Gingival tissue hemodynamic spectroscopic index construction system based on near-infrared spectroscopy

Abstract

The application discloses a kind of gingival tissue hemodynamics spectral index construction systems based on near infrared spectroscopy, it is characterized in that, including visible near infrared spectrometer and data processing unit;Wherein, the visible near infrared spectrometer is used to collect the spectral data of each target site around the tooth to be detected;The data processing unit is used to normalize the spectral curve in each spectral data collected to consistent measurement background, determine the spectral absorption characteristics of gingival tissue oxyhemoglobin and deoxyhemoglobin is extracted;Then based on the spectral absorption characteristics obtained, gingival tissue hemodynamics index is calculated.The gingival tissue hemodynamics spectral index obtained based on the application can assist in quickly, accurately, non-invasively and cost-effectively completing periodontal tissue inflammation detection, and provides accurate and effective assistance for the clinical diagnosis of periodontitis.

Description

Technical Field

[0001] This invention relates to the field of non-invasive detection, and in particular to a system and method for constructing a hemodynamic spectral index of gingival tissue based on visible and near-infrared spectral data. Background Technology

[0002] Periodontitis is an infectious and destructive inflammatory disease of the soft and hard tissues surrounding the teeth. It is a leading cause of tooth loss and is closely related to systemic diseases such as cardiovascular disease and diabetes. Currently, the clinical diagnosis of periodontitis is mainly based on clinical examination and X-rays. Periodontal pocket probing depth (PD), clinical attachment loss (CAL), and bleeding index (BI) are widely used as the gold standard for defining the severity of periodontitis. However, these clinical diagnostic methods are time-consuming, require professional operation, and can cause some discomfort to patients. Among the emerging diagnostic methods for periodontitis, visible near-infrared spectroscopy (VNIR) is a promising non-invasive auxiliary diagnostic technique. The detection process is non-contact, painless, and can obtain in-situ spectra from specific sites. It is harmless to human health and has a relatively low cost. The basic principle is that VNIR spectra at different wavelengths from 400 to 1700 nm convey unique information about local tissue hemodynamics, including oxyhemoglobin (HbO2) and deoxyhemoglobin (Hb) in the tissue capillary bed, as well as tissue water content.

[0003] Current research uses near-infrared spectroscopy to detect the extinction coefficient of HbO2 in gingival tissue and calculates gingival tissue inflammation-related indices using the Beer-Lambert decomposition model. However, this method is relatively complex, which limits its clinical application. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention aims to provide a system and method for constructing spectral indices for gingival tissue hemodynamics based on visible and near-infrared spectroscopy. This study constructs spectral indices (HSIs) closely related to the hemodynamics of inflamed gingival tissue based on the reflectance spectral characteristics after envelope removal, including oxyhemoglobin (DHbO2) and deoxyhemoglobin (D... Hb This invention utilizes three spectral absorption depths for total hemoglobin (tHb) and oxyhemoglobin (NDHbO2I), as well as two standardized difference indices for oxyhemoglobin (NDHbI) and deoxyhemoglobin (NDHbI), to explore gingival tissue hemodynamic spectral indices that are relevant to and sensitive to periodontitis, thereby reflecting the inflammatory state of periodontal tissues. Based on the gingival tissue hemodynamic spectral indices obtained in this invention, periodontal tissue inflammation can be detected rapidly, accurately, non-invasively, and cost-effectively. Furthermore, the results can be used to promptly distinguish periodontal inflammatory sites, providing accurate and effective assistance for the clinical diagnosis of periodontitis.

[0005] This invention utilizes a visible-near-infrared spectrometer to collect raw hyperspectral data of healthy gingiva from healthy individuals and inflamed gingiva from patients with periodontitis. The collected hyperspectral data undergoes preprocessing, including noise reduction, radiometric calibration, and reflectance conversion. Envelope removal is performed on the raw reflectance spectral data to extract typical absorption characteristics of oxyhemoglobin and deoxyhemoglobin from healthy and inflamed gingiva. Hemodynamic spectral indices (HSIs) are then calculated. This invention uses envelope-removed spectroscopy to calculate HSIs as a quantitative indicator for the detection and diagnosis of periodontitis.

[0006] The technical solution of this invention is as follows:

[0007] A system for constructing spectral indices of gingival tissue hemodynamics based on visible and near-infrared spectroscopy, characterized in that it includes a visible and near-infrared spectrometer and a data processing unit; wherein,

[0008] The visible and near-infrared spectrometer is used to collect spectral data of various target sites around the tooth to be tested;

[0009] The data processing unit is used to normalize the spectral curves in the collected spectral data to a consistent measurement background, determine the spectral absorption characteristics of oxyhemoglobin and deoxyhemoglobin extracted from gingival tissue, and then calculate the gingival tissue hemodynamic index based on the obtained spectral absorption characteristics.

[0010] Furthermore, the spectral absorption characteristics include a relative absorption depth D. λ And the reflectivity after removing the envelope.

[0011] Furthermore, the gingival tissue hemodynamic indices include the normalized oxygenated hemoglobin index (NDHbO2I), the normalized deoxygenated hemoglobin index (NDHbI), and the gingival tissue total hemoglobin (tHb) index.

[0012] Furthermore, in, D represents the maximum absorption depth of oxidized hemoglobin. Hb D represents the maximum absorption depth of deoxidized hemoglobin. a D represents the depth corresponding to the wavelength of the insensitive band to the left of oxyhemoglobin (HbO2). b The depth corresponds to the wavelength of the insensitive band to the right of deoxyhemoglobin (Hb).

[0013] Furthermore, D represents the maximum absorption depth of oxidized hemoglobin at a wavelength of 544 nm. Hb D represents the maximum absorption depth of deoxidized hemoglobin at a wavelength of 576 nm. aD represents the depth corresponding to the wavelength of 484 nm, which is the insensitive band to the left of oxyhemoglobin (HbO2). b This corresponds to the depth near the wavelength of 617nm, which is the insensitive band to the right of deoxyhemoglobin (Hb).

[0014] Furthermore, the target sites include six sites on the tooth to be tested: distal buccal, buccal, proximal buccal, proximal lingual, lingual, and distal lingual.

[0015] Furthermore, the visible and near-infrared spectrometer repeatedly collects data at each target site multiple times and takes the average value as the spectral data of the corresponding target site.

[0016] A method for constructing hemodynamic spectral indices of gingival tissue based on visible and near-infrared spectroscopy, comprising the following steps:

[0017] 1) Acquire spectral data of each target site around the tooth to be tested using a visible and near-infrared spectrometer;

[0018] 2) Normalize the spectral curves in each collected spectral data to a consistent measurement background to determine the spectral absorption characteristics of oxyhemoglobin and deoxyhemoglobin extracted from gingival tissue.

[0019] 3) The hemodynamic index of gingival tissue was calculated based on the obtained spectral absorption characteristics.

[0020] The advantages of this invention are as follows:

[0021] This invention fully utilizes the differences in spectral characteristics between oxyhemoglobin and deoxyhemoglobin in the human body. Envelope removal analysis of the raw spectral data effectively suppresses raw spectral noise, reduces measurement uncertainty, and highlights spectral absorption characteristics. This facilitates comparative analysis under different spectral measurement backgrounds and times. It provides more characteristics of the spectral fingerprint of gingival tissue at different disease development stages, from healthy individuals and gingivitis to mild, moderate, and severe periodontitis.

[0022] This invention constructs spectral indices (HSIs) closely related to the hemodynamics of inflamed gingival tissue, including oxyhemoglobin (DHbO2) and deoxyhemoglobin (DbO2). Hb Based on the three spectral absorption depths of gingival tissue hemodynamic spectral indices of total hemoglobin (tHb) and oxyhemoglobin (NDHbO2I) and deoxyhemoglobin (NDHbI), this study explores gingival tissue hemodynamic spectral indices that are associated with and sensitive to periodontitis, thereby reflecting the inflammatory status of periodontal tissues.

[0023] The above indices are all derived from reflectance spectra obtained after envelope removal and are correlated with various parameters of periodontal clinical examination, the gold standard for diagnosing periodontitis. Models constructed using simple and practical HSIs indices extracted from envelope-removed spectra offer significant auxiliary capabilities for non-invasive, rapid, and accurate detection and diagnosis of periodontitis. Attached Figure Description

[0024] Figure 1 This is a flowchart of the method of the present invention.

[0025] Figure 2 This is the spectral image after envelope removal analysis of the reflectance of the acquired raw spectral data.

[0026] Figure 3 To construct gingival tissue hemodynamic indices NDHbO2I and NDHbI to analyze the differences among different degrees of periodontitis;

[0027] (a) The gingival tissue hemodynamic index NDHbO2I showed significant differences between the inflammation groups and the healthy group at different degrees.

[0028] (b) The gingival tissue hemodynamic index NDHbI reflects significant differences between the inflammation group and the healthy group at different degrees. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0030] The method flow of this invention is as follows: Figure 1 As shown, this invention utilizes a visible-near-infrared spectrometer to collect raw spectral data of inflamed gingiva from patients with periodontitis;

[0031] Measurements were taken from five severity levels: healthy, gingivitis, mild, moderate, and severe periodontitis. The visible and near-infrared spectrometer probe was placed 3 mm away from the surface of the gingival tissue and placed at six sites on the tooth being tested: distal buccal, buccal, mesiobuccal, mesioglossal, lingual, and distal lingual to collect spectral data.

[0032] The collected spectral data is preprocessed, including noise reduction, radiometric calibration, and reflectance conversion.

[0033] Envelope removal analysis was performed on all spectral reflectances to normalize all spectral curves to a consistent measurement background, and the spectral absorption characteristics of oxyhemoglobin and deoxyhemoglobin extracted from gingival tissue were determined, including the relative absorption depth D of the proteins. λ and reflectivity after envelope removal;

[0034] Based on the above envelope removal reflectivity, calculate the gingival tissue hemodynamic spectral indices (HSIs), such as NDHbO2I and NDHbI indices;

[0035] Based on gingival tissue hemodynamic spectral indices, we explore gingival tissue hemodynamic spectral indices that are related to and sensitive to periodontitis, thereby reflecting the inflammatory status of periodontal tissues, assisting in the diagnosis of the degree of periodontal tissue inflammation, and comparing and validating them with traditional gold standard diagnostic methods used in clinical practice.

[0036] The visible-near-infrared spectrometer typically needs to cover a spectral range of 400-1700 nm, with a spectral resolution better than 5 nm and a signal-to-noise ratio better than 500:1. To eliminate measurement uncertainties, the average value is taken after three repetitions at each site. HbO2 and Hb can induce significant absorption at approximately 544 nm and 576 nm, respectively. A normalized spectral index is constructed based on envelope-removed reflectance, as shown below:

[0037] D λ =1-ρ λ (1)

[0038]

[0039]

[0040]

[0041] Where D λ and ρ λ These represent the depth and envelope-removed reflectivity at specific wavelengths. Therefore, calculations were performed at the maximum absorption wavelengths of HbO2 (~544 nm) and Hb (~576 nm), respectively. and D Hb . D represents the maximum absorption depth of oxidized hemoglobin, specifically the maximum absorption depth at a wavelength of 544 nm. Hb This represents the maximum absorption depth of deoxidized hemoglobin, specifically the maximum absorption depth at a wavelength of 576 nm. This absorption depth is calculated based on the spectral curve after envelope removal.

[0042] The Normalized Difference Oxyhemoglobin Index (NDHbO2I) and the Normalized Difference Deoxyhemoglobin Index (NDHbI) are based on the left insensitive band (~484 nm) of HbO2 and the right insensitive band (~617 nm) of Hb, respectively, to better indicate the dynamic changes of oxyhemoglobin and deoxyhemoglobin.

[0043] The tHb index (total hemoglobin) represents the total hemoglobin in the gingival tissue, indicating the blood flow in the gingival tissue.

[0044] To minimize measurement uncertainty and highlight spectral absorption characteristics, envelope removal was performed on all spectra, which facilitates comparative analysis under different spectral measurement backgrounds and times. Therefore, the envelope-removed spectra were normalized and generally decreased with the progression of inflammation. Based on envelope removal analysis, HSIs indices closely related to periodontal tissue hemodynamics, including oxyhemoglobin, were established. Deoxyhemoglobin (D) Hb The study used three spectral absorption depths for total hemoglobin (tHb) and oxyhemoglobin (NDHbO2I), as well as two standardized differential indices for oxyhemoglobin (NDHbI) and deoxyhemoglobin (NDHbI). Using simple and practical HSI indices (e.g., NDHbO2I and NDHbI) extracted from envelope-removed spectra, these indices can reflect the degree of periodontal tissue inflammation, showing great potential for rapid, non-invasive, and accurate detection and auxiliary diagnosis of periodontitis.

[0045] From the above description of the embodiments, those skilled in the art can clearly understand that the present invention can be implemented in hardware or software. Those skilled in the art will understand that the modules in the apparatus of the embodiments can be distributed in the apparatus of the embodiments as described in the embodiments, or can be located in one or more devices different from this embodiment with corresponding changes.

[0046] The above-disclosed embodiment is only one specific embodiment of the present invention. However, the present invention is not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A system for constructing spectral indices of gingival tissue hemodynamics based on near-infrared spectroscopy, characterized in that, Includes a visible and near-infrared spectrometer and a data processing unit; among which, The visible and near-infrared spectrometer is used to collect spectral data of various target sites around the tooth to be tested; The data processing unit is used to normalize the spectral curves in the collected spectral data to a consistent measurement background, determine the spectral absorption characteristics of extracted oxyhemoglobin and deoxyhemoglobin from the gingival tissue, and then calculate the gingival tissue hemodynamic index based on the obtained spectral absorption characteristics. The gingival tissue hemodynamic index includes the normalized oxygenated hemoglobin index NDHbO2I, the normalized deoxyhemoglobin index NDHbI, and the gingival tissue total hemoglobin tHb index. D represents the maximum absorption depth of oxidized hemoglobin. Hb D represents the maximum absorption depth of deoxidized hemoglobin. a D represents the depth corresponding to the wavelength of the insensitive band to the left of oxyhemoglobin (HbO2). b The depth corresponds to the wavelength of the insensitive band to the right of deoxyhemoglobin (Hb).

2. The system according to claim 1, characterized in that, The spectral absorption characteristics include the relative absorption depth D. λ And the reflectivity after removing the envelope.

3. The system according to claim 1, characterized in that, D represents the maximum absorption depth of oxidized hemoglobin at a wavelength of 544 nm. Hb D represents the maximum absorption depth of deoxidized hemoglobin at a wavelength of 576 nm. a D represents the depth corresponding to the wavelength of 484 nm, which is the insensitive band to the left of oxyhemoglobin (HbO2). b This corresponds to the depth near the wavelength of 617nm, which is the insensitive band to the right of deoxyhemoglobin (Hb).

4. The system according to any one of claims 1 to 3, characterized in that, The target sites include six sites on the tooth to be tested: distal buccal, buccal, proximal buccal, proximal lingual, lingual, and distal lingual.

5. The system according to claim 4, characterized in that, The visible and near-infrared spectrometer repeatedly collects data at each target site multiple times and takes the average value as the spectral data for the corresponding target site.

6. A method for constructing spectral indices of gingival tissue hemodynamics based on near-infrared spectroscopy, comprising the following steps: 1) Acquire spectral data of each target site around the tooth to be tested using a visible and near-infrared spectrometer; 2) Normalize the spectral curves in each collected spectral data to a consistent measurement background to determine the spectral absorption characteristics of oxyhemoglobin and deoxyhemoglobin extracted from gingival tissue. 3) The gingival tissue hemodynamic index was calculated based on the obtained spectral absorption characteristics; the gingival tissue hemodynamic index includes the normalized oxygenated hemoglobin index NDHbO2I, the normalized deoxygenated hemoglobin index NDHbI, and the gingival tissue total hemoglobin tHb index; wherein, D represents the maximum absorption depth of oxidized hemoglobin. Hb D represents the maximum absorption depth of deoxidized hemoglobin. a D represents the depth corresponding to the wavelength of the insensitive band to the left of oxyhemoglobin (HbO2). b The depth corresponds to the wavelength of the insensitive band to the right of deoxyhemoglobin (Hb).

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