1. Articles from Stephen J. Matcher

    1-24 of 44 1 2 »
    1. Morphological parametric mapping of 21 skin sites throughout the body using optical coherence tomography

      Morphological parametric mapping of 21 skin sites throughout the body using optical coherence tomography

      Background Changes in body posture cause changes in morphological properties at different skin sites. Although previous studies have reported the thickness of the skin, the details of the postures are not generally given. This paper presents the effect of a change in posture on parameters such as thickness and surface roughness in 21 load-bearing and non-load-bearing sites. Materials and methods A total of 12 volunteers (8 males and 4 females) were selected in an age group of 18–35 years and of Fitzpatrick skin type I-III. Images were captured using a clinically-approved VivoSight® optical coherence tomography system and analysed using ...

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    2. Polarization-sensitive optical coherence tomography with a conical beam scan for the investigation of birefringence and collagen alignment in the human cervix

      Polarization-sensitive optical coherence tomography with a conical beam scan for the investigation of birefringence and collagen alignment in the human cervix

      By measuring the phase retardance of a cervical extracellular matrix, our in-house polarization-sensitive optical coherence tomography (PS-OCT) was shown to be capable of (1) mapping the distribution of collagen fibers in the non-gravid cervix, (2) accurately determining birefringence, and (3) measuring the distinctive depolarization of the cervical tissue. A conical beam scan strategy was also employed to explore the 3D orientation of the collagen fibers in the cervix by interrogating the samples with an incident light at 45° and successive azimuthal rotations of 0-360°. Our results confirmed previous observations by X-ray diffraction, suggesting that in the non-gravid human cervix collagen ...

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    3. Superparamagnetic graphene quantum dot as a dual‐modality contrast agent for confocal fluorescence microscopy and magnetomotive optical coherence tomography

      Superparamagnetic graphene quantum dot as a dual‐modality contrast agent for confocal fluorescence microscopy and magnetomotive optical coherence tomography

      A magnetic graphene quantum dot (MGQD) nanoparticle, synthesized by hydrothermally reducing and cutting graphene oxide‐iron oxide sheet, was demonstrated to possess the capabilities of simultaneous confocal fluorescence and magnetomotive optical coherence tomography (MMOCT) imaging. This MGQD shows low toxicity, significant tunable blue fluorescence and superparamagnetism, which can thus be used as a dual‐modality contrast agent for confocal fluorescence microscopy (CFM) and MMOCT. The feasibility of applying MGQD as a tracer of cells is shown by imaging and visualizing MGQD labeled cells using CFM and our in‐house MMOCT. Since MMOCT and CFM can offer anatomical structure and intracellular ...

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    4. Sub-clinical assessment of atopic dermatitis severity using angiographic optical coherence tomography

      Sub-clinical assessment of atopic dermatitis severity using angiographic optical coherence tomography

      Measurement of sub-clinical atopic dermatitis (AD) is important for determining how long therapies should be continued after clinical clearance of visible AD lesions. An important biomarker of subclinical AD is epidermal hypertrophy, the structural measures of which often make optical coherence tomography (OCT) challenging due to the lack of a clearly delineated dermal-epidermal junction in AD patients. Alternatively, angiographic OCT measurements of vascular depth and morphology may represent a robust biomarker for quantifying the severity of clinical and sub clinical AD. To investigate this, angiographic data sets were acquired from 32 patients with a range of AD severities. Deeper vascular ...

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    5. Vascular patterning of subcutaneous mouse fibrosarcomas expressing individual VEGF isoforms can be differentiated using angiographic optical coherence tomography

      Vascular patterning of subcutaneous mouse fibrosarcomas expressing individual VEGF isoforms can be differentiated using angiographic optical coherence tomography

      Subcutaneously implanted experimental tumors in mice are commonly used in cancer research. Despite their superficial location, they remain a challenge to image non-invasively at sufficient spatial resolution for microvascular studies. Here we evaluate the capabilities of optical coherence tomography (OCT) angiography for imaging such tumors directly through the murine skin in-vivo. Data sets were collected from mouse tumors derived from fibrosarcoma cells genetically engineered to express only single splice variant isoforms of vascular endothelial growth factor A (VEGF); either VEGF120 or VEGF188 (fs120 and fs188 tumors respectively). Measured vessel diameter was found to be significantly (p<0.001) higher for ...

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    6. In vivo measurement of skin surface strain and sub-surface layer deformation induced by natural tissue stretching

      In vivo measurement of skin surface strain and sub-surface layer deformation induced by natural tissue stretching

      Stratum corneum and epidermal layers change in terms of thickness and roughness with gender, age and anatomical site. Knowledge of the mechanical and tribological properties of skin associated with these structural changes are needed to aid in the design of exoskeletons, prostheses, orthotics, body mounted sensors used for kinematics measurements and in optimum use of wearable on-body devices. In this case study, optical coherence tomography (OCT) and digital image correlation (DIC) were combined to determine skin surface strain and sub-surface deformation behaviour of the volar forearm due to natural tissue stretching. The thickness of the epidermis together with geometry changes ...

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    7. Towards in-situ process monitoring in selective laser sintering using optical coherence tomography

      Towards in-situ process monitoring in selective laser sintering using optical coherence tomography

      Selective laser sintering (SLS) enables fast, flexible and cost-efficient production of parts directly from 3D CAD data. However, compared with more established machine tools, there is a marked lack of process monitoring and feedback control of key process variables to optimize production parameters in-situ. We apply optical coherence tomography (OCT) to evaluate components produced by SLS and suggest a route for its application in in-situ process monitoring within the SLS tool for real-time monitoring of the SLS process for assurance, or even dynamic correction of defects during the build. OCT is shown to be a viable technique for evaluation of ...

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    8. Optical coherence elastography for human finger-pad skin deformation studies

      Optical coherence elastography for human finger-pad skin deformation studies

      An optical coherence tomography (OCT) system with an A-scan rate of 20 kHz was developed for measuring the biomechanical properties of human finger-pad skin. Such an OCT system operates at a center wavelength of 890 nm with a spectral bandwidth of 150 nm resulting in a very good axial resolution of 2.6 μm. The measured sensitivity and sensitivity roll-off of the system were ~93 dB and ~6 dB mm -1 , respectively. Elastographic B-scan images of the human finger-pad skin were constructed by using 1000 A-scans. Deformations of the human finger-pad before and after sliding, while pressed against a transparent ...

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    9. Evaluation of selective laser sintering processes by optical coherence tomography

      Evaluation of selective laser sintering processes by optical coherence tomography

      Selective laser sintering (SLS) enables the fast, flexible and cost-efficient production of parts directly from 3D CAD data. Unlike more established machine tools, there is a marked lack of process monitoring and feedback control of key process variables. In-situ analysis techniques permit the emergence of repair techniques, in-process optimization of production parameters, and will also serve to save time and material. In this study, optical coherence tomography (OCT) is used for the first time to evaluate components produced by SLS. Using a Polyamide-PA2200, surface defects are analyzed and the limiting factors associated with the measurement technique are quantified. OCT is ...

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    10. Optical coherence tomography measurements of biological fluid flows with picolitre spatial localization

      Optical coherence tomography measurements of biological fluid flows with picolitre spatial localization

      Interest in studying the human and animal microcirculation has burgeoned in recent years. In part this has been driven by recent advances in volumetric microscopy modalities, which allow the study of the 3-D morphology of the microcirculation without the limitations of 2-D intra-vital microscopy. In this paper we highlight the power of optical coherence tomography (OCT) to image the normal and pathological microcirculation with picolitre voxel sizes. Both Doppler and speckle-variance methods are employed to characterize complex rheological flows both in-vitro and in-vivo. GPU accelerated image registration methods are demonstrated in order to mitigate problems of bulk tissue motion in ...

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    11. Feature Of The Week 4/20/14: Conical-Scan Polarization-Sensitive Optical Coherence Tomography (CS-PS-OCT)

      Feature Of The Week 4/20/14: Conical-Scan Polarization-Sensitive Optical Coherence Tomography (CS-PS-OCT)

      We report on a new articular cartilage imaging technique with potential for clinical arthroscopic use, by supplementing the variable-incidence-angle polarization-sensitive optical coherence tomography method (VIA-PS-OCT) previously developed by us with a conical beam scan protocol. In the protocol, the beam is scanned such that the k-vector sweeps out a conical surface whose apex is chosen, for convenience, to lie at the tissue surface. In the implementation reported here we achieve this by mounting the sample on a motorized rotation stage with the sample surface roughly parallel to the stage rotating plane (i.e. normal to the stage rotation axis). The ...

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    12. Conical scan polarization-sensitive optical coherence tomography

      Conical scan polarization-sensitive optical coherence tomography

      We report on a new articular cartilage imaging technique with potential for clinical arthroscopic use, by supplementing the variable-incidence-angle polarization-sensitive optical coherence tomography method previously developed by us with a conical beam scan protocol. The technique is validated on bovine tendon by comparing experimental data with simulated data generated using the extended Jones matrix calculus. A unique capability of this new optical technique is that it can locate the “brushing direction” of collagen fibers in articular cartilage, which is structural information that extends beyond established methods such as split-line photography or birefringent fast-axis measurement in that it is uniquely defined ...

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    13. Feature Of The Week 8/25/13: Anti-biofouling Conducting Polymer Nanoparticles as a Label-Free Optical Contrast Agent for High Resolution Subsurface Biomedical Imaging

      Feature Of The Week 8/25/13: Anti-biofouling Conducting Polymer Nanoparticles as a Label-Free Optical Contrast Agent for High Resolution Subsurface Biomedical Imaging

      Optical coherence tomography (OCT) is a modern optical imaging technique that has been widely use in ophthalmic imaging for more than a decade. There has been increasing interest in extending its imaging applications to include other sub-surface biomedical imaging applications (e.g. cancer diagnosis). However, poor image contrast caused by multiple light scattering is a major challenge for OCT imaging in heterogeneous poorly transparent tissues (e.g. skin). We report an improved route for the synthesis of an oligo(ethylene glycol) methacrylate based anti-biofouling statistical copolymer, namely poly(2TMO-OEGMA). This copolymer allows the preparation of tailor-made sterically-stabilized PPy nanoparticles of ...

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    14. Anti-biofouling conducting polymer nanoparticles as a label-free optical contrast agent for high resolution subsurface biomedical imaging

      Anti-biofouling conducting polymer nanoparticles as a label-free optical contrast agent for high resolution subsurface biomedical imaging

      Optical coherence tomography (OCT) is a modern high resolution subsurface medical imaging technique. Herein we describe: (i) the synthesis of a thiophene-functionalized oligo(ethylene glycol) methacrylate (OEGMA)-based statistical copolymer, denoted poly(2TMOI–OEGMA); (ii) the preparation of sterically-stabilized polypyrrole (PPy) nanoparticles of approximately 60 nm diameter; (iii) the evaluation of these nanoparticles as a NIR-absorbing optical contrast agent for high-resolution OCT imaging. We show that poly(2TMOI–OEGMA)-stabilized PPy nanoparticles exhibit similar optical properties to poly(vinyl alcohol) (PVA)-stabilized PPy nanoparticles of comparable size prepared using commercially available PVA. Spectroscopic measurements and Mie calculations indicate that both ...

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    15. Optical Techniques in Regenerative Medicine (Textbook)

      Optical Techniques in Regenerative Medicine (Textbook)

      In regenerative medicine, tissue engineers largely rely on destructive and time-consuming techniques that do not allow in situ and spatial monitoring of tissue growth. Furthermore, once the therapy is implanted in the patient, clinicians are often unable to monitor what is happening in the body. To tackle these barriers, optical techniques have been developed to image and characterize many tissue properties, fabricate tissue engineering scaffolds, and characterize the properties of the scaffolds. Optical Techniques in Regenerative Medicine illustrates how to use optical imaging techniques and instrumentation for the fabrication, assessment, and longitudinal monitoring of regenerative medicine therapies. The book covers ...

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    16. Optical coherence tomography demonstrates differential epidermal thinning of human forearm volar skin after 2 weeks application of a topical corticosteroid vs a non-steroidal anti-inflammatory alternative

      Optical coherence tomography demonstrates differential epidermal thinning of human forearm volar skin after 2 weeks application of a topical corticosteroid vs a non-steroidal anti-inflammatory alternative

      The effects on skin of two commercially available topical creams for the treatment of eczema are quantitatively studied using optical coherence tomography. An archetypal corticosteroid (Betamethasone valerate) is compared with a nonsteroidal anti-inflammatory drug (Tacrolimus monohydrate) via left/right comparisons of the epidermal thickness of volar forearm skin on selected volunteers, at baseline and after 14 days of treatment. In 3 of 4 subjects we confirmed previous observations that corticosteroids produce pronounced physical thinning of the epidermis over timescales of a few weeks. In 3 of 4 subjects we further found that Tacrolimus produced no change in epidermal thickness. In ...

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    17. Photothermal detection of the contrast properties of polypyrrole nanoparticles using optical coherence tomography

      Photothermal detection of the contrast properties of polypyrrole nanoparticles using optical coherence tomography

      We report on a photothermal modulation detection scheme developed using a swept source-based optical coherence tomography (OCT) system centred at 1300nm. Photothermal detection is an improved technique for studying the contrast properties of exogenous contrast agents such as highly absorbing polypyrrole (PPy) nanoparticles used for OCT imaging. The swept source based OCT system has a wavelength sweep rate of 10 kHz which is used for the phase modulation detection of various concentrations of PPy nanoparticles. PPy nanoparticles have been recently reported to be a promising candidate for OCT imaging owing to their strong NIR absorption from 700–1300nm. Phase-sensitive detection ...

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    18. Contrast Agents For Biophotonic Imaging

      Contrast Agents For Biophotonic Imaging

      The present invention relates to the use of sterically-stabilised organic conducting polymeric nanoparticles as a contrast agent for biophotonic imaging, especially in optical coherence tomography (OCT) imaging. Exposing biological tissue to said contrast agent (whether in vivo or in vitro) prior to OCT imaging significantly enhances the contrast of the resulting OCT images and allows for enhanced detection and diagnosis of clinical conditions, such as cancerous tumours.

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    19. Absolute fast axis determination using non-polarization-maintaining fiber-based polarization-sensitive optical coherence tomography

      Absolute fast axis determination using non-polarization-maintaining fiber-based polarization-sensitive optical coherence tomography

      We report on a new calibration technique that permits the accurate extraction of sample Jones matrix and hence fast-axis orientation by using fiber-based polarization-sensitive optical coherence tomography (PS-OCT) that is completely based on non-polarization-maintaining fiber such as SMF-28. In this technique, two quarter-wave plates (QWPs) are used to completely specify the parameters of the system fibers in the sample arm so that the Jones matrix of the sample can be determined directly. The device was validated on measurements of a QWP and an equine tendon sample by a single-mode fiber-based swept-source PS-OCT system.

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    20. Experimental validation of an extended Jones matrix calculus model to study the 3D structural orientation of the collagen fibers in articular cartilage using polarization-sensitive optical coherence tomography

      Experimental validation of an extended Jones matrix calculus model to study the 3D structural orientation of the collagen fibers in articular cartilage using polarization-sensitive optical coherence tomography

      We report results to verify a theoretical framework to analyze the 3D depth-wise structural organization of collagen fibers in articular cartilage using polarization-sensitive optical coherence tomography. Apparent birefringence data obtained from multi-angle measurements using a time domain polarization-sensitive optical coherence tomography system has been compared with simulated data based on the extended Jones matrix calculus. Experimental data has been shown to agree with the lamellar model previously proposed for the cartilage microstructure based on scanning electron microscopy data. This tool could have potential application in mapping the collagen structural orientation information of cartilage non-invasively during arthroscopy.

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    21. Polarization-sensitive optical coherence tomography using continuous polarization modulation with arbitrary phase modulation amplitude

      Polarization-sensitive optical coherence tomography using continuous polarization modulation with arbitrary phase modulation amplitude

      We demonstrate theoretically and experimentally that the phase retardance and relative optic-axis orientation of a sample can be calculated without prior knowledge of the actual value of the phase modulation amplitude when using a polarization-sensitive optical coherence tomography system based on continuous polarization modulation (CPM-PS-OCT). We also demonstrate that the sample Jones matrix can be calculated at any values of the phase modulation amplitude in a reasonable range depending on the system effective signal-to-noise ratio. This has fundamental importance for the development of clinical systems by simplifying the polarization modulator drive instrumentation and eliminating its calibration procedure. This was validated ...

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    22. Optical coherence tomography based angle-resolved backscattering studies on bovine tendon and cartilage

      Optical coherence tomography based angle-resolved backscattering studies on bovine tendon and cartilage

      The difference in the genetic make up of the constituent molecules in collagen fibers in tendon and articular cartilage is what makes them mechanically and functionally different. A comparative study carried out on the differences in the angle-resolved back-scattering properties obtained from optical coherence tomography based studies on the two different types of scatterers: collagen I and collagen II fibers in bovine tendon and bovine articular cartilage sample, respectively, is reported here. Tendon sample shows greater anisotropy in the angle-resolved scattering profile compared to that obtained from articular cartilage sample. Rayleigh-Gans scattering approximation is used to provide the qualitative support ...

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    23. Polarization-sensitive optical coherence tomography measurements with different phase modulation amplitude when using continuous polarization modulation

      Polarization-sensitive optical coherence tomography measurements with different phase modulation amplitude when using continuous polarization modulation

      We demonstrate theoretically and experimentally that the phase retardance and relative optic-axis orientation of a sample can be calculated without prior knowledge of the actual value of the phase modulation amplitude when using a polarization-sensitive optical coherence tomography system based on continuous polarization modulation (CPM-PS-OCT). We also demonstrate that the sample Jones matrix can be calculated at any values of the phase modulation amplitude in a reasonable range depending on the system effective signal-to-noise ratio. This has fundamental importance for the development of clinical systems by simplifying the polarization modulator drive instrumentation and eliminating its calibration procedure. This was validated ...

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    24. Polypyrrole Nanoparticles: A Potential Optical Coherence Tomography Contrast Agent for Cancer Imaging

      Polypyrrole Nanoparticles: A Potential Optical Coherence Tomography Contrast Agent for Cancer Imaging

      A near-infrared (NIR) absorbing contrast agent based on polypyrrole nanoparticles is described. Quantitative optical coherence tomography studies on tissue phantoms and Mie scattering calculations indicate their potential application for early-stage cancer diagnosis.

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    1-24 of 44 1 2 »
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    1. (44 articles) Steven J. Matcher
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