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Muscle oxygenation dynamics in response to electrical stimulation as measured with near-infrared spectroscopy: A pilot study
摘要： Neuromuscular electrical stimulation (NMES) is used for preventing muscle atrophy and improving muscle strength in patients and healthy people. However, the current intensity of NMES is usually set at a level that causes the stimulated muscles to contract. This typically causes pain. Quantifying the instantaneous changes in muscle microcirculation and metabolism during NMES before muscle contraction occurs is crucial, because it enables the current intensity to be optimally tuned, thereby reducing the NMES-induced muscle pain and fatigue. We applied near-infrared spectroscopy (NIRS) to measure instantaneous and deoxygenation changes in 43 healthy young adults during NMES at 10, 15, 20, 25, 30, and 35 mA. Having been stabilized at the NIRS signal baseline, total hemoglobin concentration increased immediately after stimulation in a dose-dependent manner (p < 0.05) until stimulation was stopped at the level causing muscle contraction without pain. Tissue deoxygenation appeared relatively unchanged during NMES. We conclude that NIRS can be used to determine the optimal NMES current intensity by monitoring oxygenation changes.
关键词： Muscle oxygenation dynamics,near-infrared spectroscopy,tissue optics,neuromuscular electrical stimulation
更新于2025-09-23 15:21:21
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Review of Biomedical Applications of Contactless Imaging of Neonates Using Infrared Thermography and Beyond
摘要： The sick preterm infant monitoring is an intriguing job that medical staff in Neonatal Intensive Care Units (NICU) must deal with on a daily basis. As a standards monitoring procedure, preterm infants are monitored via sensors and electrodes that are ?rmly attached to their fragile and delicate skin and connected to processing monitors. However, an alternative exists in contactless imaging to record such physiological signals (we call it as Physio-Markers), detecting super?cial changes and internal structures activities which can be used independently of, or aligned with, conventional monitors. Countless advantages can be gained from unobtrusive monitoring not limited to: (1) quick data generation; (2) decreasing physical and direct contact with skin, which reduces skin breakdown and minimizes risk of infection; and (3) reduction of electrodes and probes connected to clinical monitors and attached to the skin, which allows greater body surface-area for better care. This review is an attempt to build a solid ground for and to provide a clear perspective of the potential clinical applications of technologies inside NICUs that use contactless imaging modalities such as Visible Light Imaging (VLI), Near Infrared Spectroscopy (NIRS), and Infrared Thermography (IRT).
关键词： infrared thermography,physio-features,short-wave infrared,optical coherence tomography,preterm infants,visible light,NICU,tissue optics,near-infrared,neonatal imaging
更新于2025-09-23 15:21:01
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Characterization of a Time-Resolved Diffuse Optical Spectroscopy Prototype Using Low-Cost, Compact Single Photon Avalanche Detectors for Tissue Optics Applications
摘要： Time-resolved diffuse optical spectroscopy (TR-DOS) is an increasingly used method to determine the optical properties of diffusive media, particularly for medical applications including functional brain, breast and muscle measurements. For medical imaging applications, important features of new generation TR-DOS systems are low-cost, small size and efficient inverse modeling. To address the issues of low-cost, compact size and high integration capabilities, we have developed free-running (FR) single-photon avalanche diodes (SPADs) using 130 nm silicon complementary metal-oxide-semiconductor (CMOS) technology and used it in a TR-DOS prototype. This prototype was validated using assessments from two known protocols for evaluating TR-DOS systems for tissue optics applications. Following the basic instrumental performance protocol, our prototype had sub-nanosecond total instrument response function and low differential non-linearity of a few percent. Also, using light with optical power lower than the maximum permissible exposure for human skin, this prototype can acquire raw data in reflectance geometry for phantoms with optical properties similar to human tissues. Following the MEDPHOT protocol, the absolute values of the optical properties for several homogeneous phantoms were retrieved with good accuracy and linearity using a best-fitting model based on the Levenberg-Marquardt method. Overall, the results of this study show that our silicon CMOS-based SPAD detectors can be used to build a multichannel TR-DOS prototype. Also, real-time functional monitoring of human tissue such as muscles, breasts and newborn heads will be possible by integrating this detector with a time-to-digital converter (TDC).
关键词： diffuse optical spectroscopy,time-resolved spectroscopy,tissue optics,single-photon avalanche diode,silicon photodetectors,time-correlated single-photon counting
更新于2025-09-23 15:21:01
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High-speed light source depth estimation using spatially-resolved diffuse imaging
摘要： We describe a system for high-speed depth estimation of a light source embedded in a scattering medium. A polynomial model estimates source depth from the spatially-resolved, diffuse reflectance profile measured with a fibre optic probe on the surface of a scattering medium. A dataset of Monte Carlo reflectance profiles is generated over a range of typical optical properties and the model is fit to the simulated reflectance at four detector locations. The model accounts for a source depth up to 15 mm. Cross-validation using the Monte Carlo dataset produced a root mean square error of 0.12 mm. Experimental reflectance data is acquired with the detector probe, which consists of four optical fibres mounted in a black acetal plastic disk. The optical fibres are coupled into avalanche photodiodes for high-speed acquisition of the reflectance profile. When applied to measurements from a tissue-mimicking phantom with an embedded light source, the polynomial model generates depth estimates within 2 mm of the true depth, up to a source depth of 15 mm.
关键词： source location,Monte Carlo simulation,tissue optics,turbid media,diffuse reflectance
更新于2025-09-19 17:15:36