Method for discernible imaging of fixed dual-band narrow-band pseudo-color contrast regions

Abstract

The present application relates to the technical field of medical imaging, and especially relates to a kind of fixed dual-band narrowband pseudo-color equal contrast region distinguishable imaging method, using fixed dual-band narrowband imaging equipment to observe target phantom including different regions, generate narrowband equivalent pseudo-color image;From narrowband equivalent pseudo-color image, find narrowband pseudo-color equal contrast, but indistinguishable candidate region;Collect multispectral data in candidate region, and according to multispectral data, from multiple candidate regions, filter out narrowband pseudo-color indistinguishable, but multispectral quantitative identification region;Mark identification region in narrowband equivalent pseudo-color image, complete the region identification of target phantom.The present application triggers or highlights analysis using narrowband pseudo-color equal contrast indistinguishable condition, improves resolution accuracy and efficiency.

Description

Technical Field

[0001] This invention belongs to the field of medical imaging technology, and in particular relates to a resolvable imaging method for fixing contrast regions such as dual-band narrowband pseudo-color. Background Technology

[0002] Fixed dual-band narrowband imaging typically utilizes the absorption characteristics of hemoglobin around 415 nm and 540 nm to enhance the visual contrast between the mucosal surface and deeper blood vessels, outputting a pseudo-color image. The advantages of this imaging method are intuitive display, good real-time performance, and mature hardware and display infrastructure; its limitation lies in its primarily providing qualitative or semi-quantitative visual contrast, with limited information contained in the fixed dual-band imaging.

[0003] Multispectral or hyperspectral tissue oxygenation imaging reconstructs oxygen saturation, total hemoglobin concentration, or related spectral parameters by acquiring reflectance images across multiple spectral bands and combining them with hemoglobin extinction coefficients, isoabsorption points, or light transmission models. This type of technology can provide quantitative or relatively quantitative functional information, but in existing systems it is typically used for full-image quantification, offline analysis, or stand-alone functional imaging.

[0004] Fixed dual-band narrowband pseudocolor imaging has a specific failure scenario: when the reflection intensity, absorption intensity, or pseudocolor mapping results of the first and second regions under the first and second narrowbands are similar, they appear to have similar colors or insufficient contrast on the narrowband pseudocolor image, making it difficult for the observer to distinguish them; however, there may be measurable differences between the two in multi-spectral reflectance curves, oxygen saturation, hemoglobin concentration, or other hemoglobin-related parameters.

[0005] Therefore, there is still a need for an imaging resolution method with clear criteria, triggering mechanisms, and verification methods for fixed dual-band narrowband pseudo-color failure scenarios. Summary of the Invention

[0006] In view of this, the present invention aims to provide a resolvable imaging method for fixed dual-band narrowband pseudocolor isocontrast regions, used to identify isocontrast indivisible candidate regions in fixed dual-band narrowband pseudocolor images where the color difference or contrast difference is below a threshold, and under this condition, to reconstruct hemoglobin-related quantitative parameters through multi-spectral reflectance data, thereby determining whether the candidate region belongs to a region that is indivisible in narrowband pseudocolor but quantitatively separable in multi-spectral regions.

[0007] To achieve the above objectives, the technical solution created by this invention is implemented as follows: A resolvable imaging method with fixed dual-band narrowband pseudo-color contrast regions includes: S1: A fixed dual-band narrowband imaging device is used to observe the target phantom, including different regions, and generate a narrowband equivalent pseudo-color image; S2: From the narrowband equivalent pseudocolor image obtained in step S1, find candidate regions that are equal in contrast to narrowband pseudocolor but cannot be separated; S3: Collect multispectral data from the candidate regions obtained in step S2, and based on the multispectral data, select the identification regions from multiple candidate regions that are inseparable from narrowband pseudo-color but quantitatively quantified in multiple spectral bands; S4: Mark the identified region obtained in step S3 in the narrow-band equivalent pseudo-color image in step S1 to complete the region identification of the target phantom in step S1.

[0008] Furthermore, the fixed dual-band narrowband imaging device includes: dual-channel narrowband LEDs for illuminating the target phantom with beams of the first and second narrowbands; a synchronization controller for controlling the dual-channel narrowband LEDs to simultaneously illuminate the target phantom; a monochrome camera for acquiring the reflected image generated by the target phantom after being illuminated by the first and second narrowbands; a pseudo-color image generator for generating a narrowband equivalent pseudo-color image based on the reflected images of the first and second narrowbands; and a spectral acquisition unit for detecting the insertion of multi-band acquisition sequences or the retrieval of cached multi-band data in candidate regions.

[0009] Furthermore, the first narrow band is the band where the hemoglobin Soret absorption band is located, and the peak wavelength of the first narrow band is 405nm~430nm; the second narrow band is the band where the hemoglobin Q band is located, and the peak wavelength of the second narrow band is 520nm~560nm.

[0010] Further, step S2 includes: calculating the first difference between different regions in the narrowband equivalent pseudocolor image, and comparing the first difference with a preset first threshold; selecting the region related to the first difference which is less than the first threshold, and determining the region as a candidate region.

[0011] Furthermore, the process of obtaining the identified region in step S3 includes: reconstructing the hemoglobin-related quantitative parameters of the candidate region based on the collected multispectral data; calculating the second difference of the hemoglobin-related quantitative parameters between the candidate regions and comparing the second difference with a preset second threshold; selecting the candidate region related to the second difference that is greater than the second threshold and determining the candidate region as the identified region.

[0012] Furthermore, the bands of the multispectral data in step S3 include bands with significant differences in extinction between oxyhemoglobin and deoxyhemoglobin, as well as bands near at least one isoabsorption point.

[0013] Furthermore, hemoglobin-related quantitative parameters include at least one of the following: blood oxygen saturation, relative concentration of oxyhemoglobin, relative concentration of deoxyhemoglobin, relative concentration of total hemoglobin, and hemoglobin-related spectral index.

[0014] Furthermore, in step S4, a marker for distinguishing the identification area, or a quantitative parameter map of the identification area, is superimposed on the narrow-band equivalent pseudo-color image.

[0015] Furthermore, the labels for the overlay output are at least one of the following: the outline of the identified region, the pseudo-color overlay heatmap, the classification label, and the region numerical summary.

[0016] Furthermore, a resolution gain index is marked on the narrowband equivalent pseudocolor image. The resolution gain index is the ratio of the normalized separability in the quantitative parameter map to the normalized separability in the narrowband equivalent pseudocolor image.

[0017] Compared with the prior art, the present invention can achieve the following beneficial effects: The present invention provides a resolvable imaging method for fixed dual-band narrowband pseudocolor and other contrast regions. Compared with imaging using only fixed dual-band narrowband pseudocolor, this method can identify and distinguish regions in the pseudocolor image that are similar in color or contrast but have different quantitative parameters related to hemoglobin. Compared with unconditional full-image multi-spectral quantitative imaging, this invention utilizes the condition of inseparable contrast of narrowband pseudocolor for triggering or focusing analysis, which can reduce unnecessary multi-spectral acquisition and calculation burden. Attached Figure Description

[0018] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a flowchart illustrating the resolvable imaging method for fixed dual-band narrowband pseudo-color and other contrast regions according to the present invention. Figure 2 This is a schematic diagram of the verification phantom described in Example 1; Figure 3 The narrowband equivalent pseudo-color image described in Example 1; Figure 4 This is the multi-spectral reflectance curve diagram described in Example 1.

[0019] Explanation of reference numerals in the attached figures: 1. Base; 2. First region; 3. Second region; 4. Gradient test area. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0021] In the description of this invention, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0022] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] like Figure 1 As shown in the embodiment of the present invention, the resolvable imaging method for fixing the contrast region of dual-band narrowband pseudo-color includes: S1: A fixed dual-band narrowband imaging device is used to observe target phantoms including different regions and generate narrowband equivalent pseudo-color images.

[0024] In some embodiments, the fixed dual-band narrowband imaging device includes dual-channel narrowband LEDs, a synchronization controller, a monochrome camera, a spectral acquisition unit, and a pseudo-color image generator. The dual-channel narrowband LEDs illuminate the target phantom with a first narrowband and a second narrowband light beam. The first narrowband band corresponds to the hemoglobin Soret absorption band, with a peak wavelength of 405 nm to 430 nm, and the second narrowband band corresponds to the hemoglobin Q band, with a peak wavelength of 520 nm to 560 nm. The synchronization controller controls the simultaneous illumination of the target phantom by the dual narrowband LEDs. The monochrome camera acquires the reflected image of the target phantom after illumination by the first and second narrowband LEDs. The pseudo-color image generator generates a narrowband equivalent pseudo-color image based on the reflected images of the first and second narrowband LEDs. The spectral acquisition unit detects the insertion of multi-band acquisition sequences or the retrieval of cached multi-band data in candidate regions.

[0025] S2: From the narrowband equivalent pseudocolor image obtained in step S1, find candidate regions that are equal in contrast to narrowband pseudocolor but cannot be separated.

[0026] In some embodiments, step S2 includes: calculating a first difference between different regions in a narrowband equivalent pseudocolor image, and comparing the first difference with a preset first threshold; selecting a region with a first difference less than the first threshold, and determining the region as a candidate region.

[0027] In a specific embodiment, the first difference can be one or more combinations of pseudo-color difference, contrast difference based on brightness or intensity, and observed numerical difference. Furthermore, the pseudo-color difference can be one or a combination of CIE Lab color difference or RGB feature distance, the contrast difference can be one or a combination of Michelson contrast or Weber contrast, and the observed numerical difference is the two-dimensional feature distance composed of the reflection intensity of the first narrow band and the second narrow band. Specifically, the two-dimensional feature distance is calculated by combining the reflection intensity values ​​of each pixel in the two narrow bands into a two-dimensional coordinate point, and by calculating the distance between different regions in the two-dimensional feature space, the comprehensive difference between different regions is measured.

[0028] Furthermore, in a particular embodiment, a first threshold is determined based on one or more of the following: the noise level of the device itself, the minimum difference that the eye can distinguish (i.e., the visual threshold), or the properties of the target phantom itself, so that the final first threshold is more reflective of whether it is distinguishable under actual observation conditions.

[0029] S3: Collect multispectral data from the candidate regions obtained in step S2, and based on the multispectral data, select the identification regions from multiple candidate regions that are inseparable from narrowband pseudo-color but quantitatively quantified across multiple spectral bands.

[0030] In some embodiments, the process of obtaining the identified region includes: reconstructing the hemoglobin-related quantitative parameters of the candidate region based on the collected multispectral data; calculating the second difference of the hemoglobin-related quantitative parameters between the candidate regions and comparing the second difference with a preset second threshold; selecting the candidate region related to the second difference that is greater than the second threshold and determining the candidate region as the identified region.

[0031] The multispectral data bands include those showing significant differences in extinction between oxyhemoglobin and deoxyhemoglobin, as well as bands near at least one isoabsorption point. Hemoglobin-related quantitative parameters include at least one of the following: blood oxygen saturation, relative concentration of oxyhemoglobin, relative concentration of deoxyhemoglobin, relative concentration of total hemoglobin, and hemoglobin-related spectral indices.

[0032] In a specific embodiment, the number of bands in the multispectral data is greater than or equal to 4. The multispectral data can be obtained by automatically inserting multispectral acquisition sequences, performing ROI multispectral acquisition on candidate regions, or calling cached multispectral reflectance data. In addition, the second threshold is determined based on at least one of the following: repeatability standard deviation, quantitative signal-to-noise ratio, quantitative contrast noise ratio, or target phantom calibration results.

[0033] S4: Mark the identified region obtained in step S3 in the narrow-band equivalent pseudo-color image in step S1 to complete the region identification of the target phantom in step S1.

[0034] In some embodiments, a marker for distinguishing the identified regions, or a quantitative parameter map of the identified regions, is superimposed on the narrow-band equivalent pseudo-color image to complete the region identification of the target phantom. The superimposed marker is at least one of the following: the outline of the identified region, a pseudo-color overlay heatmap, a classification label, and a region numerical summary.

[0035] In some embodiments, a resolution gain index is also marked on the narrowband equivalent pseudocolor image, which is the ratio of the normalized separability in the quantitative parameter map to the normalized separability in the narrowband equivalent pseudocolor image.

[0036] To verify that the method provided by this invention can achieve effective region resolution in fixed dual-band narrowband imaging, two verification embodiments are provided: In Embodiment 1, an artificially prepared verification phantom is used as the target phantom, and the method provided by this invention is used to perform effective region resolution of fixed dual-band narrowband imaging on the verification phantom; In Embodiment 2, an ex vivo biological tissue sample is used as the target phantom, and the method provided by this invention is used to perform effective region resolution of fixed dual-band narrowband imaging on the biological tissue sample.

[0037] Example 1: Verification phantoms such as Figure 2 As shown, it includes a substrate 1, and a first region 2, a second region 3, and multiple gradient test areas 4 disposed on the substrate (e.g., Figure 2 In this embodiment, G1~G4), the substrate 1 is specifically a scattering matrix, which can be one or more combinations of Intralipid, TiO2, gelatin, agar, and PDMS. In this embodiment, Intralipid is specifically used. The materials of the first region 2 and the second region 3 are hemoglobin solutions or stable dyes with different oxygenation ratios. Since both oxyhemoglobin and deoxyhemoglobin are full-rank in the first and second narrow bands, if only these two components are present, equal contrast in the two bands usually means that the components are the same. Therefore, this embodiment also introduces a neutral absorber in the first region 2 and the second region 3, so that the first region 2 and the second region 3 are regions with equal contrast in the two bands but different oxygen saturation. Multiple gradient test areas 4 can have different pseudocolor differences and different quantitative parameter differences, which are used to calibrate the first threshold, the second threshold, or the resolution gain index. In this embodiment, the first threshold T is set through multiple gradient test areas. c =2.3, the hemoglobin-related quantitative parameter selected is blood oxygen saturation, which corresponds to a second threshold T. q =3.

[0038] In this embodiment, the peak wavelengths of the first and second narrowbands of the dual-channel narrowband LED are 415nm and 540nm, respectively. Therefore, the optical path length L of the verification phantom prepared in this embodiment is 0.1cm, the reflection measurement noise is approximately 1.2%, and the bias is approximately 3.5%. The first region comprises: HbO2 content of 8.5e-5mol / L, Hb content of 1.5e-5mol / L, and N content of 3.0e-5mol / L, thus simulating that the StO2 (tissue oxygen saturation) content accounts for 85% of the total components in the first region. The second region comprises: HbO2 content of 5.97e-5mol / L, Hb content of 3.98e-5mol / L, and N content of 3.21e-5mol / L, thus simulating that the StO2 content accounts for 60% of the total components in the second region. The formulation provided in this embodiment makes the reflectance of the first and second regions in the verification phantom close at 415nm and 540nm, respectively, so that the false color difference in the fixed dual-band narrowband imaging device generated by the fixed dual-band narrowband imaging device is lower than the visual threshold that can be distinguished by the human eye.

[0039] Based on the above verification phantom, the method of this embodiment includes: S1: A fixed dual-band narrowband imaging device alternately illuminates the 415nm LED and the 540nm LED to observe the verification phantom, which includes the first and second regions, generating data such as... Figure 3 The narrowband equivalent pseudocolor image shown.

[0040] S2: Superpixel segmentation was performed on the narrowband equivalent pseudocolor image. The pseudocolor difference (i.e., the first difference) between the first and second regions was found to be 0.81 ± 0.51, which is significantly less than the first threshold T. c =2.3, thus identifying the first and second regions as candidate regions. Meanwhile, if... Figure 3 As shown, the pseudo-color difference between the third and fourth regions obtained after superpixel segmentation is 1.06 ± 0.44, which is also less than the first threshold T. c =2.3, at this point, the third and fourth regions are also identified as candidate regions.

[0041] S3: Collect multispectral data of candidate regions and reconstruct the blood oxygen saturation of candidate regions based on the collected multispectral data; calculate the second difference in blood oxygen saturation between candidate regions and compare the second difference with a preset second threshold; select candidate regions with a second difference greater than the second threshold and identify the candidate regions as the identification regions.

[0042] like Figure 4As shown, the normalized reflectance of the first and second regions is similar in the first and second narrow bands, exhibiting a fixed dual-band pseudo-color contrast. In other bands, the multispectral reflectance curves of the first and second regions show measurable differences, thus allowing for differentiation through multispectral quantitative reconstruction. In this embodiment, the reconstructed StO2 values ​​for the first and second regions are 86.4% and 62.2%, respectively, corresponding to a difference of 5.8 in blood oxygen saturation between the two regions, significantly greater than the second threshold T. q =3, at this point, the first and second regions are determined to be narrow-band pseudo-color inseparable but quantitatively separable marker regions. For the third and fourth regions, their StO2 values ​​are 86.4% and 86.8%, respectively, corresponding to a difference of 0.1 in blood oxygen saturation between the two regions, significantly less than the second threshold T. q =3, at this point it is determined that the third and fourth regions are not identified regions.

[0043] S4: Mark the identified regions obtained in step S3 in the narrowband equivalent pseudo-color image in step S1, completing the region identification of the target phantom in step S1. In this embodiment, step S3 determines that the first and second regions are identified regions, and the outlines of the first and second regions are marked in the narrowband equivalent pseudo-color image accordingly, and the resolution gain index of the two regions is calculated. Since step S3 determines that the third and fourth regions are not identified regions, the outlines of the third and fourth regions are not marked in the narrowband equivalent pseudo-color image accordingly, and naturally, the resolution gain index of the two regions is not calculated.

[0044] Example 2: Ex vivo biological tissue samples were selected as target phantoms. Oxygenation differences were created in local areas through clamping, perfusion fluid regulation, or chemical methods. At the same time, normal and hypoxic regions were formed in the biological tissue samples through optical path length, surface wettability, or background scattering conditions. The normal and hypoxic regions appeared similar in color on a fixed dual-band narrowband pseudo-color image. The reflectance of the normal and hypoxic regions at 415nm and 540nm was similar, with a relative difference of about 2%.

[0045] The verification experiment was conducted using the same method as in Example 1, and the specific operation process will not be repeated here. During the operation, the false color difference (i.e., the first difference) between the normal area and the hypoxic area was found to be 1.44±0.57, which is significantly less than the first threshold T. c =2.3, identifying the normal and hypoxic regions as candidate regions. Reconstruction yielded StO2 levels of 85% and 60% in the normal and hypoxic regions, respectively, corresponding to a blood oxygen saturation difference of 3.6 between the two regions, significantly greater than the second threshold T. q=3, at this point, the normal region and the hypoxic region are identified as indivisible but quantitatively separable regions in the narrowband pseudocolor image. The outlines of the normal region and the hypoxic region are marked in the corresponding narrowband equivalent pseudocolor image, and the resolution gain index of the two regions is calculated to be 5.8. This embodiment is used to verify the feasibility and robustness of this method under real tissue scattering background.

[0046] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0047] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A resolvable imaging method with fixed dual-band narrowband pseudo-color contrast regions, characterized in that, include: S1: A fixed dual-band narrowband imaging device is used to observe the target phantom, including different regions, and generate a narrowband equivalent pseudo-color image; S2: From the narrowband equivalent pseudocolor image obtained in step S1, find candidate regions that are equal in contrast to narrowband pseudocolor but cannot be separated; S3: Collect multispectral data from the candidate regions obtained in step S2, and based on the multispectral data, select the identification regions from multiple candidate regions that are inseparable from narrowband pseudo-color but quantitatively quantified in multiple spectral bands; S4: Mark the identified region obtained in step S3 in the narrow-band equivalent pseudo-color image in step S1 to complete the region identification of the target phantom in step S1.

2. The resolvable imaging method for fixed dual-band narrowband pseudo-color and other contrast regions according to claim 1, characterized in that, Fixed dual-band narrowband imaging equipment includes: Dual-channel narrowband LEDs are used to illuminate the target phantom with a first narrowband and a second narrowband beam. A synchronous controller is used to control the simultaneous illumination of the target phantom by dual narrowband LEDs; A monochrome camera is used to acquire reflected images of a target phantom after it has been illuminated by a first narrow band and a second narrow band. A pseudo-color image generator; used to generate a narrowband equivalent pseudo-color image based on the reflection images of a first narrowband and a second narrowband; A spectral acquisition unit is used to detect inserted multi-band acquisition sequences or retrieve cached multi-band data in candidate regions.

3. The resolvable imaging method for fixed dual-band narrowband pseudo-color and other contrast regions according to claim 2, characterized in that, The first narrow band is the band where the hemoglobin Soret absorption band is located, with a peak wavelength of 405nm~430nm; the second narrow band is the band where the hemoglobin Q band is located, with a peak wavelength of 520nm~560nm.

4. The resolvable imaging method for fixed dual-band narrowband pseudo-color and other contrast regions according to claim 1, characterized in that, Step S2 includes: Calculate the first difference between different regions in the narrowband equivalent pseudocolor image, and compare the first difference with a preset first threshold. Select the region with the first difference less than the first threshold and define it as a candidate region.

5. The resolvable imaging method for fixed dual-band narrowband pseudo-color and other contrast regions according to claim 1, characterized in that, The process of obtaining the identified region in step S3 includes: Based on the collected multispectral data, the hemoglobin-related quantitative parameters of the candidate region are reconstructed; Calculate the second difference in hemoglobin-related quantitative parameters between candidate regions and compare the second difference with a preset second threshold. Select candidate regions with a second difference greater than the second threshold, and identify these candidate regions as the identification regions.

6. The resolvable imaging method for fixed dual-band narrowband pseudo-color and other contrast regions according to claim 1, characterized in that, The bands of the multispectral data in step S3 include bands with significant differences in extinction between oxyhemoglobin and deoxyhemoglobin, as well as bands near at least one isoabsorption point.

7. The resolvable imaging method for fixed dual-band narrowband pseudo-color and other contrast regions according to claim 6, characterized in that, Hemoglobin-related quantitative parameters include at least one of the following: blood oxygen saturation, relative concentration of oxyhemoglobin, relative concentration of deoxyhemoglobin, relative concentration of total hemoglobin, and hemoglobin-related spectral index.

8. The resolvable imaging method for fixed dual-band narrowband pseudo-color and other contrast regions according to claim 1, characterized in that, In step S4, a marker or a quantitative parameter map of the marker region is superimposed on the narrow-band equivalent pseudo-color image to distinguish the marker region.

9. The resolvable imaging method for fixed dual-band narrowband pseudo-color and other contrast regions according to claim 8, characterized in that, The overlay output is labeled with at least one of the following: the outline of the identified region, the pseudo-color overlay heatmap, the classification label, and the region numerical summary.

10. The resolvable imaging method for fixed dual-band narrowband pseudo-color and other contrast regions according to claim 8, characterized in that, The narrowband equivalent pseudocolor image is also marked with a resolution gain index, which is the ratio of the normalized separability in the quantitative parameter map to the normalized separability in the narrowband equivalent pseudocolor image.

Images