arXiv subjects

Viacheslav Mazlin

Publications and source records attributed to Viacheslav Mazlin.

8 recordsLinked to original sources

arXiv2024

Full Field Transmission Tomography (FFOTT) for imaging extrachromosomal circular DNA (eccDNA) in cancer cell nuclei

Detecting the specificity of cancer cells to distinguish them from normal ones is an important step in the general framework of cancer diagnosis. A routine example of such diagnosis in cancerous tissues implies using microscope analysis of fixed, paraffined, and colored slices such as the H&E stain (1). Such a method, which takes place after surgery, is based on carefully analyzing the cell's size and shape. Often, this approach is performed in parallel with more modern genetic tests. Recent research has hypothesized that extrachromosomal circular DNA (eccDNA) could be considered a new hallmark of cancer (4). Thus, this research aims to check if using a simple, label-free microscope dynamic analysis performed on living cancer cells would allow efficient and simpler detection of cancer cells.

physics.med-ph↗

arXiv2023

Comparative analysis of full-field OCT and optical transmission tomography

This work compares two tomographic imaging technologies, time-domain full-field optical coherence tomography (FFOCT) working in reflection and optical transmission tomography (OTT), using a new optical setup that combines both. We show that, due to forward-scattering properties, the axial sectioning and contrast in OTT can be optimized by tuning illumination. The influence of sample scattering and thickness are discussed. We illustrate the comparison of the two methods in static (morphology) and dynamic (metabolic contrast) regimes using cell cultures, tissues and entire organisms emphasizing the advantages of both approaches.

physics.optics↗

arXiv2022

Compact orthogonal view OCT: clinical exploration of human trabecular meshwork and cornea at cell resolution

Glaucoma remains among the leading causes of blindness despite many treatment options available today. Effective treatment requires early diagnosis, which is difficult to achieve with existing imaging technologies that detect the already inflicted irreversible posterior eye damage. One improved approach could be to detect the changes in trabecular meshwork of the anterior eye that precede the intraocular pressure buildup and vision loss. Here we report a device that enables in vivo exploration of trabecular meshwork at cell resolution. The instrument combines two orthogonal views: en face view of time-domain full-field OCT for high-resolution and cross-sectional view of spectral-domain OCT for aligning to the meshwork. The device resolves micron-level corneoscleral and uveal pores, meshwork beams and internal elastic fibers, ciliary body tendons and trabecular cell nuclei. Capable of detecting blockage of trabecular pores, orthogonal view OCT presents a promising solution to the long-standing problem of early glaucoma diagnosis. Future clinical adoption of the device is facilitated by the compact footprint and broad functionality that includes corneal imaging in healthy subjects and patients (with keratoconus, Fuchs endothelial dystrophy) using the same design.

physics.med-ph↗

arXiv2022

Label free optical transmission tomography for biosystems: Intracellular structures and dynamics

There is an increasing need for label free methods that could reveal intracellular structures and dynamics. In this context, we develop a new optical tomography method working in transmission - Full-field optical transmission tomography (FF-OTT). The method can measure the forward scattering signals and reveal the metabolic time-dependent signals in living cells. FF-OTT is a common path interferometer taking advantage of the Gouy phase shift - a π phase shift that the light wave experiences around the focus. By modulating position of the focus one can alter the phase of the scattered light. Demodulation of images with different phases rejects the background and enhances the light from the depth-of-focus, thus producing an optical section. We test FF-OTT by imaging single-cell diatoms and ex vivo biological samples. In fresh samples, we show that the intracellular motions create visible intensity fluctuations in FF-OTT so that the method is able to reveal a metabolic dynamic contrast. FF-OTT was found to be an efficient label free technique that can be readily implemented thanks to a robust common-path speckle-free interferometer design using an incoherent light source.

physics.optics↗

arXiv2021

Optical phase modulation by natural eye movements: application to time-domain FF-OCT image retrieval

Eye movements are commonly seen as an obstacle to high-resolution ophthalmic imaging. In this context we study the natural axial movements of the in vivo human eye and show that they can be used to modulate the optical phase and retrieve tomographic images via time-domain full-field optical coherence tomography (TD-FF-OCT). This approach opens a path to a simplified ophthalmic TD-FF-OCT device, operating without the usual piezo motor-camera synchronization. The device demonstrates in vivo human corneal images under the different image retrieval schemes (2-phase and 4-phase) and different exposure times (3.5 ms, 10 ms, 20 ms). Data on eye movements, acquired with a 100 kHz spectral-domain OCT with axial eye tracking, are used to study the influence of ocular motion on the probability of capturing high-signal tomographic images without phase washout. The optimal combinations of camera acquisition speed and amplitude of piezo modulation are proposed and discussed.

physics.med-ph↗

arXiv2020

Curved-field optical coherence tomography: large-field imaging of human corneal cells and nerves

High-resolution optical imaging methods, such as confocal microscopy and full-field optical coherence tomography, capture flat optical sections of the sample. If the sample is curved, the optical field sections through several sample layers and the view of each layer is reduced. Here we present curved-field optical coherence tomography, capable of capturing optical sections of arbitrary curvature. We test the device on a challenging task of imaging the human cornea in vivo and achieve 10x larger viewing area comparing to the clinical state-of-the-art. This enables more precise cell and nerve counts, opening a path to improved diagnosis of corneal and general health conditions (e.g. diabetes). The method is non-contact, compact and works in a single-shot, making it readily available for use in optical research and clinical practice.

physics.med-ph↗

arXiv2020

Real-time, non-contact, cellular imaging and angiography of human cornea and limbus with common-path Full-field/SDOCT

In today's clinics, a cellular-resolution view of the cornea can be achieved only with an in vivo confocal microscope (IVCM) in contact with the eye. Here, we present a common-path Full-field/Spectral-domain OCT microscope (FF/SD OCT), which, for the first time, enables cell-detail imaging of the entire ocular surface (central and peripheral cornea, limbus, sclera, tear film) without contact and in real time. The device, which has been successfully tested in human subjects, is now ready for direct implementation in clinical research. Real-time performance is achieved through rapid axial eye tracking and simultaneous defocusing correction. Images, extracted from real-time videos, contain cells and nerves, which can be quantified over a millimetric field-of-view, beyond the capability of IVCM and conventional OCT. In the limbus, Palisades of Vogt, vessels and blood flow can be resolved with high contrast without contrast agent injection. The fast imaging speed of 275 frames/s (0.6 billion pixels/s) allowed direct monitoring of blood flow dynamics, enabling creation of high-resolution velocity maps for the first time. Tear flow velocity and evaporation time could be measured without fluorescein administration.

physics.med-ph↗

arXiv2018

In vivo high resolution human retinal imaging with wavefront correctionless full-field OCT

As the lateral resolution of FFOCT with spatially incoherent illumination has been shown to be insensitive to aberrations, we demonstrate high resolution en face full-field OCT (FFOCT) retinal imaging without wavefront correction in the human eye in vivo for the first time. A combination of FFOCT with spectral-domain OCT (SDOCT) is applied for real-time matching of the optical path lengths (OPL) of FFOCT. Through the real-time cross-sectional SDOCT images, the OPL of the FFOCT reference arm is matched with different retinal layers in the FFOCT sample arm. Thus, diffraction limited FFOCT images of multiple retinal layers are acquired at both the near periphery and the fovea. The en face FFOCT retinal images reveal information about various structures such as the nerve fiber orientation, the blood vessel distribution, and the photoreceptor mosaic.

physics.med-ph↗