Effects of FOLFOX Chemotherapy on Tumor Oxygenation and Perfused Vasculature: An In Vivo Study by Optical Techniques.

The effects of cytotoxic chemotherapy on tumor vasculature and oxygenation are in the focus of modern investigations because vascular structure and distribution of oxygen influence tumor behavior and treatment response. The aim of our study was to monitor changes in the vascular component of colorectal tumor xenografts induced by a clinical combination of chemotherapy drugs FOLFOX in vivo using two complementary techniques: diffuse reflectance spectroscopy (DRS) and optical coherence tomography-based microangiography (OCT-MA). These techniques revealed a slower decrease in tumor blood oxygenation in treated tumors as compared to untreated ones, faster suppression of tumor vasculature perfusion and increase in water content as a result of treatment, and decrease in total hemoglobin in untreated tumors.

Post-Operational Photodynamic Therapy of the Tumor Bed: Comparative Analysis for Cold Knife and Laser Scalpel Resection.

In this paper, we report on a study regarding the efficiency of the post-operational phototherapy of the tumor bed after resection with both a cold knife and a laser scalpel in laboratory mice with CT-26 tumors. Post-operational processing included photodynamic therapy (PDT) with a topically applied chlorin-based photosensitizer (PS), performed at wavelengths of 405 or 660 nm, with a total dose of 150 J/cm. The selected design of the tumor model yielded zero recurrence in the laser scalpel group and 92% recurrence in the cold knife group without post-processing, confirming the efficiency of the laser scalpel in oncology against the cold knife.

Monitoring of optical properties of tumors during laser plasmon photothermal therapy.

We studied grafted tumors obtained by subcutaneous implantation of kidney cancer cells into male white rats. Gold nanorods with a plasmon resonance of about 800 nm were injected intratumorally for photothermal heating. Experimental irradiation of tumors was carried out percutaneously using a near-infrared diode laser.

Digital diaphanoscopy of maxillary sinus pathologies supported by machine learning.

Maxillary sinus pathologies remain among the most common ENT diseases requiring timely diagnosis for successful treatment. Standard ENT inspection approaches indicate low sensitivity in detecting maxillary sinus pathologies. In this paper, we report on capabilities of digital diaphanoscopy combined with machine learning tools in the detection of such pathologies.

Multimodal Optical Monitoring of Auto- and Allografts of Skin on a Burn Wound.

The aim of the study was to investigate the dynamics of the state of allo- and autografts of skin on a wound using optical modalities: diffuse reflectance spectroscopy (DRS), optical coherence tomography (OCT), and laser Doppler flowmetry (LDF). A deep thermal burn was simulated in 24 rats covering 20% of the body surface. On day 3 after the injury, a fascial necrectomy of two 500 mm areas on the left and right sides of the midline of the animal body were excised.

VIS-NIR Diffuse Reflectance Spectroscopy System with Self-Calibrating Fiber-Optic Probe: Study of Perturbation Resistance.

We report on the comparative analysis of self-calibrating and single-slope diffuse reflectance spectroscopy in resistance to different measurement perturbations. We developed an experimental setup for diffuse reflectance spectroscopy (DRS) in a wide VIS-NIR range with a fiber-optic probe equipped with two source and two detection fibers capable of providing measurements employing both single- and dual-slope (self-calibrating) approaches. In order to fit the dynamic range of a spectrometer in the wavelength range of 460-1030 nm, different exposure times have been applied for short (2 mm) and long (4 mm) source-detector distances.

Autoquenching of spherical photon density waves during propagation in a turbid medium.

The effect of the formation of deep minima in frequency characteristics of photon density waves (PDWs) during their propagation in scattering media with different optical characteristics has been studied by statistical Monte Carlo modeling. The simulation was performed for the Henyey-Greenstein scattering phase function with the anisotropy factor value varying in the range of 0-0.93.

Combined Fluorescence and Optoacoustic Imaging for Monitoring Treatments against CT26 Tumors with Photoactivatable Liposomes.

The newly developed multimodal imaging system combining raster-scan optoacoustic (OA) microscopy and fluorescence (FL) wide-field imaging was used for characterizing the tumor vascular structure with 38/50 μm axial/transverse resolution and assessment of photosensitizer fluorescence kinetics during treatment with novel theranostic agents. A multifunctional photoactivatable multi-inhibitor liposomal (PMILs) nano platform was engineered here, containing a clinically approved photosensitizer, Benzoporphyrin derivative (BPD) in the bilayer, and topoisomerase I inhibitor, Irinotecan (IRI) in its inner core, for a synergetic therapeutic impact. The optimized PMIL was anionic, with the hydrodynamic diameter of 131.

Gompertz model in COVID-19 spreading simulation.

The paper reports on application of the Gompertz model to describe the growth dynamics of COVID-19 cases during the first wave of the pandemic in different countries. Modeling has been performed for 23 countries: Australia, Austria, Belgium, Brazil, Great Britain, Germany, Denmark, Ireland, Spain, Italy, Canada, China, the Netherlands, Norway, Serbia, Turkey, France, Czech Republic, Switzerland, South Korea, USA, Mexico, and Japan. The model parameters are determined by regression analysis based on official World Health Organization data available for these countries.

Dual-Wavelength Fluorescence Monitoring of Photodynamic Therapy: From Analytical Models to Clinical Studies.

Fluorescence imaging modalities are currently a routine tool for the assessment of marker distribution within biological tissues, including monitoring of fluorescent photosensitizers (PSs) in photodynamic therapy (PDT). Conventional fluorescence imaging techniques provide en-face two-dimensional images, while depth-resolved techniques require complicated tomographic modalities. In this paper, we report on a cost-effective approach for the estimation of fluorophore localization depth based on dual-wavelength probing.

Angular distribution of photon density waves radiance in media with different scattering anisotropy.

Statistical modeling of pulsed frequency responses of the light field radiance by an isotropic point source was performed by Monte Carlo technique. Scattering properties of the medium were simulated by the Henyey-Greenstein phase function with different anisotropy factor values. Angular distributions of the pulsed field and amplitudes of the photon density waves in a certain range of parameters were shown to have a qualitatively different character for media with quasi-isotropic and strongly anisotropic scattering.

Combined Application of Dual-Wavelength Fluorescence Monitoring and Contactless Thermometry during Photodynamic Therapy of Basal Cell Skin Cancer.

Unlabelled: was to assess the capabilities of combined application of dual-wavelength fluorescence visualization and contactless skin thermometry during photodynamic therapy monitoring (PDT) of basal cell cancer.

Materials And Methods: The study was performed at the University Clinic of Privolzhsky Research Medical University (Nizhny Novgorod). Nine clinically, dermatoscopically, and histologically verified foci of basal cell skin cancer were exposed to PDT sessions (wavelength of 662 nm, light dose density of 150 J/cm) with systemic application of chlorin-based photosensitizer Fotoditazin.

Optoacoustic Sensing of Surfactant Crude Oil in Thermal Relaxation and Nonlinear Regimes.

We propose a laser optoacoustic method for the complex characterization of crude oil pollution of the water surface by the thickness of the layer, the speed of sound, the coefficient of optical absorption, and the temperature dependence of the Grüneisen parameter. Using a 532 nm pulsed laser and a 1-100 MHz ultra-wideband ultrasonic antenna, we have demonstrated the capability of accurate (>95%) optoacoustic thickness measurements in the 5 to 500-micron range, covering 88% of slicks observed during 2010 oil spill in the Gulf of Mexico. In the thermal relaxation regime of optoacoustic measurements, the value of optical absorption coefficient (30 mm) agreed with the data of independent spectrophotometric measurements, while the sound speed (1430 m/s) agreed with the tabular data.

Red and blue light in antitumor photodynamic therapy with chlorin-based photosensitizers: a comparative animal study assisted by optical imaging modalities.

The goal of this study is a comparative analysis of the efficiency of the PDT protocols for CT26 tumor model treatment in Balb/c mice employing red and blue light with both topical and intravenous administration of chlorin-based photosensitizers (PSs). The considered protocols include the doses of 250 J/cm delivered at 660 nm, 200 J/cm delivered at 405 nm, and 250 J/cm delivered at both wavelengths with equal energy density contribution. Dual-wavelength fluorescence imaging was employed to estimate both photobleaching efficiency, typical photobleaching rates and the procedure impact depth, while optical coherence tomography with angiography modality (OCT-A) was employed to monitor the tumor vasculature response for up to 7 days after the procedure with subsequent histology inspection.

Effect of scattering anisotropy on the properties of photon density waves.

The frequency characteristics of spherical photon density waves excited in media with different degrees of scattering anisotropy are studied. Statistical modeling of the frequency and phase responses of the spatial irradiance of the light field emitted by a point-sized isotropic source were performed employing the Monte Carlo technique. The scattering anisotropy of the medium was determined by the Henyey-Greenstein phase function with different values of the mean scattering cosine.

Nonstationary angular distribution of optical field radiance from an isotropic source in sea water.

The spatial-angular and temporal characteristics of the radiance of the light field emitted by a nonstationary point isotropic source in sea water are studied. Using the Monte Carlo method, we calculated the pulse transfer functions and frequency responses of the angular radiance distributions at various distances from the source. Particular integral characteristics of the angular radiance distributions are estimated.

Toward whole-brain optoacoustic angiography of rodents: modeling and experimental observations.

Cerebrovascular imaging of rodents is one of the trending applications of optoacoustics aimed at studying brain activity and pathology. Imaging of deep brain structures is often hindered by sub-optimal arrangement of the light delivery and acoustic detection systems. In our work we revisit the physics behind opto-acoustic signal generation for theoretical evaluation of optimal laser wavelengths to perform cerebrovascular optoacoustic angiography of rodents beyond the penetration barriers imposed by light diffusion in highly scattering and absorbing brain tissues.

Comparative analysis of single- and dual-wavelength photodynamic therapy regimes with chlorin-based photosensitizers: animal study.

Two pronounced absorption peaks in blue and red ranges of the chlorin-based photosensitizer (PS) absorption spectrum provide additional benefits in photodynamic therapy (PDT) performance. Differing optical properties of biological tissues in these ranges allow for both dual-wavelength diagnostics and PDT performance. We provide a comparative analysis of different PDT regimes performed with blue and red lights and their combination, with doses varying from 50 to 150  J  /  cm.

A case report of Ramsay Hunt syndrome in a patient with HIV treated by dual-wavelength photodynamic therapy.

In this paper we report on the application of dual-wavelength photodynamic therapy with a topical chlorin-based photosensitizer for treatment of Ramsay Hunt syndrome in a patient with HIV. Traditional treatment approach (combination of acyclovir and a glucocorticosteroid) failed to provide a significant outcome, while photodynamic therapy resulted in fast positive dynamics. No recurrence was observed in a 5-month-long follow-up.

Time delay and width variation caused by temporal dispersion of a complex modulated signal in underwater lidar.

The parameters of an echo signal from the underwater lidar are studied for the case of modulation of a probing pulse by a high frequency signal with a frequency linearly varying with time. The analysis is based on the statistical Monte Carlo simulations of the frequency and phase responses of a signal propagating along the emitter-water-reflector-water-receiver path and an analytical representation of the signal as a pulse described by a Gaussian function with intrapulse modulation. Delays and pulse shape changes caused by temporal dispersion of the photon-density waves are estimated.

Hyperspectral imaging of human skin aided by artificial neural networks.

We developed a compact, hand-held hyperspectral imaging system for 2D neural network-based visualization of skin chromophores and blood oxygenation. State-of-the-art micro-optic multichannel matrix sensor combined with the tunable Fabry-Perot micro interferometer enables a portable diagnostic device sensitive to the changes of the oxygen saturation as well as the variations of blood volume fraction of human skin. Generalized object-oriented Monte Carlo model is used extensively for the training of an artificial neural network utilized for the hyperspectral image processing.

Diffuse optical spectroscopy assessment of rodent tumor model oxygen state after single-dose irradiation.

Modern radiation therapy of malignant tumors requires careful selection of conditions that can improve the effectiveness of the treatment. The study of the dynamics and mechanisms of tumor reoxygenation after radiation therapy makes it possible to select the regimens for optimizing the ongoing treatment. Diffuse optical spectroscopy (DOS) is among the methods used for non-invasive assessment of tissue oxygenation.

Special Section Guest Editorial: Topical Problems of Biophotonics: from Optical Bioimaging to Clinical Biophotonics.

This editorial provides an introductory overview for the Special Section on Topical Problems of Biophotonics.