[Noninvasive estimation of the oxygen state of experimental tumor by diffuse optical spectroscopy].

The potentialities of diffuse optical spectroscopy for the noninvasive estimation of the oxygen state of experimental tumors have been demonstrated. The distribution of total, oxygenated and deoxygenated hemoglobin, as well as the level oxygen saturation of blood have been shown using two tumor models differing in the histological structure and functional characteristics. The results obtained by the optical method have been verified by immunohistochemical examination of tissue specimens with the exogenous hypoxia marker pimonidazole.

[Optic coherent tomography: a new high-resolution technology of visualization of tissue structures. Communication II. Optical images of benign and malignant entities]. / Opticheskaia kogerentnaia tomografiia -- novaia vysokorazreshaiushchaia tekhnologiia vizualizatsii struktury tkanei. Soobshchenie II. Opticheskie izobrazheniia dobrokachestvennykh i zlokachestvennykh sostoianii.

This is the second communication of a series of publications on Russian studies in the field of optical coherent tomography (OCT), the newest noninvasive highly resolving technology of visualization of the structure of biological tissues. By using the investing tissues as an example, this paper demonstrates the universal types of changes in their optical properties. Optimal images permit differentiate benign and malignant processes with a high degree of diagnostic accuracy. Diverse benign processes occurring in the epithelium are detected on the OCT images as changes in its height, the scattering properties and stroke of a basilar membrane. The absence of any structure on the image is the main OCT criterion for malignancy. The diagnostic efficiency of OCT is high in recognizing neoplasia of various mucous membranes: the sensitivity of the technique is 77-98%; its specificity and diagnostic accuracy are 71-96 and 81-87%, respectively.

[Optical coherence tomography in the evaluation of the oral cavity mucosa. Part II. Benign and malignant diseases]. / Opticheskaia kogerentnaia tomografiia v otsenke sostoianiia slizistoi obolochki polosti rta. Soobshchenie II. Dobrokachestvennye i zlokachestvennye zabolevaniia.

This paper is the last one in the series of publications on the investigation of the capability of Optical Coherence Tomography (OCT) in diagnostic of state of oral cavity mucosa. Part II demonstrates the diversity of optical images, different forms specific to leukoplakia, lichen planus and squamous cell carcinoma on the basis of the investigation of 56 pathologic lesions of 43 patients with precancer and cancer of oral cavity. The OCT sensitivity in malignancy detection in oral cavity is high - 83%, specificity is 98%, and accuracy is 81%. The kappa coefficient of interobserver agreement is 0.76.

[Optic coherent tomography in evaluation of the buccal mucosa status. Communication 1. Normal mucosa]. / Opticheskaia kogerentnaia tomografiia v otsenke sostoianiia slizistoi obolochki polosti rta. Soobshchenie 1. Normal'naia slizistaia obolochka.

The potentialities of optic coherent tomography (OCT) in the diagnosis of the buccal mucosa status were studied and the results are presented in two communications. Communication 1 demonstrates the tomograms of various parts of normal buccal mucosa and methods of their identification as exemplified by analysis of 1180 in vivo and 43 ex vivo OCT images. Using parallel histo-tomographic comparison, the authors distinguished the main signs of optic images, depending on the type of epithelium and characteristic features of the connective tissue stroma in various parts of the buccal mucosa. These signs are essential for understanding the optic images of the mucosa in disease, which will be shown in communication 2.

Complementary use of cross-polarization and standard OCT for differential diagnosis of pathological tissues.

An experimental standard optical coherence tomography (OCT) setup that can be easily modified for cross-polarization OCT (CP OCT) operation has been developed to perform differential diagnosis of pathological tissues. The complementary use of CP OCT, a technique that provides a map of cross-polarization backscattering properties of an object being studied by means of low-coherence interferometry, and standard OCT imaging improves the specificity of diagnostics of pathological changes occurring in tissues. It is shown that healthy, neoplastic and scar tissues of the esophagus have different cross-polarization backscattering properties. A comparative analysis of CP OCT, OCT and histological images from one and the same tissue area has been made. A close correlation between the location of collagen fibers in biological tissue and signal intensity in CP OCT images is found.

Optical coherence tomography monitoring for laser surgery of laryngeal carcinoma.

BACKGROUND AND OBJECTIVES: The goal of this study is to apply a new bioimaging modality, the Optical Coherence Tomography (OCT), for intraoperative control in laser surgery of laryngeal carcinoma. STUDY DESIGN/MATERIALS AND METHODS: We studied 26 patients with laryngeal carcinoma in situ and in T(1), T(2) stage. We used an endoscopic OCT device for imaging at a wavelength of 0.83 microm with the acquisition rate of approximately 0.5 frames/s for a single (200 x 200 pixel) tomogram. All patients were operated with a surgical YAG:Nd laser at two switchable wavelengths of 1.44 microm and 1.32 microm by laryngofissure, direct microlaryngoscopy, and fibrolaryngoscopy. RESULTS: Information on structural alterations in laryngeal mucosa to the depth of 2 mm, obtained by OCT, makes it possible to precisely locate tumor borders, thus giving an opportunity to control the surgical treatment of laryngeal carcinoma. The YAG:Nd laser scalpel with wavelengths of 1.32 microm and 1.44 microm is successful in surgical procedures both in open and closed larynx due to efficient coagulation and minimization of collateral tissue damage area. Combination of the two wavelengths in the single laser unit and intraoperative OCT monitoring result is a new modality for minimally invasive larynx surgery. CONCLUSIONS: OCT is promising to become a new diagnosing method of laryngeal carcinoma and a tool for laser treatment monitoring.

In vivo optical coherence tomography imaging of human skin: norm and pathology.

BACKGROUND/AIMS: Since the majority of skin diseases are known to be accompanied by structural alterations, research efforts are focused on the development of various novel diagnostic techniques capable of providing in vivo information on the skin structure. An essential parameter here is spatial resolution. In this paper we demonstrate the capabilities of optical coherence tomography (OCT) in detecting in vivo specific features of thin and thick skin. A particular focus is made on the identification of OCT patterns typical of certain pathological processes in skin, by performing parallel histological and tomographical studies. METHODS: To obtain images of the skin, we used a compact fiber OCT system developed at the Institute of Applied Physics of the Russian Academy of Sciences. A low coherence source (superluminescent diode) operated at a wavelength of 1280 nm; the output power was 0.5-2 mW. This power is low enough to conform to the ANSI safety standards for light exposure. The in-depth resolution limited by the spectral bandwidth (40-50 nm) of the probing light was approximately 20 &mgr;m. The lateral resolution determined by the probe light focusing ranged from 15 to 30 &mgr;m. In this series of experiments the maximum depth of imaging did not extend beyond 1.5 mm. Obtaining images of skin regions 2-6 mm long took 2-4 s. OCT capabilities for imaging normal skin of different localization and some skin diseases were studied in 12 healthy volunteers and 24 patients. RESULTS: OCT imaging of the skin can detect in vivo such general pathological reactions of the human body as active inflammation and necrosis. OCT is useful for in vivo diagnosis of some specific processes in the skin, including hyperkeratosis, parakeratosis and formation of intradermal cavities. OCT imaging is noninvasive and therefore allows frequent multifocal examination of skin without any adverse effects. OCT can perform monitoring of disease progress and recovery in the course of therapy. Morphometric studies, measurements of the depth and extension of skin pathology within the human body can be easily performed by OCT. CONCLUSIONS: OCT allows imaging of subsurface soft tissues with the spatial resolution of 15-20 &mgr;m, a resolution one order of magnitude higher than that provided by other clinically available noninvasive diagnostic techniques. An imaging depth of up to 1.5-2 mm, given by current OCT technology, is sufficient to examine the skin. Real time OCT imaging can provide information not only on the structure, but also on some specific features in the functional state, of tissues. OCT imaging is a noninvasive technique, i.e., OCT does not cause trauma and has no side effects since it utilizes radiation in the near infrared wavelength range at a power as low as 1 mW.

In situ Monitoring of Laser Modification Process in Human Cataractous Lens and Porcine Cornea Using Coherence Tomography.

We demonstrate that optical coherence tomography (OCT) is a convenient diagnostic tool to monitor pulse-to-pulse kinetics in laser interactions with biological tissue. In experiments on laser modification and ablation of the cataractous human lens and the porcine cornea we have applied this technique in situ to investigate different modes of preablation tissue swelling, crater formation and thermally affected zone development. The cataractous lens is an example of highly scattering media whereas the cornea is initially low scattering. The radiation with different wavelengths has been employed including that of a YAG:Er laser (λ=2.94 µm), a glass:Er laser (λ=1.54 µm), YAG:Nd lasers (λ=1.32 µm and λ=1.44 µm), as well as of the fifth harmonic of a Nd:YAP laser (λ=0.216 µm). Pulse-to-pulse OCT monitoring has been accompanied by the probe beam shielding diagnostics to provide the time-resolved observation of the interaction dynamics. © 1999 Society of Photo-Optical Instrumentation Engineers.

[The role of cytochrome c in preventing postresuscitation functional disorders of the central nervous system]. / Rol' tsitokhroma c v preduprezhdenii postreanimatsionnykh narushenii funktsional'nogo sostoianiia tsentral'noi nervnoi sistemy.

The effect of intracarotid injection of cytochrome c on the course of the early postresuscitation period was studied in experimental animals (albino rats) after 5-min clinical death from acute blood loss. It was shown that the drug normalizes the disturbed metabolic processes in the brain, reduces the structural changes consequent upon total ischemia, stabilizes the activity of the cardiovascular system and, as a result of this, contributes to restoration of functional activity of the central nervous system in the early postresuscitation period.

Endoscopic applications of optical coherence tomography.

We report results of application of our endoscopic optical coherence tomography (EOCT) system in clinical experiments to image human internal organs. Based on the experience of studying more than 100 patients, we make first general conclusions on the place and capabilities of this method in diagnosing human mucous membranes. It is demonstrated that EOCT can serve for several clinical purposes such as performing directed biopsy, monitoring functional states of human body, guiding surgical and other treatments and monitoring post-operative recovery processes. We show that applications of OCT are more informative in the case of internal organs covered by epithelium separated from underlying stroma by a smooth basal membrane and therefore concentrate on the results of the EOCT study of three internal organs, namely of larynx, bladder, and uterine cervix. Finally, we report first examination of internal organs in abdomen with the use of laparoscopic OCT.

In vivo endoscopic OCT imaging of precancer and cancer states of human mucosa.

First results of endoscopic applications of optical coherence tomography for in vivo studies of human mucosa in respiratory, gastrointestinal, urinary and genital tracts are presented. A novel endoscopic OCT (EOCT) system has been created that is based on the integration of a sampling arm of an all-optical-fiber interferometer into standard endoscopic devices using their biopsy channel to transmit low-coherence radiation to investigated tissue. We have studied mucous membranes of esophagus, larynx, stomach, urinary bladder, uterine cervix and body as typical localization for carcinomatous processes. Images of tumor tissues versus healthy tissues have been recorded and analyzed. Violations of well-defined stratified healthy mucosa structure in cancered tissue are distinctly seen by EOCT, thus making this technique promising for early diagnosis of tumors and precise guiding of excisional biopsy.

[Effect of various levels of hypothermic ischemia on ATPase activity of the functional element of the myocardium]. / Vliianie razlichnykh urovnei gipotermicheskoi ishemii na aktivnost' ATFazy funktsional'nogo élementa miokarda.

Activity of ATPase in functional element of myocardium (its qualitative and quantitative aspects) has been researched in normal tissue and in one with various levels of hypothermic ischemia (28-30 degrees C and 10-12 degrees C) by methods of electron microscopic histochemistry on dogs. It has been found that hypothermia of myocardium (10-12 degrees C) optimally prevents ischemic disorders of energetic processes. Reproduction activity of ATPase during reperfusion of myocardium after that hypothermia maintains contractile function of heart in proper high level.

[The adaptive-compensatory reactions of the pulmonary microcirculatory bed in experimental pneumonia]. / Prisposobitel'no-kompensatornye reaktsii mikrotsirkuliatornogo rusla legkikh pri éksperimental'noi pnevmonii.

Pulmonary microcirculation was studied in anesthetized interbred male cats with acute pneumonia in acute experiments by the method of intravital microscopy. Due to the reticular structure of the lung microcirculatory channel and the change of the direction of the blood flow in microvessels stretching to the focus of inflammation, collateral circulation developed rapidly and facilitated redistribution of the blood flow in the pulmonary lobe involved in the inflammation.

[Erythrocyte and microcirculatory functions during artificial circulation]. / Sostoianie éritrotsitov i mikrotsirkuliatsii pri iskusstvennom krovoobrashchenii.

Erythrocyte morphology, their aggregation ability and microcirculatory pattern in the mesentery of the small intestine have been studied stepwise on 12 dogs under artificial blood circulation. It has been shown that erythrocyte lesions followed by pathological aggregation play an important role in the pathogenesis of microcirculatory failure. Prolonged artificial circulation provokes structural reorganization in erythrocytes, thus affecting both blood rheology and gas exchange.

[Optimal timing of radical surgery for tumors of the pancreaticoduodenal zone associated with jaundice]. / Optimal'nye sroki radikal'noi operatsii pri opukholiakh pankreatoduodenal'noi zony, soprovozhdaiushchikhsia zheltukhoi.

In cancer of the pancreatoduodenal zone complicated by obturative jaundice it is expedient to perform pancreatogastroduodenal resection in two steps: the first step is laparoscopic hepatocholecystostomy, the second step should be fulfilled 10-12 days after normalization of bilirubinemia. The data obtained were taken into consideration in pancreatogastroduodenal resection performed in 20 patients.

[Effect of sodium oxybutyrate on macroergic phosphates, function and ultrastructure of the myocardium in blood loss]. / Vliianie oksibutirata natriia na makroérgicheskie fosfaty, funktsiiu i ul'trastrukturu miokarda pri krovopotere.

Experiments on dogs with long-term hypotony caused by blood loss have demonstrated irreversible lesions in the majority of cardiomyocytes and hypodynamic condition of the heart with a high content of macroergic phosphates in the myocardium. Intravenous injection of sodium hydroxybutyrate in a dose of 180-200 mg/kg after 60 min of hypotony seems to improve energy transport and utilization in the ischemic myocardium. It increases the working capacity and power of the heart muscle, pump function of the heart and makes longer the period of ultrastructural changes in cardiomyocytes.