movement of the ultrasonic transducer along a predefined axis. An ultrasonic transducer mounted on the vibrator such that the predefined axis and the axis of the ultrasonic beam are coincident, characterized in such away that it includes a sealing membrane matching the outer contours of the ultrasonic transducer.

[0004] In the scientific publication "Preliminary Numerical Analysis of Mechanical Wave Propagation Due to Elastograph Measuring Head Application in Non-lnvasive Liver Condition Assessment" (Romanowska K. et al., Appl. Sci. 2023, 13, 11843. https: / / doi.orR / 10.3390 / aDD132111843) revealed numerical models of mechanical wave propagation along human tissue due to the application of the FibroScan® elastograph measuring head. The FibroScan® diagnostic device is used for diagnostic testing of liver fibrosis and steatosis. The test was conducted using an in vivo method by directly applying the surface of the ultrasonic measuring probe to the patient's skin at the liver site. The goal of the study was to develop caps for non-invasive testing of livers used for transplantation. The numerical models presented in the publication made it possible to develop the probe cap so that its application to the liver would not result in damage to the liver due to mechanical wave excitation. The said caps are made of gel- and rubber-like materials and silicones used to mimic soft tissue in terms of mechano-acoustic parameters (density, speed and attenuation of the ultrasound wave). The materials from which the caps are made are safe from the angle of their use in contact with human tissue (no chemical reactions or tissue damage). The caps are molded in a mold casting process from three different materials:

[0005] 1 ) Humimic Medical Gel #0 tissue-like gel designed for measurements with low pressure on the measuring head,

[0006] 2) Agar Progel gel agar designed for most measurements with standard measuring head pressure,

[0007] 3) Ecoflex 00-20 silicone rubber designed for measurements with the necessity of the use of high pressure on the measuring head.

[0008] However, caps made of the materials mentioned above are subject to mechanical damage after about 50-80 measurements with an elastographic measurement instrument, such as FibroScan® (except for caps made of silicone rubber, which are very tough). For example, in a cap with the ability to attach to a probe, the hole for placement deepens, and in another type of cap, without the aforementioned hole, a significant indentation forms on the surface. These defects make it impossible to obtain further correct measurements due to the insufficient distance between the surface of the measuring head and the surface to be tested. In addition, lateral cracks can appear in the measuring caps, which are the result of pressure from the head of the elastographic device from above. As a result, caps made of these materials should therefore be considered disposable.

[0009] A first object of the invention is an insert for an elastograph head cap, characterized in that it includes a circular plate with a top surface configured to contact the measuring head and a bottom surface configured to receive the measuring cap, with a circular projection extending from the bottom surface to fix the measuring cap, and the insert includes a through hole configured to receive the measuring head transducer.

[0010] In an advantageous implementation of the invention, the geometric center of the projection corresponds to the geometric center of the insert.

[0011] In the next advantageous implementation of the invention, a flange configured for positioning the measuring head extends from the top surface of the insert along its circumference. In another advantageous implementation of the invention, the ratio of the thickness of the insert to its diameter is 1 / 15 to 2 / 39.

[0012] The second object of the invention is an elastographic measurement kit, characterized in such a way that it includes an elastographic measurement cap and an insert, as defined in the first object of the invention.

[0013] In an advantageous implementation of the invention, the cap for elastographic measurements contains a first surface configured to receive the insert and a second surface configured to contact the test surface.

[0014] In the next advantageous implementation of the invention, the cap for elastographic measurements on the first surface includes a recess for receiving the protrusion of the insert and fixing the cap on the insert, with the shape ofthe recess corresponding to the shape of the protrusion.

[0015] In another advantageous implementation of the invention, the elastographic measurement cap has either a rectangular or trapezoidal cross-section.

[0016] In another advantageous implementation of the invention, the elastographic measurement cap contains a hole for inserting the transducer ofthe measurement head.

[0017] Another object of the invention is the use of a kit, as specified in the second object of the invention, for elastographic measurements.

[0018] The inserts according to the invention have a number of advantages. The insert, in its basic variant, improves the comfort of free-hand measurements and better protects the sockets from mechanical damage on the side of the measuring head, so that the sockets can be used for more measurements. In the variant with a flange along the perimeter of the insert, it additionally provides more stable positioning of the measuring head due to the encompassing flange. In addition, a durable and flexible insert fitted circumferentially with a tab in the groove of the cap reinforces it. In addition to the inserts, especially those holding the head, i.e. the flange insert, prevent the measuring head transducer from popping out ofthe cap bore and the measuring head from slipping on its surface when the head is moved during pressing and angular positioning. Even if the cap breaks, the insert protects it from breaking into two or more pieces and from contamination of the measuring field, which should be smooth and perfectly coupled to the surface of the cap mechanically (for example, the moist surface of the thin film of the tissue protection bag).

[0019] Examples of the implementation of the invention are shown in the figure, where:

[0020] - fig. 1 shows the elastograph cap insert, fig. la basic variant of the insert, fig. lb the insert with flange;

[0021] - fig. 2 shows an insert placed on the elastograph cap - the possibilities of combining different variants of elastograph caps with an insert, with or without a flange;

[0022] - fig. 3a-3b caps for elastographic measurements: 3a cap with rectangular of a curvilinear cross-section, 3b of a trapezoidal cross-section;

[0023] - fig. 4a-4c results of elastographic measurements on the CIRS Shear Wave Liver Fibrosis Phantom Model 039.

[0024] Example 1.

[0025] The insert (fig. la) is in the form of a plate 1 with a circular shape, which essentially corresponds to the shape of the caps on the elastographic measurement device. The insert according to the invention is madeof commercially available Fegura® Sil Quick shore 18-20 silicone compound, which is used in dental prosthodontics for taking impressions and making casts, also for replicating models. By design, dental silicones are designed for use in contact with human tissue. The thickness of the insert must be small so as not to increase too much the distance between the surface of the head in contact with the surface of the insert outside the measuring hole and the surface of the transducer applied to the bottom of the cap hole. The transducer of the measuring device is attached resiliently, and when it is pressed, it slightly retracts (retracts into the head), providing the pressure force established in the device. If the sum of the depth of the hole in the cap and the thickness of the insert were too large, it would not be possible to obtain the required pressing force for correct elastographic measurements. If the depth of the hole in the cap was too small then the head surface would not rest on the insert and the pressure would always be too high. As a result, the transducer surface will damage the bottom of the cap hole. The size of the insert, i.e. its diameter, corresponds to the diameter of the cap for elastographic measurements (fig. 2a, 2b). However, the diameter of the insert can also be larger or smaller than the diameter of the cap. The insert 1 has a PG top surface, which can be contact with the elastographic measurement device, and the bottom surface of the PD, which is in contact with the first surface of the elastographic measurement cap. The second surface of the cap is the surface that is directly in contact with the object on which the elastographic measurements are made. In the basic variant of the insert design, a circular protrusion 2 extends from the bottom surface of the insert for insertion into a circular recess in the cap for elastographic measurements and for fixing the cap on the insert. The position of the center of the circular protrusion 2 coincides with the geometric center of the insert l. The position of the protrusion 2 is optimally selected for stress, i.e. stable attachment of the insert to the cap. As a result, the insert does not change its shape at the pressure of the head and does not "pop" out of the cap. The length of the protrusion 2 is optimally selected for stable attachment of the insert 2 in the cap using the "push-on" method. The length of the protrusion 2 in relation to the insert 1 is about one and a half times the thickness of the insert 1. However, minor deviations from this value are possible, for example, due to the method of manufacturing the insert 1. The method of fixing the insert in the cap is shown in fig. 2a and 2b. At its central point, the insert contains a circular through hole 3 for receiving the transducer of the measuring head. The diameter of the hole 3 should fit the transducer of the measuring head with some clearance for minor movements and the possibility of filling the bottom of the hole preferably with water to provide mechanical coupling for ultrasound propagation. Hole 3 in the insert basically has the same diameter as the hole in the cap, but can also be slightly larger. However, the diameter of the hole in the insert 3 cannot be smaller, because this would blockthe insertion ofthe transducer, and it cannot be too large, because then the insert will no longer play a stiffening role. In another design variant, the insert contains a flange 4 extending from the top surface PG circumferentially along the outer edge of the insert. The inner diameter of the flange 4 corresponds to the diameter of the measuring head. On the other hand, the outer diameter of flange 4 corresponds to the diameter of the insert. The length of flange 4 has been optimally selected to position the measuring head only during measurements, without restricting its movements, and so that when the head is removed, insert 1 does not block and remain on the measuring head. Insert 1, when the measuring head is removed, is to remain on the cap. For a flanged insert, the ratio ofthe length ofthe flange 4 to the thickness ofthe insert is about 5:2. However, minor deviations from this value are possible, for example, due to the way that the insert 1 is manufactured. As mentioned, the thickness of the insert must be selected accordingly. The ratio of the thickness of the insert in relation to its diameter ranges from 1 / 15, in the variant without flange 4, to 2 / 39 in the variant of the design with flange 4.

[0026] It was mentioned above that the diameter of the insert can also be larger or smaller than the dia meter of the cap. However, the diameter of the insert without flange 4 can be slightly smaller or larger than the top surface of the cap, preferably to be equal to the diameter of the cap. On the other hand, in the case of an insert with flange 4, the inner diameter of the insert corresponds to the diameter of the measuring head. The flange 4 should be of such internal diameter as to encompass the head and position it, but not too tightly, so as not to restrict the head's minor deviations and movements.

[0027] Example 2. elastographic measurements using inserts

[0028] As part of the control test measurements, phantoms were laboratory tested using a FibroScan® device with caps and developed inserts. Specifically, a set of four certified and calibrated CIRS Shear Wave Liver Fibrosis Phantom Model 039 for shear wave imaging of liver fibrosis was tested.

[0029] Analysis of measurements made of the elastograph head caps made of Humimic Medical Gel #0, Agar Progel, Ecoflex 00-20 materials together with the corresponding inserts according to the invention confirmed their correct operation as a mechano-acoustic simulation of the intermediate layer between the skin surface and liver tissue. An elastograph, e.g. FibroScan9, with the developed inserts is capable of performing correct measurements of stiffness and attenuation of ultrasound and visualizes good-quality images of propagation of a 50 Hz transverse wave and a 3.5 MHz ultrasound wave in the tested phantoms with values of stiffness and attenuation falling within the measurement range (fig. 4a-fig.4c - left column). The inserts according to the invention do not change and do not interfere with the measurements performed with the elastograph on the phantoms (fig. 4a-fig. 4c - left column, fig. 4a-fig. 4c - right column) and most often enable better positioning of the measuring head, at the same time protecting the upper surface of the caps from rapid mechanical damage as a result of realization of repeated measurements with pressure and vibration of the measuring head.

Claims

Patent claims1 . An insert for an elastograph head cap, characterized that it includes a circular plate with a top surface (PG) configured to contact the measuring head and a bottom surface (PD) configured to receive the measuring cap, with a circular projection (2) extending from the bottom surface (PD) to fix the measuring cap, and the insert includes a through hole (3) configured to receive the measuring head transducer.

2. The insert according to claim. 1, characterized by the fact that the geometric center of the projection (2) corresponds to the geometric center of the insert.

3. The insert according to claim. 1, characterized that from the top surface (PG) of the insert along its circumference extends a flange (4) configured for positioning the measuring head.

4. The insert according to claim. 1, characterized by the fact that its ratio of thickness to its diameter is from 1 / 15 to 2 / 39.

5. An elastographic measurement kit, characterized that it includes an elastographic measurement cap and an insert as defined in the claim.

6. Assembly according to claim. 5, characterized that the cap for the elastographic measurement zwieres a first surface configured to receive the insert and a second surface configured to contact the test surface.

7. Set according to claims. 5 or 6, characterized by the fact that the cap for elastographic measurements on the first surface contains a recess for receiving the projection (2) of the insert and fixing the cap on the insert, the shape of the recess corresponding to the shape of the projection (2).

8. Set according to claim. 5, characterized by the fact that the cap for elastographic measurements has either a rectangular or trapezoidal cross-section.

9. Set according to claim. 5, characterized by the fact that the cap for elastographic measurements contains a hole for inserting the transducer of the measuring head.

10. Use of a kit as defined in claim. 5 for elastographic measurements.

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