Blood flow rate estimation in optic disc capillaries and vessels using Doppler optical coherence tomography with 3D fast phase unwrapping

The retinal volumetric flow rate contains useful information not only for ophthalmology but also for the diagnosis of common civilization diseases such as diabetes, Alzheimer's disease, or cerebrovascular diseases. Non-invasive optical methods for quantitative flow assessment, such as Doppler optical coherence tomography (OCT), have certain limitations. One is the phase wrapping that makes simultaneous calculations of the flow in all human retinal vessels impossible due to a very large span of flow velocities. We demonstrate that three-dimensional Doppler OCT combined with three-dimensional four Fourier transform fast phase unwrapping (3D 4FT FPU) allows for the calculation of the volumetric blood flow rate in real-time by the implementation of the algorithms in a graphics processing unit (GPU). The additive character of the flow at the furcations is proven using a microfluidic device with controlled flow rates as well as in the retinal veins bifurcations imaged in the optic disc area of five healthy volunteers. We show values of blood flow rates calculated for retinal capillaries and vessels with diameters in the range of 12-150 µm. The potential of quantitative measurement of retinal blood flow volume includes noninvasive detection of carotid artery stenosis or occlusion, measuring vascular reactivity and evaluation of vessel wall stiffness

Wystepowanie pasozytow czlowieka w wybranych populacjach na przykladzie badan przeprowadzonych w Slaskiej Wojewodzkiej Stacji Sanitarno-Epidemiologicznej

Frequency of human parasites in selected populations of Silesian region. Epidemiological evaluation of the most frequent human parasitoses in the group of children at age of seven years, in adult patients and in group of Polish citizens coming back from tropics between 1999-2003 was performed. All examined people were Silesian region inhabitants. The biggest average infection prevalence in children from all examined years concerned Enterobius vermicularis, in adult - Giardia intestinalis, while in group of population coming back from tropics - Entamoeba histolytica-like. High percentage of anti-Toxocara canis and Toxoplasma gondii antibodies presence can result from non randomly study group recruitment

Ultrahigh Speed Spectral / Fourier Domain Ophthalmic OCT Imaging

Ultrahigh speed spectral / Fourier domain optical coherence tomography (OCT) imaging using a CMOS line scan camera with acquisition rates of 70,000 - 312,500 axial scans per second is investigated. Several design configurations are presented to illustrate trade-offs between acquisition speed, sensitivity, resolution and sensitivity roll-off performance. We demonstrate: extended imaging range and improved sensitivity roll-off at 70,000 axial scans per second , high speed and ultrahigh resolution imaging at 106,382 axial scans per second, and ultrahigh speed imaging at 250,000-312,500 axial scans per second. Each configuration is characterized through optical testing and the trade-offs demonstrated with in vivo imaging of the fovea and optic disk in the human retina. OCT fundus images constructed from 3D-OCT data acquired at 250,000 axial scans per second have no noticeable discontinuity of retinal features and show that there are minimal motion artifacts. The fine structures of the lamina cribrosa can be seen. Long cross sectional scans are acquired at 70,000 axial scans per second for imaging large areas of the retina, including the fovea and optic disk. Rapid repeated imaging of a small volume (4D-OCT) enables time resolved visualization of the capillary network surrounding the INL and may show individual red blood cells. The results of this study suggest that high speed CMOS cameras can achieve a significant improvement in performance for ophthalmic imaging. This promises to have a powerful impact in clinical applications by improving early diagnosis, reproducibility of measurements and enabling more sensitive assessment of disease progression or response to therapy.Medical Free Electron Laser Program (contract FA9550-07-1-0101)United States. Air Force Office of Scientific Research (contract FA9550-07-1-0014)National Science Foundation (BES-0522845)United States. National Institutes of Health (R01-EY11289-21, R01-EY13178-07, R01-CA75289-11

Ultrahigh speed volumetric ophthalmic OCT imaging at 850nm and 1050nm

The performance and imaging characteristics of ultrahigh speed ophthalmic optical coherence tomography (OCT) are investigated. In vivo imaging results are obtained at 850nm and 1050nm using different configurations of spectral and swept source / Fourier domain OCT. A spectral / Fourier domain instrument using a high speed CMOS linescan camera with SLD light source centered at 850nm achieves speeds of ~91,000 axial scans per second with ~3μm axial resolution in tissue. A spectral / Fourier domain instrument using an InGaAs linescan camera with SLD light source centered at 1050nm achieves ~47,000 axial scans per second with ~7μm resolution in tissue. A swept source instrument using a novel wavelength swept laser light source centered at 1050nm achieves 100,000 axial scans per second. Retinal diseases seen in the clinical setting are imaged using the 91kHz 850nm CMOS camera and 47kHz 1050nm InGaAs camera based instruments to investigate the combined effects of varying speed, axial resolution, center wavelength, and instrument sensitivity on image quality. The novel 1050nm swept source / Fourier domain instrument using a recently developed commercially available short cavity laser source images at 100,000 axial scans per second and is demonstrated in the normal retina. The dense 3D volumetric data sets obtained with ultrahigh speed OCT promise to improve reproducibility of quantitative measurements, enabling early diagnosis as well as more sensitive assessment of disease progression and response to therapy.National Institutes of Health (U.S.) (5R01-EY011289-23)National Institutes of Health (U.S.) (5R01-EY013178-09)National Institutes of Health (U.S.) (2R01-EY013516-16)National Institutes of Health (U.S.) (1R01-EY019029-01)United States. Air Force Office of Scientific Research (Contract FA9550-07-1-0014)Medical Free Electron Laser Program (Contract FA9550-07-1-0101