KEYWORDS: Skin, Visualization, Signal intensity, Laser radiation, Collagen, Sensors, Connective tissue, Chromophores, Ultrasonography, Medical research
Laser procedures are very popular. But the effectiveness of most skin rejuvenation procedures has not been proven. Purpose: to determine the true picture of morphological processes occurring after exposure to laser radiation on the skin. Materials and methods: The work uses HiFU with a 75 MHz sensor, Er:glass laser. 15 patients aged 35 to 65 years were examined. For anesthesia numping cream with lidocaine 2.5% was used. Results: after application anesthesia, the signal intensity within the epidermis significantly decreases, which indicates the presence of signs of edema in this layer. Immediately after the procedure, pronounced signs of edema in the dermis were noted in 100% of cases. A month after the procedure, there was an increase in signal intensity within the dermis. Conclusions: As a result of laser exposure the changes manifest themselves in the production of collagen, and not in the formation of focal fibrous changes. The use of diagnostic methods will improve the effectiveness of procedures
The lack of intact skin in extensive burns makes it necessary to repeatedly use donor sites to obtain grafts. This is possible if there is sufficient thickness and structure of the donor site skin. The thickness and structure of the donor site skin may deteriorate due to sepsis. Purpose: to study the structure of the donor site skin in patients with burns and sepsis using Ultra-High Frequency Ultrasound (UHFUS) data. The study involved 44 patients with skin burns: 30 without sepsis, 14 with sepsis. Donor site was examined 12 days after graft harvesting. Methods - UHFUS (75 MHz), histology, immunohistochemistry. Results. Donor site without sepsis was characterized by thin epidermis and low overall skin thickness (72% compared to intact skin). At the same time, the papillary layer was increased to 127% (p=0.022). In patients with sepsis, all skin layers, including the papillary dermis, were thinner than in intact skin and thinner than in patients without sepsis. Histomorphometry confirmed UHFUS results.
There is a problem of the shallow depth of the OCT probing radiation, in this regard, it seems promising to study the possibilities of its combination with high-frequency ultrasound in assessing the depth of skin damage. 15 patients of the Burn Center of the Nizhny Novgorod Research Institute of Traumatology with burns of varying severity, were examined. Thus, high-frequency US is a very effective method that allows to get an answer to topical issues of Combustiology, in particular to determine the safety of appendages, which allows to differentiate burns as 3a or 3b, to fundamentally determine the presence or absence of the epidermis, to distinguish second and third degree burns, but does not provide detailed information about the epidermis, the zone of the epidermal-dermal junction, the characteristics of the microcirculatory bed, so the method can be used to determine the depth of skin damage without doubt, but the best results can be achieved with a combination of two techniques.
KEYWORDS: Optical coherence tomography, Arteries, Veins, Visualization, Skin, Ear, 3D image processing, Tissues, 3D image reconstruction, In vivo imaging
The degree and variants of structural changes in the vessels of the skin are important pathomorphological signs of the degree of tissue damage and potential possibilities and the course of its regeneration in various skin injuries, including burns. Objective: to identify arteries and veins with 3D optical coherence tomography during the experiment, describing their distinctive features. Materials and methods. To identify the vessels on OCT images of the skin, the rabbit ear was examined in vivo over the superficially located central artery and marginal vein and the vascular-free zone with a needle mark in the lumen of the vessel. Histo-tomographic comparisons were performed. Result. OCT signs of arterial and venous vessels are formulated.
Transserosal optical coherence tomography (OCT) with angiography modality (OCTA) provides real-time label-free visualization of the intestinal structure and blood vessels networks with a spatial resolution about 10-15 µm. This method is a perspective for intraoperative use in abdominal surgery, for example, for determining the depth of ischemic damage to the gut. The paper devoted to analysis the quality of OCT/OCTA data obtained from small intestine of 4 subjects - rat, rabbit, minipigs and humans. The subjects have different thickness of intestinal wall and blood circulation conditions. It was shown, that the intestine of small laboratory animals (rats and rabbits) is convenient for studying with OCT/OCTA: it can be easily stabilized by moving the intestine loop outside the body, which, together with a rigidly fixed probe, minimizes the number of possible motion artifacts. Therefore, OCT/OCTA criteria of structural changes in the intestinal wall and microcirculation disorders during ischemia, important for clinical applications, were established on these objects. Large animals (minipigs) and human proved to be a troublesome subjects for obtaining high-quality OCT/OCTA data: powerful peristaltic movements, pronounced pulse wave and the inability to take the object out of the body in order to exclude the influence of respiratory and other types of the body movements led to a sharp increase in the amount of OCT/OCTA images with artifacts (up to 39% in humans). However, in patients and minipigs the microstructure of intestinal layers was more informative than in small animals due to increased thickness. Therefore, it allowed visualize tissues in more detail: in particular, verify peritoneum edema and intramuscular fluid buildup. The study was performed under support of RFBR grant No.19-75-10096.
Tattooing and permanent makeup are very popular [1]. Nowadays there is practically no information about the effect of artificial pigment on the surrounding tissues. The issue of removing artificial pigment, the selection of individual parameters of laser radiation, depending on the level of occurrence of the pigment and individual characteristics of the skin, and control of the effectiveness of the procedure is also no less urgent. Optical coherence tomography (OCT) is a promising method for noninvasive examination of the skin, which allows one to assess its structure and morphological changes occurring in it in real time [2,3]. The purpose of this work is to assess the condition of the skin containing artificial pigment before and after laser tattoo removal using the method of optical coherence tomography (OCT).
Many skin and systemic diseases are accompanied by changes in the vessels of the skin. The role of the vascular component in the pathogenesis of diseases in most cases remains underestimated and is not sufficiently taken into account in the treatment. One of the reasons is the lack of safe, effective and accessible methods of objective assessment of skin vessels. The possibilities of the histological method are limited [1] due to vascular damage during biopsy and manufacture of the drug, as well as the inability to perform multi-focal and dynamic studies. Capillaroscopy and dermatoscopy also do not solve the problem, as they allow only indirectly to judge the condition of the skin vessels [2]. The possibilities of other non-invasive methods of examining skin vessels are being studied. One of the promising methods of lifetime examination of skin vessels is optical coherence tomography (OCT). This is a high-resolution (10-20 mk) method for visualizing the structure of biological tissues, using low-intensity near-infrared light as probing radiation [3]. The purpose of the work To study the possibilities of using OCT and 3D OCT to assess the state of the microcirculatory bed of the skin.
Objective: to study the dynamics of the state of autografts of skin and allodermal protectors on a wound using multimodal optical monitoring. Material and methods. A burn wound was simulated in rats (n = 16), 20% of the wound area was covered with skin autografts. The allodermal protector of 0.35 mm thick was applied over the autografts. Studied in vivo the state of the grafts for 10 days: saturation - according to diffuse optical spectroscopy (DOS); perfusion - according to laser Doppler flowmetry (LDF); microstructure - according to optical coherence tomography (OCT). Results. Multimodal monitoring of blood circulation, metabolism and microstructure of skin grafts on a burn wound showed that changes in auto- and allografts occur asynchronously. In the tissues of the autograft, blood saturation directly correlated with the restoration of perfusion (Spearman's coefficient = 0.795); in the allograft, the correlation between perfusion and saturation was weakly inverse (-0.179). Those differences were confirmed by OCT data and histological analysis: allografts lost their normal microstructure simultaneously with a rapid decrease of the blood saturation, despite the preservation of perfusion parameters.
In the paper we demonstrate the applicability of optical coherence tomography angiography (OCTA) and optical coherence tomography lymphangiography (OCTL) to investigate changes in intramural blood and lymph flow of the small intestine in an experimental model of spinal trauma with sympathetic denervation of the gut. Resection of sympathetic ganglia was performed in rabbits using the retroperitoneal approach. Lymph and blood circulation in the small intestine wall was evaluated before and after the spinal trauma. For OCTL images the signal attenuation coefficient was quantitatively analyzed, and the areas that did not scatter or absorb light in the infrared range were assigned to the lymph. It was shown that the changes in blood microcirulation are significant, hovewer the significance of changes in lymhatic vessels density is hard to estimate due to high variations of data.
Successful gastrointestinal surgery is based on the precise knowledge of the morphological, functional and metabolic state of the bowel wall at a specific time point. Current trends include the development of real-time, minimally invasive, label-free and rapid techniques for tissue assessment in combination with algorithms of data processing. The aim of the study was to evaluate the performance of trans-serous multimodal optical coherence tomography (MM OCT) and FLIM macro-imaging in detecting changes in microstructure, blood circulation and metabolism of intestinal wall caused by acute arterial ischemia in experiment. The study was supported by the Russian Science Foundation, project No. 19-75-10096.
A method, based on optical coherence angiography (OCA), for the intraoperative diagnosis of blood microcirculation in the ischemic intestine has been tested. The pilot clinical study involved 18 patients who had undergone urgent operations for thrombosis of segments II or III of the superior mesenteric artery, as well as for infringement of the bowel and the mesenteric vessels. In the OCA images regions of preserved blood microcirculation in the intestinal wall were characterized by the presence of branched networks of intramural microvessels and a bright background in the OCA images. Regions of the intestine in which the intramural vessels were interrupted or could not be visualized were considered as potentially non-viable. These data were used to determine the boundaries for intestinal resection. In comparison with the traditional method of intraoperative diagnosis of intestinal blood flow, the use of such OCA criteria meant the volume of bowel resection could be decreased by 21.5 [14.1; 36.0]% (p = 0.037). This observation demonstrates the great potential of OСA in the intraoperative detection of the boundaries of damaged and healthy intestinal wall in ischemic bowel disease.
The objective of the research was a multifaceted study of strangulated small intestine to reveal the optical, morphofunctional and biochemical signs of small bowel ischemia. The study was carried out in vivo using an artificially induced strangulation model of the small intestine (together with its mesentery and blood vessels) in 12 Wistar rats. Over a period of 120 minutes following the bowel ligation, changes in the density of the intramural vasculature and intestinal wall microstructure were detected using multimodal optical coherence tomography (MM OCT). Fluorescence lifetime changes of endogenous fluorophores were also measured using macro-FLIM of the strangulated loop and the adjacent segments of the intestine. At the end of the experiment, a morphometric study of the thickness of the layers and the prevalence of necrosis in the intestinal wall was carried out. A comprehensive analysis of the results of the OCT, FLIM and morphometry of the ischemic wall of the small intestine made it possible to determine the correlating morphofunctional and biochemical manifestations that are specific to this model of mesenteric blood flow disturbance.
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