Cannula and system for determining the position of a cannula tip

Abstract

cannula (10) comprising a cannula body (12) extending longitudinally along a longitudinal axis (L), a cannula tip (11) arranged at a distal end of the cannula body (12) and several sensors (13) for receiving an ultrasonic signal (B, B'), wherein the sensors (13) are arranged on a surface of the cannula body (12) at a known axial distance (d) to the cannula tip (11), so that by evaluating the received ultrasound signal (B, B') a position (P') of the sensors (13) and thereby a position (P) of the cannula tip (11) can be determined.

Description

[0001] The invention relates to a cannula and a system for determining the position of a cannula tip inside a body.

[0002] Such cannulas and systems are used, among other things, in regional anesthesia. A system known from the prior art is called "OnVision" and is designed to display the position of the cannula tip in an image plane of an ultrasound image. The known system is fully integrated into an underlying ultrasound imaging system.

[0003] The object of the invention is to provide a cannula and a system of the type mentioned above which offer advantages over the prior art.

[0004] This problem is solved by providing a cannula with the features of claim 1 and a system with the features of claim 6. Advantageous embodiments are specified in the dependent claims. The wording of the claims is incorporated herein by reference.

[0005] The cannula according to the invention comprises a cannula body, a cannula tip, and several sensors. The cannula body extends longitudinally along a longitudinal axis. The cannula tip is arranged at a distal end of the cannula body. The sensors are configured to receive an ultrasound signal. The sensors are arranged on a surface of the cannula body at a known axial distance from the cannula tip. By evaluating the ultrasound signal received by the respective sensor, the positions of the sensors can be determined. Furthermore, by relating the determined positions of the sensors, the orientation of the cannula body can be determined. The position of the cannula tip can be determined from the positions of the sensors and the orientation of the cannula body. The cannula according to the invention allows for at least an approximate determination of the position of the cannula tip within a body.By arranging the sensors at a known distance from the cannula tip, it is possible to determine the position of the cannula tip indirectly via the positions of the sensors. The sensors are attached to the cannula body in a fixed position relative to the cannula tip. The cannula according to the invention allows the sensors to be positioned within the body together with the cannula. Furthermore, the cannula according to the invention allows the sensors to be removed together with the cannula. Arranging the sensors on the surface of the cannula simplifies manufacturing and is cost-effective. In addition, by arranging the sensors on the surface, they can be exposed, and the ultrasound signal can reach the sensors with minimal attenuation. In one embodiment, the sensors are arranged at a short distance from the cannula tip, so that the position of the sensors serves as an approximation of the position of the cannula tip.Additionally, the positions of the sensors can be determined sequentially over time to track movement of the cannula body and the cannula tip.

[0006] In one embodiment of the invention, the sensors are printed onto the surface of the cannula body. This has the advantage that the sensors are precisely positioned, using minimal material and lying flat on the surface. Insertion of the cannula into the body is thus largely unaffected by the sensors. Preferably, the sensors are applied to the surface of the cannula using aerosol jet printing.

[0007] In an alternative embodiment of the invention, the sensors are printed onto or integrated into a film and attached to the cannula body via the film. This allows the sensors to be manufactured separately from the rest of the cannula. Furthermore, the sensors are easily replaceable by exchanging the film containing the sensors. The film with the sensors is, in particular, wrapped around the cannula body or attached along its length.

[0008] In a further embodiment of the invention, the cannula has a connecting conductor. The connecting conductor is connected to the sensors at one end. The connecting conductor can be connected to an evaluation unit or the like at the other end. The connecting conductor enables the sensor signals generated by the sensors when receiving the ultrasound signal to be received via a wired connection. The evaluation unit is preferably configured to assign the received sensor signals to the sensors. The connecting conductor is printed onto the surface of the cannula body or attached to the surface of the cannula body via a film. In the latter case, the connecting conductor is printed onto the film or integrated into the film. In one embodiment, the connecting conductor is attached to the surface of the cannula body in the same way as the sensors.In another embodiment, the connecting conductor is attached to the surface of the cannula body in a different manner than the sensors. In one embodiment, several connecting conductors are provided, each connected to one or more of the sensors. In particular, one connecting conductor is provided for each of the sensors.

[0009] In an alternative embodiment, the connecting conductor is not attached to the surface of the cannula body, but is integrated into the cannula body, inserted into a groove in the cannula body, or the like.

[0010] In a further embodiment of the invention, the cannula has several sensors on the surface of the cannula body. The sensors can be arranged along the longitudinal axis of the cannula body. Additionally or alternatively, the sensors can be arranged along a circumferential direction of the cannula body. The sensors are arranged at known distances from the cannula tip. The sensors are also arranged at known distances from each other with respect to the longitudinal axis and the circumferential direction. Depending on the arrangement of the sensors, it is possible to determine an inclination of the longitudinal axis of the cannula body with respect to a plane, i.e., in the sense of a pitch or yaw angle, or an inclination of the cannula body with respect to the longitudinal axis, i.e., in the sense of a roll angle.

[0011] The medical system according to the invention is designed to determine the position of a cannula tip within a body. The medical system according to the invention comprises an ultrasound transducer, the cannula according to the invention, and an evaluation unit. The ultrasound transducer is designed to couple an ultrasound signal into the body. The ultrasound signal propagates within the body and is reflected at interfaces in body tissue, particularly in the region of the cannula tip. The ultrasound transducer is designed to receive the reflected ultrasound waves. The ultrasound transducer is also designed to generate an ultrasound transducer signal representing the received ultrasound waves. The sensors of the cannula are designed to receive the ultrasound signal. The sensors are also each designed to generate a first sensor signal representing the received ultrasound waves.The evaluation unit is connected to the ultrasound transducer and the sensors. It is designed to generate an initial ultrasound image of the body tissue surrounding the cannula tip, based on the ultrasound transducer signal. The evaluation unit is also designed to determine the position of the cannula tip relative to the ultrasound transducer, again based on the initial sensor signals. By combining this with the initial ultrasound image, the position of the cannula tip can be precisely determined. Furthermore, this combination allows for a visual representation of the cannula tip position and the orientation of the cannula body within the body. Because the sensors are permanently attached to the cannula body, the position of the cannula tip can be reliably inferred from the position of the sensors.Furthermore, the reception of the ultrasound signal by the sensors is relatively unaffected because they are mounted on the surface of the cannula body and are therefore exposed. Influences on the received ultrasound signal can thus be reliably attributed to the surrounding body tissue. In one embodiment, the sensors are connected to the evaluation unit via one or more connecting conductors.

[0012] In this embodiment of the invention, the sensors are configured to receive the ultrasound signal after its interaction with the body tissue surrounding the cannula and to generate a second sensor signal representing the received, interacting ultrasound signal. The evaluation unit is configured to generate the first ultrasound image or a second ultrasound image depending on the second sensor signals. The ultrasound signal can interact with the body tissue by reflection and / or scattering. The evaluation unit is specifically designed to distinguish between the first and second sensor signals and to interpret them as originating from the ultrasound transducer or from the body tissue.If the ultrasound image generated based on the second sensor signals is the first ultrasound image, the ultrasound transducer does not need to be configured to receive ultrasound signals. It is sufficient for the transducer to be configured as an ultrasound source. If the ultrasound image generated based on the second sensor signals is the second ultrasound image, there are two ultrasound images generated from different positions: one from the position of the ultrasound transducer and one from the position of the cannula. Therefore, the first and second ultrasound images can differ from each other.

[0013] In a further embodiment of the invention, the evaluation unit is configured to generate a combined ultrasound image by fusing the first and second ultrasound images. This allows for the creation of a more precise ultrasound image of the body tissue. Furthermore, the combined ultrasound image can be three-dimensional.

[0014] Further advantages and features of the invention will become apparent from the claims and from the following description of preferred embodiments of the invention, which are illustrated with reference to the drawings. Fig. Figure 1 shows a schematic representation of an embodiment of a cannula according to the invention for determining the position of a cannula tip inside a body, Fig. 2 a section of the cannula Fig. 1, Fig. Figure 3 shows a schematic representation of an embodiment of a system according to the invention for determining the position of a cannula tip inside a body, which the cannula according to the invention is Fig. 1 includes.

[0015] According to Fig. A cannula 10 is provided. The cannula 10 is suitable for determining the position P of a cannula tip 11 inside a body K. The cannula 10 is for use in a Fig. 3 medical systems shown are suitable, especially in the context of regional anesthesia or biopsy.

[0016] The cannula 10 has a cannula body 12 extending longitudinally along a longitudinal axis L. The cannula tip 11 is located at the distal end of the cannula body 12. The cannula 10 is designed, at least with its cannula tip 11, for insertion into the body K. A connection 14 is provided at the proximal end of the cannula body 12, through which a fluid supply line can be connected to the cannula 10.

[0017] The cannula 10 has sensors 13. The sensors 13 are configured to receive an ultrasound signal B, B'. The sensors 13 can therefore also be referred to as ultrasound sensors. Each sensor 13 generates a first sensor signal S13, which is representative of the received ultrasound signal B, B'. By evaluating the first sensor signals S13, it is possible to determine the position P' of the sensors 13.

[0018] The sensors 13 are arranged on a surface of the cannula body 12. The sensors 13 are attached to the cannula body 12 at a known distance d from the cannula tip 11. In the embodiment according to Fig. Figure 2 shows, by way of example, the distance d of a sensor 13 which is closest to the cannula tip 11. Using the determined position P' of the sensors 13 and the respective distance d of the sensors 13 to the cannula tip 11, the position P of the cannula tip 11 can be determined, at least approximately.

[0019] If the position P of the cannula tip 11 is known, it is possible to position the cannula tip 11 precisely in body L. Depending on the application, an anesthetic can then be administered at the desired location in body P.

[0020] In the Fig. 1 and Fig. In the embodiment shown in Figure 2, the sensors 13 are printed on the surface of the cannula body 12.

[0021] In an alternative embodiment not shown, the sensors 13 are printed onto a film, and the printed film is attached to the cannula body 12 to secure the sensors 13 to the cannula body 12. Alternatively, instead of printing, the sensors 13 can be integrated into the film.

[0022] The cannula 10 has a connecting conductor (not shown) through which the sensors 13 can be connected. The connecting conductor is connected at one end to the sensors 13 and can be connected at the other end to an evaluation unit or the like.

[0023] In the Fig. 1 and Fig. In the embodiment shown in Figure 2, the connecting conductor is printed on the surface of the cannula body 12.

[0024] In an alternative embodiment not shown, the sensors 13 are printed onto or integrated into a film and attached to the surface of the cannula body 12 via the film. Essentially the same attachment options are available for the connecting conductor as for the sensors 13.

[0025] As in the Fig. 1 and Fig. As shown in Figure 2, the sensors 13 are arranged at intervals along the longitudinal axis L of the cannula body 12. Furthermore, the sensors 13 are arranged at intervals along a circumferential direction of the cannula body 12. The sensors 13 form a grid on the surface of the cannula body 12. The distance d between the cannula tip 11 and each of the sensors 13 is known. The distances between the sensors 13 are also known, both along the longitudinal axis L and in the circumferential direction.

[0026] By evaluating the first sensor signals S13 of each of the sensors 13, the position P' of each sensor 13 can be determined. Using the positions P' of the sensors 13, the distances d of the sensors 13 to the cannula tip 13, and the distances between the sensors 13, the position P of the cannula tip 13 can be determined very precisely. Furthermore, it is possible to determine the orientation of the cannula body 12 within the body K. This orientation primarily encompasses the inclination of the longitudinal axis L of the cannula body 12. From this, it can be deduced in which direction the cannula tip 11 will move during (further) advancement of the cannula body 12 into the body K. If necessary, a rotational position of the cannula body 12 relative to the longitudinal axis L can also be determined.

[0027] According to Fig. Figure 3 shows the medical system 1. Besides the cannula 10, system 1 includes an ultrasound probe 2 and an evaluation unit 3.

[0028] The ultrasound transducer 2 is designed to couple the ultrasound signal B into the body K. For this purpose, the ultrasound transducer 2 is applied to the outside of the body K. The coupled ultrasound waves B spread out within the body K in the form of a widening beam. When the ultrasound waves B are reflected at an interface between areas of different body tissue around the cannula tip 11, the reflected ultrasound waves B' return to the ultrasound transducer 2.

[0029] The ultrasound transducer 2 is configured to receive the reflected ultrasound waves B'. The ultrasound transducer 2 generates an ultrasound transducer signal S2, which is characteristic of the received reflected ultrasound waves B'.

[0030] Evaluation unit 3 is connected to ultrasound transducer 2 and sensors 13. Evaluation unit 3 receives the ultrasound transducer signal S2 from ultrasound transducer 2 and evaluates it. Evaluation unit 3 generates an initial ultrasound image of the body tissue based on the ultrasound transducer signal S2.

[0031] The evaluation unit 3 also receives and evaluates the first sensor signals S13 from the sensors 13. From the received first sensor signals S13, the evaluation unit 3 determines the positions P' of the sensors 13 and, based on this, the position P of the cannula tip 11.

[0032] By superimposing the determined position P and the generated ultrasound image, the position P in the body tissue can be displayed.

[0033] The ultrasound waves B emitted by the ultrasound transducer 2 are reflected at smooth interfaces in body tissue as described above. In addition, the ultrasound waves B are scattered at rough interfaces G. The reflected and scattered ultrasound waves are referred to as indirect ultrasound waves B'. To distinguish them, the ultrasound waves B originating directly from the ultrasound transducer 2 are referred to as direct ultrasound waves B.

[0034] The sensors 13 are configured to receive direct ultrasound waves B. They are also configured to receive indirect ultrasound waves B'. The sensors 13 generate a second sensor signal S13, which is characteristic of the received indirect ultrasound waves B'. The designation as first and second sensor signal S13 serves only to distinguish them according to the received ultrasound waves for which the respective sensor signal S13 is characteristic. The evaluation unit 3 receives only a single sensor signal S13 from each sensor 13. This received sensor signal S13 corresponds either to the first sensor signal S13, the second sensor signal S13, or to a superposition of the first and second sensor signals S13.

[0035] In the latter case, the sensor signal S13 represents the direct ultrasound waves B and the indirect ultrasound waves B' in superimposed form. The evaluation unit 3 is configured to determine from the received sensor signal S13 a first component, characteristic of the direct ultrasound waves B and corresponding to the first sensor signal S13, and a second component, characteristic of the indirect ultrasound waves B' and corresponding to the second sensor signal S13. From the first component, the evaluation unit 3 determines the position P of the cannula tip 11. From the second component, the evaluation unit 3 generates an ultrasound image of the body tissue surrounding the cannula tip 11.

[0036] This image can be a second ultrasound image generated by the evaluation unit 3 in addition to the first ultrasound image, which depends on the ultrasound head signal S2.

[0037] However, this image may also be the only ultrasound image generated by the evaluation unit 3. In this case, the ultrasound transducer 2 itself does not need to receive any indirect ultrasound waves B'.

[0038] If the evaluation unit 3 generates a first and a second ultrasound image, it is configured to fuse them to produce an improved, combined ultrasound image. The combined ultrasound image is more accurate than the first and second ultrasound images considered individually.

[0039] Using the multiple sensors 13, it is possible to determine the sources of reflected or scattered ultrasound signals B' via beamforming, i.e., the positions of the interfaces G. The indirect ultrasound signal B' reaches the multiple sensors 13, arranged circumferentially around the cannula body 12, with varying attenuation. By comparing the magnitude and phase of the indirect ultrasound signals B' received by each sensor 13, it is possible to determine the direction from which the indirect ultrasound signals B' originate. The evaluation unit 3 can thus generate a three-dimensional ultrasound image of the body tissue around the cannula tip 11 by evaluating the sensor signals S13.

Claims

[1] cannula (10) comprising a cannula body (12) extending longitudinally along a longitudinal axis (L), a cannula tip (11) arranged at a distal end of the cannula body (12) and several sensors (13) for receiving an ultrasonic signal (B, B'), wherein the sensors (13) are arranged on a surface of the cannula body (12) at a known axial distance (d) to the cannula tip (11), so that by evaluating the received ultrasound signal (B, B') a position (P') of the sensors (13) and thereby a position (P) of the cannula tip (11) can be determined. [2] Cannula (10) according to claim 1, wherein the sensors (13) are printed on the surface of the cannula body (12), in particular by aerosol jet printing. [3] Cannula (10) according to claim 1, wherein the sensors (13) are printed on a film or integrated into a film and attached to the cannula body (12) via the film. [4] Cannula (10) according to claim 2 or 3, wherein a connecting conductor, which is connected at one end to the sensors (13) and can be connected at the other end to an evaluation device (3), is printed on the surface of the cannula body (12) or is attached to the surface of the cannula body (12) via a film, wherein the connecting conductor is printed on the film or integrated into the film. [5] Cannula (10) according to one of the preceding claims, wherein the multiple sensors (13) are arranged on the surface of the cannula body (12) along the longitudinal axis (L) and / or along a circumferential direction of the cannula body (12) and wherein the sensors (13) are arranged at known distances (d) from the cannula tip (11) and at known distances from each other with respect to the longitudinal axis (L) and / or at known distances from each other with respect to the circumferential direction. [6] Medical system (1) for determining the position (P) of a cannula tip (11) in a body (K), comprising an ultrasound head (2) which is designed to couple an ultrasound signal (B) into the body (K), to receive an ultrasound signal (B) reflected from the body tissue surrounding the cannula tip (11) and to generate an ultrasound head signal (S2) representing the received reflected ultrasound signal (B), a cannula (10) according to one of the preceding claims, wherein the sensors (13) are configured to receive the ultrasound signal (B, B') and to generate a first sensor signal (S13) representing the received ultrasound signal (B, B'), and an evaluation unit (3) which is connected to the ultrasound head (2) and the sensors (13), wherein the evaluation unit (3) is configured to Generating a first ultrasound image of the body tissue surrounding the cannula tip (11) depending on the ultrasound head signal (S2) and Determining a position (P) of the cannula tip in relation to the ultrasound head (2) depending on the first sensor signals (S13). [7] Medical system (1) according to claim 6, where the sensors (13) are set up to receive the ultrasound signal (B') after an interaction of the ultrasound signal (B) with the body tissue surrounding the cannula (10) and to generate a second sensor signal (S13) representing the received interacting ultrasound signal (B'), wherein the evaluation unit (3) is set up to generate the first ultrasound image or a second ultrasound image depending on the second sensor signals (S13). [8] Medical system (1) according to claim 7, wherein the evaluation device (3) is configured to generate a combined ultrasound image by fusing the first and the second ultrasound image.

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