The Experts below are selected from a list of 20889 Experts worldwide ranked by ideXlab platform
Barry Vuong - One of the best experts on this subject based on the ideXlab platform.
-
Optical coherence tomography-guided Laser marking with tethered capsule endomicroscopy in unsedated patients
Biomedical optics express, 2019Co-Authors: Chia-pin Liang, Jing Dong, Tim Ford, Rohith Reddy, Hamid Hosseiny, Hamid Farrokhi, Matthew Beatty, Kanwarpal Singh, Hany Osman, Barry VuongAbstract:Tethered capsule endomicroscopy (TCE) is an emerging screening technology that comprehensively obtains microstructural OCT images of the gastrointestinal (GI) tract in unsedated patients. To advance clinical adoption of this imaging technique, it will be important to validate TCE images with co-localized histology, the current diagnostic gold standard. One method for co-localizing OCT images with histology is image-targeted Laser marking, which has previously been implemented using a driveshaft-based, balloon OCT catheter, deployed during endoscopy. In this paper, we present a TCE device that scans and targets the imaging beam using a low-cost stepper motor that is integrated inside the capsule. In combination with a 4-Laser-diode, high power 1430/1450 nm marking Laser system (800 mW on the sample and 1s pulse duration), this technology generated clearly visible marks, with a spatial targeting accuracy of better than 0.5 mm. A Laser Safety study was done on swine esophagus ex vivo, showing that these exposure parameters did not alter the submucosa, with a large, 4-5x Safety margin. The technology was demonstrated in living human subjects and shown to be effective for co-localizing OCT TCE images to biopsies obtained during subsequent endoscopy.
David R Williams - One of the best experts on this subject based on the ideXlab platform.
-
light induced retinal changes observed with high resolution autofluorescence imaging of the retinal pigment epithelium
Investigative Ophthalmology & Visual Science, 2008Co-Authors: Jessica I W Morgan, Jennifer J Hunter, Benjamin D Masella, Robert Wolfe, Daniel C Gray, William H Merigan, F Delori, David R WilliamsAbstract:PURPOSE. Autofluorescence fundus imaging using an adaptive optics scanning Laser ophthalmoscope (AOSLO) allows for imaging of individual retinal pigment epithelial (RPE) cells in vivo. In this study, the potential of retinal damage was investigated by using radiant exposure levels that are 2 to 150 times those used for routine imaging. METHODS. Macaque retinas were imaged in vivo with a fluorescence AOSLO. The retina was exposed to 568- or 830-nm light for 15 minutes at various intensities over a square 1⁄° per side. Preand immediate postexposure images of the photoreceptors and RPE cells were taken over a 2° field. Long-term AOSLO imaging was performed intermittently from 5 to 165 days after exposure. Exposures delivered over a uniform field were also investigated. RESULTS. Exposures to 568-nm light caused an immediate decrease in autofluorescence of RPE cells. Follow-up imaging revealed either full recovery of autofluorescence or long-term damage in the RPE cells at the exposure. The outcomes of AOSLO exposures and uniform field exposures of equal average power were not significantly different. No effects from 830-nm exposures were observed. CONCLUSIONS. The study revealed a novel change in RPE autofluorescence induced by 568-nm light exposure. Retinal damage occurred as a direct result of total average power, independent of the light-delivery method. Because the exposures were near or below permissible levels in Laser Safety standards, these results suggest that caution should be used with exposure of the retina to visible light and that the Safety standards should be re-evaluated for these exposure conditions. (Invest Ophthalmol Vis Sci. 2008;49:3715‐3729)
Chia-pin Liang - One of the best experts on this subject based on the ideXlab platform.
-
Optical coherence tomography-guided Laser marking with tethered capsule endomicroscopy in unsedated patients
Biomedical optics express, 2019Co-Authors: Chia-pin Liang, Jing Dong, Tim Ford, Rohith Reddy, Hamid Hosseiny, Hamid Farrokhi, Matthew Beatty, Kanwarpal Singh, Hany Osman, Barry VuongAbstract:Tethered capsule endomicroscopy (TCE) is an emerging screening technology that comprehensively obtains microstructural OCT images of the gastrointestinal (GI) tract in unsedated patients. To advance clinical adoption of this imaging technique, it will be important to validate TCE images with co-localized histology, the current diagnostic gold standard. One method for co-localizing OCT images with histology is image-targeted Laser marking, which has previously been implemented using a driveshaft-based, balloon OCT catheter, deployed during endoscopy. In this paper, we present a TCE device that scans and targets the imaging beam using a low-cost stepper motor that is integrated inside the capsule. In combination with a 4-Laser-diode, high power 1430/1450 nm marking Laser system (800 mW on the sample and 1s pulse duration), this technology generated clearly visible marks, with a spatial targeting accuracy of better than 0.5 mm. A Laser Safety study was done on swine esophagus ex vivo, showing that these exposure parameters did not alter the submucosa, with a large, 4-5x Safety margin. The technology was demonstrated in living human subjects and shown to be effective for co-localizing OCT TCE images to biopsies obtained during subsequent endoscopy.
John S. Werner - One of the best experts on this subject based on the ideXlab platform.
-
integrated adaptive optics optical coherence tomography and adaptive optics scanning Laser ophthalmoscope system for simultaneous cellular resolution in vivo retinal imaging
Biomedical Optics Express, 2011Co-Authors: Robert J Zawadzki, Suman Pilli, Sandra Balderasmata, Scot S Olivier, Steven M. Jones, John S. WernerAbstract:We describe an ultrahigh-resolution (UHR) retinal imaging system that combines adaptive optics Fourier-domain optical coherence tomography (AO-OCT) with an adaptive optics scanning Laser ophthalmoscope (AO-SLO) to allow simultaneous data acquisition by the two modalities. The AO-SLO subsystem was integrated into the previously described AO-UHR OCT instrument with minimal changes to the latter. This was done in order to ensure optimal performance and image quality of the AO- UHR OCT. In this design both imaging modalities share most of the optical components including a common AO-subsystem and vertical scanner. One of the benefits of combining Fd-OCT with SLO includes automatic co-registration between two acquisition channels for direct comparison between retinal structures imaged by both modalities (e.g., photoreceptor mosaics or microvasculature maps). Because of differences in the detection scheme of the two systems, this dual imaging modality instrument can provide insight into retinal morphology and potentially function, that could not be accessed easily by a single system. In this paper we describe details of the components and parameters of the combined instrument, including incorporation of a novel membrane magnetic deformable mirror with increased stroke and actuator count used as a single wavefront corrector. We also discuss Laser Safety calculations for this multimodal system. Finally, retinal images acquired in vivo with this system are presented.
Lihong V Wang - One of the best experts on this subject based on the ideXlab platform.
-
in vivo label free photoacoustic microscopy of the anterior segment of the mouse eye
Bios, 2010Co-Authors: Bin Rao, Konstantin Maslov, Lihong V WangAbstract:Both iris fluorescein angiography (IFA) and indocyanine green angiography (ICGA) provide ophthalmologists imaging tools in studying the microvasculature structure and hemodynamics of the anterior segment of the eye in normal and diseased status. However, a non-invasive, endogenous imaging modality is preferable for the monitoring of hemodynamics of the iris microvasculature. We investigated the in vivo, label-free ocular anterior segment imaging with photo-acoustic microscopy (PAM) in mouse eyes. We demonstrated the unique advantage of endogenous contrast that is not available in both IFA and ICGA. The Laser radiation was maintained within the ANSI Laser Safety limit. The in vivo, label-free nature of our imaging technology has the potential for ophthalmic applications.
-
In vivo imaging of subcutaneous structures using functional photoacoustic microscopy
Nature Protocols, 2007Co-Authors: Hao F. Zhang, Konstantin Maslov, Lihong V WangAbstract:Functional photoacoustic microscopy (fPAM) is a hybrid technology that permits noninvasive imaging of the optical absorption contrast in subcutaneous biological tissues. fPAM uses a focused ultrasonic transducer to detect high-frequency photoacoustic (PA) signals. Volumetric images of biological tissues can be formed by two-dimensional raster scanning, and functional parameters can be further extracted from spectral measurements. fPAM is safe and applicable to animals as well as humans. This protocol provides guidelines for parameter selection, system alignment, imaging operation, Laser Safety and data processing for in vivo fPAM. It currently takes ∼100 min to carry out this protocol, including ∼50 min for data acquisition using a 10-Hz pulse-repetition-rate Laser system. The data acquisition time, however, can be significantly reduced by using a Laser system with a higher pulse repetition rate.
