The 5th Russian_Chinese Workshop on Biophotonics and Biomedical Optics was hosted in Saratov, Russia on 26_28, September, 2012. The bilateral Workshop brought together both Russian and Chinese scientists, engineers and clinical researchers from a variety of disciplines engaged in applying optical science, photonics and imaging technologies to problems in biology and medicine. During the Workshop, 2 plenary lectures, 11 invited presentations, 4 oral presentations and 13 poster reports were presented. A special Internet session with 5 presentations—1 plenary, 2 invited, and 2 posters, was also organized. This special issue selects some papers from the attendees, and is made up of 12 original research articles and one review. Seven articles have been presented in Vol. 6, No. 1 of JIOHS; this issue presents the remaining six articles.

Complex investigation of mesh implants was performed involving laser confocal microscopy, backscattered probing and OCT imaging methods. The growth of endomysium and fat tissue with microcirculation vessels was observed in the mesh encapsulation region. Confocal microscopy analysis shows that such pathologies complications such as necrosis formation and microcavities were localized in the area near implant fibers with the size compatible with fiber diameter. And the number of such formations increase with the increase of the size, number and density of microdefects on the implant surface. Results of numerical simulations show that it is possible to control implant installation up to the depth to 4mm with a help of backscattering probing. The applicability of OCT imaging for mesh implant control was demonstrated. Special two-stage OCT image noise-reduction algorithm, including empirical mode decomposition, was proposed for contrast increase and better abnormalities visualization by halving the signal-tonoise ratio. Joint usage of backscattered probing and OCT allows to accurately ascertain implant and surrounding tissue conditions, which reduces the risk of relapse probability.

The hollow core photonic crystal waveguide biosensor is designed and described. The biosensor was tested in experiments for artificial sweetener identification in drinks. The photonic crystal waveguide biosensor has a high sensitivity to the optical properties of liquids filling up the hollow core. The compactness, good integration ability to different optical systems and compatibility for use in industrial settings make such biosensor very promising for various biomedical applications.

In this paper, the new method for OCT images denoizing based on empirical mode decomposition (EMD) is proposed. The noise reduction is a very important process for following operations to analyze and recognition of tissue structure. Our method does not require any additional operations and hardware modifications. The basics of proposed method is described. Quality improvement of noise suppression on example of edge-detection procedure using the classical Canny's algorithm without any additional pre- and post-processing operations is demonstrated. Improvement of rawsegmentation in the automatic diagnostic process between a tissue and a mesh implant is shown.

Temporal changes in structure and refractive-index distribution of adipose tissue at photodynamic/ photothermal treatment were studied with OCT in vitro. Ethanol-water solutions of indocyanine green (ICG) and brilliant green (BG) were used for fat tissue staining. CW laser diode (808 nm) and LED light source (442 and 597 nm) were used for irradiation of stained tissue slices. The data received supporting the hypothesis that photodynamic/photothermal treatment, induces fat cell lipolysis during a certain period of time after light exposure.

We are interested in investigating whether cancer therapy may alter the mitochondrial redox state in cancer cells to inhibit their growth and survival. The redox state can be imaged by the redox scanner that collects the fluorescence signals from both the oxidized-flavoproteins (Fp) and the reduced form of nicotinamide adenine dinucleotide (NADH) in snap-frozen tissues and has been previously employed to study tumor aggressiveness and treatment responses. Here, with the redox scanner we investigated the effects of chemotherapy on mouse xenografts of a human diffuse large B-cell lymphoma cell line (DLCL2). The mice were treated with CHOP therapy, i.e., cyclophosphamide (C)＋ hydroxydoxorubicin (H) + Oncovin (O) + prednisone (P) with CHO administration on day 1 and prednisone administration on days 1-5. The Fp content of the treated group was significantly decreased (p = 0:033) on day 5, and the mitochondrial redox state of the treated group was slightly more reduced than that of the control group (p = 0:048). The decrease of the Fp heterogeneity (measured by the mean standard deviation) had a border-line statistical significance (p = 0:071). The result suggests that the mitochondrial metabolism of lymphoma cells was slightly suppressed and the lymphomas became less aggressive after the CHOP therapy.

With the objective to study the variation of optical properties of rat muscle during optical clearing, we have performed a set of optical measurements from that kind of tissue. The measurements performed were total transmittance, collimated transmittance, specular reflectance and total reflectance. This set of measurements is sufficient to determine diffuse reflectance and absorbance of the sample, also necessary to estimate the optical properties. All the performed measurements and calculated quantities will be used later in inverse Monte Carlo (IMC) simulations to determine the evolution of the optical properties of muscle during treatments with ethylene glycol and glucose. The results obtained with the measurements already provide some information about the optical clearing treatments applied to the muscle and translate the mechanisms of turning the tissue more transparent and sequence of regimes of optical clearing.

Assessment of human airway lumen opening is important in diagnosing and understanding the mechanisms of airway dysfunctions such as the excessive airway narrowing in asthma and chronic obstructive pulmonary disease (COPD). Although there are indirect methods to evaluate the airway calibre, direct in vivo measurement of the airway calibre has not been commonly available. With recent advent of the flexible fiber optical nasopharyngoscope with video recording it has become possible to directly visualize the passages of upper and lower airways. However, quantitative analysis of the recorded video images has been technically challenging. Here, we describe an automatic image processing and analysis method that allows for batch analysis of the images recorded during the endoscopic procedure, thus facilitates image-based quantification of the airway opening. Video images of the airway lumen of volunteer subject were acquired using a fiber optical nasopharyngoscope, and subsequently processed using Gaussian smoothing filter, threshold segmentation, differentiation, and Canny image edge detection, respectively. Thus the area of the open airway lumen was identified and computed using a predetermined converter of the image scale to true dimension of the imaged object. With this method we measured the opening/narrowing of the glottis during tidal breathing with or without making "Hee" sound or cough. We also used this method to measure the opening/narrowing of the primary bronchus of either healthy or asthmatic subjects in response to histamine and/or albuterol treatment, which also provided an indicator of the airway contractility. Our results demonstrate that the imagebased method accurately quantified the area change waveform of either the glottis or the bronchus as observed by using the optical nasopharygoscope. Importantly, the opening/narrowing of the airway lumen generally correlated with the airflow and resistance of the airways, and could differentiate the level of airway contractility between the healthy and asthmatic subjects. Thus, this quantitative assessment of airway opening may provide a useful tool to assist clinical diagnosis of airway dysfunctions and understanding the mechanisms of associated pathophysiologies.

Concurrent chemoradiotherapy (CCRT) is the choice of treatment for locally advanced cervical cancers; however, tumors exhibit diverse response to treatment. Early prediction of tumor response leads to individualizing treatment regimen. Response evaluation criteria in solid tumors (RECIST), the current modality of tumor response assessment, is often subjective and carried out at the first visit after treatment, which is about four months. Hence, there is a need for better predictive tool for radioresponse. Optical spectroscopic techniques, sensitive to molecular alteration, are being pursued as potential diagnostic tools. Present pilot study aims to explore the fiber-optic-based Raman spectroscopy approach in prediction of tumor response to CCRT, before taking up extensive in vivo studies. Ex vivo Raman spectra were acquired from biopsies collected from 11 normal (148 spectra), 16 tumor (201 spectra) and 13 complete response (151 CR spectra), one partial response (8 PR spectra) and one nonresponder (8 NR spectra) subjects. Data was analyzed using principal component linear discriminant analysis (PC-LDA) followed by leaveone- out cross-validation (LOO-CV). Findings suggest that normal tissues can be efficiently classified from both pre- and post-treated tumor biopsies, while there is an overlap between preand post-CCRT tumor tissues. Spectra of CR, PR and NR tissues were subjected to principal component analysis (PCA) and a tendency of classification was observed, corroborating previous studies. Thus, this study further supports the feasibility of Raman spectroscopy in prediction of tumor radioresponse and prospective noninvasive in vivo applications.

Pre-operative X-ray mammography and intraoperative X-ray specimen radiography are routinely used to identify breast cancer pathology. Recent advances in optical coherence tomography (OCT) have enabled its use for the intraoperative assessment of surgical margins during breast cancer surgery. While each modality offers distinct contrast of normal and pathological features, there is an essential need to correlate image-based features between the two modalities to take advantage of the diagnostic capabilities of each technique. We compare OCT to X-ray images of resected human breast tissue and correlate different tissue features between modalities for future use in real-time intraoperative OCT imaging. X-ray imaging (specimen radiography) is currently used during surgical breast cancer procedures to verify tumor margins, but cannot image tissue in situ. OCT has the potential to solve this problem by providing intraoperative imaging of the resected specimen as well as the in situ tumor cavity. OCT and micro-CT (X-ray) images are automatically segmented using different computational approaches, and quantitatively compared to determine the ability of these algorithms to automatically differentiate regions of adipose tissue from tumor. Furthermore, two-dimensional (2D) and three-dimensional (3D) results are compared. These correlations, combined with real-time intraoperative OCT, have the potential to identify possible regions of tumor within breast tissue which correlate to tumor regions identified previously on X-ray imaging (mammography or specimen radiography).