Timely diagnosis and monitoring of wound progression or healing are key to improving the long-term outcome of diabetic foot ulcers (DFU). Diffuse reflectance spectroscopy (DRS) has the potential to noninvasively diagnose the DFU in real time, as it detects changes in local blood volume fraction and oxygenation state level that occur when tissue becomes diseased or ulcerated. Since foot soles have a thicker epidermis and deeper blood vessels/capillaries than other parts of the body, a spatially resolved fiber-optic probe (SRFP) is needed to detect the optimal spatially resolved diffuse reflectance (SRDR) signal from the local site of the ulcer for DFU diagnosis. Therefore, herein, an SRFP consisting of a linear array of seven 400-μm fibers with detector-source (D-S) fiber separation (ρ) ranging from 0.8 to 4.8 mm was designed, fabricated, tested, and evaluated for SRDR measurement from a standard reflectance plate of barium sulfate (BaSO4) and foot sole of 27 healthy human subjects. The variation in SRDR spectra for each detector and source fiber pair measured with BaSO4 was found to be less than 1.6%. In-vivo measurements from the foot sole demonstrate that the fabricated probe has the ability to spatially resolve and distinguish the SRDR spectra from sites, namely, the fifth metatarsal, ball of great joint, calcaneum, and great toe. Experimentally and theoretically, the detector and source fiber pair of ρ=1.6 and 2.4 mm were optimal for SRDR measurements from a human foot. To evaluate and validate the performance of SRFP in a context relevant to DFU diagnosis, further SRDS measurements were performed on the solid tissue phantoms that mimic the optical properties of the normal and diabetic foot sole, and their results are statistically found different. Preliminary results suggest that developed SRFP can be explored for DRS measurement from foot ulcer patients to confirm its potential clinical applicability.
KEYWORDS: Arrhythmia, Signal detection, Feature extraction, Artificial neural networks, Pulse signals, Photoplethysmography, Atrial fibrillation, Electrocardiography, Medical research, Education and training
Photoplethysmography (PPG) is a non-invasive optical-based technique used to measure various hemodynamic parameters. State-of-the-art proposed various methods for arrhythmia (premature ventricular contraction (PVC), atrial fibrillation) detection using PPG signals. However, restricted research has been carried out for detecting other arrhythmias that could be life-threatening. In this research work, the detection of atrial flutter (AFl) from Normal, Sinus Tachycardia (ST), and PVC signals have been carried out using PPG signals. The method relies on time-domain and entropy features for characterizing the AFl PPG pulse. A sliding window approach has been applied to extract features, and an artificial neural network has been implemented for feature classification. The ground-truth generation for the PPG signals has been carried out on publically available and prospective data. The comparative analysis of the results obtained from the two datasets is useful in the effective identification of the abnormality.
Skin mimicking optical tissue phantoms are widely used in diagnostics systems for characterization, optimization, routine calibration and validation. In general, solid phantoms are more preferred in comparison to liquid phantoms. Therefore, our aim is to prepare and characterize the solid tissue phantoms having skin equivalent optical properties. In this work, we have used epoxy resin and hardener as a base material and titanium oxide (TiO2) nanoparticles and ink as a scatterer and absorber media, respectively. The total transmission (Tt), collimated transmission (Tc), and diffuse reflectance (Rd) spectra of the developed phantoms were measured with an integrating sphere installed in UV-VIS spectrometer within the wavelength range 400-700 nm. To characterize the optical properties such as absorption (μa), reduced scattering (μs’), and anisotropy factor (g) of the developed tissue phantoms, the numerical model based on Inverse Adding Doubling (IAD) has been used. With various concentrations of absorber and scatterer, a calibration curve was prepared. The calculated experimental optical properties from IAD matched with the predicted intrinsic optical properties of the skin. Thus, the preliminary results suggest that the recipe used in this study may be used as an alternative approach to developing skin mimicking solid optical phantom for diagnostics system applications.
Diabetic foot ulcer is one of the most common causes of lower-extremity amputation of diabetic patients worldwide. Researchers have identified several optical diagnostic techniques to diagnose diabetic foot ulcer by monitoring average blood oxygenation state in the foot tissue. However, they need sophisticated equipment and specialized expertise. In addition, they may not be able to resolve the relative local blood volume fraction of reduced/- oxyhemoglobin within the bulk of highly scattering tissue media. Therefore, aim of the study is to extract localized blood volume fraction of reduced/-oxyhemoglobin by using diffuse reflectance spectroscopy (DRS). To prove the feasibility of DRS for diabetic foot ulcer detection, we measured the localized blood volume concentrations of reduced hemoglobin (RHb), oxyhemoglobin (HbO2), and oxygen saturation (SO2) from different sites such as lips, earlobe, finger and foot of human subjects by using DRS. The measured average level of HbO2 and SO2 found highest in lips followed by a finger, earlobe, and foot, while the average level of RHb followed the reverse trend. Thus, the preliminary results suggest that the proposed approach could be used for real-time, accurate, and noninvasive monitoring of blood oxygenation parameters from the site of ulcerated foot that may help in early diagnosis, treatment planning, and monitoring of diabetic foot. This may reduce the health-care cost and improve the quality of life of diabetic foot patients.
Diabetic foot is a serious chronic complication of diabetes mellitus affecting 15 % diabetic patients during their lifetime. Approximately 85 % lower-limb amputations are preceded by an untreated diabetic foot. Several techniques are available to diagnose foot ulceration by monitoring average blood oxygenation state of the diabetic foot. However, these techniques couldn’t resolve relative local blood volume fraction of reduced/-oxyhemoglobin within the bulk of highly scattering tissue media. Therefore, the aim of this study is to extract localized blood volume fraction of reduced/- oxyhemoglobin from vascular beds of human foot. In this study, we investigated the ability of diffuse reflectance spectroscopy to quantitatively measure localized blood volume fraction of reduced hemoglobin (RHb), oxyhemoglobin (HbO2), and oxygen saturation (SO2) from various sites of the human foot sole. The preliminary investigation shows that the proposed approach can reliably determine the local volume fractions of RHb, HbO2 and SO2 in four different sites namely great toe, ball of great joint, 5th metatarsal, and calcaneum of the human foot sole. In addition, it also concludes that each part of the foot has different levels of blood volume fraction. Thus, the preliminary results suggest that this method may be used as a diagnostic tool for monitoring blood oxygenation parameters of ulcerated diabetic foot. It may help in to reduce the health-care cost and improve the quality of life of diabetic patient.
Coherent light propagating through turbid media is attenuated due to scattering and absorption. The decrease of the intensity of the coherent light is described by the attenuation coefficient. The measured decay of the coherent light through turbid media with optical coherence tomography (OCT) can be used to reconstruct the attenuation coefficient. Since most of the OCT systems work in the near-infrared region, they are the optical window from 800-1400 nm in tissue. Hence, the most part of the attenuation coefficient is caused due to the scattering. Therefore, deriving the attenuation coefficient is one way to get an approximation of the scattering coefficient which is difficult to access even up to day. Moreover, OCT measurements are one of the few possibilities to derive physical properties with micrometre resolution of the media under investigation.
Rajesh Kanawade, Benjamin Lengenfelder, Tassiana Marini Menezes, Martin Hohmann, Stefan Kopfinger, Tim Hohmann, Urszula Grabiec, Florian Klämpfl, Jean Gonzales Menezes, Maximilian Waldner, Michael Schmidt
Optical-coherence tomography (OCT) is a promising non-invasive, high-resolution imaging modality which can be used for cancer diagnosis and its therapeutic assessment. However, speckle noise makes detection of cancer boundaries and image segmentation problematic and unreliable. Therefore, to improve the image analysis for a precise cancer border detection, the performance of different image processing algorithms such as mean, median, hybrid median filter and rotational kernel transformation (RKT) for this task is investigated. This is done on OCT images acquired from an ex-vivo human cancerous mucosa and in vitro by using cultivated tumour applied on organotypical hippocampal slice cultures. The preliminary results confirm that the border between the healthy and the cancer lesions can be identified precisely. The obtained results are verified with fluorescence microscopy. This research can improve cancer diagnosis and the detection of borders between healthy and cancerous tissue. Thus, it could also reduce the number of biopsies required during screening endoscopy by providing better guidance to the physician.
Medical shock is still a common cause for the unacceptably high mortality rate in trauma patient in Intensive Care Units
(ICU), because limitations of the monitoring/ diagnostic techniques and short time span of shock development. In this
paper we introduce a method for monitoring of the vessel density spatial pattern, using spatially resolved diffuse
reflectance measurement. The setup contains a spatially resolved optical fiber probe coupled to supersensitive
spectrometer and high power light source. The experiment was done on skin tissue phantom model containing grid
pattern which mimicks optical properties of the skin and capillary network. The spatially resolved diffuse reflectance
spectra are collected over the phantom with various detector to source distance. The measured spatially resolved diffuse
reflectance spectra were analyzed yielding grid spatial pattern. This novel technique of the vessel density spatial pattern
monitoring will help to detect the early signs of shock development in intensive care units.
Monitoring of the vessel capillary density and blood oxygenation spatial pattern in epithelium is important for shock
detection and it's preventing interventions. The challenge is the complex epithelium structure, absorption and scattering
of light in the multiple tissue layers. In this paper we describe results of estimating the vessel capillary density pattern in
tissue phantoms collecting spatially resolved reflectance spectra. We designed tissue phantom which mimics optical
properties of epithelium including microvasculature. Grids grooved in the phantom plates mimicking the blood capillary
network containing freshly prepared oxy-hemoglobin solution. The preliminary results shows that the new method can
reasonably extracts minor spatial deviations of oxygenation and local volume blood fraction - parameters, directly related
to the local vessel density patterns.
Monitoring the epithelium vessel capillary density pattern is critically important for preventing rapidly developing life
threatening syndromes such as shock or systemic organ failures. The objective of this study is real time monitoring of
epithelium vessel density pattern. The fiber sensor will be based on spatially resolved diffuse reflectance spectra. The
parameters comprising period and depth of capillary spatial modulation are exploited for shock detection. The
preliminary investigations with simulated spectra have shown that the new method can reasonably extracts minor
deviations of oxygenation and local volume blood fraction - parameters, directly related to the local vessel density. The
original method developed to use these parameters is much less dependent on light scattering in visible range as opposed
to the most of the currently used methods.
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