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Biomedical subjects

Tomasz Bajraszewski

Publications and source records attributed to Tomasz Bajraszewski.

8 recordsLinked to original sources
PubMed2006

In vivo imaging of posterior capsule opacification using Spectral Optical Coherence Tomography.

Three years after uneventful extracapsular cataract extraction with implantation of a poly(methyl methacrylate) (PMMA) intraocular lens (IOL) (MZ60BD, Alcon) in a 74-year-old man, the anterior segment of the right eye was photographed with a Canon EOS 300D digital camera and examined with a slitlamp and a prototype spectral optical coherence tomography (SOCT) instrument. Subsequently, a neodymium:YAG laser posterior capsulotomy was performed, followed by another examination. The quality of the SOCT images was adequate for detailed cross-sectional evaluation of the IOL, posterior capsule opacification (PCO), and morphological changes after laser capsulotomy. En face contour maps of PCO distribution were created from 3-dimensional SOCT data. The results presented indicate future applicability of SOCT technology in evaluating modern IOL designs and investigating the process of PCO formation.

Aged↗
PubMed2006

Spectral optical coherence tomography: a novel technique for cornea imaging.

PURPOSE: Spectral optical coherence tomography (SOCT) is a new, noninvasive, noncontact, high-resolution technique that provides cross-sectional images of the objects that weakly absorb and scatter light. SOCT, because of very short acquisition time and high sensitivity, is capable of providing tomograms of substantially better quality than the conventional OCT. The aim of this paper is to show the application of the SOCT to cross-sectional imaging of the cornea and its pathologies. METHODS: Eleven eyes with different corneal pathologies were examined with a slit lamp and the use of a prototype SOCT instrument constructed in the Institute of Physics, Nicolaus Copernicus University, Toruń, Poland. RESULTS: Our SOCT system provides high-resolution (4 microm axial, 10 microm transversal) tomograms composed of 3000-5000 A-scans with an acquisition time of 120-200 ms. The quality of the images is adequate for detailed cross-sectional evaluation of various corneal pathologies. Objective assessment of the localization, size, shape, and light-scattering properties of the changed tissue is possible. Corneal and epithelial thickness and the depth and width of lesions can be estimated. CONCLUSION: SOCT technique allows acquiring clinically valuable cross-sectional optical biopsy of the cornea and its pathologies.

Cornea↗
PubMed2006

Spectral optical coherence tomography: a new imaging technique in contact lens practice.

PURPOSE: Spectral optical coherence tomography (SOCT) is a new non-invasive, non-contact, high-resolution technique, which provides cross-sectional images of objects that weakly absorb and scatter light. The aim of this article is to demonstrate the application of SOCT to imaging of eyes fitted with contact lenses. METHODS: Nine eyes of six different subjects fitted with various contact lenses have been examined with a slit-lamp and a prototype SOCT instrument. RESULTS: Our SOCT system provides high-resolution (4-6 mum longitudinal, 10 mum transversal) tomograms composed of 3000-5000 A-scans with acquisition time of 100-250 ms. The quality of the images is adequate for detailed evaluation of contact lens fit. Design, shape and lens edge position were assessed, and complications of contact lens wear could be visualized. Thickness of the lens, corneal epithelium and stroma as well as the space between the lens and the eye surface have been measured. CONCLUSIONS: SOCT allows high-resolution, cross-sectional visualization of the eye fitted with a contact lens. The ability to carry out a detailed evaluation of the fitting relationship between the lens and the ocular surface might be useful in research and optometric practice. SOCT can also be helpful in diagnosis, evaluation and documentation of contact lens complications.

Contact Lenses↗
PubMed2004

Real-time measurement of in vitro flow by Fourier-domain color Doppler optical coherence tomography.

The possibility of measuring a full Doppler flow depth profile in parallel by use of frequency-domain optical coherence tomography is demonstrated. The method is based on a local phase analysis of the backscattered signal and allows for imaging of bidirectional Doppler flow. The Doppler frequency limit is 5 kHz for the presented measurements and is set by half of the frame rate of the CCD detector array. We measured the flow of 0.3-microm microspheres suspended in distilled water at controlled flow rates and in vitro human blood flow through a 200-microm capillary with a real-time color-encoded Doppler tomogram rate of 2-3/s.

Blood Cells↗
PubMed2004

Ophthalmic imaging by spectral optical coherence tomography.

PURPOSE: To demonstrate two novel ophthalmic imaging techniques based on fast Spectral Optical Coherence Tomography (SOCT). DESIGN: Prospective observation case report. METHODS SETTING: Research laboratory. STUDY POPULATION: A normal human subject. MAIN OUTCOME MEASURES: Correlation of an optical coherence retinal tomogram with known retinal anatomy, reduction of eye exposure to the probing light beam during Optical Coherence Tomography (OCT) examination. RESULTS: High resolution (3- x 20-microm) cross-sectional 2-dimensional images of the human retina in vivo have been obtained with only 0.1-second total illumination time (for 1024 A-scans), and approximately 200- microW eye exposure. Details of the optic disk in vivo have been visualized at a rate of eight frames per second, which is sufficient to provide real time analysis. The 3-dimensional images of the optic nerve correspond to the images obtained from a fundus camera. CONCLUSIONS: Because of its short acquisition time and high sensitivity, SOCT uses a 100 times lower exposure/A-scan to obtain images of comparable quality to those obtained by the commercial instrument based on traditional time-domain OCT. Spectral Optical Coherence Tomography therefore provides a much wider safety margin than the traditional method and allows relaxation of the current safety precautions forbidding more than 10 minutes/day scanning of the same location of a retina. As a result of the high speed offered by the new technique, the 3-dimensional tomograms, which allow a surgeon access to a comprehensive and detailed view of relevant pathologies, are obtained in a much shorter, clinically more reasonable time.

Adult↗
PubMed2003

Phase-shifting algorithm to achieve high-speed long-depth-range probing by frequency-domain optical coherence tomography.

Standard Fourier-domain optical coherence tomography (FDOCT) suffers from the presence of autocorrelation terms that obscure the object information and degrade the sensitivity and signal-to-noise ratio. By exploiting the phase information of the recorded interferograms, it is possible to remove those autocorrelation terms and to double the measurement range. However, standard phase-retrieval algorithms need three to five interferograms. We present a novel technique that shows all the features of complex FDOCT with only two recorded interferograms.

Algorithms↗
PubMed2002

In vivo human retinal imaging by Fourier domain optical coherence tomography.

We present what is to our knowledge the first in vivo tomograms of human retina obtained by Fourier domain optical coherence tomography. We would like to show that this technique might be as powerful as other optical coherence tomography techniques in the ophthalmologic imaging field. The method, experimental setup, data processing, and images are discussed.

Adult↗