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Biomedical subjects

Maciej Wojtkowski

Publications and source records attributed to Maciej Wojtkowski.

13 recordsLinked to original sources
PubMed2006

Retinal assessment using optical coherence tomography.

Over the 15 years since the original description, optical coherence tomography (OCT) has become one of the key diagnostic technologies in the ophthalmic subspecialty areas of retinal diseases and glaucoma. The reason for the widespread adoption of this technology originates from at least two properties of the OCT results: on the one hand, the results are accessible to the non-specialist where microscopic retinal abnormalities are grossly and easily noticeable; on the other hand, results are reproducible and exceedingly quantitative in the hands of the specialist. However, as in any other imaging technique in ophthalmology, some artifacts are expected to occur. Understanding of the basic principles of image acquisition and data processing as well as recognition of OCT limitations are crucial issues to using this equipment with cleverness. Herein, we took a brief look in the past of OCT and have explained the key basic physical principles of this imaging technology. In addition, each of the several steps encompassing a third generation OCT evaluation of retinal tissues has been addressed in details. A comprehensive explanation about next generation OCT systems has also been provided and, to conclude, we have commented on the future directions of this exceptional technique.

Anatomy, Cross-Sectional↗
PubMed2006

Persistence of Cloquet's canal in normal healthy eyes.

PURPOSE: Optic nerve head (ONH) structural imaging with state-of-the-art, high-speed, ultra-high-resolution optical coherence tomography (hsUHR-OCT). DESIGN: Observational cohort study. METHODS: ONH centered 3-dimensional (94,371,840 voxel measurements in a 6- x 6- x 1.4-mm tissue volume) hsUHR-OCT data were obtained in one eye from each of six males and nine females normal healthy volunteers (40 +/- 9 years of age). The presence of structures projecting anteriorly from the disk into the vitreous was noted. RESULTS: Structures were noted in 14 of 15 (93%) examined eyes, emanating from the rim of the ONH at the nasal inferior sector, presenting as thin tissue meandering into the vitreous. CONCLUSIONS: Previous technologies provided limited visualization of ONH structures. The ability to scan the entire disk using 3-dimensional OCT (3D-OCT) in a high-density raster pattern reveals a high frequency of persistence of Cloquet's canal in the normal healthy eye.

Adult↗
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

High-definition and 3-dimensional imaging of macular pathologies with high-speed ultrahigh-resolution optical coherence tomography.

OBJECTIVE: To assess high-speed ultrahigh-resolution optical coherence tomography (OCT) image resolution, acquisition speed, image quality, and retinal coverage for the visualization of macular pathologies. DESIGN: Retrospective cross-sectional study. PARTICIPANTS: Five hundred eighty-eight eyes of 327 patients with various macular pathologies. METHODS: High-speed ultrahigh-resolution OCT images were obtained in 588 eyes of 327 patients with selected macular diseases. Ultrahigh-resolution OCT using Fourier/spectral domain detection achieves approximately 3-mum axial image resolutions, acquisition speeds of approximately 25 000 axial scans per second, and >3 times finer resolution and >50 times higher speed than standard OCT. Three scan protocols were investigated. The first acquires a small number of high-definition images through the fovea. The second acquires a raster series of high-transverse pixel density images. The third acquires 3-dimensional OCT data using a dense raster pattern. Three-dimensional OCT can generate OCT fundus images that enable precise registration of OCT images with the fundus. Using the OCT fundus images, OCT results were correlated with standard ophthalmoscopic examination techniques. MAIN OUTCOME MEASURES: High-definition macular pathologies. RESULTS: Macular holes, age-related macular degeneration, epiretinal membranes, diabetic retinopathy, retinal dystrophies, central serous chorioretinopathy, and other pathologies were imaged and correlated with ophthalmic examination, standard OCT, fundus photography, and fluorescein angiography, where applicable. High-speed ultrahigh-resolution OCT generates images of retinal pathologies with improved quality, more comprehensive retinal coverage, and more precise registration than standard OCT. The speed preserves retinal topography, thus enabling the visualization of subtle changes associated with disease. High-definition high-transverse pixel density OCT images improve visualization of photoreceptor and pigment epithelial morphology, as well as thin intraretinal and epiretinal structures. Three-dimensional OCT enables comprehensive retinal coverage, reduces sampling errors, and enables assessment of 3-dimensional pathology. CONCLUSIONS: High-definition 3-dimensional imaging using high-speed ultrahigh-resolution OCT improves image quality, retinal coverage, and registration. This new technology has the potential to become a useful tool for elucidating disease pathogenesis and improving disease diagnosis and management.

Adult↗
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

Noninvasive volumetric imaging and morphometry of the rodent retina with high-speed, ultrahigh-resolution optical coherence tomography.

PURPOSE: To demonstrate high-speed, ultrahigh-resolution optical coherence tomography (OCT) for noninvasive, in vivo, three-dimensional imaging of the retina in rat and mouse models. METHODS: A high-speed, ultrahigh-resolution OCT system using spectral, or Fourier domain, detection has been developed for small animal retinal imaging. Imaging is performed with a contact lens and postobjective scanning. An axial image resolution of 2.8 mum is achieved with a spectrally broadband superluminescent diode light source with a bandwidth of approximately 150 nm at approximately 900-nm center wavelength. Imaging can be performed at 24,000 axial scans per second, which is approximately 100 times faster than previous ultrahigh-resolution OCT systems. High-definition and three-dimensional retinal imaging is performed in vivo in mouse and rat models. RESULTS: High-speed, ultrahigh-resolution OCT enabled high-definition, high transverse pixel density imaging of the murine retina and visualization of all major intraretinal layers. Raster scan protocols enabled three-dimensional volumetric imagingand comprehensive retinal segmentation algorithms allowed measurement of retinal layers. An OCT fundus image, akin to a fundus photograph was generated by axial summation of three-dimensional OCT data, thus enabling precise registration of OCT measurements to retinal fundus features. CONCLUSIONS: High-speed, ultrahigh-resolution OCT enables imaging of retinal architectural morphology in small animal models. OCT fundus images allow precise registration of OCT images and repeated measurements with respect to retinal fundus features. Three-dimensional OCT imaging enables visualization and quantification of retinal structure, which promises to allow repeated, noninvasive measurements to track disease progression, thereby reducing the need for killing the animal for histology. This capability can accelerate basic research studies in rats and mice and their translation into clinical patient care.

Animals↗
PubMed2006

[Spectral optical coherence tomography (SOCT) in diagnosis of diseases of macula--own results].

In this paper general information about spectral optical coherent tomography (SOCT) is presented. SOCT was used in diagnosis of choroidal neovascularization (16 eyes), central serous chorioretinopathy (4 eyes), macular hole (8 eyes), epiretinal membrane (3 eyes) and familial dominant drusen (2 eyes). In all cases SOCT examination revealed new data useful in detailed diagnosis. SOCT is a valuable complementary examination to fluorescein and indocianine green angiography in diagnosis of macula diseases.

Adult↗
PubMed2005

Three-dimensional retinal imaging with high-speed ultrahigh-resolution optical coherence tomography.

PURPOSE: To demonstrate high-speed, ultrahigh-resolution, 3-dimensional optical coherence tomography (3D OCT) and new protocols for retinal imaging. METHODS: Ultrahigh-resolution OCT using broadband light sources achieves axial image resolutions of approximately 2 microm compared with standard 10-microm-resolution OCT current commercial instruments. High-speed OCT using spectral/Fourier domain detection enables dramatic increases in imaging speeds. Three-dimensional OCT retinal imaging is performed in normal human subjects using high-speed ultrahigh-resolution OCT. Three-dimensional OCT data of the macula and optic disc are acquired using a dense raster scan pattern. New processing and display methods for generating virtual OCT fundus images; cross-sectional OCT images with arbitrary orientations; quantitative maps of retinal, nerve fiber layer, and other intraretinal layer thicknesses; and optic nerve head topographic parameters are demonstrated. RESULTS: Three-dimensional OCT imaging enables new imaging protocols that improve visualization and mapping of retinal microstructure. An OCT fundus image can be generated directly from the 3D OCT data, which enables precise and repeatable registration of cross-sectional OCT images and thickness maps with fundus features. Optical coherence tomography images with arbitrary orientations, such as circumpapillary scans, can be generated from 3D OCT data. Mapping of total retinal thickness and thicknesses of the nerve fiber layer, photoreceptor layer, and other intraretinal layers is demonstrated. Measurement of optic nerve head topography and disc parameters is also possible. Three-dimensional OCT enables measurements that are similar to those of standard instruments, including the StratusOCT, GDx, HRT, and RTA. CONCLUSION: Three-dimensional OCT imaging can be performed using high-speed ultrahigh-resolution OCT. Three-dimensional OCT provides comprehensive visualization and mapping of retinal microstructures. The high data acquisition speeds enable high-density data sets with large numbers of transverse positions on the retina, which reduces the possibility of missing focal pathologies. In addition to providing image information such as OCT cross-sectional images, OCT fundus images, and 3D rendering, quantitative measurement and mapping of intraretinal layer thickness and topographic features of the optic disc are possible. We hope that 3D OCT imaging may help to elucidate the structural changes associated with retinal disease as well as improve early diagnosis and monitoring of disease progression and response to treatment.

Anatomy, Cross-Sectional↗
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↗
PubMed2004

[Application of spectral optical coherent tomography (SOCT) in ophthalmology].

The article describes spectral optical coherent tomography (SOCT) constructed by Medical Physics Group, Faculty of Physics, Astronomy and Informatics at Nicholas Copernicus University in Toruń (Poland). It presents the physical bases for the functioning of the constructed device and includes pictures of optical sections of various elements of the eyeball: an optic disc and the region of central fovea, a cornea and angle structures (trabecular meshwork). The article also discusses potential application of SOCT in ophthalmic diagnosis of anterior and posterior segments of the eye.

Eye Diseases↗
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↗