1. Articles from Adam Wax

    1-24 of 61 1 2 3 »
    1. Deep imaging with 1.3 µm dual-axis optical coherence tomography and an enhanced depth of focus

      Deep imaging with 1.3 µm dual-axis optical coherence tomography and an enhanced depth of focus

      For many clinical applications, such as dermatology, optical coherence tomography (OCT) suffers from limited penetration depth due primarily to the highly scattering nature of biological tissues. Here, we present a novel implementation of dual-axis optical coherence tomography (DA-OCT) that offers improved depth penetration in skin imaging at 1.3 µm compared to conventional OCT. Several unique aspects of DA-OCT are examined here, including the requirements for scattering properties to realize the improvement and the limited depth of focus (DOF) inherent to the technique. To overcome this limitation, our approach uses a tunable lens to coordinate focal plane selection with image ...

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    2. Connectivity-based deep learning approach for segmentation of the epithelium in in vivo human esophageal OCT images

      Connectivity-based deep learning approach for segmentation of the epithelium in in vivo human esophageal OCT images

      Optical coherence tomography (OCT) is used for diagnosis of esophageal diseases such as Barrett's esophagus. Given the large volume of OCT data acquired, automated analysis is needed. Here we propose a bilateral connectivity-based neural network for in vivo human esophageal OCT layer segmentation. Our method, connectivity-based CE-Net (Bicon-CE), defines layer segmentation as a combination of pixel connectivity modeling and pixel-wise tissue classification. Bicon-CE outperformed other widely used neural networks and reduced common topological prediction issues in tissues from healthy patients and from patients with Barrett's esophagus. This is the first end-to-end learning method developed for automatic segmentation of ...

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    3. Optical coherence tomography of small intestine allograft biopsies using a handheld surgical probe

      Optical coherence tomography of small intestine allograft biopsies using a handheld surgical probe

      Significance: The current gold standard for monitoring small intestinal transplant (IT) rejection is endoscopic visual assessment and biopsy of suspicious lesions; however, these lesions are only superficially visualized by endoscopy. Invasive biopsies provide a coarse sampling of tissue health without depicting the true presence and extent of any pathology. Optical coherence tomography (OCT) presents a potential alternative approach with significant advantages over traditional white-light endoscopy. Aim: The aim of our investigation was to evaluate OCT performance in distinguishing clinically relevant morphological features associated with IT graft failure. Approach: OCT was applied to evaluate the small bowel tissues of two rhesus ...

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    4. A review of low-cost and portable optical coherence tomography

      A review of low-cost and portable optical coherence tomography

      Optical coherence tomography (OCT) is a powerful optical imaging technique capable of visualizing the internal structure of biological tissues at near cellular resolution. For years, OCT has been regarded as the standard of care in ophthalmology, acting as an invaluable tool for the assessment of retinal pathology. However, the costly nature of most current commercial OCT systems has limited its general accessibility, especially in low-resource environments. It is therefore timely to review the development of low-cost OCT systems as a route for applying this technology to population-scale disease screening. Low-cost, portable and easy to use OCT systems will be essential ...

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    5. Optical coherence tomography through a rigid borescope applied to quantification of articular cartilage thickness in a porcine knee model

      Optical coherence tomography through a rigid borescope applied to quantification of articular cartilage thickness in a porcine knee model

      There exists an unmet need for an optical coherence tomography (OCT) delivery scheme that is simple, robust, and applicable to general surgical applications. To deliver the beam in a narrow form factor, optical borescopes present an attractive potential solution. We present a method for enabling endoscopic delivery of OCT using a handheld rigid borescope adapted to a low-cost OCT engine. The system reduces the distal profile of the scanner, enabling application of the system in otherwise hard-to-access regions. The clinical potential of this design is demonstrated through real-time quantification of articular cartilage thickness, a primary biomarker of joint health during ...

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      Mentions: Duke University
    6. First Clinical Application of Low-Cost OCT

      First Clinical Application of Low-Cost OCT

      Purpose : We present the design of a new low-cost optical coherence tomography (OCT) system and compare its retinal imaging capabilities to a standard commercial system through a clinical study. Methods : A spectral-domain OCT system was designed using various cost-reduction techniques to be low-cost, highly portable, and completely stand-alone. Clinical imaging was performed on 120 eyes of 60 patients (60 eyes of normal volunteers and 60 eyes with retinal disease) using both the low-cost OCT and a Heidelberg Engineering Spectralis OCT. Contrast-to-noise ratio (CNR) was measured from resulting images to determine system performance. Results : The low-cost OCT system was successfully applied ...

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    7. Light-scattering methods for tissue diagnosis

      Light-scattering methods for tissue diagnosis

      Light scattering has become a common biomedical research tool, enabling diagnostic sensitivity to myriad tissue alterations associated with disease. Light–tissue interactions are particularly attractive for diagnostics due to the variety of contrast mechanisms that can be used, including spectral, angle-resolved, and Fourier-domain detection. Photonic diagnostic tools offer further benefits in that they are non-ionizing, non-invasive, and give real-time feedback. In this review, we summarize recent innovations in light-scattering technologies, with a focus on clinical achievements over the previous ten years.

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      Mentions: Duke University
    8. OCT Promising as Clear Point-of-Care Solution

      OCT Promising as Clear Point-of-Care Solution

      Medical devices at the point of care allow clinicians to do what they do best: determine a patient’s exact condition and a course of treatment. These technologies work best when they fit seamlessly into the provider-patient workflow without a steep learning curve or worry about the underlying scientific principles, and without the high cost seen for so many medical technologies. Optical coherence tomography (OCT) is an imaging technology that has become well-known in recent years for its proven diagnostic ability, particularly in the eye care realm. This technology is now the gold standard for diagnosing eye diseases such as ...

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      Mentions: Duke University
    9. Design and implementation of a low-cost, portable OCT system

      Design and implementation of a low-cost, portable OCT system

      Optical coherence tomography (OCT) is a widely used biomedical imaging tool, primarily in ophthalmology to diagnose and stage retinal diseases. In order to increase access for a wider range of applications and in low resource settings, we developed a portable, low-cost OCT system that has comparable imaging performance to commercially available systems. Here, we present the system design and characterization and compare the system performance to other commercially available OCT systems. In addition, future cost reductions and potential additional applications of the low-cost OCT system are discussed.

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      Mentions: Duke University
    10. Real-time speckle reduction in optical coherence tomography using the dual window method

      Real-time speckle reduction in optical coherence tomography using the dual window method

      Speckle is an intrinsic noise of interferometric signals which reduces contrast and degrades the quality of optical coherence tomography (OCT) images. Here, we present a frequency compounding speckle reduction technique using the dual window (DW) method. Using the DW method, speckle noise is reduced without the need to acquire multiple frames. A ~25% improvement in the contrast-to-noise ratio (CNR) was achieved using the DW speckle reduction method with only minimal loss (~17%) in axial resolution. We also demonstrate that real-time speckle reduction can be achieved at a B-scan rate of ~21 frames per second using a graphic processing unit (GPU ...

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      Mentions: Duke University
    11. Systems and methods for deep spectroscopic imaging of biological samples with use of an interferometer and spectrometer

      Systems and methods for deep spectroscopic imaging of biological samples with use of an interferometer and spectrometer

      Disclosed herein are systems and methods for deep spectroscopic imaging of a biological sample. In an aspect, a system includes a broad bandwidth light source configured to generate an illumination beam, an interferometer, and a spectrometer. The interferometer includes a first beam splitter configured to split the illumination beam into an incident beam and a reference beam; an optical lens directs the incident beam onto a biological sample at a predefined offset from corresponding optical axis, and receive a beam scattered from the biological sample. The beams are configured to intersect with each other within a focal zone of the ...

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      Mentions: Duke University
    12. OCT for the People

      OCT for the People

      I’ve been working in the field of biomedical optics for 20 years and, in that time, I’ve brought a number of different products through clinical trials and to market – mostly endoscopes. In general, I’ve been frustrated with how expensive it is to bring a new medical product to market. By the time you’ve completed research and clinical trials, you end up with a device that could cost upwards of a hundred thousand dollars, and costing up to a thousand dollars per use.

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    13. Label-free analysis of tenofovir delivery to vaginal tissue using co-registered confocal Raman spectroscopy and optical coherence tomography

      Label-free analysis of tenofovir delivery to vaginal tissue using co-registered confocal Raman spectroscopy and optical coherence tomography

      Vaginally applied microbicide products offer a female-controlled strategy for preventing sexual transmission of HIV. Microbicide transport processes are central to their functioning, and there is a clear need for a better understanding of them. To contribute to that end, we developed an assay to analyze mass transport rates of microbicide molecules within the epithelial and stromal layers of polarized vaginal mucosal tissue during contact with a gel vehicle. The assay utilizes a new diffusion chamber mounted in a custom instrument that combines confocal Raman spectroscopy and optical coherence tomography. This measures depth-resolved microbicide concentration distributions within epithelium and stroma. Data ...

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    14. Multiple window processing schemes for spectroscopic optical coherence tomography (OCT) and fourier domain low coherence interferometry

      Multiple window processing schemes for spectroscopic optical coherence tomography (OCT) and fourier domain low coherence interferometry

      Current apparatuses and methods for analysis of spectroscopic optical coherence tomography (SOCT) signals suffer from an inherent tradeoff between time (depth) and frequency (wavelength) resolution. In one non-limiting embodiment, multiple or dual window (DW) apparatuses and methods for reconstructing time-frequency distributions (TFDs) that applies two windows that independently determine the optical and temporal resolution is provided. For example, optical resolution is provided. For example, optical resolution may relate to scattering information about a sample, and temporal resolution may be related to absorption or depth related information. The effectiveness of the apparatuses and methods is demonstrated in simulations and in processing ...

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      Mentions: Duke University
    15. Dual-axis optical coherence tomography for deep tissue imaging

      Dual-axis optical coherence tomography for deep tissue imaging

      We have developed dual-axis optical coherence tomography (DA-OCT) which enables deep tissue imaging by using a novel off-axis illumination/detection configuration. DA-OCT offers a 100-fold speed increase compared with its predecessor, multispectral multiple-scattering low coherence interferometry (ms2/LCI), by using a new beam scanning mechanism based on a microelectro-mechanical system (MEMS) mirror. The data acquisition scheme was altered to take advantage of this scanning speed, producing tomographic images at a rate of 4 frames (B-scans) per second. DA-OCT differs from ms2/LCI in that the dual axes intersect at a shallower depth ( ∼ 1    mm ∼1  mm ). This difference, coupled with ...

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      Mentions: Duke University
    16. Optical Coherence Tomography: Advances in functional OCT

      Optical Coherence Tomography: Advances in functional OCT

      A range of extensions enable optical coherence tomography (OCT) to achieve functional imaging, providing useful information about tissue dynamics and expanding OCT's clinical relevance. Optical coherence tomography (OCT) is used mainly to depict structural characteristics. But this versatile imaging technique is also able to provide functional imaging of live, intact tissue, and in recent years, researchers have increasingly pursued extensions to realize this potential. These extensions expand OCT's relevance for clinical work by providing richer information about such dynamics as blood flow, collagen organization, and oxygenation. This article, a summary of an extensive and fully referenced review, 1 ...

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      Mentions: Duke University
    17. Analyzing spatial correlations in tissue using angle-resolved low coherence interferometry measurements guided by co-located optical coherence tomography

      Analyzing spatial correlations in tissue using angle-resolved low coherence interferometry measurements guided by co-located optical coherence tomography

      Angle-resolved low coherence interferometry (a/LCI) is an optical technique used to measure nuclear morphology in situ . However, a/LCI is not an imaging modality and can produce ambiguous results when the measurements are not properly oriented to the tissue architecture. Here we present a 2D a/LCI system which incorporates optical coherence tomography imaging to guide the measurements. System design and characterization are presented, along with example cases which demonstrate the utility of the combined measurements. In addition, future development and applications of this dual modality approach are discussed.

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    18. Dual window processing schemes for spectroscopic optical coherence tomography (OCT) and fourier domain low coherence interferometry

      Dual window processing schemes for spectroscopic optical coherence tomography (OCT) and fourier domain low coherence interferometry

      Current apparatuses and methods for analysis of spectroscopic optical coherence tomography (SOCT) signals suffer from an inherent tradeoff between time (depth) and frequency (wavelength) resolution. In one non-limiting embodiment, multiple or dual window (DW) apparatuses and methods for reconstructing time-frequency distributions (TFDs) that applies two windows that independently determine the optical and temporal resolution is provided. For example, optical resolution may relate to scattering information about a sample, and temporal resolution may be related to absorption or depth related information. The effectiveness of the apparatuses and methods is demonstrated in simulations and in processing of measured OCT signals that contain ...

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      Mentions: Duke University
    19. Evaluation of burn severity in vivo in a mouse model using spectroscopic optical coherence tomography

      Evaluation of burn severity in vivo in a mouse model using spectroscopic optical coherence tomography

      Clinical management of burn injuries depends upon an accurate assessment of the depth of the wound. Current diagnostic methods rely primarily on subjective visual inspection, which can produce variable results. In this study, spectroscopic optical coherence tomography was used to objectively evaluate burn injuries in vivo in a mouse model. Significant spectral differences were observed and correlated with the depth of the injury as determined by histopathology. The relevance of these results to clinical burn management in human tissues is discussed

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      Mentions: Duke University
    20. Co-localized confocal Raman spectroscopy and optical coherence tomography (CRS-OCT) for depth-resolved analyte detection in tissue

      Co-localized confocal Raman spectroscopy and optical coherence tomography (CRS-OCT) for depth-resolved analyte detection in tissue

      We report the development of a combined confocal Raman spectroscopy (CRS) and optical coherence tomography (OCT) instrument (CRS-OCT) capable of measuring analytes in targeted biological tissues with sub-100-micron spatial resolution. The OCT subsystem was used to measure depth-resolved tissue morphology and guide the acquisition of chemically-specific Raman spectra. To demonstrate its utility, the instrument was used to accurately measure depth-resolved, physiologically-relevant concentrations of Tenofovir, a microbicide drug used to prevent the sexual transmission of HIV, in ex vivo tissue samples.

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      Mentions: Duke University
    21. Functional optical coherence tomography: principles and progress

      Functional optical coherence tomography: principles and progress

      In the past decade, several functional extensions of optical coherence tomography (OCT) have emerged, and this review highlights key advances in instrumentation, theoretical analysis, signal processing and clinical application of these extensions. We review five principal extensions: Doppler OCT (DOCT), polarization-sensitive OCT (PS-OCT), optical coherence elastography (OCE), spectroscopic OCT (SOCT), and molecular imaging OCT. The former three have been further developed with studies in both ex vivo and in vivo human tissues. This review emphasizes the newer techniques of SOCT and molecular imaging OCT, which show excellent potential for clinical application but have yet to be well reviewed in the ...

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      Mentions: Duke University
    22. Feature Of The Week 11/16/14: In Vivo Analysis of Burns in a Mouse Model using Spectroscopic OCT

      Feature Of The Week 11/16/14: In Vivo Analysis of Burns in a Mouse Model using Spectroscopic OCT

      Evaluation of burn severity is a significant clinical problem with over 2 million burns reported each year in the United States [1]. The magnitude of this clinical need has inspired the development of many technologies to assess burn depth, but none of these have been widely adopted as clinical judgment still relies primarily on visual inspection, with an accuracy of about 70% [2]. A recent study by researchers at Duke University used spectroscopic optical coherence tomography (OCT) to evaluate burned animal tissues in vivo. Spectroscopic OCT is an extension of conventional OCT that can measure depth-resolved scattering and absorption spectra ...

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      Mentions: Duke University
    23. Noise characterization of supercontinuum sources for low-coherence interferometry applications

      Noise characterization of supercontinuum sources for low-coherence interferometry applications

      We examine the noise properties of supercontinuum light sources when used in low-coherence interferometry applications. The first application is a multiple-scattering low-coherence interferometry (ms2/LCI) system, where high power and long image acquisition times are required to image deep into tissue. For this system, we compare the noise characteristics of two supercontinuum sources from different suppliers. Both sources have long-term drift that limits the amount of time over which signal averaging is advantageous for reducing noise. The second application is a high-resolution optical coherence tomography system, where broadband light is needed for high axial resolution. For this system, we compare ...

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    1-24 of 61 1 2 3 »
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