IMAGING USING CAVITATION BUBBLES

Abstract

An imaging method for mapping a human or animal tissue area includes generating a plurality of cavitation bubbles in a liquid in the tissue area by ultrasound pulses being irradiated into the tissue area by at least one ultrasound source. A center of a focus area of the irradiated ultrasound pulses is positioned within a first subarea of the tissue area. The first subarea is separated from a second subarea of the tissue area by a tissue boundary, and/or a flow of liquid is present in the first subarea. A spatial distribution and/or movement of the plurality of cavitation bubbles developing in the tissue area on account of a pressure field caused by the irradiated ultrasound pulses is mapped by an imaging modality.

Claims

1. An imaging method for mapping a tissue area of a human or an animal, the imaging method comprising: generating, in a liquid, in the tissue area, a plurality of cavitation bubbles, the generating of the plurality of cavitation bubbles comprising irradiating ultrasound pulses into the tissue area using at least one ultrasound source; positioning a center of a focus area of the irradiated ultrasound pulses within a first subarea of the tissue area, wherein the first subarea is separated from a second subarea of the tissue area by a tissue boundary, a flow of liquid is present in the first subarea, or a combination thereof; and mapping a spatial distribution, movement of the plurality of cavitation bubbles developing in the tissue area on account of a pressure field caused by the irradiated ultrasound pulses, or the spatial distribution and the movement of the plurality of cavitation bubbles using an imaging modality.

2. The imaging method of claim 1, wherein the mapping of the spatial distribution, the movement of the plurality of cavitation bubbles, or the spatial distribution and the movement of the plurality of cavitation bubbles includes an x-ray based imaging, a magnetic resonance tomography, or an ultrasound-based imaging.

3. The imaging method of claim 2, wherein the mapping of the spatial distribution, the movement of the plurality of cavitation bubbles, or the spatial distribution and the movement of the plurality of cavitation bubbles is carried out without administration of contrast agent.

4. The imaging method of claim 1, wherein the first subarea is separated from the second subarea by the tissue boundary, and wherein the first subarea corresponds to an inner area of an object within the tissue area, and the second subarea corresponds to an outer area surrounding the object at least partially.

5. The imaging method of claim 4, wherein the ultrasound pulses are generated such that the pressure field has a minimum in the inner area.

6. The imaging method of claim 4, wherein the ultrasound pulses are generated such that at least one part of the plurality of cavitation bubbles is generated in the outer area.

7. The imaging method of claim 6, further comprising determining, based on a result of the mapping of the movement of the plurality of cavitation bubbles, a movement direction, a movement speed, or the movement direction and the movement speed of one or more cavitation bubbles of the at least one part of the plurality of cavitation bubbles generated in the outer area through a vessel, and wherein the vessel extends through the tissue boundary and fluidically connects the inner area with the outer area.

8. The imaging method of claim 4, wherein the ultrasound pulses are generated such that at least one part of the plurality of cavitation bubbles is generated in the outer area.

9. The imaging method of claim 4, wherein the first subarea is separated from the second subarea by the tissue boundary, and wherein the flow of liquid is present in the first subarea, and the ultrasound pulses are generated such that at least one part of the plurality of cavitation bubbles is generated in the inner area.

10. The imaging method of claim 9, further comprising determining a flow direction, a flow speed, a viscosity, or any combination thereof of the liquid in the inner area based on a result of the mapping of the spatial arrangement, the movement of the plurality of cavitation bubbles, or the spatial arrangement and the movement of the plurality of cavitation bubbles.

11. The imaging method of claim 10, wherein the position of the center of the focus area within the inner area is moved, and wherein the flow direction, the flow speed, the viscosity, or the respective combination thereof within the inner area is determined in a location-dependent manner.

12. An imaging device for mapping a tissue area of a human or an animal, the imaging device comprising: an imaging modality comprising: at least one ultrasound source; and a positioning system for the at least one ultrasound source; and a controller configured to: control the at least one ultrasound source, such that ultrasound pulses are irradiated into the tissue area; and adjust at least one configuration parameter for controlling the at least one ultrasound source, such that a plurality of cavitation bubbles is generated by the irradiated ultrasound pulses in a liquid in the tissue area, wherein the positioning system is configured to position a center of a focus area of the irradiated ultrasound pulses within a first subarea of the tissue area, wherein the first subarea is separated from a second subarea of the tissue area by a tissue boundary, a flow of liquid is present in the first subarea, or a combination thereof, and wherein the imaging modality is configured to map a spatial distribution, movement of the plurality of cavitation bubbles developing in the tissue area on account of a pressure field caused by the irradiated ultrasound pulses, or the spatial distribution and the movement of the plurality of cavitation bubbles.

13. The imaging device of claim 12, further comprising at least one histotripsy converter that includes the at least one ultrasound source.

14. The imaging device of claim 12, wherein the imaging modality is configured as an x-ray-based imaging modality, as a magnetic resonance tomography device, or as an ultrasound-based imaging modality.

15. In a non-transitory computer-readable storage medium that stores instructions executable by an imaging device to map a tissue area of a human or an animal, the instructions comprising: generating, in a liquid, in the tissue area, a plurality of cavitation bubbles, the generating of the plurality of cavitation bubbles comprising irradiating ultrasound pulses into the tissue area using at least one ultrasound source; positioning a center of a focus area of the irradiated ultrasound pulses within a first subarea of the tissue area, wherein the first subarea is separated from a second subarea of the tissue area by a tissue boundary, a flow of liquid is present in the first subarea, or a combination thereof; and mapping a spatial distribution, movement of the plurality of cavitation bubbles developing in the tissue area, or the spatial distribution and the movement of the plurality of cavitation bubbles on account of a pressure field caused by the irradiated ultrasound pulses using an imaging modality.

16. The non-transitory computer-readable storage medium of claim 15, wherein the mapping of the spatial distribution, the movement of the plurality of cavitation bubbles, or the spatial distribution and the movement of the plurality of cavitation bubbles includes an x-ray based imaging, a magnetic resonance tomography, or an ultrasound-based imaging.

17. The non-transitory computer-readable storage medium of claim 16, wherein the mapping of the spatial distribution, the movement of the plurality of cavitation bubbles, or the spatial distribution and the movement of the plurality of cavitation bubbles is carried out without administration of contrast agent.

18. The non-transitory computer-readable storage medium of claim 15, wherein the first subarea is separated from the second subarea by the tissue boundary, and wherein the first subarea corresponds to an inner area of an object within the tissue area, and the second subarea corresponds to an outer area surrounding the object at least partially.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] FIG. 1 shows a schematic representation of an embodiment of an imaging device;

[0066] FIG. 2 shows a schematic representation of an object that is mapped by an embodiment of an imaging method; and

[0067] FIG. 3 shows a schematic representation of a further object that is mapped by a further exemplary embodiment of an imaging method.

DETAILED DESCRIPTION

[0068] FIG. 1 shows a schematic of an embodiment of an imaging device 1.

[0069] The imaging device 1 has an imaging modality 5 (e.g., a sonography system for ultrasound-based imaging). In alternative embodiments, the imaging modality 5 may, however, be configured as a computed tomography device or magnetic resonance tomography device, for example.

[0070] The imaging device 1 also has at least one ultrasound source 3 that may be part of a histotripsy device, for example.

[0071] The imaging device 1 has one or more controllers, computing units, and/or devices for data processing, and is referred to and shown below as a shared controller 4, in order to simplify the representation and the description.

[0072] The controller is therefore configured to control both the at least one ultrasound source 3 and also the imaging modality 5, or obtain images or signals generated by the imaging modality 5. In various embodiments, the different objects and functions of the controller 4 may, however, as mentioned above, be divided over a number of control units, computing units, and/or devices for data processing.

[0073] The controller 4 may adjust at least one configuration parameter in order to control the at least one ultrasound source 3, so that the at least one ultrasound source 3 may irradiate ultrasound pulses according to the configuration parameter into a tissue area 7 of a patient 6. The ultrasound pulses merge, for example, in a focus area, the center of which is located in the inner area of an object 8 inside the tissue area 7. The object 8 may be, for example, a tumor or a vessel or a nidus or other vascular malformation.

[0074] Further, the imaging device 1 contains a positioning system (not shown) that may likewise be controlled by the controller 4 and is configured, controlled by the controller 4, to position the center 2 of the focus area (e.g., in the inner area 8a of the object 8), as shown schematically in FIGS. 2 and 3.

[0075] The object 8 or the inner area 8a of the object 8 is separated by a tissue boundary 8c from an outer area 8b, within the tissue area 7, at least partially surrounding the object 8.

[0076] The controller 4 is configured to adjust the at least one configuration parameter such that stable cavitation bubbles 9 are generated, as shown in FIG. 2 and FIG. 3, by the irradiated ultrasound pulses in a liquid in the tissue area 7 (e.g., in the inner area 8a and/or the outer area 8b).

[0077] The irradiated ultrasound pulses cause a pressure field (e.g., an inhomogenous pressure field) in the tissue area 7, which has a minimum in the center 2 of the focus area. This pressure field exerts a force on the cavitation bubbles 9, and this force causes a specific spatial distribution and/or movement of the plurality of cavitation bubbles 9 to develop, which is caused by the force and the anatomical conditions in the tissue area 7 (e.g., the anatomical structure and shape of the object 8 or the tissue boundary 8c), and possibly also by further forces acting on the cavitation bubbles 9 (e.g., by liquids flowing in the tissue area 7).

[0078] The controller 4 may control the imaging modality 5 accordingly such that the imaging modality 5 maps the tissue area 7 at least partially and as a result maps the developing spatial distribution and/or movement of the plurality of cavitation bubbles 9.

[0079] In the example in FIG. 2, the object 8 is a tumor, for example. The cavitation bubbles 9 are generated, for example, so that the cavitation bubbles 9 develop exclusively or preferably in the outer area 8b. On account of the low pressure that is strongest in the center 2 of the focus area, the cavitation bubbles 9 outside of the tissue boundary 8c are also drawn in the direction of the center 2 of the focus area and adsorb accordingly to the exterior of the tissue boundary 8c in the outer area 8b, since the cavitation bubbles 9 cannot pass through the tissue boundary 8c. The shape and structure of the tissue boundary 8c may therefore be reproduced by mapping the cavitation bubbles 9 using the imaging modality 5.

[0080] For example, tumors or also vascular malformations may have a network-type vascular structure, where it may be important for accurate modeling and/or treatment planning to identify or differentiate supplying and discharging vessels. Such a vessel 10, which passes through the tissue boundary 8c, is shown schematically in FIG. 2.

[0081] Cavitation bubbles 9 that are located in the vessel 10 are therefore subjected not solely to the force caused by the low pressure in the center 2 of the focus area, but also to a force caused by the inflowing or outflowing liquid. If the imaging is now carried out by the controller using the imaging modality 5 in a time-resolved manner, then the movement of such cavitation bubbles 9 in the direction of the inner area 8a or away from the inner area 8c may be observed, and as a result, it is possible to infer the flow direction of the liquid in the vessel 10.

[0082] From the result of the imaging, it may be possible to determine not only the direction of the flow in the vessel 10 in qualitative terms but also the flow speed in the vessel 10 in quantitative or semiquantitative terms.

[0083] A blood vessel is shown schematically as the object 8 in FIG. 3. The cavitation bubbles 9 are generated by a corresponding adaptation or adjustment of the configuration parameters at least partially in the inner area 8a (e.g., exclusively in the inner area 8a). In the inner area 8a of the object 8, a liquid 11 (e.g., blood) flows from left to right in the example shown in FIG. 3. As explained above, the cavitation bubbles 9 that develop about the center 2 of the focus area are subjected to a force in the direction of the center 2 on account of the low pressure. By the liquid flow of the liquid 11 in the vessel (e.g., the blood flow), the cavitation bubbles 9 are moved downstream of the center 2 away from the center 2 or upstream toward the center 2 of the focus area. The cavitation bubbles 9 may, for example, dissipate again downstream on account of the pressure increasing with the distance from the center 2.

[0084] Based on the at least one configuration parameter, the strength of the low pressure in the center 2, the rate of generation of the cavitation bubbles 9 and the size of the cavitation bubbles 9 may be adapted. For example, the configuration parameters may be adapted so that the cavitation bubbles 9 remain spatially stationary downstream of the center 2. In this case, the forces are to some extent balanced out on account of the low pressure in the center 2 and the flow of the liquid 11. Using the at least one configuration parameter, it is then possible to infer the flow parameters (e.g., the flow speed and/or flow direction) of the liquid 11 and/or other fluid properties of the liquid 11 (e.g., a viscosity).

[0085] In various embodiments, differences in the flow parameters or fluid parameters may be identified and determined in a spatially resolved manner by a movement of the center 2 along the vessel. For example, the center 2 may be moved along the vessel. If a spatially stationary distribution of the cavitation bubbles 9 was adjusted as described, it is then possible to infer, for example, with a resolution or change in the stationary distribution that with constant configuration parameters, the force on the cavitation bubbles 9 has changed on account of the flow of liquid 11. It is therefore possible to infer the corresponding changes in the flow parameters or fluid parameters, such as may occur, for example, in vascular restrictions or stenoses.

[0086] As described, for example, on the basis of the figures, the present embodiments allow for contrast agent to be dispensed with in an imaging method and at the same time for tissue boundaries and/or flow parameters or fluid properties to be identified or quantified.

[0087] The elements and features recited in the appended claims may be combined in different ways to produce new claims that likewise fall within the scope of the present invention. Thus, whereas the dependent claims appended below depend from only a single independent or dependent claim, it is to be understood that these dependent claims may, alternatively, be made to depend in the alternative from any preceding or following claim, whether independent or dependent. Such new combinations are to be understood as forming a part of the present specification.

[0088] While the present invention has been described above by reference to various embodiments, it should be understood that many changes and modifications can be made to the described embodiments. It is therefore intended that the foregoing description be regarded as illustrative rather than limiting, and that it be understood that all equivalents and/or combinations of embodiments are intended to be included in this description.