阅读说明：本技术 用于创建数字减影血管造影的方法和设备 (Method and apparatus for creating digital subtraction angiography ) 是由 M.科瓦希克 S.沙弗 于 2020-09-21 设计创作，主要内容包括：本发明涉及用于创建数字减影血管造影的方法和设备。为了全面地识别空心器官系统,用于创建患者的空心器官系统的数字减影血管造影的方法包括：提供借助X射线设备记录的掩模图像数据；提供借助X射线设备记录的至少第一填充图像数据,从第一静脉内造影剂注射和在时间上在后的第二动脉内造影剂注射开始,在利用造影剂对空心器官系统的至少部分造影剂填充期间,记录至少第一填充图像数据；通过从至少第一填充图像数据中减去掩模图像数据,来确定至少第一减影图像数据；根据至少第一减影图像数据,来确定最终的减影图像数据；以及分割最终的减影图像数据,并且对最终的减影图像数据的像素或者体素,根据其相应的强度值,分配至少两个不同的强度等级。(The invention relates to a method and apparatus for creating digital subtraction angiography. To fully identify the hollow organ system, a method for creating a digital subtraction angiography of the hollow organ system of a patient includes: providing mask image data recorded by means of an X-ray device; providing at least first filling image data recorded by means of an X-ray device, the at least first filling image data being recorded during at least partial contrast agent filling of the hollow organ system with contrast agent, starting from a first intravenous contrast agent injection and a temporally subsequent second intra-arterial contrast agent injection; determining at least first subtracted image data by subtracting the mask image data from the at least first filler image data; determining final subtraction image data from at least the first subtraction image data; and segmenting the final subtracted image data and assigning at least two different intensity levels to pixels or voxels of the final subtracted image data according to their respective intensity values.)

1. A method for creating a digital subtraction angiography of a hollow organ system of a patient, comprising the steps of:

providing mask image data recorded by means of the X-ray device (10);

providing at least first fill image data recorded by means of the X-ray device (10), which are recorded during at least partial contrast agent filling of the hollow organ system with contrast agent, starting from a first intravenous contrast agent injection and a temporally subsequent second intra-arterial contrast agent injection;

determining at least first subtracted image data by subtracting mask image data from the at least first filler image data;

determining final subtracted image data from the at least first subtracted image data; and

the final subtracted image data is segmented and at least two different intensity levels are assigned to the pixels or voxels of the final subtracted image data depending on their respective intensity values.

2. The method according to claim 1, wherein the first subtracted image data is used as final subtracted image data.

3. The method according to claim 1, having the steps of:

providing at least first and second fill image data recorded by means of the X-ray device (10), which are recorded starting from a first intravenous contrast agent injection and a temporally subsequent second intra-arterial contrast agent injection during at least partial contrast agent filling of the hollow organ system with contrast agent;

determining at least first and second subtracted image data by subtracting mask image data from the at least first and second filler image data; and

determining the final subtracted image data from the at least first and second subtracted image data by determining the maximum intensity value of the corresponding pixel or voxel of the at least first and second subtracted image data as the intensity value of each pixel or voxel of the final subtracted image data.

4. The method according to any of the preceding claims, wherein mask image data is formed by at least one series of projection mask images and at least first and/or second fill image data is formed by at least one first and/or second series of projection fill images, wherein the series of projection mask images are reconstructed into a mask volume and the at least first and/or second series of projection fill images are reconstructed into at least one first and/or second fill volume, wherein the at least one first and/or second subtraction volume is determined by subtracting a mask volume from the at least first and/or second fill volume, wherein a final subtraction volume is determined from the at least first and/or second subtraction volume, and wherein the final subtraction volume is segmented, wherein at least two different intensity levels are assigned to the voxels of the final subtracted volume in accordance with their respective intensity values.

5. The method according to any of the preceding claims, wherein mask image data is formed by at least one series of projection mask images and at least first and/or second fill image data is formed by at least one first and/or second series of projection fill images, wherein at least one first and/or second series of subtracted images is determined by subtracting the series of projection mask images from at least the first and/or second series of projection fill images, wherein the at least one first and/or second series of subtracted images is reconstructed into at least one first and/or second subtracted volume, wherein a final subtracted volume is determined from the at least first and/or second subtracted volume, and wherein the final subtracted volume is segmented, wherein voxels of the final subtracted volume, at least two different intensity levels are assigned according to their respective intensity values.

6. The method according to any of the preceding claims, wherein at least two intensity levels are distinguished by applying at least one intensity threshold.

7. Method according to any of the preceding claims, wherein a digital subtraction angiography of the hollow organ system is displayed on a display unit, wherein the parts of the hollow organ system assigned to different intensity levels are marked in different colors.

8. The method according to claim 4 or 5, wherein at least one series of projection mask images and at least one first and/or second series of projection fill images are recorded during a respective at least one rotational progression of the recording system around the patient.

9. A device (9) for carrying out the method according to any one of claims 1 to 8, the device having an image processing unit (12) which is configured for determining subtraction image data by subtracting mask image data from fill image data; determining final subtraction image data; and segmenting the final subtracted image data; and assigning at least two different intensity levels to pixels or voxels of the final subtracted image data according to their corresponding intensity values; and the device has a storage unit (13) for storing image data.

10. The device according to claim 9, having an X-ray device, in particular a C-arm X-ray device (10), which is designed for recording mask image data and fill image data of a hollow organ system of a patient.

11. The device according to claims 9 and 10, having a contrast agent injection device (IN1, IN2, 15) with at least two injectors arranged at a distance, wherein a first injector (IN1) is configured for triggered intravenous injection of contrast agent and a second injector (IN2) is configured for temporally subsequent intra-arterial injection of contrast agent, and having a trigger device (15) for automatically activating the injectors (IN1, IN2) IN a controlled manner.

12. The device as claimed IN claim 11, having a system controller (11) for controlling the X-ray device (10), the image processing unit (12) and the contrast agent injection device (IN1, IN2, 15).

Technical Field

The invention relates to a method for creating a digital subtraction angiography of a hollow organ system of a patient and to a device for carrying out such a method.

Background

Digital Subtraction Angiography (DSA) is commonly used to examine blood vessels or, more generally, hollow organs. In the simplest two-dimensional variant, temporally successive (two-dimensional) projection images of the vascular system of the patient to be examined are created by means of an X-ray angiography system (for example by means of a C-arm system), during which contrast agent is injected. A projection image without contrast agent, also called mask image, is generated and a further projection image with contrast agent distribution in the vessel system, the so-called projection fill image, is generated. The digital mask image is subtracted from the subsequent projection fill image. Only the different parts, i.e. in general, exactly the vascular system, remain.

Three-dimensional digital subtraction angiography (3D DSA) enables contrast (kontrastitert) vascular systems to be displayed with high resolution, for example as 3D volumes. For this purpose, a masking process without contrast agent is generally carried out, and a filling process with contrast agent is carried out, and a series of projection images is accordingly created here. The two-dimensional projection images are usually derived from the recording protocol of a C-arm X-ray apparatus (for example Cone-beam CT or Cone-beam CT) which is rotated around the patient. A series of projection mask images are typically subtracted from a series of projection fill images and the resulting series of two-dimensional subtraction images are reconstructed into a three-dimensional subtraction angiographic image. Time resolved 3D digital subtraction angiography is referred to as 4D DSA.

For the diagnosis and treatment of clinical conditions, it is necessary to display the vascular system in organs such as the brain, the heart or the liver particularly well and accurately. In this case, it is important to display the arterial and venous vascular system. Therefore, it is increasingly important for different applications that the venous vasculature in the brain can be accurately displayed. For example in so-called AVM (═ AVM)Malformation (arteriovenous Malformation)), that is, a spherical Malformation of a blood vessel (a)Fehlbildung) in which the artery is directly connected to the vein without capillaries. In the case of brain AVM, there is a great risk of rupture of, for example, severe cerebral hemorrhage due to high pressure in the blood vessels. For the prophylactic treatment of AVMs, for example venous AVM embolization is performed, wherein an embolization that occludes a blood vessel is injected into the blood vessel inside the AVM under X-ray monitoring. In order to perform such an intervention, an image of the complete cerebrovascular system must be presented, and the AVM supply artery must also be identified, and in particular (because of the more difficult to determine) the drainage vein.

With known DSA methods, although the cerebrovascular system can be visualized, it is generally difficult to find the AVM supply artery and the drainage vein from the many arteries that are visualized.

Disclosure of Invention

The object of the invention is to provide a method for creating a digital subtraction angiography of a hollow organ system of a patient, which enables the AVM drainage vein and the AVM supply artery to be identified; furthermore, the object of the invention is to provide a device suitable for carrying out the method.

According to the invention, the above-mentioned technical problem is solved by a method according to the invention for creating a digital subtraction angiography of a hollow organ system of a patient and by a device according to the invention. Advantageous embodiments of the invention are accordingly the subject matter of the following description.

The method according to the invention for creating a digital subtraction angiography of a hollow organ system of a patient comprises the following steps: providing mask image data recorded by means of an X-ray device; providing at least first fill image data recorded by means of an X-ray device, the at least first fill image data being recorded starting from a first intravenous contrast agent injection and a temporally subsequent second intra-arterial contrast agent injection during at least partial contrast agent filling of the hollow organ system with contrast agent; determining at least first subtracted image data by subtracting the mask image data from the at least first filler image data; determining final subtraction image data from at least the first subtraction image data; and segmenting the final subtracted image data and assigning at least two different intensity levels to pixels or voxels of the final subtracted image data according to their respective intensity values.

By the method according to the invention, particularly in the case of spatially and temporally suitable preceding contrast agent injections, not only a comprehensive image of the desired hollow organ system can be created, but also, by dividing into a plurality of intensity levels, a clear indication can be given for, in particular, the draining veins and the supply arteries. The invention assumes that hollow organs through which a particularly large amount of contrast medium flows have particularly high intensity values on the X-ray image, at least for a short time. Since in AVM there are no capillaries between the artery and the vein, the flow from the artery to the vein is particularly high here. For physicians commissioned, for example, to diagnose and treat AVM, this information is of great significance and can contribute to significantly improved care for the patient. Thus, in the case of AVMs present in the brain of a patient, for example by means of DSA produced in the method, it is possible for the physician to clearly identify which veins drain the AVM and which arteries supply the AVM, so that the physician can then perform a safe, correct treatment, for example in the form of an embolism. Here, the injection site of the first intravenous injection of the contrast medium performed in advance may be, for example, an arm vein, and the injection site of the second intra-arterial injection is preferably an intra-cerebral artery.

According to one embodiment of the invention, the first subtraction image data is used as the final subtraction image data. This is advantageous for the case where only the first subtraction image data is present.

According to a further embodiment of the invention, the following steps are carried out: providing at least first and second fill image data recorded by means of an X-ray device, the at least first and second fill image data being recorded during at least partial contrast agent filling of the hollow organ system with contrast agent, starting from a first intravenous contrast agent injection and a temporally subsequent second intra-arterial contrast agent injection; determining at least first and second subtracted image data by subtracting the mask image data from the at least first and second filler image data; and determining final subtracted image data from the at least first and second subtracted image data by determining the maximum intensity value of the corresponding pixel or voxel of the at least first and second subtracted image data as the intensity value of each pixel or voxel of the final subtracted image data. .

In the case of the presence of at least a first and a second fill-in image data, i.e. two or more sets of fill-in image data, the maximum intensity value is selected accordingly from all subtraction image data for each pixel or voxel and used for the final subtraction image data in an advantageous manner. That is, for example, if the intensity value of a specific pixel in the first subtracted image data is smaller than the intensity value of a specific pixel in the second subtracted image data, the intensity value of the second subtracted image data is used as the final value. In this way, the intensity values are compared for all pixels or voxels of the image data, and the corresponding maximum intensity value is then selected. That is, the final subtracted image data consists of the respective maximum intensity values of all pixels/voxels of the hollow organ system. In this way, a comprehensive image of the hollow organ system can be created independently of the temporally individual degree of filling of the corresponding filling image data. That is to say, a time-independent filling image is created, which then shows the physician a systematic overview of the entire hollow organ system. There may also be more than two sets of fill-in image data, in which case the maximum intensity value per pixel/voxel is then also selected from three or more values. Since hollow organs through which a particularly large amount of contrast medium flows have particularly high intensity values on the X-ray image at least for a short time, a particularly good overview of the hollow organ system can be created by using the maximum intensity values.

According to a further embodiment of the invention, the mask image data is formed from at least one series of projection mask images and the at least first and/or second fill image data is formed from at least one first and/or second series of projection fill images, wherein the series of projection mask images is reconstructed to a mask volume and the at least first and/or second series of projection fill images is reconstructed to at least one first and/or second fill volume, wherein the at least one first and/or second subtraction volume is determined by subtracting the mask volume from the at least first and/or second fill volume, wherein a final subtraction volume is determined from the at least first and/or second subtraction volume, and wherein the final subtraction volume is segmented, wherein voxels of the final subtraction volume, at least two different intensity levels are assigned according to their respective intensity values. The method can be performed as 3D, or even 4D-DSA, in addition to 2D. In particular, at least one series of projection mask images and at least one first and/or second series of projection fill images are recorded during a respective at least one rotational pass of the recording system around the patient. The projection images are recorded during a rotational progression of the C-arm around the patient, for example as 3D-DSA. In this case, for example, a cone beam CT process may be involved. According to a preferred embodiment, there is for example projection image data from two consecutive mask passes (200 ± x degrees forward and backward) and fill image data from three fill passes (200 ± x degrees forward, backward and again forward) after the mask pass.

As an alternative thereto, in 3D-DSA it is also possible to first subtract 2D image data from each other and subsequently reconstruct the image sequence into a volume: according to a further embodiment of the invention, the mask image data are formed from at least one series of projection mask images, and at least first and/or second filler image data are formed from at least one first and/or second series of projected filler images, wherein at least one first and/or second series of subtracted images is determined by subtracting the series of projection mask images from at least a first and/or second series of projection fill images, wherein the at least one first and/or second series of subtracted images are reconstructed into at least one first and/or second subtracted volume, wherein a final subtracted volume is determined from at least the first and/or the second subtracted volume, and wherein the final subtracted volume is segmented, wherein at least two different intensity levels are assigned to the voxels of the final subtracted volume in accordance with their respective intensity values.

According to a further embodiment of the invention, at least two intensity levels are distinguished by using at least one intensity threshold. In other words, exactly one threshold value is selected or, in particular, preset, for example, when two intensity levels are distinguished. All pixels or voxels having an intensity value below the threshold belong to the first intensity level and all pixels or voxels having an intensity value above the threshold belong to the second intensity level. For the purpose of differentiation, an image processing unit with an algorithm, for example, is used, which divides the intensity values into intensity classes. Three or more intensity levels may also be used, which are then distinguished by two or more thresholds.

In an advantageous manner, in order to be able to particularly well identify the different intensity levels, a digital subtraction angiography of the hollow organ system is displayed on the display unit, wherein the parts of the hollow organ system assigned to the different intensity levels are marked in different colors. Thus, for example, it can be provided that all pixels or voxels assigned a first intensity level are colored in a first color, for example green, and all pixels or voxels assigned a second intensity level are colored in a second color, for example red.

Furthermore, the invention claims a device for carrying out the method, having an image processing unit, in particular having at least one image processing algorithm, which is designed to determine subtraction image data by subtracting mask image data from fill image data; determining final subtraction image data; and segmenting the final subtracted image data; and assigning at least two different intensity levels to pixels or voxels of the final subtracted image data according to their corresponding intensity values; and the device has a storage unit for storing image data. In an advantageous manner, the device has an X-ray device, in particular a C-arm X-ray device, which is designed for recording mask image data and fill-in image data of a hollow organ system of a patient. The device may also expediently have a contrast agent injection device with at least two injectors arranged at a distance from one another, wherein the first injector is designed for triggered intravenous injection of contrast agent and the second injector is designed for temporally subsequent intra-arterial injection of contrast agent, and the contrast agent injection device has a trigger device for automatically activating the injectors in a controlled manner. Furthermore, the device may have a system controller for controlling the X-ray device, the image processing unit and the contrast agent injection device.

Drawings

The invention and further advantageous embodiments of the features according to the invention are explained in detail below with the aid of exemplary embodiments which are schematically illustrated in the drawings, without the invention being restricted to these exemplary embodiments.

FIG. 1 shows a series of steps of a method according to the invention;

fig. 2 shows a view of a possible acquisition protocol for recording image data provided for the method; and

fig. 3 shows a view of a C-arm X-ray device for performing the method.

Detailed Description

Fig. 1 shows a series of the most important steps of the method according to the invention for creating a digital subtraction angiography of a hollow organ system of a patient. The hollow organ system may be, for example, a cerebrovascular system or also a vascular system in the heart or the liver or other organs of the patient. By means of the method, the desired vascular system can be displayed in its entirety and particularly high-flow vessels, for example AVM drainage veins, can be identified.

In a first step 1 mask image data of the hollow organ system recorded by means of an X-ray apparatus are provided, and in a second step 2 at least first fill image data recorded by means of the same X-ray apparatus are provided, which first fill image data are recorded during contrast filling of the hollow organ system with contrast agent at least partially starting from a first intravenous contrast agent injection and a temporally subsequent second intra-arterial contrast agent injection. Depending on the application, these image data may be 2D, 3D or 4D image data. An exemplary 4D-DSA acquisition protocol for creating mask image data and pad image data is shown in fig. 2 and described in more detail below. In case of 2D-DSA the mask image data is a number of single projection mask images and the filler image data is a number of single projection filler images, in case of 3D-DSA the mask image data is a series of projection mask images and the filler image data is a series of projection filler images. 4D-DSA is time-resolved 3D-DSA, wherein the temporal information is generated by means of 2D image data on the basis of the 3D-DSA image data.

In one possible embodiment of the method, first mask image data and first and second pad image data are provided. Two or more sets of mask image data and three or more sets of fill image data may also be provided.

In a third step 3, which may be optional or only occur in case of 3D or 4D-DSA, the (at least first) series of projection mask images is reconstructed as a mask volume, the (at least) first series of projection fill images is reconstructed as a first fill volume, and the (if present) second series of projection fill images is reconstructed as a second fill volume. Here, a known reconstruction algorithm is used.

In a fourth step 4, the first and second subtracted image data are determined by subtracting the mask image data from at least the first and second fill image data, that is to say, in the 3D case, the first and second subtracted volumes are determined by subtracting the mask volume from the first and second fill volumes. If only the first filler image data is present, only the first subtracted image data is also obtained. If there is third or more filler image data, three or more subtraction image data are also obtained.

In a fifth step 5, the final subtraction image data is determined from all the existing subtraction image data. If only the first subtracted image data (e.g., subtracted volume) is present, the first subtracted image data is determined to be the final subtracted image data (e.g., final subtracted volume). If first and second subtracted image data (e.g., first and second subtracted volumes) are present, the maximum intensity value of the corresponding pixel or voxel of the first and second subtracted image data is always selected and used as the intensity of each pixel or voxel of the final subtracted image data. That is, of the low and high intensity values, the high intensity value is always used. That is, an image or volume is produced from the maximum intensity values. If there are three or more, for example subtraction volumes, then the largest intensity value is selected from all the existing intensity values and used. After this step, a comprehensive image of the hollow organ system of the examined organ, e.g. the brain, has been obtained. The final subtracted image data, e.g. the final subtracted volume, may be displayed on a display unit.

In a sixth step 6, the final subtracted image data (e.g. the final subtracted volume) is segmented and at least two different intensity levels are assigned to the pixels or voxels of the final subtracted image data (e.g. the final subtracted volume) depending on their respective intensity values. The segmentation and assignment may be performed, for example, by known segmentation methods, such as known clustering algorithms (e.g., k-means algorithms). At least two intensity levels may be distinguished, for example, by using at least one intensity threshold. The intensity threshold value can be set or selected beforehand or during the method. The intensity threshold may be selected automatically or manually. The final subtracted image data, e.g. the final subtracted volume, may be displayed in segmented form on a display unit. Thus, for example, parts of the hollow organ system assigned to different intensity levels can be marked in different colors. Thus, for example, it can be provided that all pixels or voxels assigned a first intensity level are colored in a first color, for example green, and all pixels or voxels assigned a second intensity level are colored in a second color, for example red. In this way, it is particularly simple for the user to identify which parts of the vascular system are systemic and which parts are supplied with blood by the artery (of the brain, for example) into which the second injection was injected. In this way, for example, the AVM draining vein and the AVM supplying artery can be made visible.

An exemplary 4D-DSA acquisition protocol for creating mask image data and filler image data is shown in fig. 2. This or a similar protocol is performed prior to the actual method to record the corresponding mask image data and fill image data. The projection images are recorded during a rotational progression of the C-arm of the (angiographic) X-ray device around the patient, in particular around the organ to be displayed. In this case, for example, a cone beam CT process may be involved. The exemplary protocol consists of two consecutive mask processes (MBv + z; 200+ x degrees forward and backward) and of three fill processes (FB1v + z and FB2 v; 200+ x degrees forward and backward, and again forward) following the mask processes. Three padding procedures are performed to cover a particularly long period of time for 4D-DSA. For normal 3D-DSA, for example, one masking process and one filling process often suffice. The duration of each individual process may typically be 5s, for example.

First, a first injection is started at a first time point t1, for example a first syringe for an intravenous injection of contrast agent is activated in the first injection. The syringe may be located in a peripheral vein, such as an arm vein (armgene). Approximately simultaneously with the first injection, a forward mask process is started (forward and backward here relates to a direction of rotation around the patient), from which a first series of projection mask images (MBv) of, for example, the brain of the patient are taken, after which a backward mask process is directly performed, from which a second series of projection mask images (MBz) of the brain are recorded. When the two mask passes each last about 5s, the cerebral vessels are not yet filled with contrast agent, since this usually lasts about 10s before the contrast agent reaches the brain. After the masking procedure, a second injection is started directly, for example in which a second injector for intra-arterial injection of contrast agent is activated, at a second point in time t2, for example approximately 10s after the first point in time t 1.

The second syringe may be located in a cerebral artery, preferably the supply artery of the AVM to be displayed. For example, the carotid artery may be used. Approximately simultaneously with the second injection, three filling passes are performed in sequence, namely a first forward filling pass, a first backward filling pass and a second forward filling pass, a first series of projected filling images being obtained from the first forward filling pass (FB1v), a second series of projected filling images being obtained from the first backward filling pass (FB1z) and a third series of projected filling images being obtained from the second forward filling pass (FB2 z).

During the execution of three filling sessions (each about 5s, thus about 15s in total), it is generally desirable that the contrast agent from the first injection is distributed in the cerebral vascular system, and that a particularly large amount of contrast agent from the second injection flows from the supply artery of the AVM into the corresponding vein. In the case of a particular protocol, it may make sense to subtract image data from a similar process in a later subtraction of fill image data and mask image data (i.e., a forward fill process minus a forward mask process, and a backward fill process minus a backward mask process). In the reconstructed volume, this is usually not required. Two injections may typically be performed with the same contrast agent. Other acquisition protocols, for example with only one or at least three mask passes and one, two or at least four filling passes, other durations, more injections, other organs, etc. may also be used. The 4D-DSA recording protocol may be similarly implemented. In the 2D-DSA recording protocol, only a few single projection images are realized, no rotation process is performed, and the sequence is similar to that of 3D-DSA.

The corresponding acquisition protocol may be automatically controlled by the system controller.

A device 9 suitable for performing the method is shown for example in fig. 3. The device 9 has an image processing unit 12, the image processing unit 12 having in particular at least one image processing algorithm. The image processing unit is designed to determine subtraction image data by subtracting the mask image data from the fill image data, to determine final subtraction image data and to segment the final subtraction image data, and to assign at least two different intensity levels to the pixels or voxels of the final subtraction image data as a function of their respective intensity values. Furthermore, the apparatus has a storage unit 13 for storing image data. Furthermore, the device 9 comprises an X-ray device, in particular a C-arm X-ray device 10, which is configured for recording mask image data and fill-in image data of a hollow organ system of a patient.

The C-arm X-ray device may have, for example, a C-arm which is designed to record a series of projection images during a rotational progression of the C-arm around the patient. Furthermore, the device 9 can have a contrast agent injection device with at least two injectors IN1 and IN2 arranged at a distance from one another, wherein the first injector IN1 is designed for an automatically triggered intravenous injection of contrast agent and the second injector IN2 is designed for an automatically triggered, temporally subsequent intra-arterial injection of contrast agent, and the contrast agent injection device has a trigger device 15 for automatically activating the two injectors IN a controlled manner. Furthermore, the device 9 has a system controller 11 for controlling the X-ray device 10, the image processing unit 12 and the contrast agent injection device. Furthermore, the device 9 has a display unit 14 for displaying image data.

The acquisition protocol described in fig. 2 or other similar acquisition protocols may be controlled fully automatically by the device 9, for example.

The invention describes a method for creating a DSA, which, after a multiple injection recording protocol with at least one first intravenous injection and a second intra-arterial injection (in particular in the artery supplying the AVM), shows the possibility of not only displaying the entire hollow organ system, for example the brain, but also highlighting the particularly compelling connecting vessels, for example between the entire system in the brain and the AVM. In particular, the contribution of a single blood vessel (for example one of the two carotid arteries) can also be identified. Multi-level images obtained for Hounsfield Units (HU) are segmented and the differences can be displayed in a way that is well visible to the physician. This gives the possibility for the physician to develop a suitable treatment strategy, for example in the case of AVM or venous stenosis in the brain.

The invention can be briefly summarized in the following manner: in order to identify hollow organ systems particularly comprehensively, a method for creating a digital subtraction angiography of a hollow organ system of a patient is provided, comprising the following steps: providing mask image data recorded by means of an X-ray device; providing at least first fill image data recorded by means of the X-ray device, which was recorded during at least partial contrast agent filling of the hollow organ system with contrast agent, starting from a first intravenous contrast agent injection and a temporally subsequent second intra-arterial contrast agent injection; determining at least first subtracted image data by subtracting mask image data from the at least first filler image data; determining final subtracted image data from the at least first subtracted image data; and segmenting the final subtracted image data and assigning at least two different intensity levels to pixels or voxels of the final subtracted image data according to their respective intensity values.