Photoplethysmography Analysis of Artery Properties in Patients with Cardiovascular Diseases
In this study arterial parameters of healthy subjects were compared to those of patients with cardiovascular diseases. The photoplethysmography (PPG) measurements of blood volume pulsations have been performed. Using a novel algorithm for analysis of simultaneously measured ear and finger PPG signals, arterial parameters were evaluated in representative groups of healthy subjects and patients with cardiovascular diseases. Digital volume pulse (DVP), pulse cycle duration (T), augmentation index (AIx), reflection index (RI) and transit time of reflected wave (RTT) were evaluated in every heartbeat cycle. Correlations between the AIx and RI, T and RTT, AIx and standard deviation of AIx, RTT an…
Application of colour magnification technique for revealing skin microcirculation changes under regional anaesthetic input
In this work the colour magnification technique was applied for monitoring of palm skin microcirculation changes under peripheral (Plexus Brachialis with axiliary access) Regional Anaesthesia (RA). During the RA procedure 20 minute video of patient’s forearm was taken at steady light conditions. Video content was processed offline by custom developed Matlab software with build-in colour magnification algorithm that performs temporal filtering of video sequence near-heartbeat frequency, spatial decomposition of video and amplification of pulsatile signal in every pixel of skin image. Using this method, we are able to visualize the subcutaneous microcirculation changes in high spatial resolut…
A snapshot multi-wavelengths imaging device for in-vivo skin diagnostics
A portable proof-of-concept prototype device for single snapshot capturing of four spectral line images has been designed, assembled and laboratory-tested. It comprises optical unit that ensures even illumination of the skin target area simultaneously at four laser wavelengths - 450 nm, 523 nm, 638 nm and 850 nm, double-camera image recording system, micro-computer managed operation system and a touch-screen display for image control and displaying the concentration distribution maps of four skin chromophores - melanin, oxy-hemoglobin, deoxy-hemoglobin and bilirubin. Besides, the device captures skin auto fluorescence image at 405 nm laser excitation to separate seborrheic keratosis from ot…
LASCA and PPG imaging for non-contact assessment of skin blood supply
Laser speckle contrast analysis (LASCA) offers a non-contact, full-field, and real-time mapping of capillary blood flow and can be considered as an alternative method to Laser Doppler perfusion imaging (LDPI). Photoplethysmography (PPG) is well known technique for assessment of skin blood pulsations that can be related to blood flow. In recent years several studies have been done on development of non-contact PPG imaging (PPGI). LASCA and PPGI techniques are simpler and cheaper compared with LDPI. LASCA technique has been implemented in several commercial instruments. However, these systems are still too expensive and bulky to be widely available. Several optical techniques have found new i…
Skin chromophore mapping by modified video-microscope
Possibilities to map skin chromophores using a modified low-cost digital video-microscope is discussed. The device comprises CMOS digital imaging sensor, four-colour LED illumination system and image acquisition optics. The main goal is to obtain a set of spectral images of the skin area of interest for further conversion into maps of the main skin chromophores
Micro-circulation of skin blood: optical monitoring by advanced photoplethysmography techniques
Blood micro-circulation in upper skin layers has been studied experimentally in real time by advanced two-channel photoplethysmography (PPG) techniques. The blood volume changes caused by micro-vessel expansion and dilution during the cardiac cycles have been detected by infrared optical contact sensors. A newly developed portable monitoring device comprising a lap-top computer was used for accumulation and processing of the bio-signals. Shapes of the PPG signals detected at different sites of the body were compared with these obtained by computer modeling.
Two-stage multi-Gaussian fitting of conduit artery photoplethysmography waveform during induced unilateral hemodynamic events.
Photoplethysmography (PPG) is an optical technique with high diagnostic potential, yet clinical applications remain underdeveloped. Standardization of signal recording and quantification of waveform are essential prerequisites for broader clinical use. The aim of this study was to utilize a two-stage multi-Gaussian fitting technique in order to examine the parameters of conduit artery PPG waveform recorded during increasing the unilateral regional vascular resistance (RVR). This study was conducted on 14 young and healthy volunteers; various external compressions (ECs) were performed by inflating a tight cuff at 0, 40, 80, and 200 mmHg, while registering femoral PPG (wavelength 880 nm), dia…
The blood perfusion mapping in the human skin by photoplethysmography imaging
A CMOS camera-based imaging photoplethysmographic (PPGI) system is described to detect the blood pulsations in tissue. Attention of PPGI is drawn to the potential applications in visualized blood perfusion. Intensity variations of three wavelengths (620 nm, 520 nm and 432 nm) were detected and analyzed in each pixel of image. To obtain a twodimensional mapping of the dermal perfusion measurement, custom image-processing software has been developed. The high-resolution PPGI images were derived from human fingers (transmission mode) and face (reflection mode), evaluated at three wavelengths. The newly developed system can be usable in skin blood perfusion monitoring for clinical applications.
Rosacea assessment by erythema index and principal component analysis segmentation maps
RGB images of rosacea were analyzed using segmentation maps of principal component analysis (PCA) and erythema index (EI). Areas of segmented clusters were compared to Clinician’s Erythema Assessment (CEA) values given by two dermatologists. The results show that visible blood vessels are segmented more precisely on maps of the erythema index and the third principal component (PC3). In many cases, a distribution of clusters on EI and PC3 maps are very similar. Mean values of clusters’ areas on these maps show a decrease of the area of blood vessels and erythema and an increase of lighter skin area after the therapy for the patients with diagnosis CEA = 2 on the first visit and CEA=1 on the …
Effect of probe contact pressure on the photoplethysmographic assessment of conduit artery stiffness
Currently, photoplethysmography (PPG) is a frequently studied optical blood pulsation detection tech- nique among biophotonic and biomedical researchers due to the fact that it shows high potential for estimating the arterial stiffness (AS). The extraction of diagnostically useful information requires standardized measurement pro- cedure with good repeatability. However, the effects of a crucially important factor—the optimal contact pressure (CP) of the probe—are often ignored. Also, CP values are not reported to evaluate those effects. It is hypothesized that AS estimated from PPG pulse wave 2nd derivative parameter b∕a is strongly inconsistent when recorded at nonoptimal probe CP. Our pi…
The assessment of gingivitis using remote photoplethysmography
Gum disease caused by bacterial infection, systemic conditions or neurogenic inflammation remains a prevalent and important concern of public health in both, developing and developed countries, potentially causing tooth loss if left untreated. Therefore, a simple, cost-effective, and contactless diagnostic tool is needed in dentistry. The present study aims to develop and investigate the feasibility of a motion artefact-free, miniature imaging photoplethysmography system which is dedicated for assessment of gingivitis in the dental office. The device comprised of a sub-miniature monochromatic camera equipped with miniature lens, 4-LED ring illuminator, cross polarizers and bandpass optical …
Remote photoplethysmography for skin perfusion monitoring using narrowband illumination
The purpose of this study was to determine potential of remote photoplethysmography for skin perfusion monitoring, using 540 nm narrowband and 530 nm broadband illuminations. The alterations of cutaneous circulation were produced by topical skin heating protocol. The setup comprises of 530 nm LED light source and two identical cameras operated simultaneously: one equipped with narrowband optical filter (CWL=540nm), and another without filter. Results demonstrate the typical heating test response curve- comprising first peak, nadir and plato phase, which were significantly different in narrowband and broadband illumination. It was concluded that selection of optimal light source parameters i…
Evaluation of nitroglycerin effect on remote photoplethysmogram waveform acquired at green and near infra-red illumination
Assessment of skin microcirculation provides diagnostically valuable information during the early stages of pathologies. The simple, cost-effective and intrusive alternative to existing circulation assessment methods is remote photoplethysmography (rPPG). The objective of the present pilot study was to reveal an effect on sublingual administration of 1 mg nitroglycerin on systemic hemodynamic parameters and rPPG waveforms, at 810 nm and 530nm illumination. The protocol comprised 3 minutes of baseline recording, 15 minutes recording of NTG effect, 2 minutes of arterial occlusion and the following 3 min reactive hyperemia. Two PPG signals were acquired from glabrous skin of the middle finger …
Photoplethysmography system for blood pulsation detection in unloaded artery conditions
Photoplethysmography (PPG) is an optical method of blood pulsation recording and has been extensively studied for decades. Recently PPG is widely used in the medical equipment for patient monitoring and in laboratories for research and physiological studies. In spite of the technological progress in the field of medical equipment, there are no generally accepted standards for clinical PPG measurements up to date. One of the most important factors affecting PPG waveform is the contact pressure between tissue and PPG probe. The aim of the current study was to develop and evaluate a system for software-assisted PPG signal acquisition from the unloaded artery. Novel PPG waveform derived Optimal…
Microvascular blood flow changes of the abductor pollicis brevi muscle during sustained static exercise
ABSTRACTA practical assessment of the health of the palm muscle, abductor pollicis brevis (APB), is important for diagnosis of different conditions. Here we have developed a protocol and a probe to utilize diffuse correlation spectroscopy (DCS) to characterize microvascular blood flow changes in the APB during and after sustained isometric exercise, during and after thumb abduction at at 55% of maximum voluntary contraction (MVC). Blood flow in the APB decreased during exercise in the subjects (n=13) with high MVC (n=7) and stayed constant in the ones with low MVC (n=6) suggesting that the mechanical occlusion due to increased intramuscular pressure exceeded the vasodilation elicited by the…
Semi-automatic detection of skin malformations by analysis of spectral images
The multi-spectral imaging technique to reveal skin malformations has been described in this work. Four spectral images taken at polarized monochromatic LED illumination (450nm, 545nm, 660nm and 940 nm) and polarized white LED light imaged by CMOS sensor via cross-oriented polarizing filter were analyzed to calculate chromophore maps. The algorithm based on skin color analysis and user-defined threshold selection allows highlighting of skin areas with predefined chromophore concentration semi-automatically. Preliminary results of clinical tests are presented.
Clinical measurements with multi-spectral photoplethysmography sensors
A portable multi-spectral photoplethysmography device has been used for studies of 40 subjects. Multi-spectral monitoring was performed by means of a four - wavelengths (465 nm, 530 nm, 630 nm and 870 nm) light emitted diodes (LED) and a single photodiode with multi-channel signal output processing. The proposed methodology and potential clinical applications are discussed.
Portable remote photoplethysmography device for monitoring of blood volume changes with high temporal resolution
The compact remote photoplethysmography device for monitoring of blood volume pulsations from human skin were developed. The prototype device comprises electronics board with twelve circullary oriented bright near-infrared LED illuminators, which are precisely controlled, high-speed video camera and battery charging circuit. Device was tested in laboratory and could be used for non-contact monitoring of human blood volume changes in palm.
Multi-spectral photoplethysmography technique for parallel monitoring of pulse shapes at different tissue depths
A photoplethysmography (PPG) signal can provide very useful information about a subject's hemodynamic status in a hospital or home environment. A newly developed portable multi-spectral photoplethysmography device has been used for studies of 11 healthy subjects. Multi-spectral photoplethysmography (MS-PPG) biosensor intended for analysis of peripheral blood volume pulsations at different vascular depths has been designed and experimentally tested. Multi-spectral monitoring was performed by means of a three–wavelengths (405 nm, 660 nm and 780 nm) laser diode and a single photodiode with multi-channel signal output processing. The proposed methodology and potential clinical applications are …
Imaging photoplethysmography for clinical assessment of cutaneous microcirculation at two different depths
The feasibility of bispectral imaging photoplethysmography (iPPG) system for clinical assessment of cutaneous microcirculation at two different depths is proposed. The iPPG system has been developed and evaluated for in vivo conditions during various tests: (1) topical application of vasodilatory liniment on the skin, (2) skin local heating, (3) arterial occlusion, and (4) regional anesthesia. The device has been validated by the measurements of a laser Doppler imager (LDI) as a reference. The hardware comprises four bispectral light sources (530 and 810 nm) for uniform illumination of skin, video camera, and the control unit for triggering of the system. The PPG signals were calculated and…
Imaging photoplethysmography for evaluation of cutaneous sensory nerve fiber function
Peripheral neuropathy refers to peripheral nervous system dysfunction which affects up to 2% of the world's population. This condition is caused by damage to the small nerve fibers, hence its assessment is still challenging due to the lack of simple, non-invasive and objective diagnostic techniques. The present study aimed to develop and evaluate a simple, objective and non-invasive technique for assessment of small cutaneous sensory nerve fiber function. Our approach is based on utilization of imaging photoplethysmography and local skin heating. The effectiveness of the method was evaluated on young, healthy volunteers (n = 14) after 10 minutes of 45-degree local skin heating, while record…
Remote Photoplethysmography for Evaluation of Cutaneous Sensory Nerve Fiber Function
About 2% of the world’s population suffers from small nerve fiber dysfunction, neuropathy, which can result in severe pain. This condition is caused by damage to the small nerve fibers and its assessment is challenging, due to the lack of simple and objective diagnostic techniques. The present study aimed to develop a contactless photoplethysmography system using simple instrumentation, for objective and non-invasive assessment of small cutaneous sensory nerve fiber function. The approach is based on the use of contactless photoplethysmography for the characterization of skin flowmotions and topical heating evoked vasomotor responses. The feasibility of the technique was evaluated on volunt…
Multimodal Device for Real-Time Monitoring of Skin Oxygen Saturation and Microcirculation Function
The present study introduces a recently developed compact hybrid device for real-time monitoring of skin oxygen saturation and temperature distribution. The prototype involves a snapshot hyperspectral camera, multi-wavelength illuminator, thermal camera, and built-in computer with custom-developed software. To validate this device in-vivo we performed upper arm vascular occlusion on eight healthy volunteers. Palm skin oxygen saturation maps were analyzed in real-time using k-means segmentation algorithm and two-layer optical diffuse model. The prototype system demonstrated a satisfying performance of skin hyperspectral measurements in the spectral range of 507&ndash
Multi-spectral photoplethysmography biosensor
A photoplethysmography (PPG) signal can provide very useful information about a subject's hemodynamic status in a hospital or home environment. A newly developed portable multi-spectral photoplethysmography device has been used for studies of 11 healthy subjects. The developed optical fiber biosensor comprises one multi-wavelength laser diode (405nm, 660nm and 780nm) and a single photodiode with multi-channel signal output processing and built in Li-ion accumulator; special software was created for visualization and measuring of the MS-PPG signals. ARM7TDMI-S LPC2148, NXP (founded by Philips) 32 bit processor with clock frequency of 60 MHz performs measurement and analysis of the signal.
Real-Time Photoplethysmography Imaging System
Real-time non-contact photoplethysmography imaging (PPGI) system for high-resolution blood perfusion mapping in human skin has been proposed. The PPGI system comprises of LED lamp, webcam and computer with video processing software. The purpose of this study is to evaluate the reliability of the PPGI system when measuring blood perfusion. The validation study of PPGI and laser-Doppler perfusion imager (LDPI) was performed during local warming of palm skin. Results showed that the amplitude of PPGI increases immediately after warming and well correlated with the mean LDPI amplitude (R=0.92+-0.03, p<0.0001). We found that PPGI technique has good potential for non-contact monitoring of blood p…
Snapshot hyperspectral system for noninvasive skin blood oxygen saturation monitoring
The present study introduces recently developed compact hyperspectral snapshot system (device and software) for skin oxygen saturation monitoring. This prototype device involves compact snapshot hyperspectral camera, multi-wavelength illuminator, optical filter and crossed polarizers. The device was validated using reference color samples and and in-vivo during finger arterial occlusion tests. The prototype system demonstrated good performance of skin hyperspectral measurements in spectral range of 500-630nm. The results confirmed reliability of developed system for in-vivo assessment of skin blood oxygen saturation.
Hyperspectral evaluation of skin blood oxygen saturation at baseline and during arterial occlusion
Skin capillary blood oxygen saturation is a clinically important diagnostic parameter, which provides valuable information for timely treatment of pathological conditions e.g. sepsis, hypoxemia or decompression illness. Hyperspectral imaging is non-invasive optical techniques with high clinical potential, however its use for skin blood oxygen saturation detection is still challenging, therefore in the present study, a method for in-vivo manipulation of skin oxygen saturation was developed, and reliability of the method evaluated by means of hyperspectral imaging in detection of oxygen saturation. In order to produce alterations of skin capillary blood parameters and oxygen saturation, the p…
Multimodal device for assessment of skin malformations
A variety of multi-spectral imaging devices is commercially available and used for skin diagnostics and monitoring; however, an alternative cost-efficient device can provide an advanced spectral analysis of skin. A compact multimodal device for diagnosis of pigmented skin lesions was developed and tested. A polarized LED light source illuminates the skin surface at four different wavelengths – blue (450 nm), green (545 nm), red (660 nm) and infrared (940 nm). Spectra of reflected light from the 25 mm wide skin spot are imaged by a CMOS sensor. Four spectral images are obtained for mapping of the main skin chromophores. The specific chromophore distribution differences between different skin…
Simple and convenient remote photoplethysmography system for monitoring regional anesthesia effectiveness
Simple and inexpensive remote photoplethysmography system for monitoring the effectiveness of regional anesthesia was developed and tested. The system involves surgical lamp as light source, compact video camera and computer with custom developed software. Data from eight patients were processed and the effectiveness of regional anesthesia was calculated. The results showed that the standard surgical lamp can be used as a light source together with camera for remote monitoring of regional anesthesia effectiveness.
Remote photoplethysmography for assessment of oral mucosa
The present study is devoted to the assessment of oral mucosa perfusion using remote photoplethysmography (rPPG) technique. The alterations of mucosal perfusion were evoked by regional infiltration anesthesia containing adrenaline. Simple rPPG setup comprising white LED light source, video camera and narrowband optical filter (CWL=540nm), are able to detect subtle microcirculation changes in gingiva. Results demonstrate substantial decrease of rPPG waveform amplitude and subsequently perfusion index in affected gingiva region, following administration of anesthetics. The present study emphasizes clinical advantages of remote photoplethysmography and perfusion index mapping as a simple and c…
RGB imaging system for mapping and monitoring of hemoglobin distribution in skin
A prototype R-G-B imaging system for mapping of skin hemoglobin distribution has been designed and tested. Device basically consists of a commercial RGB sensor (CMOS, max. frame rate 87 fps for VGA resolution), RGB LED ringlight illuminator and orthogonally orientated polarizers for reducing specular reflectance. The system was examined for monitoring of hemoglobin concentration changes during specific provocations - arterial/venous occlusions and heat test. Hemoglobin distribution maps of several skin malformations were obtained, as well.
Monitoring of blood pulsation using non-contact technique
Time resolved detection and analysis of the skin back-scattered optical signals (reflection photoplethysmography or contact PPG) provide rich information on skin blood volume pulsations and can serve for cardiovascular assessment. The widely used contact PPG technique has many limitations, like high sensitivity to sensor movement etc. The newly developed non-contact PPG technique has been developed in this work. Potential of the new technique for express-assessment of human cardio-vascular condition has been demonstrated.
Multimodal imaging device for skin diagnostics: improvements and tests
In our work we have demonstrated our developed skin diagnostic imaging device and its hardware and software improvements. The device was tested in laboratory, to determine the stability of light uniformity and stability, as well as the performance of data processing. The improvements were focused to fulfill all requirements of doctors-dermatologists who use this device. Results showed that light field uniformity and stability were acceptable to get chromophore concentration maps of skin malformations.
Photoplethysmographic sensor with smoothed output signals
A reflectance-type photoplethysmographic sensor probe connected to personal computer has been constructed and tested. Special algorithms and PC programs providing fast processing and smoothing of the output signals were developed. High-quality single period photoplethysmography signals were recorded from various locations of the body (fingers, forearm, neck). Clear differences in the shapes of detected single-period signals have been observed for different persons, and also for the same person at various measurement locations and before/after physical exercise.
Remote photoplethysmography system for unsupervised monitoring regional anesthesia effectiveness
Determining the level of regional anesthesia (RA) is vitally important to both an anesthesiologist and surgeon, also knowing the RA level can protect the patient and reduce the time of surgery. Normally to detect the level of RA, usually a simple subjective (sensitivity test) and complicated quantitative methods (thermography, neuromyography, etc.) are used, but there is not yet a standardized method for objective RA detection and evaluation. In this study, the advanced remote photoplethysmography imaging (rPPG) system for unsupervised monitoring of human palm RA is demonstrated. The rPPG system comprises compact video camera with green optical filter, surgical lamp as a light source and a …
Multispectral Photophletysmography for Evaluation of Cutaneous Flowmotions
Human skin may reflect health conditions. Important and possibly diagnostically potent components of microcirculation are slow flow oscillations-flowmotions, however there is a lack of studies in this field. The present pilot study was devoted to evaluation of multispectral imaging photoplethysmography in determination of different components of flowmotions. Eight subjects were enrolled for the study. During resting conditions video was captured from dorsal aspect of hand at seven different wavelength and flowmotion analysis performed. Results indicate that at the resting conditions neurogenic component along with endothelial are dominant regardless of wavelength, while myogenic has the low…
Optical coherence tomography and Raman spectroscopy for ex vivo characterization of canine skin and subcutaneous tumors: preliminary results
Cancer is one of the leading causes of companion animal mortality. Up to 30% of all canine and feline tumors appear on or directly under the skin. To date, only a limited number of studies applied biophotonics techniques for optical characterization and detection of tumors in pets. In this work, we acquired ex vivo optical coherence tomography (OCT) images and Raman spectra of native skin and the most common canine and feline skin and subcutaneous tumors; lipomas, mast cell tumors, and soft tissues sarcomas. Lipomas exhibited the most distinctive tissue morphology (i.e., honeycomb structure) and biochemistry (lipid-related Raman peaks of 1063, 1301, and 1652 cm-1). Moreover, lipomas had sig…
Microvascular blood flow changes of the abductor pollicis brevis muscle during sustained static exercise
A practical assessment of the general health and microvascular function of the palm muscle, abductor pollicis brevis (APB), is important for the diagnosis of different conditions. In this study, we have developed a protocol and a probe to study microvascular blood flow using near-infrared diffuse correlation spectroscopy (DCS) in APB during and after thumb abduction at 55% of maximum voluntary contraction (MVC). Near-infrared time resolved spectroscopy (TRS) was also used to characterize the baseline optical and hemodynamic properties. Thirteen (n=13) subjects were enrolled and subdivided in low MVC (N=6, MVC<2.3 kg) and high MVC (N=7, MVC≥2.3 kg) groups. After ruling out significant cha…
Agar-based phantoms for skin diagnostic imaging
Agar-based skin phantoms with different thicknesses and hemoglobin concentration were evaluated for diagnostics of skin lesions by RGB imaging. Scattering properties of the phantoms were simulated using intralipid, absorption properties – using lyophilized powder of human hemoglobin. RGB images of phantoms were captured by self-developed laboratory made devices. The algorithm for calculation of chromophore concentrations are based on Beer-Lambert law and includes the photon path length evaluated from the measured photon-time-of-flight signals. Optical properties and chromophore concentration maps of phantoms obtained from RGB images were analyzed. The influence of chromophore concentration …
The analysis of blood flow changes under local anesthetic input using non-contact technique
In this work photoplethysmography imaging (PPGI) technique was used to obtain blood flow changes in human skin under regional anesthesia (RA). PPGI was evaluated from video taken by video camera for 26 patients 2 minutes before and immediately after RA, using custom developed software. Results showed that blood flow obtained by PPGI increases immediately after RA effect and the amplitude of PPGI showed correlation with temperature changes in human skin (r=0.8±0.14, p<0.0001). We found that PPGI technique can be usable for non-contact monitoring of quality of RA.
Skin-remitted photon path lengths: experimental study
Skin-remitted picosecond laser pulses were detected at four input-output fiber distances in the spectral range 560-800 nm. After deconvolution procedures, distributions and mean values of the remitted photon path lengths in forearm skin were analyzed.
pEGFP transfection into murine skeletal muscle by electrosonoporation
In this study, we aimed to determine whether the combination of electroporation (EP) and ultrasound (US) waves (sonoporation) can affect the plasmid DNA transfection to mice tibialis cranialis muscle. Multispectral imaging technique combined with fluorescence spectroscopy point measurements has been used for the transcutaneous detection of enhanced green fluorescent protein (EGFP) fluorescence, providing information on location and duration of EGFP expression. We found that electrosonoporation, commonly enhancing pDNA transfection in vitro , had no positive effect on EGFP transfection efficiency increase in vivo with respect to electroporation alone. We presume that this may be associated w…
A device for multimodal imaging of skin
A compact prototype device for diagnostic imaging of skin has been developed and tested. Polarized LED light at several spectral regions is used for illumination, and round skin spot of diameter 30mm is imaged by a CMOS sensor via crossoriented polarizing filter. Four consecutive imaging series are performed: (1) RGB image at white LED illumination for revealing subcutaneous structures; (2) four spectral images at narrowband LED illumination (450nm, 540nm, 660nm, 940nm) for mapping of the main skin chromophores; (3) video-imaging under green LED illumination for mapping of skin blood perfusion; (4) autofluorescence video-imaging under UV (365nm) LED irradiation for mapping of the skin fluor…
Express RGB mapping of three to five skin chromophores
Skin melanin, oxy- and deoxy-hemoglobin were snapshot-mapped under simultaneous 448-532-659 nm laser illumination by a smartphone RGB camera. Experimental prototypes for double-snapshot RGB mapping of four (melanin, bilirubin, oxy- and deoxy-hemoglobin) and five (melanin, bilirubin, lipids, oxy- and deoxy-hemoglobin) skin chromophores with reduced laser speckle artefacts have been developed and tested. A set of 405-448-532-659 nm lasers were used for four chromophores mapping, and a set of 405-448-532-659-842 nm lasers for five chromophores mapping. Clinical tests confirmed functionality of the developed devices.
Towards direct measurements of remitted photon path lengths in skin: kinetic studies in the range 520-800 nm
Skin-remitted picosecond laser pulses have been detected at variable input-output fiber distances (8 … 20 mm) in the spectral range 520-800 nm, with subsequent analysis of the pulse shape changes. Transfer functions representing the temporal responses of remitted photons to infinitely narrow δ-pulse excitation have been calculated. Parameters related to the photon path length in skin – input-output pulse peak delays, pulse FWHM, travel times of the “initial” photons and distributions of the remitted photon path lengths – are presented and analyzed. The measurement results are in general agreement with the photon propagation model expectations
Multi-spectral skin imaging by a consumer photo-camera
The possibilities to perform multi-band spectral imaging by means of a consumer color camera without external filters have been studied. Images at up to 6 spectral bands may be extracted from a single color image after appropriate signal processing. The proposed technique was tested in pilot measurements of in-vivo skin hemoglobin maps and laser-excited autofluorescence images.
Remitted photon path lengths in human skin: in-vivo measurement data
The remitted photon path lengths in human skin can be estimated by modelling; however, there are very few experimental data available to validate the simulations. This study exploited the photon time of flight method where picosecond laser pulses at seven wavelength bands in the spectral range 560-800 nm were launched into in-vivo forearm skin of 10 volunteers via an optical fiber. The pulses of back-scattered light were detected via another optical fiber placed at variable distance (1, 8, 12, 16 or 20 mm) from the input fiber, with subsequent analysis of their shapes for all 35 spectral-spatial combinations. Using a deconvolution algorithm, the distribution functions of remitted photon arr…
Remitted photon path length in human skin, skin phantoms and cell cultures
An experimental method for remitted photon path length measurements in scattering media has been developed and tested on human skin and skin neoplasms, skin phantoms and cell cultures. The photon time-of-flight (PTOF) measurement method was used in this study, where the photon travel time was converted into path length. Remitted light signals were obtained using a picosecond broadband laser and a set of narrowband interference filters in spectral rang 520 – 760 nm. Five different distances of 1, 8, 12, 16 and 20 mm between the source and detector fibers were used. Measurements were performed at different wavelengths and distance combinations; they were taken from human skin and skin malform…
Novel hybrid technology for early diagnostics of sepsis
Sepsis is a potentially fatal disease with mortality rate as high as 50% in patients with septic shock; mortality rate can increase by 7.6% per hour if appropriate treatment is not started. Internationally accepted guidelines for diagnosis of sepsis rely on vital sign monitoring and laboratory tests in order to recognize organ failure. This pilot study aims to explore the potential of hyperspectral and thermal imaging techniques to identify and quantify early alterations in skin oxygenation and perfusion induced by sepsis. The study comprises both physiological model experiments on healthy volunteers in a laboratory environment, as well as screening case series of patients with septic shock…
Skin chromophore mapping from multi-spectral laser line images
Skin chromophore maps can be used for assessment of various skin malformations and early cancer diagnostics. Commercially available devices are bulky and expensive. We present two portable proof-of-concept device prototypes for multi-spectral laser line imaging with three (448 nm, 532 nm and 659 nm) and four (450 nm, 523 nm, 638 nm and 850 nm) wavelength laser illumination. Laser modules and special optics that ensure uniform light distribution over the region of interest have been exploited. Skin chromophore maps were calculated using Beer-Lambert law, considering light scattering properties in the skin and including photon path length evaluated from the directly measured photon-time-of-fl…
Skin chromphore mapping by means of a modified video-microscope for skin malformation diagnosis
Many spectral imaging devices are commercially available and used to detect certain skin pathology; however an alternative cost-efficient device can provide an advanced spectral analisys of skin. Multispectral device for diagnosis of pigmented skin lesions was developed and tested. Possibilities to map skin chromophores using a modified low-cost digital video-microscope is discussed. It was adapted for an advanced skin microscopy and used for detailed spectral analysis of skin. The device comprises CMOS digital imaging sensor, four-colour LED illumination system and image acquisition optics. The main goal is to obtain a set of spectral images of the skin area of interest for further convers…
Imaging photoplethysmography for assessment of chronic pain patients
In present pilot study application of multi-spectral imaging photoplethysmography for assessment of chronic pain patients during topical skin heating test was proposed. Photoplethysmography signal was recorded at 420nm, 530nm and 810nm illumination from the skin and corresponding perfusion indexes and perfusion maps were calculated. The novel parameter-PPGflare index was introduced and compared in neuropathic patients and healthy volunteers. Preliminary results suggest that neuropathic patients exhibited significantly lower PPGflare index, and that local heating substantially change PPG waveform at heat exposed skin region. Present study emphasizes advantages of imaging photoplethysmography…