Background/Objectives: The integration of Artificial Intelligence (AI) into clinical workflows raises critical questions regarding decision-making responsibility, as fully autonomous systems inevitably carry a margin of error that can be fatal in high-stakes fields like surgery. This study addresses this challenge by evaluating a "Human-in-the-Loop" (HITL) workflow, using intraoperative Optical Coherence Tomography (OCT) for glioma detection. We aimed to determine if integrating Machine Learning (ML)-generated segmentation maps with human contextual analysis resolves the tension between automation and clinical responsibility, yielding superior diagnostic reliability compared to structural or quantitative imaging alone. Methods: We retrospectively analyzed 86 intraoperative OCT scans from 27 patients. Five neurosurgeons blindly assessed the data across three progressive levels of processing: (1) structural scans, (2) physics-based parametric maps, and (3) SVM-based generated segmentation maps. Crucially, the HITL inference performance on segmentation maps was benchmarked against "models-only" inference pipeline: a SVM and a state-of-the-art multimodal reasoning model, Gemini 3.1 Pro. To evaluate interpretability and the operator's ability to confidently exercise their authority, we measured inter-rater consistency alongside diagnostic performance. Results: The results demonstrate that, while quantitative parametric maps improved Global Accuracy (87% [95% CI: 82-92%]) compared to structural scans (80% [95% CI: 73-86%]), they suffered from an "interpretability gap," resulting in a moderate inter-rater consistency of 0.68 [95% CI: 0.59-0.78]. In contrast, the HITL approach using segmentation maps maximized consensus to 0.98 [95% CI: 0.95-1.00] and achieved the highest performance (Accuracy 94% [95% CI: 88-98%] and Sensitivity 98% [95% CI: 92-100%]). Compared to the standalone models, the HITL approach significantly outperformed the SVM baseline (Accuracy 84% [95% CI: 81-87%]; Sensitivity 83% [95% CI: 78-88%]). Furthermore, it surpassed the SOTA Gemini 3.1 Pro model (Accuracy 90% [95% CI: 83-95%]; Sensitivity 86% [95% CI: 74-95%]). While the HITL sensitivity demonstrated a definitive and statistically significant edge over the Gemini model, the accuracy improvement fell just slightly short of undisputed statistical significance due to overlapping confidence intervals. Conclusions: By utilizing their clinical domain knowledge of tumor invasion patterns and topological priors, surgeons effectively filtered algorithmic noise-overriding ML errors in 69% (9 out of 13) false positive cases that models alone could not resolve. This demonstrates exactly how and where HITL optimally utilizes human contextual intelligence to outperform autonomous "models-only" pipelines, confirming a human-ML synergy that augments the objectivity of machine learning with human domain knowledge. This paradigm ensures that the ultimate responsibility for diagnostic inference remains safely and practically in human hands. Open Data Initiative: To ensure essential reproducibility, enable independent multi-center validation and support open science, all examples of intraoperative in vivo OCT brain scans used in this study are made publicly available. To the best of our knowledge, this represents the first open-access data of its kind globally.

Background/Objectives: As a result of metabolic changes and the disruption of tissue architecture and microcirculation, the regenerative potential of the liver decreases with violations at both micro and macro levels. The development of intraoperative approaches for assessing its regenerative potential is important for reducing the risk of the occurrence of post-resection liver failure. In this study, we used multimodal optical coherence tomography (MM OCT), a combination of three optical coherence tomography modalities-OCT-angiography (OCTA), attenuation coefficient mapping, and OCT-elastography (OCE) to provide real-time three-dimensional and label-free assessment of changes in microcirculation, and in the structure and stiffness of the liver during regeneration. Methods: In our study, the regeneration of a healthy liver was induced by 70% partial hepatectomy. Monitoring of changes was carried out on the 0 (normal liver), 3rd and 7th day of regeneration using modalities of MM OCT. OCT offers the benefits of higher resolution and specificity compared with other clinical imaging modalities, and can be used, even intraoperatively. Results: By the 3rd day of liver regeneration, a decreased density of all observable vessels, together with increased values of the liver tissue's attenuation coefficient and stiffness, was revealed compared to their initial state. However, by the 7th day, the studied parameters tended to return to their normal values, except that the density of large-caliber vessels continued to increase further. Histological and biochemical blood analysis methods were used to verify the MM OCT data. Conclusions: Such data are a first step towards further investigation of liver regeneration in pathology, and, taken in perspective, this should serve as a basis for predictive intraoperative assessment of the regenerative potential of the liver in a clinical setting.

The aim of the study is to demonstrate the effect of fractional CO2 laser treatment on vulvar skin in lichen sclerosus using multimodal optical coherence tomography (MM OCT). Materials and Methods:The study included 3 clinical cases of vulvar lichen sclerosus (VLS) (histologically classified as early, early with dermal edema, late) and 2 control cases without vulvar pathology. Patients with VLS underwent 3 procedures of fractional CO2 laser treatment with an interval of 30-40 days. In patients without vulvar pathology, the MM OCT examination was performed once, in patients with VLS it was done at the point of the greatest visible skin damage just before a punch biopsy, immediately after the first laser session, and 1 month after a full course of treatment. Results:Analyzing the case series of vulvar skin recovery 1 month after fractional CO2 laser treatment, it has been found that the recovery depended on the dermal condition before the treatment. In early VLS and early VLS with dermal edema (clinical cases 1 and 2) before the treatment, the MM OCT examination has shown a decreased epidermal thickness, unclear contrast between the epidermis and dermis, a decrease in the values of the OCT signal attenuation coefficient in the dermis, and a sharp reduction in the density of blood and lymphatic vessels. After treatment, the MM OCT examination demonstrated a complete recovery of vulvar skin structure and all quantitative values reached the level characteristic of normal vulvar skin. Before the treatment, a homogenization zone (sclerosis) was clearly visible in the MM OCT images of the dermis in late VLS (clinical case 3). After the treatment, complete recovery of the vulvar skin structure was not observed; the area of sclerosis was preserved; however, visually, there was an increase in the density of blood and lymphatic vessels in the affected area, which almost reached the level of normal vulvar skin. Conclusion:MM OCT can be proposed as a promising non-invasive method for monitoring skin recovery after fractional CO2 laser treatment of VLS.

We propose a nonlinear stress–strain law to describe nonlinear elastic properties of biological tissues using an analogy with the derivation of nonlinear constitutive laws for cracked rocks. The derivation of such a constitutive equation has been stimulated by the recently developed experimental technique—quasistatic Compression Optical Coherence Elastography (C-OCE). C-OCE enables obtaining nonlinear stress–strain dependences relating the applied uniaxial compressive stress and the axial component of the resultant strain in the tissue. To adequately describe nonlinear stress–strain dependences obtained with C-OCE for various tissues, the central idea is that, by analogy with geophysics, nonlinear elastic response of tissues is mostly determined by the histologically confirmed presence of interstitial gaps/pores resembling cracks in rocks. For the latter, the nonlinear elastic response is mostly determined by elastic properties of narrow cracks that are highly compliant and can easily be closed by applied compressing stress. The smaller the aspect ratio of such a gap/crack, the smaller the stress required to close it. Upon reaching sufficiently high compressive stress, almost all such gaps become closed, so that with further increase in the compressive stress, the elastic response of the tissue becomes nearly linear and is determined by the Young’s modulus of the host tissue. The form of such a nonlinear dependence is determined by the distribution of the cracks/gaps over closing pressures; for describing this process, an analogy with geophysics is also used. After presenting the derivation of the proposed nonlinear law, we demonstrate that it enables surprisingly good fitting of experimental stress–strain curves obtained with C-OCE for a broad range of various tissues. Unlike empirical fitting, each of the fitting parameters in the proposed law has a clear physical meaning. The linear and nonlinear elastic parameters extracted using this law have already demonstrated high diagnostic value, e.g., for differentiating various types of cancerous and noncancerous tissues.

We report a new application of compression optical coherence elastography (C-OCE) to monitor the emergence of ruptures in individual layers of longitudinally stretched small-intestine walls using tissue samples (n = 36) from nine minipigs. Before stretching, C-OCE successfully estimated stiffness for each intestine-wall layer: longitudinal muscular layer with serosa, circumferential muscular layer, submucosa and mucosa. In stretched samples, C-OCE clearly visualized initial stiffening in both muscular layers. By 25% elongation, a sharp stiffness decrease for the longitudinal muscular layer, indicated emergence of tears in all samples. With further stretching, for most samples, ruptures emerged in the circumferential muscular layer and submucosa, while mucosa remained undamaged. Histology confirmed the OCE-revealed damaging and absence of tissue damage for ~15% elongation. Thus, C-OCE has demonstrated a high potential for determining the safety tissue-stretching threshold which afterward may be used intraoperatively to prevent rupture risk in intestinal tissues stretched during various diagnostic/therapeutic procedures.

While cryotherapy is one of the traditional ways to reduce postoperative complications in maxillofacial surgery, the cooling degree is not regulated in most cases and the achieved effect is not properly controlled. Therefore, to develop optimal cooling modes, we propose to study the buccal vascular response to cooling, which has not been previously shown. To evaluate the effect of cooling, we analyzed vessel networks using optical coherence tomography angiography (OCT-A). The cheek vessels were OCT-A monitored using cooling by an ice bag/cooling mask. We found the advantages of using a cooling mask over an ice bag consist of a statistically significant decrease in the perfused vessel density (PVD) of the papillary layer at the oral mucosa. The absence of the reticular layer vessel reaction to any type of cooling was noted. We argue for the necessity to develop optimal modes of cryotherapy, which will contribute to blood perfusion reduction and reduction of PVD recovery. In this pilot study, we propose to use optical coherence tomography angiography technology for the first time to objectively monitor the condition of blood vessels during the cooling of cheek tissues and the oral mucosa. The dynamics of perfused vessel density reduction during cooling and its recovery after cold exposure cessation are shown.image

The presence of molecular mutations in colorectal cancer (CRC) is a decisive factor in selecting the most effective first-line therapy. However, molecular analysis is routinely performed only in a limited number of patients with remote metastases. We propose to use tissue stiffness as a marker of the presence of molecular mutations in CRC samples. For this purpose, we applied compression optical coherence elastography (C-OCE) to calculate stiffness values in regions corresponding to specific CRC morphological patterns (n = 54). In parallel to estimating stiffness, molecular analysis from the same zones was performed to establish their relationships. As a result, a high correlation between the presence of KRAS/NRAS/BRAF driver mutations and high stiffness values was revealed regardless of CRC morphological pattern type. Further, we proposed threshold stiffness values for label-free targeted detection of molecular alterations in CRC tissues: for KRAS, NRAS, or BRAF driver mutation—above 803 kPa (sensitivity—91%; specificity—80%; diagnostic accuracy—85%), and only for KRAS driver mutation—above 850 kPa (sensitivity—90%; specificity—88%; diagnostic accuracy—89%). To conclude, C-OCE estimation of tissue stiffness can be used as a clinical diagnostic tool for preliminary screening of genetic burden in CRC tissues.

Objectives: The most important phase in the endometrial pathologies diagnostics is the histological examination of tissue biopsies obtained under visual hysteroscopic control. However, the unclear visual diagnostics characteristics of subtle focal endometrial pathologies often lead to selection errors regarding suspicious endometrial lesions and to a subsequent false pathological diagnosis/underestimation of precancer or early-stage cancer. Methods: In this study, we investigate the potential of Multimodal Optical Coherence Tomography (MM OCT) to verify suspicious endometrial lesion regions before biopsy collection. We study the polarization (by cross-polarization OCT, CP OCT) and elastic (by compression OCT-elastography, C-OCE) properties of ex vivo endometrial tissue samples in normal conditions (proliferative and secretory phases to the menstrual cycle, atrophic endometrium) with endometrial hyperplasia (non-atypical and endometrial intraepithelial neoplasia) and endometrial cancer subtypes (low-grade, high-grade, clear cell and serous). Results: To the best of our knowledge, this is the first quantitative assessment of relevant OCT parameters (depth-resolved attenuation coefficient in co-[Att(co) values] and cross-[(Att(cross) values] polarizations and Young’s elastic modulus [stiffness values]) for the selection of the most objective criteria to identify the clinically significant endometrial pathologies: endometrial intraepithelial neoplasia and endometrial cancer. The study demonstrates the possibility of detecting endometrial pathologies and establishing optimal threshold values of MM OCT criteria for the identification of endometrial cancer using CP OCT (by Att(co) values = 3.69 mm−1, Sensitivity (Se) = 86.1%, Specificity (Sp) = 92.6%; by Att(cross) values = 2.27 mm−1, Se = 86.8%, Sp = 87.0%) and C-OCE (by stiffness values = 122 kPa, Se = 93.2%, Sp = 91.1%). The study also differentiates endometrial intraepithelial neoplasia from non-atypical endometrial hyperplasia and normal endometrium using C-OCE (by stiffness values = 95 kPa, Se = 87.2%, Sp = 90.1%). Conclusions: The results are indicative of the efficacy and potential of clinical implementation of in vivo hysteroscopic-like MM OCT in the diagnosis of endometrial pathologies.

Detection of radiation-induced changes of the brain white matter is important for brain neoplasms repeated surgery. We investigated the influence of irradiation on the scattering properties of the white matter using optical coherence tomography (OCT). Healthy Wistar rats undergone the irradiation of the brain right hemisphere. At seven time points from the irradiation procedure (2-14 weeks), an ex vivo OCT study was performed with subsequent calculation of attenuation coefficient values in the corpus callosum followed by immunohistochemical analysis. As a result, we discovered acute and early-delayed changes characterized by the edema of different severity, accompanied by a statistically significant decrease in attenuation coefficient values. In particular, these changes were found at 2 weeks after irradiation in the irradiated hemisphere, while at 6- and 12-week time points they affected both irradiated and contralateral hemisphere. Thus, radiation-induced changes occurring in white matter during the first 3 months after irradiation can be detected by OCT.

BACKGROUND: In patients with colorectal cancer, the intestinal wall, which is not involved in the malignant process, despite histological signs of intactness, is characterized by impaired structure and metabolism. Modern optical bioimaging technologies make it possible to objectively assess these changes. AIM: To study metabolism and morphological structure features of the mucous membrane of the relatively normal colon in patients with colorectal cancer. MATERIAL AND METHODS: The object of study was the colon mucosa in patients with colorectal cancer stages I–IV. The study included 59 patients. There were 33 (56%) men, 26 (44%) women; median age — 67 [61; 74] years. In 10 cases, the tumor was localized in the right colon, in 9 — in the transverse colon, in 23 — in the sigmoid colon, in 17 — in the rectum. 7 samples were obtained from patients with stage I, 25 — with stage II, 21 — with stage III, 6 — with stage IV colorectal cancer. The metabolism of colon tissue from the mucosal side was studied using fluorescence-lifetime macroimaging, and the microstructure was studied using optical coherence tomography and histological examination. The results of calculating the weighted average fluorescence lifetime were presented as median values Me [Q1; Q3], comparison of this indicator between groups was carried out using the nonparametric Kruskal–Wallis test. RESULTS: According to histological examination, progression signs of structural changes with increasing stage of colorectal cancer were revealed: from the conventional norm in samples with stage I to the appearance of signs of chronic colitis, atrophy and erosion of the mucous membrane in samples with stages II, III and IV. Visual analysis of optical coherence tomograms obtained from colon samples showed a high degree of agreement with histological data: the Spearman correlation coefficient was r=0.96. According to fluorescence-lifetime macroimaging, statistically significant differences (p=0.027) in the weighted average fluorescence lifetime were detected between stages IV and II of colorectal cancer: the values were 1.6 [1.4; 1.8] ns and 1.3 [1.1; 1.4] ns, respectively, which indicated an intensification of the glycolysis process in the tissues of the colon mucosa in stage IV colorectal cancer. Presumably, the identified changes will become the pathophysiological and anatomical basis of postoperative complications. In clinical oncology, it is advisable to use the obtained data to optimize the volume of intestinal resection and postoperative therapy algorithms. CONCLUSION: Long-term tumor carriage and progression of colorectal cancer (invasion and metastasis) are associated with an increasing incidence of atrophy/erosion of the mucous membrane, the signs of which are determined both by optical coherence tomography and by histological examination.

In the present work, we carried out a comparative study of the attenuation coefficient of the white matter of the rat brain during the growth of glial tumors characterized by different degrees of malignancy (glioblastoma 101/8, astrocytoma 10-17-2, glioma C6) and during irradiation. We demonstrated that some tumor models cause a pronounced decrease in white matter attenuation coefficient values due to infiltration of tumor cells, myelinated fiber destruction, and edema. In contrast, other tumors cause compression of the myelinated fibers of the corpus callosum without their ruptures and prominent invasion of tumor cells, which preserved the attenuation coefficient values changeless. In addition, for the first time, the possibility of using the attenuation coefficient to detect late radiation-induced changes in white matter characterized by focal development of edema, disruption of the integrity of myelinated fibers, and a decrease in the amount of oligodendrocytes and differentiation of these areas from tumor tissue and healthy white matter has been demonstrated. The results indicate the promise of using the attenuation coefficient estimated from OCT data for in vivo assessment of the degree of destruction of peritumoral white matter or its compression, which makes this method useful not only in primary resections but also in repeated surgical interventions for recurrent tumors.

The condition of gastrointestinal tract determines in many respects the regenerative capacity and the risk of complications in patients with extensive skin burns. However, the mechanism of developing vascular dysfunction in the colon in the burned individuals has so far been poorly studied. The aim of the investigation is to study intramural circulatory disorders of the colon using optical coherence tomography angiography (OCTA) and laser Doppler flowmetry (LDF) in different time periods after modeling a thermal burn. Materials and Methods:A deep thermal skin burn was induced on the area covering 10% of the body surface of Wistar rats (n=15). The blood flow of the colon wall was continuously monitored for 15 min before and 45 min after the burn using OCTA and LDF. The colon wall was again studied on days 7 and 14 using the same OCTA and LDF techniques. At each time point (45 min, day 7 and 14), 5 animals were withdrawn from the experiment, the colon wall was taken for histological study. The colon wall samples from three control rats without thermal skin burns were also histologically investigated. Results:During 45 min after the induction of the thermal burn, the in vivo OCTA and LDF techniques registered changes in intramural blood flow in the form of dropping of some arterioles and capillaries out of the general blood flow with concurrent activation of vascular shunts as a compensatory mechanism. Histologically, a marked edema of the submucosa, erythrocyte aggregation, and stasis in the capillary network were observed in this period. According to the OCTA and LDF data, the microcirculatory disorders in the colon were partially resolved by day 7, and by day 14 the analyzed indicators returned to the initial level. The data of the histological evaluation have shown that on day 7 after the burn induction, submucosal edema was absent, however, the signs of microcirculatory disorder and inflammatory changes remained. On day 14, the pathological changes in the tissues were not observed. Conclusion:The OCTA and LDF methods allowed us to establish experimentally that during the first 45 min thermal burn causes considerable disturbances of the blood flow in the colon wall, which normalizes only by day 14 if no therapy is administered. The obtained data on the mechanism of circulatory disorder development in the colon may become a basis for choosing therapy directed to prevention of intestine dysfunction in people with burns.

Introduction. Primary urethral pain syndrome (PUPS) is a part of chronic primary pelvic pain syndrome with predominant localisation of pain in the urethra. The pathogenesis of PUPS has not been adequately studied and there are no unified guidelines for the prevention and treatment of this condition. It is known that one of the main factors in the development of chronic pain is a violation of regional blood flow. Objective. To identify the features of blood supply of urethral tissues, as well as to assess the concomitant changes in the connective tissue in patients with PUPS. Materials & methods. The study included 98 patients: 78 patients with primary urethral pain syndrome (group "PUPS"), without clinical manifestations of inflammation; 20 patients with stones of the upper urinary tract without pyelonephritis, in which the urethra is taken as the norm (group "N"). The hemodynamics of the urethral tissues was studied using transvaginal ultrasound (TVUS) and laser Doppler flowmetry (LDF). Changes in the blood supply to organs often lead to disruption of tissue structure; therefore, in vivo cross-polarisation optical coherence tomography (CP OCT) and ex vivo nonlinear confocal microscopy were included in the study. Results. In the PUPS group, the LDF method revealed a violation of the neurogenic regulation of the tone of the microcirculatory vascular wall of the urethral tissues with a predominance of passive regulatory components. The analysis of the LDF parameters by the method of principal components made it possible to establish the division of data into several clusters, which indicates a different pathogenesis of microcirculation disorders in the tissues of the urethra. The TVUS method in the PUPS group revealed an increase in resistance to blood flow in the blood vessels of the urethra and paraurethral plexus, blood stasis in the veins of the small pelvis in 19% of patients. Violation of the urethral blood flow leads to structural changes in tissues: using nonlinear microscopy, it was found that with PUPS in the urethral connective tissue, collagen fibres are quantitatively larger relative to elastic ones, they are more uniform in thickness, and have a co-directional arrangement. These data correlate with the results of an intravital CP OCT study, during which fibrosis of the subepithelial connective tissue structures was revealed. Conclusion. TVUS and LDF made it possible to reveal the presence of microcirculatory and, as a result, structural changes in urethral tissues in vivo . The inclusion of these methods in the diagnostic algorithm will provide more information about the main links in the pathogenesis of PUPS.

Optical coherence tomography (OCT) is a promising tool for intraoperative tissue morphology determination. Several studies suggest that attenuation coefficient derived from the OCT images, can differentiate between tissues of different morphology, such as normal and pathological structures of the brain, skin, and other tissues. In the present study, the depth-resolved method for attenuation coefficient calculation was adopted for the real-world situation of the depth-dependent OCT sensitivity and additive imaging noise with nonzero mean. It was shown that in the case of sharp focusing (~10 μm spot full width at half maximum [FWHM] or smaller at 1.3 μm central wavelength) only the proposed method for depth-dependent sensitivity compensation does not introduce misleading artifacts into the calculated attenuation coefficient distribution. At the same time, the scanning beam focus spot with FWHM greater than 10 μm at 1.3 μm central wavelength allows one to use multiple approaches to the attenuation coefficient calculation without introducing noticeable bias. This feature may hinder the need for robust corrections for the depth-resolved attenuation coefficient estimations from the community.

Ailm: to assess metabolic processes in the serous layer of the large intestine in the acute period of spinal injury.Materials and Methods: the experiment was carried out on laboratory animals — Wistar rats (n = 20). Spinal injury was simulated by complete transection of the spinal cord at the level of Th5-Th6 vertebrae. Metabolic changes in the intestinal wall were assessed before injury, 3 and 24 hours after spinal cord transection. Metabolism was assessed in vivo using fluorescence time-resolved macroimaging technology (macroFLIM) by autofluorescence in the spectral channel of the metabolic cofactor NAD(P)H.Results: a significant (p = 0.041) increase in the mean fluorescence lifetime (τm) by 12% and the lifetime of the long component (τ2) of the NAD(P)H cofactor by 13% (p = 0.008) was detected 24 hours after injury. MacroFLIM showed an increase in the intensity of metabolism in the large intestine wall.Conclusion: for the first time in an in vivo experiment, it has been shown that the acute period of spinal injury is accompanied by an increase in metabolic activity in the tissues of the large intestine. The revealed phenomenon confirms the role of the large intestine in compensatory reactions to spinal injury and open up new possibilities for therapy in the acute period of spinal cord injury.

IntroductionTo improve the quality of brain tumor resections, it is important to differentiate zones with myelinated fibers destruction from tumor tissue and normal white matter. Optical coherence tomography (OCT) is a promising tool for brain tissue visualization and in the present study, we demonstrate the ability of cross-polarization (CP) OCT to detect damaged white matter and differentiate it from normal and tumor tissues.Materials and methodsThe study was performed on 215 samples of brain tissue obtained from 57 patients with brain tumors. The analysis of the obtained OCT data included three stages: 1) visual analysis of structural OCT images; 2) quantitative assessment based on attenuation coefficients estimation in co- and cross-polarizations; 3) building of color-coded maps with subsequent visual analysis. The defining characteristics of structural CP OCT images and color-coded maps were determined for each studied tissue type, and then two classification tests were passed by 8 blinded respondents after a training.ResultsVisual assessment of structural CP OCT images allows detecting white matter areas with damaged myelinated fibers and differentiate them from normal white matter and tumor tissue. Attenuation coefficients also allow distinguishing all studied brain tissue types, while it was found that damage to myelinated fibers leads to a statistically significant decrease in the values of attenuation coefficients compared to normal white matter. Nevertheless, the use of color-coded optical maps looks more promising as it combines the objectivity of optical coefficient and clarity of the visual assessment, which leads to the increase of the diagnostic accuracy of the method compared to visual analysis of structural OCT images.ConclusionsAlteration of myelinated fibers causes changes in the scattering properties of the white matter, which gets reflected in the nature of the received CP OCT signal. Visual assessment of structural CP OCT images and color-coded maps allows differentiating studied tissue types from each other, while usage of color-coded maps demonstrates higher diagnostic accuracy values in comparison with structural images (F-score = 0.85-0.86 and 0.81, respectively). Thus, the results of the study confirm the potential of using OCT as a neuronavigation tool during resections of brain tumors.

RELEVANCE A special place in the development of enteral insufficiency is given to dysproteinemia, which is one of the leading causes of the development of decubital ulcers in patients with spinal cord injury. Early enteral nutrition partially solved this problem, but the incidence of bedsores still remains high and reaches 68%. The risk of metabolic disorders in the acute period of spinal injury is largely determined by non-occlusive intestinal ischemia against the background of spinal shock, neurohumoral dysregulation; intra-intestinal and intra-abdominal hypertension; change in intestinal microflora. Pathological changes in the intestinal wall occur during the first 20 days after injury and further exacerbate chronic maldigestion, malabsorption, intestinal dyskinesia in patients with traumatic spinal cord disease. New knowledge about the features of early enteral nutrition in patients in the acute period of traumatic spinal cord disease will reduce the risk of decubitus ulcerative defects. AIM OF THE STUDY To study the dynamics of metabolic processes in the tissues of the small intestine in the acute period of spinal injury. MATERIAL AND METHODS Wistar rats (n=22). Spinal injury was simulated by acute complete transection of the spinal cord at the level of Th5–Th6 vertebrae. The assessment of metabolic changes in the cells of the serous membrane of the intestine was performed immediately, 3 and 24 hours after injury. The metabolism was assessed in vivo using fluorescence time-resolved macroimaging technology FLIM by autofluorescence in the spectral channel of the metabolic cofactor nicotinamide adenine dinucleotide (phosphate). RESULTS The acute period of spinal cord injury is accompanied by a change in the endogenous autofluorescence of the serous membrane of the small intestine: a statistically significant decrease in the mean fluorescence lifetime (τm), the lifetime of the long component (τ2), and the relative contribution of the long component (а2) in 24 h after injury was recorded. The changes observed using FLIM confirm the catabolic type of metabolism in the tissues of the small intestine after spinal cord injury. CONCLUSION For the first time in the experiment in vivo it has been shown that the acute period of spinal injury is accompanied by a violation of metabolic processes in the tissues of the small intestine. This fact requires a more balanced approach in calculating the calorie content of nutrients used for early enteral nutrition in patients with spinal cord injury.

Identifying the precise topography of cancer for targeted biopsy in colonoscopic examination is a challenge in current diagnostic practice. For the first time we demonstrate the use of compression optical coherence elastography (C-OCE) technology as a new functional OCT modality for differentiating between cancerous and non-cancerous tissues in colon and detecting their morphological features on the basis of measurement of tissue elastic properties. The method uses pre-determined stiffness values (Young's modulus) to distinguish between different morphological structures of normal (mucosa and submucosa), benign tumor (adenoma) and malignant tumor tissue (including cancer cells, gland-like structures, cribriform gland-like structures, stromal fibers, extracellular mucin). After analyzing in excess of fifty tissue samples, a threshold stiffness value of 520 kPa was suggested above which areas of colorectal cancer were detected invariably. A high Pearson correlation (r =0.98; p <0.05), and a negligible bias (0.22) by good agreement of the segmentation results of C-OCE and histological (reference standard) images was demonstrated, indicating the efficiency of C-OCE to identify the precise localization of colorectal cancer and the possibility to perform targeted biopsy. Furthermore, we demonstrated the ability of C-OCE to differentiate morphological subtypes of colorectal cancer - low-grade and high-grade colorectal adenocarcinomas, mucinous adenocarcinoma, and cribriform patterns. The obtained ex vivo results highlight prospects of C-OCE for high-level colon malignancy detection. The future endoscopic use of C-OCE will allow targeted biopsy sampling and simultaneous rapid analysis of the heterogeneous morphology of colon tumors.