An experimental RGB imaging system based on commercial color camera was constructed, and its pote... more An experimental RGB imaging system based on commercial color camera was constructed, and its potential for mapping of hemoglobin distribution in skin was studied. Two types of LEDs (RGB and white "warm" LEDs) were compared as illuminators for acquiring images of vascular and pigmented skin malformations. A novel approach for studies of skin capillary refill by RGB analysis has been proposed and discussed.
The PPG measurements of the study Cugmas et al, 2018. Notes.txt include all information about the... more The PPG measurements of the study Cugmas et al, 2018. Notes.txt include all information about the dataset.
Studies of the physiological response of human half-body illumination by a specially designed bed... more Studies of the physiological response of human half-body illumination by a specially designed bed comprising large number of LEDs emitting in the red and near infrared spectral range were carried out in a group of 32 volunteers comprising healthy subjects and hypertension patients. Blood pressure, heart rate and arterial blood oxygen saturation, as well as the bed surface temperature were continuously monitored during the measurement sessions with and without aluminum foil cover on the bed surface. None of the volunteers exhibited any notable changes in the heart rate and blood oxygenation during the procedures. The LightStim LED-bed session did not produce changes of arterial pressure in normotensive group, while decreased blood pressure exhibited 2/3 of hypertensive patients. The thermal emission from the bed may serve as a dominant contributor to the observed effects on cardiovascular system.
Laser Speckle Contrast Imaging (LSCI) is a powerful low-cost method for visualization of flow, mi... more Laser Speckle Contrast Imaging (LSCI) is a powerful low-cost method for visualization of flow, microcirculation and blood perfusion. Due to the fact that diseased and healthy tissues has different blood perfusion, LSCI can be a perspective tool for cancer diagnostics and discrimination between different types of tissues. Previously, multispectral diffuse reflectance imaging method for melanoma diagnostics has been introduced. In this work, multi-wavelength (532-, 655-and 850-nm) LSCI technique combined with hyperspectral camera and diffuse reflectance imaging method will be used for assessment of tissues with different skin perfusion properties. An in vivo experiment with occlusion in human finger was performed serving as a model of tissues with different perfusion properties. The proposed method still requires further development and improvements to become a real clinical laboratory tool for non-invasive skin cancer diagnostics.
In 51 lesions from 15 patients with the inflammatory skin condition chronic graft‐versus‐host‐dis... more In 51 lesions from 15 patients with the inflammatory skin condition chronic graft‐versus‐host‐disease, hyperspectral imaging accurately delineated active erythema and post‐inflammatory hyperpigmentation. The method was validated by dermatologist‐approved confident delineations of only definitely affected and definitely unaffected areas in photographs. A prototype hyperspectral imaging system acquired a 2.5 × 3.5 cm2 area of skin at 120 wavelengths in the 450–850 nm range. Unsupervised extraction of unknown absorbers by endmember analysis achieved a comparable accuracy to that of supervised extraction of known absorbers (melanin, hemoglobin) by chromophore mapping: 0.78 (IQR: 0.39–0.85) vs. 0.83 (0.53–0.91) to delineate erythema and 0.74 (0.57–0.87) vs. 0.73 (0.52–0.84) to delineate hyperpigmentation. Both algorithms achieved higher specificity than sensitivity. Whereas a trained human confidently marked a median of 7% of image pixels, unsupervised and supervised algorithms delineated a median of 14% and 27% pixels. Hyperspectral imaging could overcome a fundamental practice gap of distinguishing active from inactive manifestations of inflammatory skin disease.
In this work, we use a statistical skin model to compare the measured distribution of optical pat... more In this work, we use a statistical skin model to compare the measured distribution of optical path lengths to time-resolved Monte Carlo simulated reflectance and validate the simulations by the use of optical phantoms.
Canine atopic dermatitis (CAD) is a common inflammatory and pruritic skin disease associated with... more Canine atopic dermatitis (CAD) is a common inflammatory and pruritic skin disease associated with allergy to exogenous allergens. The regular monitoring of skin lesions is essential to execute the anti-allergic therapy successfully. Erythema is one of the most important CAD-related lesions since it represents acute skin inflammation. Previously, we studied two optical systems (i.e., multispectral and dermatoscopic devices), which could objectively estimate erythema severity. However, we did not investigate, which image sampling method for selecting erythema-representing pixels and erythema index (EI) are correlated with the visual erythema assessment the most. In this paper, we tested three image sampling methods and four EIs for erythema severity estimation in 43 dogs. We discovered that all studied sampling methods and EIs were strongly correlated (r> 0.58) with the visual CADESI-4-based erythema severity assessment. However, the highest average Spearman’s correlations coefficient r of 0.77 was achieved when the average pixel value from the two small squared image sections without the hair and pigment was considered. On the other hand, EI, which was calculated from all three RGB values, achieved the highest r of 0.78. In this study, we identified a reliable image sampling method and erythema index (EI), which are well correlated with the visual erythema estimation.
Experimental methodology for parallel measurements of in-vivo skin autofluorescence (AF) lifetime... more Experimental methodology for parallel measurements of in-vivo skin autofluorescence (AF) lifetimes and photobleaching dynamic has been developed and tested. The AF lifetime decay distributions were periodically collected from fixed tissue area with subsequent detection of the fluorescence intensity decrease dynamic at different time gates after the pulse excitation. Temporal distributions of human in-vivo skin AF lifetimes and bleaching kinetics were collected and analyzed by means of commercial time-correlated single photon counting system.
Near-infrared spectroscopy has a potential for noninvasive determination of skin moisture level d... more Near-infrared spectroscopy has a potential for noninvasive determination of skin moisture level due to high water absorption. In this study, diffuse reflectance spectra of in vivo skin were acquired in the spectral range of 900 nm to 1700 nm by using near-infrared spectrometer, optical fiber and halogen bulb light source. Absorption changes after applying skin moisturizers were analyzed over time at different body sites. Results show difference in absorption when comparing dry and normal skin. Comparison of absorption changes over time after applying moisturizer at different body sites is analyzed and discussed. Some patterns of how skin reacts to different skin moisturizers are shown, although no clear pattern can be seen due to signal noise.
Two prototype models of pressure sensors using side-scattering optic fiber as the sensitive eleme... more Two prototype models of pressure sensors using side-scattering optic fiber as the sensitive element have been designed and experimentally assessed. The study showed that the use of 600-micron silica core side-scattering fiber resulted in 5 to 6 times higher sensitivity compared to the oridinary PCS fibers.
Capillary refill time (CRT) is a part of the cardiorespiratory examination in dogs. Changes in CR... more Capillary refill time (CRT) is a part of the cardiorespiratory examination in dogs. Changes in CRT can reflect pathological conditions like shock or anemia. Visual CRT estimation has low repeatability; therefore, optical systems for automated estimation have recently appeared. Since existing systems are unsuitable for use in dogs, we designed a simple, small and portable device, which could be easily used at veterinary clinic. The device was preliminarily tested on several measurement sites in two dogs. Not all measurement sites were suitable for CRT measurements due to underlying tissue optical and mechanical properties. The CRT measurements were possible on the labial mucosa, above the sternum and on the digit where CRT was in the range of values, retrieved from the color video of the visual CRT measurement. It seems that light penetration predominantly governs tissue optical response when the pressure is applied. Therefore, it is important to select a proper light, which reaches only superficial capillaries and does not penetrate deeper. Blue or green light is probably suitable for light skin or mucosa, on the other hand, red or near-infrared might be used for skin with pigmented or thick epidermis. Additionally, further improvements of the device design are considered, like adding a calibrated spring, which would insure application of consistent pressure.
A new technique for parallel recording of reflection photoplethysmography (PPG) signals in a broa... more A new technique for parallel recording of reflection photoplethysmography (PPG) signals in a broad spectral band (violet to near-infrared) has been developed, and its potential for assessment of blood microcirculation at various depths from the skin surface is discussed. PPG signals have been simultaneously detected at cw laser wavelength sets comprising 405, 532, 645, 807, and 1064 nm. Various signal baseline responses to breath holding and different shapes of the PPG pulses originated from the same heartbeat but recorded at different wavelengths have been observed, indicating a depth variety of the skin blood pulsation dynamics.
Time-resolved detection and analysis of skin backscattered optical signals (remission photoplethy... more Time-resolved detection and analysis of skin backscattered optical signals (remission photoplethysmography or PPG) provide rich information on skin blood volume pulsations and can serve for reliable cardiovascular assessment. Single-and multiple-channel PPG concepts are discussed. Simultaneous data flow from several locations on the human body allows us to study heartbeat pulse-wave propagation in real time and to evaluate vascular resistance. Portable single-, dual-, and four-channel PPG monitoring devices with special software have been designed for real-time data acquisition and processing. The prototype devices have been clinically studied, and their potential for monitoring heart arrhythmias, drug-efficiency tests, steady-state cardiovascular assessment, body fitness control, and express diagnostics of the arterial occlusions has been confirmed.
Сборник трудов конференции «International Conference on Advanced Laser Technologies (ALT)», 2019
RGB snapshot triple-spectral-line imaging 3 monochromatic spectral images from a single-snapshot ... more RGB snapshot triple-spectral-line imaging 3 monochromatic spectral images from a single-snapshot RGB image data can be extracted if object is illuminated simultaneously at 3 laser wavelengths, and the RGB-band sensitivities of the image sensor are known corrected R-, G-and B-band images*. 3 *) WO 2013135311 (A1). Method and device for imaging of spectral reflectance at several wavelength bands.
Four different Beer-Lambert law expanded models for skin chromophore mapping are discussed. Each ... more Four different Beer-Lambert law expanded models for skin chromophore mapping are discussed. Each model is analyzed in a diffuse reflectance case, when reference is white reference or healthy skin. Advantages and limitations will be presented.
The new non invasive in -vivo diagnostics method have been developed and clinical tested. Overall... more The new non invasive in -vivo diagnostics method have been developed and clinical tested. Overall 22 melanomas and 59 pigmented nevi were measured and analyzed using multispectral imaging system.
A commercially available point measurement device, the Mexameter(®), and an experimental RGB imag... more A commercially available point measurement device, the Mexameter(®), and an experimental RGB imaging prototype device were used for erythema index estimation of 50 rosacea patients by analysing the level of skin redness on the forehead, both cheeks and both sides of a nose. Results are compared with Clinician's Erythema Assessment (CEA) values given by two dermatologists. The Mexameter uses 568 nm and 660 nm LEDs and a photodetector for estimation of erythema index, while the used prototype device acquired RGB images at 460 nm, 530 nm and 665 nm LED illumination. Several erythema index estimation algorithms were compared to determine which one gives the best contrast between increased erythema and normal skin. The erythema index estimations and CEA values correlated much better for the RGB imaging data than for those obtained by the conventional Mexameter technique that is widely used by dermatologists and in clinical trials. In result, we propose an erythema index estimation approach that represents increased erythema with higher accuracy than other available methods.
An experimental RGB imaging system based on commercial color camera was constructed, and its pote... more An experimental RGB imaging system based on commercial color camera was constructed, and its potential for mapping of hemoglobin distribution in skin was studied. Two types of LEDs (RGB and white "warm" LEDs) were compared as illuminators for acquiring images of vascular and pigmented skin malformations. A novel approach for studies of skin capillary refill by RGB analysis has been proposed and discussed.
The PPG measurements of the study Cugmas et al, 2018. Notes.txt include all information about the... more The PPG measurements of the study Cugmas et al, 2018. Notes.txt include all information about the dataset.
Studies of the physiological response of human half-body illumination by a specially designed bed... more Studies of the physiological response of human half-body illumination by a specially designed bed comprising large number of LEDs emitting in the red and near infrared spectral range were carried out in a group of 32 volunteers comprising healthy subjects and hypertension patients. Blood pressure, heart rate and arterial blood oxygen saturation, as well as the bed surface temperature were continuously monitored during the measurement sessions with and without aluminum foil cover on the bed surface. None of the volunteers exhibited any notable changes in the heart rate and blood oxygenation during the procedures. The LightStim LED-bed session did not produce changes of arterial pressure in normotensive group, while decreased blood pressure exhibited 2/3 of hypertensive patients. The thermal emission from the bed may serve as a dominant contributor to the observed effects on cardiovascular system.
Laser Speckle Contrast Imaging (LSCI) is a powerful low-cost method for visualization of flow, mi... more Laser Speckle Contrast Imaging (LSCI) is a powerful low-cost method for visualization of flow, microcirculation and blood perfusion. Due to the fact that diseased and healthy tissues has different blood perfusion, LSCI can be a perspective tool for cancer diagnostics and discrimination between different types of tissues. Previously, multispectral diffuse reflectance imaging method for melanoma diagnostics has been introduced. In this work, multi-wavelength (532-, 655-and 850-nm) LSCI technique combined with hyperspectral camera and diffuse reflectance imaging method will be used for assessment of tissues with different skin perfusion properties. An in vivo experiment with occlusion in human finger was performed serving as a model of tissues with different perfusion properties. The proposed method still requires further development and improvements to become a real clinical laboratory tool for non-invasive skin cancer diagnostics.
In 51 lesions from 15 patients with the inflammatory skin condition chronic graft‐versus‐host‐dis... more In 51 lesions from 15 patients with the inflammatory skin condition chronic graft‐versus‐host‐disease, hyperspectral imaging accurately delineated active erythema and post‐inflammatory hyperpigmentation. The method was validated by dermatologist‐approved confident delineations of only definitely affected and definitely unaffected areas in photographs. A prototype hyperspectral imaging system acquired a 2.5 × 3.5 cm2 area of skin at 120 wavelengths in the 450–850 nm range. Unsupervised extraction of unknown absorbers by endmember analysis achieved a comparable accuracy to that of supervised extraction of known absorbers (melanin, hemoglobin) by chromophore mapping: 0.78 (IQR: 0.39–0.85) vs. 0.83 (0.53–0.91) to delineate erythema and 0.74 (0.57–0.87) vs. 0.73 (0.52–0.84) to delineate hyperpigmentation. Both algorithms achieved higher specificity than sensitivity. Whereas a trained human confidently marked a median of 7% of image pixels, unsupervised and supervised algorithms delineated a median of 14% and 27% pixels. Hyperspectral imaging could overcome a fundamental practice gap of distinguishing active from inactive manifestations of inflammatory skin disease.
In this work, we use a statistical skin model to compare the measured distribution of optical pat... more In this work, we use a statistical skin model to compare the measured distribution of optical path lengths to time-resolved Monte Carlo simulated reflectance and validate the simulations by the use of optical phantoms.
Canine atopic dermatitis (CAD) is a common inflammatory and pruritic skin disease associated with... more Canine atopic dermatitis (CAD) is a common inflammatory and pruritic skin disease associated with allergy to exogenous allergens. The regular monitoring of skin lesions is essential to execute the anti-allergic therapy successfully. Erythema is one of the most important CAD-related lesions since it represents acute skin inflammation. Previously, we studied two optical systems (i.e., multispectral and dermatoscopic devices), which could objectively estimate erythema severity. However, we did not investigate, which image sampling method for selecting erythema-representing pixels and erythema index (EI) are correlated with the visual erythema assessment the most. In this paper, we tested three image sampling methods and four EIs for erythema severity estimation in 43 dogs. We discovered that all studied sampling methods and EIs were strongly correlated (r> 0.58) with the visual CADESI-4-based erythema severity assessment. However, the highest average Spearman’s correlations coefficient r of 0.77 was achieved when the average pixel value from the two small squared image sections without the hair and pigment was considered. On the other hand, EI, which was calculated from all three RGB values, achieved the highest r of 0.78. In this study, we identified a reliable image sampling method and erythema index (EI), which are well correlated with the visual erythema estimation.
Experimental methodology for parallel measurements of in-vivo skin autofluorescence (AF) lifetime... more Experimental methodology for parallel measurements of in-vivo skin autofluorescence (AF) lifetimes and photobleaching dynamic has been developed and tested. The AF lifetime decay distributions were periodically collected from fixed tissue area with subsequent detection of the fluorescence intensity decrease dynamic at different time gates after the pulse excitation. Temporal distributions of human in-vivo skin AF lifetimes and bleaching kinetics were collected and analyzed by means of commercial time-correlated single photon counting system.
Near-infrared spectroscopy has a potential for noninvasive determination of skin moisture level d... more Near-infrared spectroscopy has a potential for noninvasive determination of skin moisture level due to high water absorption. In this study, diffuse reflectance spectra of in vivo skin were acquired in the spectral range of 900 nm to 1700 nm by using near-infrared spectrometer, optical fiber and halogen bulb light source. Absorption changes after applying skin moisturizers were analyzed over time at different body sites. Results show difference in absorption when comparing dry and normal skin. Comparison of absorption changes over time after applying moisturizer at different body sites is analyzed and discussed. Some patterns of how skin reacts to different skin moisturizers are shown, although no clear pattern can be seen due to signal noise.
Two prototype models of pressure sensors using side-scattering optic fiber as the sensitive eleme... more Two prototype models of pressure sensors using side-scattering optic fiber as the sensitive element have been designed and experimentally assessed. The study showed that the use of 600-micron silica core side-scattering fiber resulted in 5 to 6 times higher sensitivity compared to the oridinary PCS fibers.
Capillary refill time (CRT) is a part of the cardiorespiratory examination in dogs. Changes in CR... more Capillary refill time (CRT) is a part of the cardiorespiratory examination in dogs. Changes in CRT can reflect pathological conditions like shock or anemia. Visual CRT estimation has low repeatability; therefore, optical systems for automated estimation have recently appeared. Since existing systems are unsuitable for use in dogs, we designed a simple, small and portable device, which could be easily used at veterinary clinic. The device was preliminarily tested on several measurement sites in two dogs. Not all measurement sites were suitable for CRT measurements due to underlying tissue optical and mechanical properties. The CRT measurements were possible on the labial mucosa, above the sternum and on the digit where CRT was in the range of values, retrieved from the color video of the visual CRT measurement. It seems that light penetration predominantly governs tissue optical response when the pressure is applied. Therefore, it is important to select a proper light, which reaches only superficial capillaries and does not penetrate deeper. Blue or green light is probably suitable for light skin or mucosa, on the other hand, red or near-infrared might be used for skin with pigmented or thick epidermis. Additionally, further improvements of the device design are considered, like adding a calibrated spring, which would insure application of consistent pressure.
A new technique for parallel recording of reflection photoplethysmography (PPG) signals in a broa... more A new technique for parallel recording of reflection photoplethysmography (PPG) signals in a broad spectral band (violet to near-infrared) has been developed, and its potential for assessment of blood microcirculation at various depths from the skin surface is discussed. PPG signals have been simultaneously detected at cw laser wavelength sets comprising 405, 532, 645, 807, and 1064 nm. Various signal baseline responses to breath holding and different shapes of the PPG pulses originated from the same heartbeat but recorded at different wavelengths have been observed, indicating a depth variety of the skin blood pulsation dynamics.
Time-resolved detection and analysis of skin backscattered optical signals (remission photoplethy... more Time-resolved detection and analysis of skin backscattered optical signals (remission photoplethysmography or PPG) provide rich information on skin blood volume pulsations and can serve for reliable cardiovascular assessment. Single-and multiple-channel PPG concepts are discussed. Simultaneous data flow from several locations on the human body allows us to study heartbeat pulse-wave propagation in real time and to evaluate vascular resistance. Portable single-, dual-, and four-channel PPG monitoring devices with special software have been designed for real-time data acquisition and processing. The prototype devices have been clinically studied, and their potential for monitoring heart arrhythmias, drug-efficiency tests, steady-state cardiovascular assessment, body fitness control, and express diagnostics of the arterial occlusions has been confirmed.
Сборник трудов конференции «International Conference on Advanced Laser Technologies (ALT)», 2019
RGB snapshot triple-spectral-line imaging 3 monochromatic spectral images from a single-snapshot ... more RGB snapshot triple-spectral-line imaging 3 monochromatic spectral images from a single-snapshot RGB image data can be extracted if object is illuminated simultaneously at 3 laser wavelengths, and the RGB-band sensitivities of the image sensor are known corrected R-, G-and B-band images*. 3 *) WO 2013135311 (A1). Method and device for imaging of spectral reflectance at several wavelength bands.
Four different Beer-Lambert law expanded models for skin chromophore mapping are discussed. Each ... more Four different Beer-Lambert law expanded models for skin chromophore mapping are discussed. Each model is analyzed in a diffuse reflectance case, when reference is white reference or healthy skin. Advantages and limitations will be presented.
The new non invasive in -vivo diagnostics method have been developed and clinical tested. Overall... more The new non invasive in -vivo diagnostics method have been developed and clinical tested. Overall 22 melanomas and 59 pigmented nevi were measured and analyzed using multispectral imaging system.
A commercially available point measurement device, the Mexameter(®), and an experimental RGB imag... more A commercially available point measurement device, the Mexameter(®), and an experimental RGB imaging prototype device were used for erythema index estimation of 50 rosacea patients by analysing the level of skin redness on the forehead, both cheeks and both sides of a nose. Results are compared with Clinician's Erythema Assessment (CEA) values given by two dermatologists. The Mexameter uses 568 nm and 660 nm LEDs and a photodetector for estimation of erythema index, while the used prototype device acquired RGB images at 460 nm, 530 nm and 665 nm LED illumination. Several erythema index estimation algorithms were compared to determine which one gives the best contrast between increased erythema and normal skin. The erythema index estimations and CEA values correlated much better for the RGB imaging data than for those obtained by the conventional Mexameter technique that is widely used by dermatologists and in clinical trials. In result, we propose an erythema index estimation approach that represents increased erythema with higher accuracy than other available methods.
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Papers by Janis Spigulis