PROVIDING THERMAL CONDUCTIVITY DATA CONCERNING AN ANATOMICAL STRUCTURE FOR CRYOABLATION

Description

[0001] The invention relates to a method for providing thermal conductivity data relating to an anatomical structure. The invention further relates to a data processing system, a medical imaging system, and a medical cryoablation system.

[0002] Cryoablation plays a vital role in the treatment of tumors, for example tumors of the kidney, pancreas or bone.

[0003] US 2010 / 185087 A1 discloses a method for performing a thermal ablation procedure within a volume of interest in a patient.

[0004] US 2011 / 196385 A1 discloses a method for determining a removed object area for removing an object of interest.

[0005] Similar to any thermal tissue destruction, visualization of the ablation zone and changes in temperature in the treated and adjacent tissue are crucial factors for the success of cryoablation therapy. It is essential to achieve complete ablation of the tumor tissue without damaging relevant neighboring structures.

[0006] Pre-interventional determination of thermal tissue conductivity is essential for planning probe placement and assessing potential damage to healthy tissue. Both factors are incorporated into the intervention plan. During ablation, the frozen zone must be visualized as accurately as possible. Similar to other thermal ablations, thermal bridges (large vessels) can lead to inaccurate results. The temporal changes in the ablation zone are particularly relevant in this regard. Generally, image artifacts caused by the inserted probes pose a problem during thermal ablations.

[0007] A medical imaging system, such as one based on ultrasound imaging, magnetic resonance imaging (MRI) or computed tomography (CT), can be used to plan and control cryoablation.

[0008] In ultrasound images, the freezing causes reflection and thus the obliteration of tissue information. The fat content of the tissue influences the visual representation of the organ texture. Thermal bridges in the form of vessels can be assessed (Doppler, CEUS). The problem here is that this is purely qualitative information, and both the probe and the freezing alter the image information, thus making an accurate depiction of the ablation zone difficult.

[0009] MRI can be used to visualize temperature changes in tissue using special sequences. It is also possible to perform a semi-quantitative fat analysis. However, these measurement sequences are highly susceptible to artifacts. Furthermore, susceptibility artifacts occur due to freezing, leading to an inadequate assessment of the precise extent of damaged tissue.

[0010] The invention aims to provide an alternative to conventional planning and monitoring of cryoablation. Each independent claim achieves this objective. The dependent claims address further advantageous aspects of the invention.

[0011] The invention relates to a method for providing thermal conductivity data relating to an anatomical structure, the method comprising: Receiving initial spectral computed tomography data relating to the anatomical structure, wherein the anatomical structure is a kidney and has a fluid-carrying substructure in the form of a renal calyx system, calculating a fat map of the anatomical structure and a water map of the anatomical structure based on the initial spectral computed tomography data, calculating the thermal conductivity data relating to the anatomical structure based on the fat map and the water map, and providing the thermal conductivity data.

[0012] Furthermore, a method for providing thermal conductivity data relating to an anatomical structure is hereby disclosed, the method comprising: Receiving initial spectral computed tomography data relating to the anatomical structure, calculating thermal conductivity data relating to the anatomical structure based on the initial spectral computed tomography data, and providing the thermal conductivity data.

[0013] Spectral computed tomography data, especially the first spectral computed tomography data, may, for example, be based on photon-counting computed tomography and / or dual-energy computed tomography, especially dual-source computed tomography.

[0014] The anatomical structure can be, for example, an organ, in particular a kidney, pancreas, or bone. The anatomical structure can, for example, include the organ and adjacent tissue. The fat map and water map of the anatomical structure can be calculated, for example, based on material decomposition and / or multi-compartment segmentation. For example, the fat map and water map of the anatomical structure can be calculated by segmenting a fat compartment and a water compartment based on the initial spectral computed tomography data, in particular by segmenting them simultaneously.

[0015] The thermal conductivity data can, for example, include a thermal conductivity map of the anatomical structure. This data can relate to thermal tissue conductivity and / or be used for planning and / or monitoring cryoablation. Thermal tissue conductivity is essentially determined by the relative ratio of fat to water. For example, a pixel with a relatively high water content may have a higher thermal conductivity than a pixel with a relatively high fat content. The fat and water maps can be used, for example, to plan cryotherapy of a region of the anatomical structure to be treated, such as to calculate the extent of cryoablation and / or to position a cryoablation probe.

[0016] According to the invention, it is provided that a representation of the fluid-carrying substructure of the anatomical structure is generated based on the fat map of the anatomical structure and / or the water map of the anatomical structure, wherein the thermal conductivity data are calculated based on the representation of the fluid-carrying substructure of the anatomical structure.

[0017] The fluid-bearing substructure of the anatomical structure can, for example, form a thermal bridge. This thermal bridge allows heat to be introduced into the cryoablation zone, counteracting the heat removal by the cryoablation probe. The representation of the fluid-bearing substructure can be generated, for example, by calculating it based on an increased water content within the fluid-bearing substructure.

[0018] One embodiment provides that the anatomical structure has a region to be treated, wherein a representation of a freezing zone for cryoablation of the region to be treated is calculated based on the thermal conductivity data.

[0019] The region to be treated could, for example, be a tumor. The freezing zone can be understood as a target ablation zone, the freezing of which ensures successful treatment of the region without damaging relevant adjacent structures. The freezing zone can also be calculated based on a representation of the region to be treated and / or a region to be spared. In particular, a boundary zone of interest, such as a transition between the cortex and the perirenal tissue, can be taken into account when calculating the freezing zone.

[0020] One embodiment provides that, based on the thermal conductivity data, a representation of the icing zone pertaining to each point in time within a plurality of consecutive time points is calculated. From this, information about the icing rate, for example, can be generated.

[0021] One embodiment provides that, based on thermal conductivity data, a position for a cryoablation probe is calculated, particularly for the cryoablation of the region to be treated. The position of the cryoablation probe can, for example, be related to the anatomical structure and / or to a coordinate system of a cryoablation system. Furthermore, it can be provided that, for each of a plurality of cryoablation probes, a position for that probe is calculated based on thermal conductivity data, particularly for the cryoablation of the region to be treated.

[0022] The heat extraction using the cryoablation probe can induce icing and thus a change in density. The magnitude of this density change corresponds to a degree of icing. The density change map can, in particular, represent an X-ray density and / or assign a CT value, for example on a Hounsfield scale, to each pixel of a plurality of pixels.

[0023] With the help of spectral computed tomography, the density change can be determined, in particular independently of an assessment of the water content and fat content, since there is no complete annihilation of the X-rays in the area of ​​icing.

[0024] One embodiment provides that an icing map of the region to be treated is calculated based on the density change map.

[0025] Furthermore, the icing map can be calculated based on thermal conductivity data and / or based on the fat map and / or water map of the anatomical structure. In particular, the icing map can assign a degree of icing to each pixel within a set of pixels. These pixels can be, for example, 2D pixels or 3D voxels (volume elements).

[0026] Furthermore, it may be provided that the representation of the icing zone calculated on the basis of the thermal conductivity data is superimposed on the density change map and / or the icing map.

[0027] One embodiment involves calculating an operating parameter of the cryoablation probe by applying a control algorithm to the representation of the icing zone as the reference variable and to the icing map as the controlled variable. This allows, for example, monitoring the achievement of optimal icing and / or improved adaptation to a region requiring protection, in order to achieve the most complete ablation possible. The operating parameter of the cryoablation probe can, for example, relate to the probe's temperature and / or its heat extraction rate. In particular, the cryoablation probe can be controlled based on this operating parameter.

[0028] A temporal progression of icing can, for example, be analyzed based on a vector analysis over the majority of icing maps and / or correlated with the thermal conductivity data and / or the representation of the icing zone, in particular for each point in time of the majority of successive points in time for which a representation of the icing zone was calculated, in particular to be able to assess the extent of icing, for example to be able to assess its conformity with a planned course of cryoablation.

[0029] The first spectral computed tomography data can be acquired, in particular, without having to apply a contrast agent to the anatomical structure.

[0030] Should contrast-enhanced computed tomography become necessary during cryoablation, for example in case of suspected acute bleeding, spectral segmentation of iodine is also possible within the ablation zone with reference to the existing density maps, for example to generate an iodine map of the anatomical structure.

[0031] Residual hemorrhages and larger areas of necrosis can also be visualized and / or monitored during cryoablation as described above. Changes in water content and / or density can also be used to monitor the effectiveness of the freezing process.

[0032] The invention further relates to a data processing system for providing thermal conductivity data relating to an anatomical structure, comprising a data interface and a processor, wherein the data processing system is configured to execute a method according to the invention.

[0033] The invention further relates to a medical imaging system comprising the data processing system according to the invention and a computed tomography device for recording the first spectral computed tomography data.

[0034] The computed tomography device can be set up, for example, to acquire spectral computed tomography data, in particular the first spectral computed tomography data, based on photon-counting computed tomography and / or dual-energy computed tomography, in particular dual-source computed tomography.

[0035] The invention further relates to a medical cryoablation system comprising the medical imaging system and a cryoablation probe.

[0036] Therefore, providing thermal conductivity data can facilitate functional therapy planning. In particular, compared to image fusion in magnetic resonance imaging, the effort required for imaging prior to ablation is reduced. During ablation, the advantages of computed tomography, such as 3D imaging, speed, and the use of metal components in the treatment area, can also be utilized.

[0037] Furthermore, therapy monitoring of the cryoablation zone under freezing is possible. This allows for the assessment and documentation of cryoablation with regard to precise and complete coverage of the region to be treated, as well as the degree of freezing, and in particular, its quantitative evaluation and documentation.

[0038] The method for providing thermal conductivity data can, in particular, be a computer-implemented method.

[0039] The invention further relates to a computer program product comprising instructions which, when executed by a computer, cause the computer to execute the method according to the invention.

[0040] The computer program product can be, for example, a computer program or, in addition to the computer program, it can comprise at least one additional component. This additional component can be implemented as hardware and / or software.

[0041] The computer program product may, for example, include a storage medium on which at least part of the computer program product is stored, and / or a key for authenticating a user of the computer program product, particularly in the form of a dongle. The computer program product and / or the computer program may, for example, include a cloud application program configured to distribute instructions to different processing units, particularly different computers, of a cloud computing system, each processing unit being configured to execute one or more of the instructions.

[0042] The invention further relates to a computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to execute the method according to the invention.

[0043] The computer-readable storage medium can, for example, store the computer program product according to one of the embodiments disclosed in this application and / or the computer program according to one of the embodiments disclosed in this application. The computer-readable storage medium can, for example, be a memory stick, a hard drive, or another data carrier, which can be detachably connected to a computer or permanently integrated into a computer. The computer-readable storage medium can, for example, form part of a storage system, wherein the data processing system is connected to the storage system via the data interface.

[0044] The data processing system can, for example, comprise one or more hardware components and / or one or more software components. The data processing system can, for example, be at least partially comprised of a cloud computing system. The data processing system can be, for example, a cloud computing system, a computer network, a computer, a tablet computer, a smartphone, or a combination thereof.

[0045] The hardware can, for example, interact with software and / or be configurable by software. The software can, for example, be executed using the hardware. The hardware can be, for example, a memory system, an FPGA system (field-programmable gate array), an ASIC system (application-specific integrated circuit), a microcontroller system, a processor system, and combinations thereof. The processor system can, for example, consist of one microprocessor and / or several interacting microprocessors.

[0046] The steps of the procedure can be executed, for example, in the processor of the data processing system, particularly in the form of calculations. A calculation, such as calculating thermal conductivity data and / or calculating the representation of the icing zone, can be performed, in particular, by applying an algorithm, for example, a trained machine learning algorithm, to the data on which the calculation is based.

[0047] Data transfer between components of the medical imaging system and / or the medical cryoablation system can be achieved, for example, via a suitable data transfer interface. The data transfer interface for transferring data to and / or from a component of the medical imaging system and / or the medical cryoablation system can be implemented at least partially in software and / or at least partially in hardware. The data transfer interface can, for example, be configured to store data in and / or read data from a storage area, which can be accessed by one or more components of the medical imaging system and / or the medical cryoablation system.

[0048] Data, in particular the initial computed tomography data, can be received, for example, by receiving a signal carrying the data and / or by reading the data, in particular from a computer-readable storage medium. Data, in particular the thermal conductivity data, the representation of the icing zone, the grease map, the water map, the density change map, the icing map, and the operating parameters of the cryoablation probe, can be provided, for example, by transmitting a signal carrying the data and / or by writing the data to a computer-readable storage medium and / or by displaying the data on a screen.

[0049] The thermal conductivity data, the representation of the icing zone, the grease map, the water map, the density change map and the icing map can each be structured in particular in the form of two-dimensional image data or three-dimensional image data.

[0050] Within the scope of the invention, features described in relation to different embodiments of the invention and / or different claim categories (method, use, device, system, arrangement, etc.) can be combined to form further embodiments of the invention. For example, a claim relating to a device can also be further developed with features described or claimed in connection with a method, and vice versa. Functional features of a method can be implemented by appropriately designed physical components. The use of the indefinite article "a" or "an" does not preclude the possibility that the feature in question may be present multiple times. The expression "based on" can, in the context of this application, be understood in particular as meaning "using" or "based on".In particular, a formulation according to which a first characteristic is calculated (alternatively: determined, generated, etc.) based on a second characteristic does not preclude the possibility that the first characteristic may also be calculated (alternatively: determined, generated, etc.) based on a third characteristic.

[0051] The invention is explained below with reference to exemplary embodiments and the accompanying figures. The representation in the figures is schematic, greatly simplified, and not necessarily to scale.

[0052] The Fig. 1 shows an anatomical structure in a first state of the anatomical structure.

[0053] The Fig. 2 shows the anatomical structure in a second state of the anatomical structure.

[0054] The Fig. 3 shows a flowchart of a procedure for providing thermal conductivity data relating to an anatomical structure N.

[0055] The Fig. 4 shows a medical cryoablation system.

[0056] The Fig. 1 Figure 1 shows anatomical structure N in its initial state, in which no cryoablation probe is inserted. Anatomical structure N is represented as a kidney, including the renal capsule C and the perirenal tissue F. Structure N includes a fluid-filled substructure in the form of blood vessels B, specifically the renal artery BA and the renal vein BV, and a fluid-filled substructure in the form of the renal calyces K. Structure N also includes the region to be treated, T, in the form of a tumor.

[0057] The Fig. 2 Figure 1 shows anatomical structure N in a second state, in which the cryoablation probe D is inserted into anatomical structure N. The freezing zone E for cryoablation of the region T to be treated is also shown.

[0058] The Fig. 3 shows a flowchart of a procedure for providing thermal conductivity data relating to an anatomical structure N, encompassing the procedure: a receiving S1 of first spectral computed tomography data relating to the anatomical structure N, a calculating S2 of a fat map of the anatomical structure N and a water map of the anatomical structure N based on the first spectral computed tomography data, a calculating S3 of the thermal conductivity data relating to the anatomical structure N based on the fat map and the water map, a providing S4 of the thermal conductivity data.

[0059] The Fig. 4 Figure 1 shows the medical cryoablation system 1D, comprising the medical imaging system 1 and the cryoablation probe D. The medical imaging system 1 includes the data processing system 3 and the computed tomography unit 2 for acquiring the initial spectral computed tomography data. The data processing system 3 for providing thermal conductivity data includes the data interface 3A and the processor 3B, wherein the data processing system 3 is configured to process the data contained in the Fig. 3 To carry out the methods shown. The data processing system 3 is connected to the computed tomography device 2, in particular via cable or wirelessly, to receive the spectral computed tomography data from the computed tomography device. The data processing system 3 is connected to the cryoablation probe D, in particular via cable or wirelessly, to provide the operating parameters of the cryoablation probe D to the cryoablation probe D.

Claims

1. Method for providing thermal conductivity data relating to an anatomical structure (N), the method comprising: - receiving (S1) first spectral computed tomography data relating to the anatomical structure (N), wherein the anatomical structure (N) is a kidney and has a fluid-guiding substructure in the form of a renal calyx system, - calculating (S2) a fat map of the anatomical structure (N) and a water map of the anatomical structure (N) on the basis of the first spectral computed tomography data, - calculating (S3) the thermal conductivity data relating to the anatomical structure (N) on the basis of the fat map and the water map, wherein a representation of a fluid-guiding substructure of the anatomical structure (N) is generated on the basis of the fat map of the anatomical structure (N) and / or the water map of the anatomical structure (N), wherein the thermal conductivity data is calculated on the basis of the representation of the fluid-guiding substructure of the anatomical structure (N), - providing (S4) the thermal conductivity data.

2. Method according to claim 1, - wherein the anatomical structure (N) has a region to be treated (T), - wherein a representation of a freezing zone (E) for a cryoablation of the region to be treated (T) is calculated on the basis of the thermal conductivity data.

3. Method according to claim 2, - wherein, for each time point of a plurality of consecutive time points, a representation of the freezing zone (E) relating to this time point is calculated in each case on the basis of the thermal conductivity data.

4. Method according to one of claims 1 to 3, - wherein a position for a cryoablation probe (D) is calculated on the basis of the thermal conductivity data.

5. Data processing system (3) for providing thermal conductivity data, having a data interface (3A) and a processor (3B), wherein the data processing system (3) is configured to carry out a method according to one of claims 1 to 4.

6. Medical imaging system (1), having the data processing system (3) according to claim 5 and a computed tomography device (2) for recording the first spectral computed tomography data.

7. Medical cryoablation system (1D), having the medical imaging system (1) according to claim 6 and a cryoablation probe (D).

8. Computer program product, comprising instructions which, when the instructions are executed by a computer, cause the computer to carry out the method according to one of claims 1 to 4.

9. Computer-readable storage medium, comprising instructions which, when the instructions are executed by a computer, cause the computer to carry out the method according to one of claims 1 to 4.