Among the numerous methods for improving the informative value of the optical coherence tomography (OCT), a special place is taken by the methods for increasing the spatial resolution of the resulting images. Increasing the resolution allows one to identify more clinically significant structures in OCT images and thus improve the diagnostic value of OCT. Since the transverse resolution of OCT images is determined by the physical principles different from those for the longitudinal resolution, the ways of their improvement are also different. The aim of the study is to develop a method for increasing the transverse resolution of OCT by ...

We propose an alternative optical coherence tomography (OCT) contrast mechanism based on analysis of speckle temporal synchronization using B-mode OCT structural images. We show that the changes in synchronized speckle intensities with time may be used to distinguish between different tissue types, thus providing a novel and potentially useful contrast for OCT imaging. The developed methodology is tested in scattering flow phantoms, and in vivo on cervical cancer tumour grown within a mouse dorsal skin window chamber model. Derived speckle synchronization metric is compared with autocorrelation function analysis to demonstrate its different nature. The phantom and pre-clinical in vivo results ...

Determining boundaries of infiltrative glial tumors remains a challenging problem in neurooncology. Optical coherence tomography (OCT) with cross-polarization (CP) visualization is a promising technique as a surgical guidance tool. However, the outcome of the procedures performed under OCT guidance strongly depends on the surgeon’s qualification. Thus, a quantitative method for assessing resection margins with OCT is required. The aim of this study was to develop a robust quantitative approach for CP OCT data to differentiate tumorous from non-tumorous tissues in a rat glioma model. Materials and Methods. The study was carried out on the rats’ brains (n=6) with ...

The aim of the study was to provide visual and quantitative evaluation of tumorous and normal brain tissue images obtained by cross-polarization optical coherence tomography (CP OCT) in a comparative in vivo and ex vivo study. Materials and Methods. The CP OCT as a non-damaging noninvasive optical method for tissue structure imaging was used in the study. It enables obtaining volumetric images of 2.4×2.4×1.25 mm 3 in size in real time within a short time of 26 s. The objects were tumorous and normal brain tissues of 12 experimental animals (Wistar rats): 4 — intact, 4 ...

The aim of the study is to demonstrate the potential of cross-polarization optical coherence tomography (CP OCT) as a minimally invasive real-time technique for detection of bladder cancer against a background of severe inflammation. Materials and Methods. For the verification of CP OCT diagnostic data related to the condition of collagen comparison with high-resolution microscopy inspection was performed and correlation of the results was calculated. The CP OCT study was performed on samples of tissue with muscle-invasive urothelial carcinoma T 2–3 N 0–х M 0 (G2, 3) in 18 patients ranging in age from 50 to 64 obtained ...

The aim of the investigation was to evaluate the performance of multimodal OCT (MM OCT) for differential diagnostics of normal and diseased brain tissue using an experimental model of glioblastoma. Materials and Methods. The spectral domain MM OCT device developed at the Institute of Applied Physics of the Russian Academy of Sciences (Nizhny Novgorod, Russia) was used for the study. It provides two modes of investigation: cross-polarization OCT (CP OCT) and microangiographic OCT (MA OCT). The instrument features the following characteristics: rate of information gathering — 20,000 A-scans per second; wavelength — 1.3 µm; shot size — ~4 × 2 mm; lateral ...

The recent development of optical coherence tomography in ophthalmology has shown great interests in using the system in 1 µm in contrast to 800 nm wavelength range due to the less reflection and absorption of retinal pigment epithelium and pigmented choroidal melanocytes in 1 µm wavelength. The clinical value of using 1 µm system has been demonstrated in choroid imaging, retinal and choroidal microcirculation, etc. By examining different aspects of the posterior eye, the specificity and sensitivity of diagnosis can be increased. On the other hand, higher speed can greatly reduce the measuring time and motion artifacts, which brings comfort ...

The aim of the investigation was to develop an approach to quantitative evaluation of polarization properties (birefringence and cross-scattering) basing on cross-polarization OCT images (CP OCT) in order to characterize the development stages of atherosclerotic plaques and to reveal unstable ones. Materials and Methods. We report on quantitative analysis of CP OCT images of the seven development stages of atherosclerotic plaques ex vivo . Integral depolarization factor (IDF) and effective birefringence coefficient (Δ n ) were proposed as parameters for quantitative characterization of the CP OCT images. Results. Calculation of the IDF and Δ n in the local region of interest (intima/fibrous cap ...

The aim of the investigation was to evaluate the possibilities for using cross-polarization optical coherence tomography (CP OCT) to monitor the effectiveness of treatment of cancer of the mouth cavity and of the cervix uteri after photodynamic therapy (PDT) and radiation therapy (RT). Materials and Methods. The CP OCT investigation was performed with an OCT-1300U (Institute of Applied Physics of the Russian Academy of Sciences, LLC “Biomedtech”, Russia) tomograph. The monitoring of the two types of treatment was performed after different periods of exposure: for RT of the mouth cavity cancer — once every 2–3 days throughout the whole course ...

The objective of the research was to study the features of transplantation, growth and visualization of experimental tumors of animals, using multi-functional optical coherence tomography (OCT) to develop the methodology of evaluation of individual tumor response to anti-cancer therapy. Materials and Methods. The research was carried out using an experimental high-speed spectral-domain multimodal OCT system developed at the Institute of Applied Physics of the Russian Academy of Sciences (Russia). The technical characteristics of the system are the following: speed of information acquisition, 20,000 А-scans per second; 1.3 μm wavelength; frame size, approximately 4×2 mm; lateral resolution, 25 ...

Optical coherence tomography (OCT) generates its primary form of contrast from elastic backscatter. It is now the gold standard technique for retinal screening and is emerging rapidly in cardiovascular research however it remains a research goal to establish it to the same degree in epithelial cancer detection and diagnosis. In this report we compare two different OCT systems: an 890 nm spectrometer-based OCT system with 2.5 µm axial resolution and a 1300 nm swept-source OCT system with 7.5 µm axial resolution to determine the effect of these different OCT parameters on the endogenous backscatter contrast of dysplastic/malignant ...

In many developing parts of the world, colposcopy supplemented by aceto-whitening remains the most widespread means of reliably diagnosing cervical dysplasia, potentially leading to cervical cancer. The use of aceto-whitening to enhance detection rates for Barrett’s esophagus is also emerging in recent years. Here we quantitatively study the aceto-whitening phenomenon using 1300 nm optical coherence tomography. By exposing a simple epithelial tissue model (excised rabbit cornea) to 0.5 M acetic acid we report for the first time to our knowledge the direct measurement of the time over which the cellular brightening effect propagates down through the epithelial layer ...

This review emphasizes the current knowledge related to optical coherence tomography (OCT) as a non-invasive diagnostic tool to perform ex vivo and showing great potential for in vivo structural imaging of features in the oral cavity. OCT technology can generate high-resolution cross-sectional and en-face images of the internal architecture of the investigated sample (2–3 mm in depth). To this goal, en-face time domain OCT (TD-OCT) and spectral domain OCT (SD-OCT) were employed. Topics included in this review refer to OCT non-destructive evaluations of: dental abfraction and attrition, material defects and micro-leakages at the tooth-filling interface, temporal-mandibular joint disc, quality ...

Optical coherence tomography (OCT) is a relatively new imaging modality similar with ultrasound where the sound waves are replaced by ballistic photons. OCT provides images at high spatial resolution which allow for the identification of micron size morphological tissue structures. A high impact application is visualization of arterial wall and atherosclerotic plaques. Despite high spatial resolution to complete the transfer of this imaging modality into clinical environment there is a need for markers which would quantify the physiological condition of the sample. Finding the proper markers is a topic of high interest for many research groups. A potential marker suggested ...

Detection of atherosclerotic plaque from optical coherence tomography (OCT) images by visual inspection is difficult. We developed a texture based segmentation method to identify atherosclerotic plaque automatically from OCT images without any reliance on visual inspection. Our method involves extraction of texture statistical features (spatial gray level dependence matrix method), application of an unsupervised clustering algorithm (K-means) on these features, and mapping of the clustered regions: background, plaque, vascular tissue and an OCT degraded signal region in feature-space, back to the actual image. We verified the validity of our results by visual comparison to photographs of the vascular tissue with ...

We present an optical coherence tomography based methodology to determine freshness of soft tissue samples by evaluation of their interaction with low frequency electric field. Various biological tissues samples of different stages of freshness were exposed by low frequency electric current. The influence of the low frequency electric field on tissues was observed and quantified by the double correlation optical coherence tomography (dcOCT) approach developed in house. The quantitative evaluation of electric field — tissue interaction by dcOCT shows an increase of its relative magnitude with the tissue freshness from fresh to the non-fresh ones. The presented approach has a strong ...

Spectrometer based optical coherence tomography suffers from fringe washout for fast flow, a drawback for flow visualization, which is of interest for both lable-free optical angiography and flow quantification. We presented a method, which can be used to contrast very fast flows, while maintaining relatively low A-scan rates. It is based on introducing a phase shift of during acquisition such that the interference fringes associated to moving sample structures are recovered depending on the axial velocity. This enables the use of slower line scan cameras for measuring the fast blood flows within the large vessels in the region of the ...

Common path probes are highly desirable for optical coherence tomography as they reduce system complexity and cost by eliminating the need of dispersion compensation and polarization controlling optics. In this work, we demonstrate a monolithic ball lens based, common path, side viewing probe that is suitable for Fourier domain optical coherence tomography. The probe design parameters were simulated in Zemax modeling software and the simulated performance parameters were compared with experimental results. We characterized the performance of the probe by measuring its collection efficiency, resolution, and sensitivity. Our results demonstrated that with a source input power of 25 mW, we ...