1. 1-24 of 136 1 2 3 4 5 6 »
    1. Three-dimensional optical coherence elastography by phase-sensitive comparison of C-scans

      Three-dimensional optical coherence elastography by phase-sensitive comparison of C-scans

      We present an acquisition method for optical coherence elastography (OCE) that enables acquisition of three-dimensional elastograms in 5 s, an order of magnitude faster than previously reported. In this method, based on compression elastography, the mechanical load applied to the sample is altered between acquisitions of consecutive optical coherence tomography volume scans (C-scans). The voxel-by-voxel phase difference between the volumes is used to determine the axial displacement and determining the gradient of the axial displacement versus depth gives the local axial strain. We demonstrate sub-100-microstrain sensitivity and high contrast in elastograms, acquired in 5 s, of structured phantoms and freshly ...

      Read Full Article
    2. Special section guest editorial: selected topics in biophotonics: optical coherence tomography and biomolecular imaging with coherent Raman scattering microscopy

      Special section guest editorial: selected topics in biophotonics: optical coherence tomography and biomolecular imaging with coherent Raman scattering microscopy

      The Special Section on Selected Topics in Biophotonics: Optical Coherence Tomography and Biomolecular Imaging with Coherent Raman Scattering Microscopy comprises two invited review papers and several contributed papers from the summer school Biophotonics ’13, as well as contributed papers within this general scope.

      Read Full Article
    3. Three-dimensional correction of conduction velocity in the embryonic heart using integrated optical mapping and optical coherence tomography

      Three-dimensional correction of conduction velocity in the embryonic heart using integrated optical mapping and optical coherence tomography

      Optical mapping (OM) of cardiac electrical activity conventionally collects information from a three-dimensional (3-D) surface as a two-dimensional (2-D) projection map. When applied to measurements of the embryonic heart, this method ignores the substantial and complex curvature of the heart surface, resulting in significant errors when calculating conduction velocity, an important electrophysiological parameter. Optical coherence tomography (OCT) is capable of imaging the 3-D structure of the embryonic heart and accurately characterizing the surface topology. We demonstrate an integrated OCT/OM imaging system capable of simultaneous conduction mapping and 3-D structural imaging. From these multimodal data, we obtained 3-D activation maps ...

      Read Full Article
    4. Spiking cortical model-based nonlocal means method for speckle reduction in optical coherence tomography images

      Spiking cortical model-based nonlocal means method for speckle reduction in optical coherence tomography images

      Optical coherence tomography (OCT) images are usually degraded by significant speckle noise, which will strongly hamper their quantitative analysis. However, speckle noise reduction in OCT images is particularly challenging because of the difficulty in differentiating between noise and the information components of the speckle pattern. To address this problem, the spiking cortical model (SCM)-based nonlocal means method is presented. The proposed method explores self-similarities of OCT images based on rotation-invariant features of image patches extracted by SCM and then restores the speckled images by averaging the similar patches. This method can provide sufficient speckle reduction while preserving image details ...

      Read Full Article
    5. Speckle reduction in optical coherence tomography images based on wave atoms

      Speckle reduction in optical coherence tomography images based on wave atoms

      Optical coherence tomography (OCT) is an emerging noninvasive imaging technique, which is based on low-coherence interferometry. OCT images suffer from speckle noise, which reduces image contrast. A shrinkage filter based on wave atoms transform is proposed for speckle reduction in OCT images. Wave atoms transform is a new multiscale geometric analysis tool that offers sparser expansion and better representation for images containing oscillatory patterns and textures than other traditional transforms, such as wavelet and curvelet transforms. Cycle spinning-based technology is introduced to avoid visual artifacts, such as Gibbs-like phenomenon, and to develop a translation invariant wave atoms denoising scheme. The ...

      Read Full Article
    6. Optical coherence tomography microangiography for monitoring the response of vascular perfusion to external pressure on human skin tissue

      Optical coherence tomography microangiography for monitoring the response of vascular perfusion to external pressure on human skin tissue

      Characterization of the relationship between external pressure and blood flow is important in the examination of pressure-induced disturbance in tissue microcirculation. Optical coherence tomography (OCT)-based microangiography is a promising imaging technique, capable of providing the noninvasive extraction of functional vessels within the skin tissue with capillary-scale resolution. Here, we present a feasibility study of OCT microangiography (OMAG) to evaluate changes in blood perfusion in response to externally applied pressure on human skin tissue in vivo . External force is loaded normal to the tissue surface at the nailfold region of a healthy human volunteer. An incremental force is applied step ...

      Read Full Article
    7. Robot-assisted three-dimensional registration for cochlear implant surgery using a common-path swept-source optical coherence tomography probe

      Robot-assisted three-dimensional registration for cochlear implant surgery using a common-path swept-source optical coherence tomography probe

      Cochlear implantation offers the potential to restore sensitive hearing in patients with severe to profound deafness. However, surgical placement of the electrode array within the cochlea can produce trauma to sensorineural components, particularly if the initial turn of the cochlea is not successfully navigated as the array is advanced. In this work, we present a robot-mounted common-path swept-source optical coherence tomography endoscopic platform for three-dimensional (3-D) optical coherence tomography (OCT) registration and preoperative surgical planning for cochlear implant surgery. The platform is composed of a common-path 600- μ m diameter fiber optic rotary probe attached to a five degrees of freedom ...

      Read Full Article
    8. Evaluation of the marginal fit at implant–abutment interface by optical coherence tomography

      Evaluation of the marginal fit at implant–abutment interface by optical coherence tomography

      Vertical misfit of implant–abutment interface can affect the success of implant treatment; however, currently available modalities have limitations to detect these gaps. This study aimed to evaluate implant–abutment gaps in vitro using optical coherence tomography (OCT). Vertical misfit gaps sized 50, 100, 150, or 200 μ m were created between external hexagonal implants and titanium abutments (Nobel Biocare, Göteborg, Sweden). A porcine gingival tissue slice, 0.5, 1.0, 1.5, or 2.0 mm in thickness, was placed on each implant–abutment interface. The gaps were evaluated by swept-source OCT at a center wavelength of 1330 nm ...

      Read Full Article
    9. Monitoring the blood coagulation process under various flow conditions with optical coherence tomography

      Monitoring the blood coagulation process under various flow conditions with optical coherence tomography

      Our previous work demonstrated that an optical coherence tomography (OCT) technique was able to characterize the whole blood coagulation process. The 1 / e light penetration depth ( d 1 / e ) derived from the profiles of reflectance versus depth was developed for detecting the whole blood coagulation process in static state. To consider the effect of blood flow, in the present study, d 1 / e versus time from the coagulating porcine blood circulated in a mock flow loop with various steady laminar flows at mean flow speed in the range from 5 to 25     mm / s . The variation of d 1 / e ...

      Read Full Article
    10. Detection of breast surgical margins with optical coherence tomography imaging: a concept evaluation study

      Detection of breast surgical margins with optical coherence tomography imaging: a concept evaluation study

      This study aimed to evaluate the concept of using high-resolution optical coherence tomography (OCT) imaging to rapidly assess surgical specimens and determine if cancer positive margins were left behind in the surgical bed. A mouse model of breast cancer was used in this study. Surgical specimens from 30 animals were investigated with OCT and automated interpretation of the OCT images was performed and tested against histopathology findings. Specimens from 10 animals were used to build a training set of OCT images, while the remaining 20 specimens were used for a validation set of images. The validation study showed that automated ...

      Read Full Article
    11. Full anterior segment biometry with extended imaging range spectral domain optical coherence tomography at 1340 nm

      Full anterior segment biometry with extended imaging range spectral domain optical coherence tomography at 1340 nm

      We demonstrate an extended-imaging-range anterior-segment optical coherence tomography (eAS-OCT) system for the biometric assessment of full AS in human eye. This newly developed eAS-OCT operating at 1340-nm wavelength band is simultaneously capable of an imaging speed of 120 kHz A-line scan rate, an axial resolution of 7.2 μ m, and an extended imaging range of up to 16 mm in air. Imaging results from three healthy subjects and one subject with a narrow-angle demonstrate the instrument’s utility. With this system, it can provide anatomical dimensions of AS, including central corneal thickness, anterior chamber width, anterior chamber depth, crystalline lens ...

      Read Full Article
      Mentions: Ruikang K. Wang
    12. Label-free cell-based assay with spectral-domain optical coherence phase microscopy

      Label-free cell-based assay with spectral-domain optical coherence phase microscopy

      Quantitative measurement of dynamic responses of unstained living cells is of great importance in many applications ranging from investigation of fundamental cellular functions to drug discoveries. Conventional optical methods for label-free cell-based assay examine cellular structural changes proximal to sensor surfaces under external stimuli, but require dedicated nanostructure-patterned substrates for operation. Here, we present a quantitative imaging method, spectral-domain optical coherence phase microscopy (SD-OCPM), as a viable optical platform for label-free cell-based assay. The instrument is based on a low-coherence interferometric microscope that enables quantitative depth-resolved phase measurement of a transparent specimen with high phase stability. We demonstrate SD-OCPM measurement ...

      Read Full Article
    13. Parallelized multi–graphics processing unit framework for high-speed Gabor-domain optical coherence microscopy

      Parallelized multi–graphics processing unit framework for high-speed Gabor-domain optical coherence microscopy

      Gabor-domain optical coherence microscopy (GD-OCM) is a volumetric high-resolution technique capable of acquiring three-dimensional (3-D) skin images with histological resolution. Real-time image processing is needed to enable GD-OCM imaging in a clinical setting. We present a parallelized and scalable multi-graphics processing unit (GPU) computing framework for real-time GD-OCM image processing. A parallelized control mechanism was developed to individually assign computation tasks to each of the GPUs. For each GPU, the optimal number of amplitude-scans (A-scans) to be processed in parallel was selected to maximize GPU memory usage and core throughput. We investigated five computing architectures for computational speed-up in processing ...

      Read Full Article
    14. Nondestructive observation of teeth post core space using optical coherence tomography: a pilot study

      Nondestructive observation of teeth post core space using optical coherence tomography: a pilot study

      Coronal tooth lesions, such as caries, enamel cracking, and composite resin restoration cavities, have been observed by optical coherence tomography (OCT). This pilot study was performed to verify whether OCT could reveal details of root canals filled with resin core build-up. A dual-cure, one-step, self-etch adhesive system-bonding agent (Clearfil Bond SE ONE, Kuraray Noritake Dental) and dual-cure resin composite core material (Clearfil DC Core Automix ONE, Kuraray Noritake Dental) were used according to the manufacturer’s instructions in root canals. OCT was performed at three stages of the core build-up: after the post space preparation, after bonding application, and after ...

      Read Full Article
      Mentions: Osaka University
    15. Monte Carlo simulation of optical coherence tomography for turbid media with arbitrary spatial distributions

      Monte Carlo simulation of optical coherence tomography for turbid media with arbitrary spatial distributions

      We developed a Monte Carlo-based simulator of optical coherence tomography (OCT) imaging for turbid media with arbitrary spatial distributions. This simulator allows computation of both Class I diffusive reflectance due to ballistic and quasiballistic scattered photons and Class II diffusive reflectance due to multiple scattered photons. It was implemented using a tetrahedron-based mesh and importance sampling to significantly reduce computational time. Our simulation results were verified by comparing them with results from two previously validated OCT simulators for multilayered media. We present simulation results for OCT imaging of a sphere inside a background slab, which would not have been possible ...

      Read Full Article
    16. Coregistered autofluorescence-optical coherence tomography imaging of human lung sections

      Coregistered autofluorescence-optical coherence tomography imaging of human lung sections

      Autofluorescence (AF) imaging can provide valuable information about the structural and metabolic state of tissue that can be useful for elucidating physiological and pathological processes. Optical coherence tomography (OCT) provides high resolution detailed information about tissue morphology. We present coregistered AF-OCT imaging of human lung sections. Adjacent hematoxylin and eosin stained histological sections are used to identify tissue structures observed in the OCT images. Segmentation of these structures in the OCT images allowed determination of relative AF intensities of human lung components. Since the AF imaging was performed on tissue sections perpendicular to the airway axis, the results show the ...

      Read Full Article
    17. In vivo detection of inhalation injury in large airway using three-dimensional long-range swept-source optical coherence tomography

      In vivo detection of inhalation injury in large airway using three-dimensional long-range swept-source optical coherence tomography

      We report on the feasibility of using long-range swept-source optical coherence tomography (OCT) to detect airway changes following smoke inhalation in a sheep model. The long-range OCT system (with axial imaging range of 25 mm) and probe are capable of rapidly obtaining a series of high-resolution full cross-sectional images and three-dimensional reconstructions covering 20-cm length of tracheal and bronchial airways with airway diameter up to 25 mm, regardless of the position of the probe within the airway lumen. Measurements of airway thickness were performed at baseline and postinjury to show mucosal thickness changes following smoke inhalation.

      Read Full Article
    18. Spatially resolved optical and ultrastructural properties of colorectal and pancreatic field carcinogenesis observed by inverse spectroscopic optical coherence tomograph

      Spatially resolved optical and ultrastructural properties of colorectal and pancreatic field carcinogenesis observed by inverse spectroscopic optical coherence tomograph

      Field carcinogenesis is the initial stage of cancer progression. Understanding field carcinogenesis is valuable for both cancer biology and clinical medicine. Here, we used inverse spectroscopic optical coherence tomography to study colorectal cancer (CRC) and pancreatic cancer (PC) field carcinogenesis. Depth-resolved optical and ultrastructural properties of the mucosa were quantified from histologically normal rectal biopsies from patients with and without colon adenomas ( n = 85 ) as well as from histologically normal peri-ampullary duodenal biopsies from patients with and without PC ( n = 22 ). Changes in the epithelium and stroma in CRC field carcinogenesis were separately quantified. In both compartments, optical and ultra-structural ...

      Read Full Article
    19. Improved microcirculation imaging of human skin in vivo using optical microangiography with a correlation mapping mask

      Improved microcirculation imaging of human skin in vivo using optical microangiography with a correlation mapping mask

      Optical microangiography based on optical coherence tomography (OCT) is prone to noise that arises from a static tissue region. Here, we propose a method that can significantly reduce this noise. The method is developed based on an approach that uses the magnitude information of OCT signals to produce tissue microangiograms, especially suitable for the case where a swept-source OCT system is deployed. By combined use of two existing OCT microangiography methods—ultrahigh-sensitive optical microangiography (UHS-OMAG) and correlation mapping OCT (cmOCT)—the final tissue microangiogram is generated by masking UHS-OMAG image using the binary representation of cmOCT image. We find that ...

      Read Full Article
    20. Three-dimensional, distendable bladder phantom for optical coherence tomography and white light cystoscopy

      Three-dimensional, distendable bladder phantom for optical coherence tomography and white light cystoscopy

      We describe a combination of fabrication techniques and a general process to construct a three-dimensional (3-D) phantom that mimics the size, macroscale structure, microscale surface topology, subsurface microstructure, optical properties, and functional characteristics of a cancerous bladder. The phantom also includes features that are recognizable in white light (i.e., the visual appearance of blood vessels), making it suitable to emulate the bladder for emerging white light + optical coherence tomography (OCT) cystoscopies and other endoscopic procedures of large, irregularly shaped organs. The fabrication process has broad applicability and can be generalized to OCT phantoms for other tissue types or phantoms ...

      Read Full Article
    21. Three-dimensional volumetric human meibomian gland investigation using polarization-sensitive optical coherence tomography

      Three-dimensional volumetric human meibomian gland investigation using polarization-sensitive optical coherence tomography

      In this study, polarization-sensitive optical coherence tomography (PS-OCT) capable of providing polarization contrasts such as phase retardation and degree of polarization uniformity (DOPU) was used for visualizing human meibomian glands (MGs) and investigating morphological characteristics of them. Especially, with the help of the DOPU contrast, MGs were exclusively extracted from the volumetric OCT image. In vivo PS-OCT measurements were performed on the upper eyelids of different age groups. From these measurements, different age-dependent aspects of the MG structure were also observed. Based on these observations, it can be inferred that the PS-OCT system has the potential for clinical diagnosis and ...

      Read Full Article
    22. Stimulated penetrating keratoplasty using real-time virtual intraoperative surgical optical coherence tomography

      Stimulated penetrating keratoplasty using real-time virtual intraoperative surgical optical coherence tomography

      An intraoperative surgical microscope is an essential tool in a neuro- or ophthalmological surgical environment. Yet, it has an inherent limitation to classify subsurface information because it only provides the surface images. To compensate for and assist in this problem, combining the surgical microscope with optical coherence tomography (OCT) has been adapted. We developed a real-time virtual intraoperative surgical OCT (VISOCT) system by adapting a spectral-domain OCT scanner with a commercial surgical microscope. Thanks to our custom-made beam splitting and image display subsystems, the OCT images and microscopic images are simultaneously visualized through an ocular lens or the eyepiece of ...

      Read Full Article
    23. Truncated-correlation photothermal coherence tomography of artificially demineralized animal bones: two- and three-dimensional markers for mineral loss monitoring

      Truncated-correlation photothermal coherence tomography of artificially demineralized animal bones: two- and three-dimensional markers for mineral loss monitoring

      The challenge of depth-resolved, nonionizing (hybrid-optical) detection of mineral loss in bones is addressed using truncated-correlation photothermal coherence tomography (TC-PCT). This approach has importance not only in ground-based clinical procedures, but also in microgravity space applications. Analogous to x-ray morphometric parameters, two- and three-dimensional markers have been defined and estimated for chemically demineralized goat rib bones. Cortical and trabecular regions have been analyzed independently and together using the computational slicing advantage of TC-PCT, and the results have been verified using micro-CT imaging (the gold standard). For low-demineralization levels, both modalities follow the same trend. However, for very high mineral loss ...

      Read Full Article
    24. Optical Coherence Tomography and Interferometry: Advanced Engineering and Biomedical Applications

      Optical Coherence Tomography and Interferometry: Advanced Engineering and Biomedical Applications

      Since its invention in the late ‘80s and early ‘90s, optical coherence interferometry (OCI) and its imaging version, optical coherence tomography (OCT), techniques experienced rapid scientific and technological advancements allowing high-resolution imaging and analysis of tissues and cells in three dimensions, with micrometer-level resolution and with speeds approaching and recently exceeding video rate. The unique capabilities of OCI and OCT to assess tissues, coupled with their noninvasive and contrast agent-free nature has resulted in a wide variety of exciting biomedical applications across the clinical spectrum, including ophthalmology, cardiology, and dentistry, among others. As a result, many labs and more than ...

      Read Full Article
    1-24 of 136 1 2 3 4 5 6 »
  1. Categories

    1. Applications:

      Art, Cardiology, Dentistry, Dermatology, Developmental Biology, Gastroenterology, Gynecology, Microscopy, NDE/NDT, Neurology, Oncology, Ophthalmology, Other Non-Medical, Otolaryngology, Pulmonology, Urology
    2. Business News:

      Acquisition, Clinical Trials, Funding, Other Business News, Partnership, Patents
    3. Technology:

      Broadband Sources, Probes, Tunable Sources, Velocimetry
    4. Miscellaneous:

      Jobs & Studentships, Student Theses, Textbooks