Blood vessel inner diameter measuring method and device based on total attenuation inversion

Abstract

The invention discloses a blood vessel inner diameter correction method and device based on an X-ray total attenuation conservation principle and a storage medium, and belongs to the technical field of medical image processing. The core of the method is to discover and utilize the total net attenuation of a blood vessel filled with a contrast agent in an actual motion state and the total net attenuation of the blood vessel in an ideal static state to be kept in conservation. The method comprises the steps that an angiography image is acquired, and a target area and an initial inner diameter measuring line are determined; calculating the gray scale decline amount and the maximum value of each pixel of the line; on the basis of the conservation principle, the inner diameter of the blood vessel in an ideal state is inversely calculated through the formula that the inner diameter is corrected to be equal to sigma [(delta Ii / delta Imax) * Li]. Furthermore, based on the same principle, the method can be expanded and applied to correction of the two-dimensional contour of the target blood vessel. According to the method, errors caused by motion artifacts and resolution limitation are fundamentally compensated through a volume measurement method based on integration and distribution, and the method is particularly suitable for accurate measurement of severe stenosis blood vessels.

Description

Technical Field

[0001] This invention relates to the field of medical image processing technology, specifically to a method, apparatus, and storage medium for correcting errors in vascular diameter measurement caused by motion artifacts and imaging resolution limitations in X-ray digital subtraction angiography (DSA) images based on the principle of state conservation. Background Technology

[0002] Digital subtraction angiography (DSA) is the gold standard for the clinical diagnosis of vascular stenosis. It clearly displays the morphology of blood vessels by comparing images before and after contrast agent injection. Currently, the measurement of blood vessel diameter, especially in stenotic segments, mainly relies on the caliper method or automatic edge detection algorithms based on principles such as full width at half maximum (FWHM) and full width at half maximum (HWHM) on DSA images.

[0003] However, these methods face significant challenges when measuring severely stenotic vessels (often with an inner diameter of less than 1 mm), primarily because: 1. Physiological motion artifacts: During the exposure time, physiological movements such as the patient's heartbeat and breathing cause blood vessels to appear blurred or trailed on the image, making it difficult to determine the boundaries of the blood vessels; Image registration error: During the two acquisitions of the mask and the angiography film, any slight displacement of the patient (especially complex rotational displacement) will introduce artifacts in the subtraction image, further interfering with the identification of the real blood vessel boundaries; 3. Physical resolution limitation: The minimum pixel size of modern DSA equipment is usually around 0.25mm. When imaging a blood vessel with an inner diameter of 1mm or smaller, its projection on the image can only cover a few pixels. The edge of the blood vessel on the image appears as a blurred boundary and a transitional area with gradual grayscale. Measurement methods based on edge detection produce huge errors due to partial volume effect.

[0004] For normal blood vessels with larger diameters (e.g., 5-8 mm), the absolute error mentioned above accounts for a small proportion of their inner diameter and is clinically acceptable. However, for severely stenotic blood vessels, the same absolute error will lead to a sharp amplification of the relative error of the measurement results, seriously affecting the judgment of the degree of stenosis and potentially misleading the formulation of treatment plans (such as balloon size selection).

[0005] Existing technologies primarily focus on suppressing motion artifacts by improving image registration algorithms or employing techniques such as ECG gating, but these methods are difficult to completely eliminate and are costly. Therefore, there is an urgent need for a precise method for measuring inner diameters that can fundamentally compensate for the effects of motion artifacts and overcome the limitations of physical resolution. Summary of the Invention

[0006] Purpose of the invention: The purpose of this invention is to provide a method, device, and storage medium for correcting the inner diameter of blood vessels. This method does not rely on completely eliminating motion artifacts, but instead uses innovative physical principles to infer the true inner diameter of blood vessels in an ideal static state from image data after motion and affected by partial volume effects. This solves the problem of inaccurate measurement results of small blood vessel inner diameters caused by motion artifacts and imaging resolution limitations in existing measurement technologies.

[0007] Technical solution: To achieve the above objectives, this invention proposes an innovative principle based on "X-ray attenuation state conservation." Its core finding is that for a blood vessel containing a fixed amount of contrast agent, the total net attenuation (i.e., the sum of the grayscale decreases of all affected pixels) exhibited in an "actual DSA image that is in motion and affected by partial volume effects" is conserved from the total net attenuation that the blood vessel should exhibit in an "ideal static state."

[0008] The combined effect of motion artifacts (including translation and rotation) and partial volumetric effects is to spatially redistribute the fixed total attenuation that was originally concentrated in a narrow region under ideal conditions (diffusing it across a wider pixel area). This results in wider blood vessel projections, blurred boundaries, and decreased contrast of individual pixels in the image, but it does not change the integral value of the total attenuation.

[0009] Based on the above principles, this invention measures the total attenuation (Σ ΔIi_motion) under motion and utilizes the maximum single-pixel attenuation (ΔI_ideal, approximated as ΔImax in the image) achievable when the attenuation is concentrated under ideal static conditions. This allows the inverse calculation of the ideal blood vessel projection width, i.e., the true inner diameter (d). The basic relationship is: Σ ΔIi_motion = d × ΔI_ideal.

[0010] Specific methods include: S1. Image acquisition and preprocessing: Acquire two-dimensional DSA image sequences and obtain angiography images through subtraction; S2. Region Determination: Determine the region of interest for the target blood vessel; S3. Initial Measurement: Draw the initial inner diameter measurement line at the suspected narrowest point; S4. Pixel Analysis: Calculate the grayscale decrease (ΔIi) and its maximum value (ΔImax) for each pixel in the line. S5. Inner Diameter Correction: The core correction formula of this invention, D_corrected = Σ [(ΔIi / ΔImax) × Li], is applied for calculation. This formula is the mathematical implementation of the aforementioned conservation principle Σ ΔIi_motion = d × ΔI_ideal in discrete pixel images. Essentially, it recovers the attenuated signal dispersed across multiple pixels due to motion and partial volume effects through integration (Σ) operations, and reconstructs the equivalent ideal projection width through normalization and weighted integration, thereby achieving sub-pixel level accurate measurement.

[0011] Furthermore, the principles of this invention can be extended to correct the two-dimensional contours of blood vessels. Specifically, this application is based on the same principle of "total attenuation conservation" and the formula for measuring inner diameter, and is achieved as follows: using the central axis of the blood vessel as the geometric framework, a series of points are selected on the central axis; a line segment perpendicular to the central axis is drawn through each point, and this line segment is regarded as the "initial inner diameter measurement line," and the correction dimension at this position is calculated using the core formula; then, new contour points on both sides of this position are generated. Connecting all the new contour points allows for the reconstruction of a more accurate two-dimensional contour of the blood vessel.

[0012] The present invention also provides corresponding devices and computer-readable storage media.

[0013] Beneficial effects Compared with the prior art, the beneficial effects of the present invention include: 1. Overcoming physical resolution limitations and partial volumetric effects: This invention abandons the traditional measurement approach that relies on sharp edges and adopts a volumetric measurement method based on integration and distribution. By accumulating sub-pixel level signals dispersed across multiple pixels to invert the true size, it fundamentally overcomes the measurement bottleneck caused by partial volumetric effects, enabling accurate measurement of vascular structures smaller than pixel size; 2. Innovative Principles to Compensate for Motion Artifacts: Starting from the physical essence, the principle of state conservation is used to transform the difficult-to-eliminate motion artifacts into a computable signal distribution problem, which significantly improves the measurement robustness under physiological motion interference. 3. Significantly improved accuracy: It is particularly suitable for measuring severely stenotic blood vessels with an inner diameter of less than 1 mm. It can effectively correct measurement deviations caused by blurred edges and motion, providing more reliable diagnostic evidence for clinical practice. 4. Strong functional expandability: The same core principle can simultaneously support high-precision single-point inner diameter measurement and overall two-dimensional contour correction, with wide application value; 5. Low cost and easy to promote: It does not require changes to the existing DSA imaging hardware and can be integrated into the existing medical imaging system as a software algorithm module, resulting in low implementation cost. Attached Figure Description

[0014] Figure 1 Flowchart of the blood vessel diameter correction method provided in this embodiment of the invention; Figure 2 : A schematic diagram of pixel-level inner diameter correction provided in an embodiment of the present invention; Figure 3 : A schematic diagram illustrating the application of the core method of this invention to two-dimensional contour correction of blood vessels. Detailed Implementation

[0015] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0016] Reference Figure 1 and Figure 2 The specific implementation steps of the method of the present invention are as follows: S101: Image Acquisition. The system acquires DSA image sequences of the patient's target blood vessels via the DICOM protocol, including masked images and angiographic images, and performs digital subtraction. S102: Region Determination. Using the semi-automatic vascular analysis tool integrated into the workstation, the preliminary outline of the target vessel is determined (e.g., Figure 2-1 (as shown) S103: Initial Measurement. The physician marks the suspected narrowest point on the vascular image, and the system automatically generates an initial inner diameter measurement line perpendicular to the center line of that point (e.g., ...). Figure 2-2 (as shown) S104: Pixel Analysis. The system iterates through all pixels traversed by the measurement line. For each pixel, it calculates the grayscale difference between the mask and the image, obtaining ΔIi. Simultaneously, it identifies the maximum value ΔImax among these ΔIi values ​​(e.g., ...). Figure 2 (as shown in -4) S105: Inner Diameter Correction. This is the core step of the invention. For each pixel traversed, the system calculates the traversal length Li of the initial inner diameter measurement line within that pixel. Subsequently, the processor executes the correction formula: D_corrected = Σ [ (ΔIi / ΔImax) × Li ] (such as Figure 2 (as shown in -5) The physical meaning of this process is as follows: (ΔIi / ΔImax) is the normalized attenuation contribution of each pixel. (ΔIi / ΔImax) × Li is the equivalent length provided by that pixel along the measurement line direction. Summing all these sub-pixel level equivalent length information from different pixels (Σ) yields the concentrated projection width that the blood vessel should have in an ideal static state to reconstruct the total attenuation currently observed. Therefore, the accuracy of this method no longer primarily depends on the spatial resolution of the imaging system, but rather on the ability to utilize the image signal-to-noise ratio. S106: Result Output. The system displays the calculated corrected inner diameter value D_corrected on the screen, which has been converted to the actual physical size (e.g., millimeters) using a calibration object (such as a conduit) in the image.

[0017] Extended Application Notes It should be noted that the total attenuation conservation principle on which this invention is based can be directly extended to the correction of two-dimensional vascular contours, and its essence is the systematic application of the aforementioned inner diameter measurement method. The specific correction process is as follows: First, obtain the initial two-dimensional contour of the blood vessel and its central axis (e.g., Figure 3-1 (As shown); then, select a series of points on the central axis; draw a line segment perpendicular to the central axis at each point, and use it as the "initial inner diameter measurement line". Calculate the corrected inner diameter at that point using the core formula D_corrected = Σ [ (ΔIi / ΔImax) × Li ]; based on this, determine the new contour points on both sides along the direction of this line segment (as shown). Figure 3-2 (As shown). Finally, connect all the new contour points on the same side to form the corrected, precise two-dimensional vascular contour (as shown). Figure 3-3 (as shown) Therefore, two-dimensional contour correction is the result of spatial mapping and repeated application of the core measurement principle along the central axis of the blood vessel.

[0018] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for measuring the inner diameter of a blood vessel based on total attenuation inversion, characterized by, The method comprises the following steps: obtaining a digital subtraction angiography (DSA) image of a target; based on the image, determining a region of a blood vessel to be measured and an initial inner diameter measurement line; based on the gray scale variation information of the pixels through which the initial inner diameter measurement line passes, calculating a corrected blood vessel inner diameter according to the principle that the total net attenuation of the target blood vessel under actual motion state and the total net attenuation of the target blood vessel under ideal static state remain constant.

2. The method of claim 1, wherein, The calculation of the corrected blood vessel inner diameter specifically comprises: calculating the gray scale value drop (ΔIi) of each pixel through which the initial inner diameter measurement line passes; determining the maximum value (ΔImax) of the gray scale value drops of all the pixels; calculating the corrected blood vessel inner diameter (D_corrected) based on the following formula: D_corrected = Σ [ (ΔIi / ΔImax) × Li ] wherein, Li represents the length of the initial inner diameter measurement line in the i-th pixel, and Σ represents the summation of all the pixels passed through.

3. The method of claim 2, wherein, The "gray scale value drop (ΔIi)" is obtained by calculating the difference between the gray scale values of the mask image and the angiography image at the corresponding pixel position.

4. The method of claim 2, wherein, The "length of the initial inner diameter measurement line in the i-th pixel (Li)" is obtained by calculating the intersection coordinates of the measurement line and the pixel boundary.

5. The method according to any one of claims 1 to 4, characterized in that, The method recovers the attenuation signal dispersed in multiple pixels by integration, and realizes the measurement and correction of the inner diameter of a narrow blood vessel.

6. The method of claim 2, wherein, The method can be extended and applied to correct the two-dimensional profile of a blood vessel, specifically comprising: obtaining an initial two-dimensional profile of a blood vessel and a central axis thereof; based on the direction perpendicular to the central axis at each point along the central axis, determining a radial measurement line segment; taking each radial measurement line segment as the initial inner diameter measurement line, applying the measurement method comprising the formula D_corrected = Σ [ (ΔIi / ΔImax) × Li ], and obtaining a corrected profile point; connecting each corrected profile point to form a corrected two-dimensional profile of the blood vessel.

7. A blood vessel image processing apparatus characterized by comprising: comprise: a memory for storing a computer program; a processor for implementing the method of any one of claims 1 to 6 when executing the computer program.

8. A computer-readable storage medium, characterized in that, The computer program stored on the computer readable storage medium is executed by the processor to implement the method of any one of claims 1 to 6.

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