Blood vessel image generation method, electronic equipment and computer program product

Abstract

The invention is suitable for the technical field of medical treatment, and provides a blood vessel image generation method, electronic equipment and a computer program product. The blood vessel image generation method comprises the following steps: acquiring an energy spectrum CT image; performing first base material decomposition on the energy spectrum CT image to determine a calcium region mask; performing second base material decomposition on the energy spectrum CT image to obtain a first virtual calcium-free image; acquiring a virtual single energy spectrum image; and generating a blood vessel image according to the calcium region mask, the first virtual calcium-free image and the virtual single energy spectrum image. According to the method, calcification can be removed, iodine substances (contrast agents) can be reserved, the boundary of the blood vessel stenosis can be clearly displayed, and therefore the accuracy and speed / convenience of assessment of the stenosis rate of the blood vessel are improved.

Description

Technical Field

[0001] The present application belongs to the field of medical technology, and in particular relates to a method for generating a vascular image, an electronic device, and a computer program product. Background Art

[0002] Vascular calcification and stenosis can affect multiple organs and are closely related to the occurrence of cardiovascular diseases. In clinical practice, computed tomography (CT) is often used to assist in the examination of whether patients have diseases such as vascular calcification, stenosis or infarction. However, the CT value of certain calcified plaques in blood vessels is close to the CT value of contrast agents in the vascular lumen, and the artifacts associated with high-density calcification can easily affect the identification of the vascular lumen boundary, resulting in inaccurate assessment of vascular stenosis rate. Some related technologies will try to add a CT plain scan to identify calcified plaques to further separate calcified plaques from contrast agent areas in CT angiography (CTA). This method will increase the patient's radiation dose, and because there is a time deviation between the two scans, it is easy to cause image mismatch problems due to patient movement, which ultimately affects the accuracy of vascular stenosis rate assessment. Summary of the invention

[0003] The embodiments of the present application provide a method for generating a vascular image, an electronic device, and a computer program product, which can remove calcification while retaining iodine substances (contrast agents), helping to clearly display the boundaries of vascular stenosis, thereby improving the accuracy and speed / convenience of evaluating the stenosis rate of the blood vessel.

[0004] A first aspect of an embodiment of the present application provides a method for generating a vascular image, comprising: acquiring an energy spectrum CT image; performing a first basis material decomposition on the energy spectrum CT image to determine a calcium region mask; performing a second basis material decomposition on the energy spectrum CT image to obtain a first virtual calcium-free image; acquiring a virtual single energy spectrum image; and generating a vascular image based on the calcium region mask, the first virtual calcium-free image, and the virtual single energy spectrum image.

[0005] In some embodiments of the first aspect, generating a vascular image based on the calcium area mask, the first virtual calcium-free image and the virtual mono-energy spectral image includes: correcting the image value of the iodine area within the calcium area in the first virtual calcium-free image to obtain a second virtual calcium-free image; generating the vascular image based on the calcium area mask, the second virtual calcium-free image, and the virtual mono-energy spectral image.

[0006] In some embodiments of the first aspect, generating the vascular image based on the calcium area mask, the second virtual calcium-free image, and the virtual mono-energy spectral image includes: determining the calcium area within the second virtual calcium-free image and the non-calcium area within the virtual mono-energy spectral image based on the calcium area mask; generating the vascular image based on the image value of the calcium area within the second virtual calcium-free image and the image value of the non-calcium area within the virtual mono-energy spectral image.

[0007] In some embodiments of the first aspect, the generating of the vascular image according to the image values ​​of the calcium areas in the second virtual calcium-free image and the image values ​​of the non-calcium areas in the virtual mono-energy spectrum image includes: determining the boundary fusion area between the calcium areas and the non-calcium areas in the vascular image; for the non-boundary fusion area within the calcium areas in the vascular image, using the image values ​​in the second virtual calcium-free image as the image values ​​of the vascular image; for the non-boundary fusion area within the non-calcium areas in the vascular image, using the image values ​​in the virtual mono-energy spectrum image as the image values ​​of the vascular image; for the boundary fusion area, performing a fusion operation on the image values ​​in the second virtual calcium-free image and the image values ​​in the virtual mono-energy spectrum image to obtain the image values ​​of the vascular image.

[0008] In some embodiments of the first aspect, before correcting the image value of the iodine area within the calcium area in the first virtual calcium-free image, it also includes: removing the blood signal in the energy spectrum CT image, and performing a third-base material decomposition operation on the energy spectrum CT image from which the blood signal is removed to obtain an iodine map; determining the calcium area in the first virtual calcium-free image based on the calcium area mask; and determining the iodine area within the calcium area in the first virtual calcium-free image based on the iodine map.

[0009] In some embodiments of the first aspect, the correcting the image value of the iodine area within the calcium area in the first virtual calcium-free image includes: correcting the image value of the iodine area within the calcium area in the first virtual calcium-free image to the CT value of blood and iodine substance.

[0010] In some embodiments of the first aspect, the CT value of the blood is obtained according to a CT value mapping relationship, and the CT value mapping relationship records the CT value of the blood under different virtual single energies.

[0011] In some embodiments of the first aspect, after correcting the image value of the iodine area within the calcium area in the first virtual calcium-free image, the generating method further includes: determining the calcium area in the first virtual calcium-free image based on the calcium area mask; determining the non-iodine area in the first virtual calcium-free image based on the iodine map; in the first virtual calcium-free image, correcting the image value of the target area to the virtual calcium-free image value of the soft tissue, wherein the target area is the intersection area of ​​the calcium area and the non-iodine area in the first virtual calcium-free image.

[0012] In some embodiments of the first aspect, the spectral CT image is subjected to a first base material decomposition to determine a calcium region mask, comprising: performing a base material decomposition operation of non-iodine substances and iodine substances on the spectral CT image to obtain the material density map, wherein the material density map includes a non-iodine substance map; and performing image segmentation on the non-iodine substance map to obtain the calcium region mask.

[0013] In some embodiments of the first aspect, when the non-iodine substance image is a denoised image, performing image segmentation on the non-iodine substance image to obtain the calcium region mask comprises: performing threshold segmentation on the non-iodine substance image to obtain the calcium region mask; when the non-iodine substance image is an image to be denoised, performing image segmentation on the non-iodine substance image to obtain the calcium region mask comprises: performing image segmentation on the non-iodine substance image according to spatial features within the non-iodine substance image to obtain the calcium region mask.

[0014] In some embodiments of the first aspect, performing a second-based substance decomposition operation on the energy spectrum CT image to obtain a first virtual calcium-free image includes: performing a water-calcium-based substance pair decomposition operation on the energy spectrum CT image, and obtaining the first virtual calcium-free image according to a water map obtained by the decomposition.

[0015] A second aspect of an embodiment of the present application provides a device for generating a vascular image, comprising: a CT image acquisition unit, used to acquire an energy spectrum CT image; a first basis substance decomposition unit, used to perform a first basis substance decomposition on the energy spectrum CT image to determine a calcium region mask; a second basis substance decomposition unit, used to perform a second basis substance decomposition on the energy spectrum CT image to obtain a first virtual calcium-free image; a virtual mono-energy spectrum image acquisition unit, used to acquire a virtual mono-energy spectrum image; and a vascular image generation unit, used to generate a vascular image based on the calcium region mask, the first virtual calcium-free image and the virtual mono-energy spectrum image.

[0016] A third aspect of an embodiment of the present application provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the method for generating a vascular image as described in any one of the first aspects are implemented.

[0017] A fourth aspect of the embodiments of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above-mentioned method for generating a vascular image are implemented.

[0018] A fifth aspect of the embodiments of the present application provides a computer program product, including a computer program, and when the computer program is executed, the method for generating a blood vessel image according to the first aspect is executed.

[0019] In an embodiment of the present application, a first basis material decomposition operation and a second basis material decomposition operation are performed on the energy spectrum CT image to obtain a first virtual calcium-free image and a calcium area mask, respectively, and a vascular image is generated based on the calcium area mask, the first virtual calcium-free image, and the virtual single energy spectrum image. The vascular image can be obtained through a single energy spectrum CT scan, thereby avoiding inaccurate analysis of vascular conditions due to time deviation when two scans are used. In addition, combined with the calcium area indicated by the calcification mask area, calcification can be removed while retaining iodine substance (contrast agent), which helps to clearly display the boundary of vascular stenosis, thereby improving the accuracy and speed / convenience of vascular stenosis rate assessment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0021] Figure 1 It is a schematic diagram of the implementation process of the method for generating a blood vessel image provided in an embodiment of the present application;

[0022] Figure 2 It is a material density map obtained by calcium-iodine decomposition provided in the embodiment of the present application;

[0023] Figure 3 It is a material density map obtained by water-iodine decomposition provided in the embodiment of the present application;

[0024] Figure 4 The water map and calcium map obtained by water-calcium decomposition provided in the examples of the present application;

[0025] Figure 5 This is a schematic diagram of a first specific implementation process of generating a blood vessel image provided by an embodiment of the present application;

[0026] Figure 6 is a schematic diagram of blooming artifacts provided in an embodiment of the application;

[0027] Figure 7 The calcium map and iodine map obtained by calcium-iodine decomposition provided in the examples of the present application;

[0028] Figure 8 is a schematic diagram of a second specific implementation flow of generating a blood vessel image provided by an embodiment of the present application;

[0029] Fig. 9 is a structural schematic diagram of a device for generating a blood vessel image provided in an embodiment of the present application;

[0030] Fig.10 It is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work are protected by the present application.

[0032] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0033] In the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0034] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0035] In clinical practice, CT examinations are often used to assist in checking whether patients have diseases such as vascular calcification, stenosis or infarction. However, the CT value of certain calcified plaques in blood vessels is close to the CT value of contrast agents in the vascular lumen, and the artifacts associated with high-density calcification can easily affect the identification of the vascular lumen boundary, resulting in inaccurate assessment of vascular stenosis rate. Some related technologies will try to add a CT plain scan to identify calcified plaques to further separate calcified plaques from contrast agent areas in CT angiography. This method will increase the patient's radiation dose, and because of the time deviation between the two scans, it is easy for the image to mismatch due to patient movement, which ultimately affects the accuracy of vascular stenosis rate assessment.

[0036] In view of this, the present application proposes a method for generating a vascular image, which can remove calcification alone and retain iodine substance (contrast agent), while avoiding excessive removal of calcium tissue blooming artifacts, clearly displaying the boundary of vascular stenosis, thereby improving the accuracy and speed / convenience of vascular stenosis rate assessment.

[0037] In order to illustrate the technical solution of the present application, a specific embodiment is provided below for illustration.

[0038] Please refer to Figure 1 , Figure 1 A schematic diagram of the implementation flow of a method for generating a vascular image provided in an embodiment of the present application is shown. The method can be applied to an electronic device, which can be a computer, a smart phone, a medical device specifically used for image processing, or other smart devices, and the present application does not impose any restrictions on this.

[0039] Specifically, the above-mentioned method for generating a blood vessel image may include the following steps S101 to S105.

[0040] Step S101, acquiring a spectral CT image.

[0041] The spectral CT image is a CT image generated by utilizing the absorption characteristics of the object to be measured under different X-ray energies, and may specifically refer to a vascular angiography image obtained by a spectral CT system.

[0042] In some embodiments of the present application, the above-mentioned spectral CT image may be a dual-energy image, i.e., a high- and low-energy image. A dual-energy image is an image corresponding to two different energies, which may be obtained by scanning an object with X-rays of two different energies, or by scanning an object with X-rays of one energy and separating the information of the two energies by a detector, and the present application does not impose any limitation on this.

[0043] Step S102: performing a first basis material decomposition operation on the spectral CT image to determine a calcium region mask.

[0044] The basis material decomposition operation is used to express the attenuation information of the object to be measured as a combination of two or more basis materials with known attenuation characteristics, thereby separating an image representing the distribution of a specific basis material. The present application may implement the basis material decomposition operation by using image domain basis material decomposition, projection domain basis material decomposition, direct inversion method or other existing methods, and the present application does not limit this.

[0045] In an embodiment of the present application, a first basis substance decomposition operation is used to separate the distribution of calcium substances and iodine substances. By performing the first basis substance decomposition operation on the spectral CT image, a substance density map can be obtained. The obtained substance density map can be used to indicate the distribution of calcium substances. By representing the area containing calcium substances and the area not containing calcium substances with different image values, a calcium area mask can be extracted. The calcium area mask is a mask image that can be used to indicate the calcium area in the substance density map, that is, the area containing calcium substances.

[0046] In some embodiments of the present application, within the calcium region mask, the image value of the calcium region may be 1, and the image value of other regions outside the calcium region may be 0. Of course, the present application does not exclude the possibility of representing the calcium region and other regions with other image values, as long as the calcium region and other regions can be distinguished.

[0047] Step S103: performing a second basis material decomposition operation on the energy spectrum CT image to obtain a first virtual calcium-free image.

[0048] In the embodiment of the present application, the second basis substance decomposition operation is used to separate the distribution of water and calcium substances. By performing the second basis substance decomposition operation on the energy spectrum CT image, a first virtual calcium-free image (Virtual NonCalcium, VNCa) can be obtained. The obtained first virtual calcium-free image is a CT image with calcium signals preliminarily removed.

[0049] Step S104, obtaining a virtual mono-energy spectrum image.

[0050] Among them, the virtual monoenergetic image (VMI) is used to describe the image of an object at a specific single photon energy (keV), which can be generated using the existing virtual monoenergetic image calculation method. The energy level of the virtual monoenergetic image can be selected by the user or set according to the recommended value. Among them, the recommended value can be determined based on the similarity between the virtual monoenergetic image and the traditional CT image style. For example, a 120kvp tube voltage is commonly used in cardiovascular imaging, and a recommended value can be given based on the equivalent single energy corresponding to the system at 120kvp; the recommended value can also be determined based on the contrast between the contrast agent and the calcium signal, such as obtaining the contrast-to-noise ratio of calcium and iodine at different keV through calcium and iodine phantom energy spectrum imaging, and giving a recommended value based on the single energy with the largest contrast-to-noise ratio. This application does not impose any restrictions on this.

[0051] Step S105 , generating a blood vessel image according to the calcium region mask, the first virtual calcium-free image and the virtual mono-energy spectrum image.

[0052] Among them, the vascular image is an image used to display the morphology of the blood vessels and can be used to evaluate the stenosis rate of the blood vessels.

[0053] In an embodiment of the present application, a first basis material decomposition operation and a second basis material decomposition operation are performed on the energy spectrum CT image to obtain a first virtual calcium-free image and a calcium area mask, respectively, and a vascular image is generated based on the calcium area mask, the first virtual calcium-free image, and the virtual single energy spectrum image. The vascular image can be obtained through a single energy spectrum CT scan, thereby avoiding inaccurate analysis of vascular conditions due to time deviation when two scans are used. In addition, combined with the calcium area indicated by the calcification mask area, calcification can be removed while retaining iodine substance (contrast agent), which helps to clearly display the boundary of vascular stenosis, thereby improving the accuracy and speed / convenience of vascular stenosis rate assessment.

[0054] In some embodiments of the present application, performing a first base substance decomposition operation on the spectral CT image to obtain a substance density map may include: performing a base substance decomposition operation of non-iodine substances and iodine substances on the spectral CT image to obtain a substance density map, wherein the substance density map includes a non-iodine substance map; performing image segmentation on the non-iodine substance map to obtain a calcium region mask.

[0055] Wherein, the base substance decomposition operation of non-iodine substance and iodine substance can be used to separate iodine and non-iodine substance. In some embodiments of the present application, the base substance decomposition operation of non-iodine substance and iodine substance can be: calcium-iodine base substance pair decomposition operation, water-iodine base substance pair decomposition operation, or water-calcium-iodine three base substance decomposition operation. Of course, the present application does not exclude other non-iodine substances other than calcium and water, and actual application can also be combined with iodine substance and more different base substances for decomposition.

[0056] The above-mentioned image segmentation can adopt threshold segmentation, deep learning-based image segmentation or other existing image segmentation methods, which is not limited in this application.

[0057] In some embodiments of the present application, when the non-iodine substance image is a noise-reduced image, performing image segmentation on the non-iodine substance image to obtain a calcium region mask may include: performing threshold segmentation on the non-iodine substance image to obtain a calcium region mask.

[0058] Taking the decomposition operation of calcium-iodine based material pairs as an example, the decomposition operation of calcium-iodine based material pairs is performed on the spectral CT image, and the obtained material density map may include a calcium map (non-iodine material map) and an iodine map. Figure 2 As shown in the figure, 2A represents the calcium map obtained by performing the calcium-iodine based substance pair decomposition operation, and 2B represents the iodine map obtained by performing the calcium-iodine based substance pair decomposition operation. Although calcium and iodine have similar CT values ​​in the spectral CT image, the distribution of calcium and iodine substances can be displayed in the calcium map and iodine map respectively by performing the calcium-iodine based substance pair decomposition operation. At this time, the calcium map is threshold segmented by setting a threshold value to obtain a calcium area mask.

[0059] Similarly, if the decomposition operation of the non-iodine substance and the iodine substance is a water-iodine substance pair decomposition operation, such as Figure 3 As shown, 3A represents the water map obtained by performing the water-iodine base substance pair decomposition operation, and 3B represents the iodine map obtained by performing the water-iodine base substance pair decomposition operation. The distribution of calcium substance and iodine substance will be respectively displayed in the water map (non-iodine substance map) and the iodine map, and at this time, the water map is subjected to threshold segmentation by setting a threshold value, and a calcium regional mask can be obtained. If the base substance decomposition operation of the non-iodine substance and the iodine substance is a water-calcium-iodine three-base substance decomposition operation, the distribution of calcium substance and iodine substance will be respectively displayed in the calcium map (non-iodine substance map) and the iodine map, and at this time, the calcium map is subjected to threshold segmentation by setting a threshold value, and a calcium regional mask can be obtained.

[0060] In other embodiments of the present application, when a non-iodine substance image is an image to be denoised, threshold segmentation is performed on the non-iodine substance image to obtain a calcium region mask, which may include: performing image segmentation on the non-iodine substance image according to spatial features within the non-iodine substance image to obtain a calcium region mask.

[0061] Specifically, in some embodiments, it can be determined whether the non-iodine substance image is an image to be de-noised by performing image clarity analysis or noise analysis on the non-iodine substance image. In other embodiments, since the source of the non-iodine substance image is known, that is, the algorithm used by the base substance decomposition operation is known, whether the non-iodine substance image is an image to be de-noised is a priori information. If the non-iodine substance image is an image after de-noising, the calcium image can be threshold segmented by setting a threshold value to obtain a calcium region mask. If the non-iodine substance image is an image to be de-noised, the non-iodine substance image can be segmented according to the spatial features in the non-iodine substance image to obtain a calcium region mask, to achieve the effect of de-noising.

[0062] Specifically, according to the spatial features in the non-iodine substance map, the non-iodine substance map is threshold segmented, which can be implemented by using a region-based image segmentation method, such as a region growing method; or by using other methods such as superpixel image segmentation and Markov random field classification based on a Gaussian mixture model. The non-iodine substance map itself has a good degree of distinction between calcium areas and non-calcium areas. Considering the spatial features during segmentation can reduce the sensitivity to noise and obtain an ideal segmentation result.

[0063] In some embodiments of the present application, performing a second base substance decomposition operation on the energy spectrum CT image to obtain a first virtual calcium-free image may include: performing a water-calcium base substance pair decomposition operation on the energy spectrum CT image, and obtaining the first virtual calcium-free image according to a water map obtained by the decomposition.

[0064] Specifically, Figure 4 As shown, 4A represents a water image obtained by performing a water-calcium-based substance pair decomposition operation, and 4B represents a calcium image obtained by performing a water-calcium-based substance pair decomposition operation. By performing a water-calcium-based substance pair decomposition operation, since the water image does not contain calcium, a first virtual calcium-free image can be obtained.

[0065] When there are high-concentration calcification foci in blood vessels, blooming artifacts will be generated, affecting the display of blood vessels and leading to an overestimation of the stenosis rate. Blooming artifacts also exist in the base material decomposition operation. The blooming artifacts appear consistent with the calcification foci in the CT energy spectrum image, that is, the calcium area mask will include the blooming artifact area, and the blooming artifact and iodine contrast agent exist in the image at the same time. Figure 4 As shown in Figure 4, the iodine contrast agent shows a bright signal in the calcium map (4B). At this time, the iodine contrast agent will be mistaken for a calcium signal through water-calcium decomposition, overestimating the actual calcium component, resulting in a low calcium-free image value in this area. In order to solve this problem, Figure 5 As shown, generating a blood vessel image according to the calcium region mask, the first virtual calcium-free image and the virtual mono-energy spectrum image may include: step S501 to step S502.

[0066] Step S501 , correcting the image value of the iodine region within the calcium region in the first virtual calcium-free image to obtain a second virtual calcium-free image.

[0067] Specifically, in some embodiments of the present application, the blood signal can be removed from the spectral CT image, and the spectral CT image with the blood signal removed can be subjected to a third-base material decomposition operation to obtain an iodine map; based on the calcium area mask, the calcium area in the first virtual calcium-free image is determined; and based on the iodine map, the iodine area within the calcium area in the first virtual calcium-free image is determined.

[0068] The blood signal refers to the blood CT value, which can be obtained through prior information, such as scanning data of the object to be tested or other objects, or by scanning a blood phantom. Figure 6 As shown, for the blood vessel area, it contains iodine signals carried by blood and contrast agents, for the calcified area in the blood vessel, it contains calcium signals, and for the blooming artifact area produced by calcification, it contains blood, iodine signals carried by contrast agents, and calcium artifact signals, and the calcium artifact signals have similar spectral properties to the calcium signals. By removing the blood signal from the spectral CT image, the enhanced blood signal can be separated. By performing a base substance decomposition operation of non-iodine substances and iodine substances on the spectral CT image with the blood signal removed, the iodine signal and the calcium signal can be separated to obtain an iodine map.

[0069] It should be noted that the third base substance decomposition operation here is used to separate the distribution of calcium substances and iodine substances, and can be a calcium-iodine base substance pair decomposition or other base substance decomposition operation, which is not limited in this application. Taking the calcium-iodine base substance pair decomposition as an example, Figure 7 As shown, 7A represents a calcium map obtained by performing a calcium-iodine based substance pair decomposition operation on the energy spectrum CT image with blood signals removed, and 7B represents an iodine map obtained by performing a calcium-iodine based substance pair decomposition operation on the energy spectrum CT image with blood signals removed.

[0070] In other embodiments, since the calcium concentration in the blooming artifact area in the base material decomposition may be lower than that of the calcification itself, the iodine area within the calcium area in the first virtual calcium-free image may be determined based on the area below the calcium concentration threshold in the calcium area mask to continue image value correction of the iodine area within the calcium area.

[0071] In some embodiments of the present application, correcting the image value of the iodine area in the first virtual calcium-free image may include: correcting the image value of the iodine area within the calcium area in the first virtual calcium-free image to the CT value of blood and iodine substance.

[0072] Specifically, in the calcium area indicated by the calcium area mask, the area where the iodine concentration exceeds the threshold in the iodine map can be extracted by threshold judgment, that is, the iodine area in the calcium area. For this area, the image value of the virtual calcium-free image is replaced with the blood CT value and the CT value of the iodine substance, so as to achieve the effect of removing the calcium signal and retaining the blood and iodine signals.

[0073] Among them, the CT value of blood can be obtained according to the CT value mapping relationship, and the CT value mapping relationship records the CT value of blood under different virtual single energies. The virtual single energy corresponds to the energy level of the aforementioned virtual single energy spectrum image. The CT value of the iodine substance can be calculated by the iodine concentration in the iodine map and the theoretical attenuation value of iodine. This application does not limit the method for obtaining the CT value of blood and the CT value of iodine substances.

[0074] Step S502 : generating a blood vessel image according to the calcium region mask, the second virtual calcium-free image, and the virtual mono-energy spectrum image.

[0075] In an embodiment of the present application, the image value of the iodine area in the first virtual calcium-free image can be corrected according to the calcium area indicated by the calcium area mask and the iodine area indicated by the iodine map, and the iodine substance (contrast agent) can be retained while the blooming is removed, so as to avoid the iodine substance (contrast agent) affected by the blooming artifact being mistaken for a calcified plaque and removed. A vascular image is generated according to the calcium area mask, the second virtual calcium-free image, and the virtual mono-energy spectrum image, so that the signals of each substance in the vascular image can be made more accurate, thereby improving the accuracy of the assessment of the stenosis rate of the blood vessel.

[0076] like Figure 4 In the water map (4A) shown in FIG, calcium-containing tissues such as bones appear darker in the virtual calcium-free image, which is significantly lower than soft tissues, resulting in black holes in the final generated vascular image. To solve this problem, in some embodiments of the present application, after correcting the image value of the iodine area within the calcium area in the first virtual calcium-free image, the image value of the area containing calcium tissue in the first virtual calcium-free image can also be corrected.

[0077] Specifically, in some embodiments of the present application, after correcting the image value of the iodine area within the calcium area in the first virtual calcium-free image, it may also include: determining the calcium area in the first virtual calcium-free image based on the calcium area mask; determining the non-iodine area in the first virtual calcium-free image based on the iodine map; in the first virtual calcium-free image, correcting the image value of the target area to the virtual calcium-free image value of the soft tissue.

[0078] The iodine map may be obtained by performing a third-base material decomposition operation on the energy spectrum CT image with the blood signal removed. The target area is the intersection area of ​​the calcium area and the non-iodine area.

[0079] Specifically, in the first virtual calcium-free image, for the part that belongs to the calcium area and does not belong to the iodine area (i.e., the target area), its original water density value OldWater is linearly mapped to a new water density value NewWater, and then the corresponding virtual calcium-free image value is calculated according to the single photon energy. The linear mapping can be expressed as: NewWater = OldWater*k+b. Among them, the mapping coefficients k and b can be determined according to the water density value of the bone area and the water density value of the soft tissue area, so that the new water density value NewWater is close to the water density value of the soft tissue.

[0080] In addition to linear mapping, in some other implementations, Poisson fusion can also be used to utilize the surrounding soft tissue pixel values ​​and the image value gradient in the region to determine the virtual calcium-free image value of the soft tissue in the target region.

[0081] In some embodiments of the present application, generating a vascular image based on a calcium area mask, a second virtual calcium-free image, and a virtual mono-energy spectral image may include: determining the calcium area in the second virtual calcium-free image and the non-calcium area in the virtual mono-energy spectral image based on the calcium area mask; generating the vascular image based on the image value of the calcium area in the second virtual calcium-free image and the image value of the non-calcium area in the virtual mono-energy spectral image.

[0082] Specifically, the image value of 1 in the calcium area mask represents the calcium area, and the image value of 0 represents the non-calcium area. When generating a vascular image, the calcium area can retain the image value of the calcium area in the second virtual calcium-free image, and the non-calcium area can retain the image value of the non-calcium area in the virtual mono-energy spectrum image. At this time, the fused vascular image can remove the calcified plaque, leaving only the contrast agent enhancement signal in the blood vessel, and clearly displaying the contrast agent boundary at the stenosis of the blood vessel, so as to obtain accurate stenosis assessment more quickly.

[0083] In some embodiments of the present application, Figure 8 As shown, generating a blood vessel image according to the image value of the calcium area in the second virtual calcium-free image and the image value of the non-calcium area in the virtual mono-energy spectrum image may also include: step S801 to step S804.

[0084] Step S801, determining the boundary fusion area between the calcium area and the non-calcium area in the blood vessel image.

[0085] Specifically, the boundary fusion area refers to the area where the calcium area and the non-calcium area meet. The boundary line between the calcium area and the non-calcium area can be determined, and the image area surrounded by a number of pixels adjacent to the boundary line can be used as the boundary fusion area.

[0086] Step S802 : For the non-boundary fusion area in the calcium area in the blood vessel image, the image value in the second virtual calcium-free image is used as the image value of the blood vessel image.

[0087] The non-boundary fusion area in the calcium region is an area outside the boundary fusion area in the calcium region. This area is far away from the boundary line between the calcium region and the non-calcium region. Therefore, for this area, the image value in the second virtual calcium-free image can be used as the image value of the vascular image, so that the image value of the non-boundary fusion area in the calcium region in the vascular image is the same as the CT value of the calcium substance in the scanned image of the preset voltage, so as to accurately represent the calcium region.

[0088] Step S803 : for the non-boundary fusion area in the non-calcium area in the blood vessel image, the image value in the virtual mono-energy spectrum image is used as the image value of the blood vessel image.

[0089] The non-boundary fusion area in the non-calcium area is an area outside the boundary fusion area in the non-calcium area. This area is far away from the boundary line between the calcium area and the non-calcium area. Therefore, for this area, the image value in the virtual mono-energy spectrum image can be used as the image value of the vascular image, so that the image value of the non-boundary fusion area in the non-calcium area is the same as the image value in the virtual mono-energy spectrum image, so as to accurately represent the non-calcium area.

[0090] Step S804: For the boundary fusion area, a fusion operation is performed on the image values ​​in the second virtual calcium-free image and the image values ​​in the virtual mono-energy spectrum image to obtain image values ​​of the blood vessel image.

[0091] For the boundary fusion area, the image values ​​in the second virtual calcium-free image and the image values ​​in the virtual mono-energy spectrum image are fused to obtain the image values ​​of the blood vessel image, thereby achieving a smooth boundary transition effect.

[0092] The present application does not limit the algorithm used in the fusion operation. For example, a weighted averaging method, a filtering blur method (weighted averaging of the images before and after filtering to obtain a vascular image), and a Laplacian pyramid image fusion method (constructing a Laplacian pyramid for the second virtual calcium-free image and the virtual monoenergy spectrum image, constructing a Gaussian pyramid in the boundary fusion area, and weighted fusion of each layer to reconstruct a vascular image) may be used.

[0093] In the embodiment of the present application, calcified plaques are removed from the image based on the spectral CT image while the contrast agent is completely retained to obtain a vascular image. The vascular image can more clearly show the difference between the vascular lumen and the calcified plaques, so as to more accurately identify the stenosis boundary when evaluating the stenosis rate, thereby improving the accuracy of the stenosis rate evaluation.

[0094] It should be noted that, for the sake of simplicity of description, the aforementioned method embodiments are all expressed as a series of action combinations, but those skilled in the art should know that the present application is not limited to the described order of actions, because according to the present application, certain steps can be performed in other orders.

[0095] like Fig. 9 FIG. 1 is a schematic structural diagram of a device 900 for generating a blood vessel image provided in an embodiment of the present application. The device 900 for generating a blood vessel image is configured on an electronic device.

[0096] Specifically, the blood vessel image generating device 900 may include:

[0097] CT image acquisition unit 901, used to acquire energy spectrum CT images;

[0098] A first basis material decomposition unit 902, configured to perform first basis material decomposition on the spectral CT image to determine a calcium region mask;

[0099] A second basis material decomposition unit 903 is used to perform a second basis material decomposition on the energy spectrum CT image to obtain a first virtual calcium-free image;

[0100] A virtual mono-energy spectrum image acquisition unit 904, used to acquire a virtual mono-energy spectrum image;

[0101] The blood vessel image generating unit 905 is configured to generate a blood vessel image according to the calcium region mask, the first virtual calcium-free image and the virtual mono-energy spectrum image.

[0102] In some embodiments of the present application, the vascular image generation unit 905 is specifically used to: correct the image value of the iodine area within the calcium area in the first virtual calcium-free image to obtain a second virtual calcium-free image; and generate the vascular image based on the calcium area mask, the second virtual calcium-free image, and the virtual mono-energy spectrum image.

[0103] In some embodiments of the present application, the vascular image generation unit 905 is specifically used to: determine the calcium area in the second virtual calcium-free image and the non-calcium area in the virtual mono-energy spectral image according to the calcium area mask; generate the vascular image according to the image value of the calcium area in the second virtual calcium-free image and the image value of the non-calcium area in the virtual mono-energy spectral image.

[0104] In some embodiments of the present application, the vascular image generation unit 905 is specifically used to: determine the boundary fusion area between the calcium area and the non-calcium area in the vascular image; for the non-boundary fusion area within the calcium area in the vascular image, use the image value in the second virtual calcium-free image as the image value of the vascular image; for the non-boundary fusion area within the non-calcium area in the vascular image, use the image value in the virtual mono-energy spectrum image as the image value of the vascular image; for the boundary fusion area, perform a fusion operation on the image value in the second virtual calcium-free image and the image value in the virtual mono-energy spectrum image to obtain the image value of the vascular image.

[0105] In some embodiments of the present application, the vascular image generation unit 905 is also used to: remove blood signals from the spectral CT image, and perform a third-base material decomposition operation on the spectral CT image from which the blood signals are removed to obtain an iodine map; determine the calcium region in the first virtual calcium-free image based on the calcium region mask; and determine the iodine region within the calcium region in the first virtual calcium-free image based on the iodine map.

[0106] In some embodiments of the present application, the blood vessel image generating unit 905 is further configured to correct the image value of the iodine region within the calcium region in the first virtual calcium-free image to the CT value of blood and iodine substance.

[0107] In some embodiments of the present application, the CT value of the blood is obtained according to a CT value mapping relationship, and the CT value mapping relationship records the CT value of the blood under different virtual single energies.

[0108] In some embodiments of the present application, the vascular image generation unit 905 is also used to: determine the calcium area in the first virtual calcium-free image based on the calcium area mask; determine the non-iodine area in the first virtual calcium-free image based on the iodine map; in the first virtual calcium-free image, correct the image value of the target area to the virtual calcium-free image value of the soft tissue, wherein the target area is the intersection area of ​​the calcium area and the non-iodine area in the first virtual calcium-free image.

[0109] In some embodiments of the present application, the first base material decomposition unit 902 is specifically used to: perform base material decomposition operations of non-iodine substances and iodine substances on the energy spectrum CT image to obtain the material density map, and the material density map includes a non-iodine material map; perform image segmentation on the non-iodine material map to obtain the calcium area mask.

[0110] In some embodiments of the present application, the first base material decomposition unit 902 is specifically used for: when the non-iodine material image is a denoised image, performing threshold segmentation on the non-iodine material image to obtain the calcium area mask; when the non-iodine material image is an image to be denoised, performing image segmentation on the non-iodine material image according to the spatial features within the non-iodine material image to obtain the calcium area mask.

[0111] In some embodiments of the present application, the second base substance decomposition unit 903 is specifically used to: perform a water-calcium base substance pair decomposition operation on the energy spectrum CT image, and obtain the first virtual calcium-free image according to the water map obtained by the decomposition.

[0112] It should be noted that, for the convenience and simplicity of description, the specific working process of the above-mentioned blood vessel image generation device 900 can refer to Figures 1 to 8 The corresponding process of the method will not be repeated here.

[0113] like Fig.10 FIG. 1 is a schematic diagram of an electronic device 10 provided in an embodiment of the present application. Specifically, the electronic device 10 may include: a processor 100, a memory 101, and a computer program 102 stored in the memory 101 and executable on the processor 100, such as a vascular image generation program. When the processor 100 executes the computer program 102, the steps in the above-mentioned vascular image generation method embodiments are implemented, such as Figure 1 Alternatively, when the processor 100 executes the computer program 102, the functions of each module / unit in the above-mentioned device embodiments are implemented, for example Fig. 9 The functions of the CT image acquisition unit 901, the first basis substance decomposition unit 902, the second basis substance decomposition unit 903, the virtual mono-energy spectrum image acquisition unit 904 and the blood vessel image generation unit 905 are shown.

[0114] The computer program may be divided into one or more modules / units, which are stored in the memory 101 and executed by the processor 100 to complete the present application. The one or more modules / units may be a series of computer program instruction segments capable of completing specific functions, which are used to describe the execution process of the computer program in the electronic device 10.

[0115] For example, the computer program can be divided into: a CT image acquisition unit, a first basis substance decomposition unit, a second basis substance decomposition unit, a virtual single energy spectrum image acquisition unit and a blood vessel image generation unit. The specific functions of each unit are as follows: a CT image acquisition unit, used to acquire a spectral CT image; a first basis substance decomposition unit, used to perform a first basis substance decomposition on the spectral CT image to determine a calcium region mask; a second basis substance decomposition unit, used to perform a second basis substance decomposition on the spectral CT image to obtain a first virtual calcium-free image; a virtual single energy spectrum image acquisition unit, used to acquire a virtual single energy spectrum image; a blood vessel image generation unit, used to generate a blood vessel image according to the calcium region mask, the first virtual calcium-free image and the virtual single energy spectrum image.

[0116] The electronic device 10 may include, but is not limited to, a processor 100 and a memory 101. Those skilled in the art will appreciate that Fig.10 It is only an example of the electronic device 10 and does not constitute a limitation of the electronic device 10. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the electronic device 10 may also include input and output devices, network access devices, buses, etc.

[0117] The processor 100 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), off-the-shelf programmable gate arrays or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0118] The memory 101 may be an internal storage unit of the electronic device 10, such as a hard disk or memory of the electronic device 10. The memory 101 may also be an external storage device of the electronic device 10, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. equipped on the electronic device 10. Further, the memory 101 may also include both an internal storage unit of the electronic device 10 and an external storage device. The memory 101 is used to store the computer program and other programs and data required by the electronic device 10. The memory 101 may also be used to temporarily store data that has been output or is to be output.

[0119] It should be noted that, for the convenience and brevity of description, the structure of the electronic device 10 can also refer to the specific description of the structure in the method embodiment, which will not be repeated here.

[0120] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0121] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0122] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0123] In the embodiments provided in the present application, it should be understood that the disclosed devices / equipment and methods can be implemented in other ways. For example, the device / equipment embodiments described above are merely schematic, for example, the division of the modules or units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0124] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0125] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0126] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.

[0127] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for generating a blood vessel image, characterized in that: include: Acquire spectral CT images; performing a first basis material decomposition on the spectral CT image to determine a calcium region mask; Performing a second basis material decomposition on the energy spectrum CT image to obtain a first virtual calcium-free image; Acquire a virtual mono-energy spectrum image; A blood vessel image is generated according to the calcium region mask, the first virtual calcium-free image and the virtual mono-energy spectral image.

2. The method for generating a blood vessel image according to claim 1, wherein: The step of generating a blood vessel image according to the calcium region mask, the first virtual calcium-free image and the virtual mono-energy spectrum image comprises: Correcting the image value of the iodine region within the calcium region in the first virtual calcium-free image to obtain a second virtual calcium-free image; The blood vessel image is generated according to the calcium region mask, the second virtual calcium-free image, and the virtual mono-energy spectral image.

3. The method for generating a blood vessel image according to claim 2, wherein: The step of generating the blood vessel image according to the calcium region mask, the second virtual calcium-free image, and the virtual mono-energy spectrum image comprises: determining a calcium region in the second virtual calcium-free image and a non-calcium region in the virtual mono-energy spectrum image according to the calcium region mask; The blood vessel image is generated according to the image value of the calcium region in the second virtual calcium-free image and the image value of the non-calcium region in the virtual mono-energy spectral image.

4. The method for generating a blood vessel image according to claim 3, wherein: The step of generating the blood vessel image according to the image value of the calcium region in the second virtual calcium-free image and the image value of the non-calcium region in the virtual mono-energy spectrum image comprises: Determine a boundary fusion region between a calcium region and a non-calcium region in the blood vessel image; For a non-boundary fusion area within the calcium region in the blood vessel image, using an image value in the second virtual calcium-free image as an image value of the blood vessel image; For a non-boundary fusion area in a non-calcium area in the blood vessel image, using an image value in the virtual mono-energy spectrum image as an image value of the blood vessel image; For the boundary fusion area, a fusion operation is performed on the image values ​​in the second virtual calcium-free image and the image values ​​in the virtual mono-energy spectrum image to obtain the image values ​​of the blood vessel image.

5. The method for generating a blood vessel image according to claim 2, wherein: Before correcting the image value of the iodine area within the calcium area in the first virtual calcium-free image, the method further includes: removing blood signals from the energy spectrum CT image, and performing a third-base substance decomposition operation on the energy spectrum CT image from which the blood signals are removed, to obtain an iodine image; determining a calcium region in the first virtual calcium-free image according to the calcium region mask; An iodine region within a calcium region in the first virtual calcium-free image is determined according to the iodine map.

6. The method for generating a blood vessel image according to claim 2, wherein: The correcting the image value of the iodine region within the calcium region in the first virtual calcium-free image includes: The image value of the iodine region within the calcium region in the first virtual calcium-free image is corrected to the CT value of blood and iodine substance.

7. The method for generating a blood vessel image according to claim 2, wherein: After correcting the image value of the iodine area within the calcium area in the first virtual calcium-free image, the generating method further includes: determining a calcium region in the first virtual calcium-free image according to the calcium region mask; determining a non-iodine region in the first virtual calcium-free image according to the iodine map; In the first virtual calcium-free image, the image value of the target area is corrected to the virtual calcium-free image value of the soft tissue, wherein the target area is the intersection area of ​​the calcium area and the non-iodine area in the first virtual calcium-free image.

8. The method for generating a blood vessel image according to any one of claims 1 to 7, characterized in that: Performing a second basis material decomposition on the energy spectrum CT image to obtain a first virtual calcium-free image includes: A water-calcium-based substance pair decomposition operation is performed on the energy spectrum CT image, and the first virtual calcium-free image is obtained according to a water map obtained by the decomposition.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method for generating a blood vessel image according to any one of claims 1 to 8 are implemented.

10. A computer program product, characterized in that The invention comprises a computer program, which, when being executed, enables the method for generating a blood vessel image according to any one of claims 1 to 8 to be executed.

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