1. 745-765 of 765 « 1 2 ... 29 30 31 32
    1. Intra and interoperator reproducibility of retinal nerve fibre and macular thickness measurements using Cirrus Fourier-domain OCT

      Intra and interoperator reproducibility of retinal nerve fibre and macular thickness measurements using Cirrus Fourier-domain OCT
      Purpose:  To test intrasession, intersession, intervisit and interoperator reproducibility of retinal nerve fibre (RNFL) measurements and retinal thickness in healthy subjects using Cirrus Fourier-domain optical coherence tomography (OCT) (Carl Zeiss Meditec, Inc).Methods:  Seventy-two eyes of 72 healthy subjects were included in the study. All the eyes underwent three 512 × 128 volume cube centred on the fovea and three 360° circular scans centred on the optic disc by one observer. This sequence was redone by another observer on a second visit within a 2-week period. Descriptive statistics, analysis of variance, intraclass correlation coefficients (ICCs) and coefficients of variation (COVs) were ...
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    2. Cross-polarization optical coherence tomography for early bladder-cancer detection: statistical study

      Cross-polarization optical coherence tomography for early bladder-cancer detection: statistical study
      The capabilities of cross-polarization optical coherence tomography (CP OCT) for early bladder-cancer detection are assessed in statistical study and compared with the traditional OCT. Unlike the traditional OCT that demonstrates images only in copolarization, CP OCT acquires images in cross-polarization and copolarization simultaneously. 116 patients with localized flat suspicious lesions in the bladder were enrolled, 360 CP OCT images were obtained and analyzed. CP OCT demonstrated sensitivity 93.7% (vs. 81.2%, <0.0001), specificity 84% (vs. 70.0%, <0.001) and accuracy 85.3% (vs. 71.5%, <0.001) in detecting flat malignant bladder lesions, which is significantly better ...
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    3. Perimetric and peri-papillary nerve fibre layer thickness findings in multiple sclerosis

      Perimetric and peri-papillary nerve fibre layer thickness findings in multiple sclerosis
      Background and purpose:  Several previous studies have employed optical coherence tomography (OCT) of the optic disc and ‘white-on-white’ automated perimetry to evaluate optic neuritis (ON) associated with multiple sclerosis (MS). This study employed OCT, white-on-white automated perimetry as well as ‘blue-on-yellow’ automated perimetry to evaluate MS patients with or without episodes of ON. Methods:  The MS group consisted of 56 patients with MS (27 patients with no history of ON in both eyes and 29 patients with at least one ON attack in one or both eyes), whereas the control group consisted of 56 age- and sex-matched healthy subjects. All ...
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    4. Wavelength swept amplified spontaneous emission source for high speed retinal optical coherence tomography at 1060 nm

      Wavelength swept amplified spontaneous emission source for high speed retinal optical coherence tomography at 1060 nm
      The wavelength swept amplified spontaneous emission (ASE) source presented in this paper is an alternative approach to realize a light source for high speed swept source optical coherence tomography (OCT). ASE alternately passes a cascade of different optical gain elements and tunable optical bandpass filters. In this work we show for the first time a wavelength swept ASE source in the 1060 nm wavelength range, enabling high speed retinal OCT imaging. We demonstrate ultra-rapid retinal OCT at a line rate of 170 kHz, a record sweep rate at 1060 nm of 340 kHz with 70 nm full sweep width, enabling ...
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    5. Comparison of the influence of cataract and pupil size on retinal nerve fibre layer thickness measurements with time domain and spectral domain optical coherence tomography

      Comparison of the influence of cataract and pupil size on retinal nerve fibre layer thickness measurements with time domain and spectral domain optical coherence tomography
      Background: To investigate the effect of cataract and pupil size on retinal nerve fibre layer (RNFL) thickness measurements using spectral-domain optical coherence tomography (Cirrus OCT) and to compare against time-domain OCT (Stratus OCT). Design: Prospective, hospital-based study. Participants or Samples: 25 eyes from 25 normal subjects undergoing cataract surgery. Methods: 3 RNFL thickness measurements were taken before and after dilation, pre-and post-operatively, using Cirrus 200x200 Optic Disc Scan and Stratus Fast RNFL Scan. Main Outcome Measures: Linear regression, intraclass correlation coefficient (ICC), and coefficient of variation analysis of RNFL thickness measurements. Results: Cataract removal caused significant increase in RNFL measurements ...
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    6. Quantifying glucose permeability and enhanced light penetration in ex vivo human normal and cancerous esophagus tissues with optical coherence tomography

      Quantifying glucose permeability and enhanced light penetration in ex vivo human normal and cancerous esophagus tissues with optical coherence tomography

      We report our pilot results on quantification of glucose (G) diffusion permeability in human normal esophagus and ESCC tissues in vitro by using OCT technique. The permeability coefficient of 40% aqueous solution of G was found to be (1.74±0.04)×10–5 cm/s in normal esophagus and (2.45±0.06)×10–5 cm/s in ESCC tissues. The results from this study indicate that ESCC tissues had a higher permeability coefficient compared to normal esophageal tissues, and the light penetration depths gradually increase with the increase of applied topically with G time for the normal esophageal ...

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    7. Phenotyping Airways Disease With Optical Coherence Tomography

      Phenotyping Airways Disease With Optical Coherence Tomography

      Airway diseases are a major concern around the world. However, the pace of new drug and biomarker discovery has lagged behind those of other common disorders such as cardiovascular diseases and diabetes. One major barrier in airways research has been the inability to accurately visualize large and small airway remodeling or dysplastic/neoplastic (either pre or early cancerous) changes using non or minimally invasive instruments. The advent of optical coherence tomography (OCT) has the potential to revolutionize airway research and management by allowing investigators and clinicians to visualize the airway with resolution approaching histology without exposing patients to harmful effects ...

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    8. Interpretation of RNFLT values in multiple sclerosis-associated acute optic neuritis using high-resolution SD-OCT device

      Interpretation of RNFLT values in multiple sclerosis-associated acute optic neuritis using high-resolution SD-OCT device

      Purpose:  Optical coherence tomography (OCT) has emerged as the technique of choice in measuring the retinal nerve fibre layer (RNFL) quantitatively. It is suggested that RNFL reduction may correlate with lesion burden and diffuse axonal degeneration in the whole CNS of patients with multiple sclerosis (MS). However, RNFL changes because of optic neuritis (ON) must be taken into account.Methods:  Twenty-three patients with acute ON (46 eyes) associated with clinical definite MS (23 ON eyes, 23 fellow eyes) and 23 sex- and age-matched healthy controls were studied. Retinal nerve fibre layer thickness (RNFLT) was measured at baseline, using a high-resolution ...

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    9. A comparison of imaging methodologies for 3D tissue engineering

      A comparison of imaging methodologies for 3D tissue engineering
      Imaging of cells in two dimensions is routinely performed within cell biology and tissue engineering laboratories. When biology moves into three dimensions imaging becomes more challenging, especially when multiple cell types are used. This review compares imaging techniques used regularly in our laboratory in the culture of cells in both two and three dimensions. The techniques reviewed include phase contrast microscopy, fluorescent microscopy, confocal laser scanning microscopy, electron microscopy, and optical coherence tomography. We compare these techniques to the current “gold standard” for imaging three-dimensional tissue engineered constructs, histology.
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    10. Comparison of two retinal nerve fiber layer thickness measurement patterns of RTvue optical coherence tomography

      Comparison of two retinal nerve fiber layer thickness measurement patterns of RTvue optical coherence tomography
      Background: To evaluate the agreement and repeatability between operator-dependent centering and automatic centering RNFL thickness measurement patterns (RNFL3.45 and NHM4) of RTvue Optical Coherence Tomography in normal and glaucomatous eyes. Design: Cross-sectional observational study Participants: A total of 153 eyes from 149 normal subjects and subjects with glaucoma were analyzed. Methods: The RNFL thickness was measured using RNFL3.45 and NHM4 3 times on the same day to determine the repeatability and agreement between the two scan patterns. Main outcome measures: Student's paired t testing, intra-class correlation coefficient (ICC), coefficient of variation (CV), test-retest viability, Pearson's correlation ...
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    11. Performance of time-domain and spectral-domain Optical Coherence Tomography for glaucoma screening

      Performance of time-domain and spectral-domain Optical Coherence Tomography for glaucoma screening
      Purpose:  To investigate the measures of validity for selective or population screening of the time-domain Stratus and the spectral-domain Cirrus Optical Coherence Tomography (OCT) imaging techniques in a population-based sample and in clinical glaucoma patients at different stages of glaucoma. Patients and methods:  A random sample of 307 subjects living in two rural areas in southern Sweden, and a random sample of 394 clinical glaucoma patients were selected. A large battery of examinations, including Stratus and Cirrus OCT was performed. OCT retinal nerve fibre layer (RNFL) thickness analyses for average thickness, quadrant and clock-hour sectors were compared with normative significance ...
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    12. Anterior segment optical coherence tomography (AS-OCT): a novel diagnostic instrument for conjunctivochalasis

      Anterior segment optical coherence tomography (AS-OCT): a novel diagnostic instrument for conjunctivochalasis
      Purpose To evaluate cross-sectional conjunctivochalasis area (CChA) and tear meniscus area (TMA) using Fourier-Domain-RTVue-100 optical coherence tomography (OCT) before and after conjunctival cauterization and to evaluate inter- and intraobserver reliability. Methods A total of twelve eyes of 7 patients with conjunctivochalasis aged 56 to 87 were evaluated. After topical anesthesia, conjunctival cauterization was performed on the inferior bulbar conjunctiva. All patients underwent anterior segment OCT (AS-OCT) imaging prior to and 4 weeks after the procedure. Cross-sectional TMA and CChA at 3 locations (nasal, center and temporal areas) were measured in all patients. Results Non-significant increases (p= 0.177) in TMA ...
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    13. Comparison of pulsed photothermal radiometry, optical coherence tomography and ultrasound for melanoma thickness measurement in PDMS tissue phantoms

      Comparison of pulsed photothermal radiometry, optical coherence tomography and ultrasound for melanoma thickness measurement in PDMS tissue phantoms

      Melanoma accounts for 75% of all skin cancer deaths. Pulsed photothermal radiometry (PPTR), optical coherence tomography (OCT) and ultrasound (US) are non-invasive imaging techniques that may be used to measure melanoma thickness, thus, determining surgical margins. We constructed a series of PDMS tissue phantoms simulating melanomas of different thicknesses. PPTR, OCT and US measurements were recorded from PDMS tissue phantoms and results were compared in terms of axial imaging range, axial resolution and imaging time. A Monte Carlo simulation and three-dimensional heat transfer model was constructed to simulate PPTR measurement. Experimental results show that PPTR and US can provide a ...

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    14. Spectral domain anterior segment optical coherence tomography assessment of pterygium and pinguecula

      Spectral domain anterior segment optical coherence tomography assessment of pterygium and pinguecula
      Purpose:  To study the morphological patterns of pterygia and pingueculae using high-resolution anterior segment spectral domain optical coherence tomography (SD-OCT). Methods:  Prospective cross-sectional study of 25 eyes presented with pterygia and pingueculae was conducted, and the eyes were examined by anterior segment SD-OCT. Results:  We examined 25 eyes, including 13 eyes with primary pterygia, six eyes with recurrent pterygia, one case with a pseudopterygium and five eyes with pingueculae. Primary pterygia revealed elevation of the corneal epithelium by a wedge-shaped mass of tissue separating the corneal epithelium from the underlying Bowman’s membrane, which became wavy and interrupted. We found ...
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    15. Imaging modalities to assess structural birth defects in mutant mouse models

      Imaging modalities to assess structural birth defects in mutant mouse models
      Assessment of structural birth defects (SBDs) in animal models usually entails conducting detailed necropsy for anatomical defects followed by histological analysis for tissue defects. Recent advances in new imaging technologies have provided the means for rapid phenotyping of SBDs, such as using ultra-high frequency ultrasound biomicroscopy, optical coherence tomography, micro-CT, and micro-MRI. These imaging modalities allow the detailed assessment of organ/tissue structure, and with ultrasound biomicroscopy, structure and function of the cardiovascular system also can be assessed noninvasively, allowing the longitudinal tracking of the fetus in utero. In this review, we briefly discuss the application of these state-of-the-art imaging ...
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    16. Ability of optical coherence tomography to detect caries beneath commonly used dental sealants

      Ability of optical coherence tomography to detect caries beneath commonly used dental sealants
      Background and Objective The onset and progression of early tooth decay is often preventable with dental sealants. However, occasionally decay progresses underneath the sealant. Current technology does not permit monitoring of potential lesion progression or arrest. Dental sealants themselves mask the visual cues that identify early tooth decay, and radiographs are not sufficiently sensitive. Therefore, clinicians can be reluctant to use dental sealant. The objective of this ex vivo study was to evaluate the ability of dentists to detect decay beneath commonly used dental sealants using optical coherence tomography (OCT) imaging. Study Designs/Materials/Methods Forty extracted teeth were divided ...
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    17. Optical coherence tomography allows for the reliable identification of laryngeal epithelial dysplasia and for precise biopsy: A clinicopathological study of 61 patients undergoing microlaryngoscopy

      Optical coherence tomography allows for the reliable identification of laryngeal epithelial dysplasia and for precise biopsy: A clinicopathological study of 61 patients undergoing microlaryngoscopy
      Objectives/Hypothesis: A newly developed microscope-based spectral-domain optical coherence tomography (SD-OCT) device and an endoscope-based time-domain OCT (TD-OCT) were used to assess the inter-rater reliability, sensitivity, specificity, and accuracy of benign and dysplastic laryngeal epithelial lesions. Study Design: Prospective study. Methods: OCT during microlaryngoscopy was done on 35 patients with an endoscope-based TD-OCT, and on 26 patients by an SD-OCT system integrated into an operating microscope. Biopsies were taken from microscopically suspicious lesions allowing comparative study of OCT images and histology. Results: Thickness of the epithelium was seen to be the main criterion for degree of dysplasia. The inter-rater reliability ...
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    18. Local retinal sensitivity in relation to specific retinopathy lesions in diabetic macular oedema

      Local retinal sensitivity in relation to specific retinopathy lesions in diabetic macular oedema

      Purpose:  To study microperimetric macular sensitivity in diabetic macular oedema (DMO) in relation to lesion characteristics obtained by optical coherence tomography (OCT), colour fundus photography, and fluorescein angiography (FA). Methods:  The study comprised 20 eyes in 15 patients with nonproliferative diabetic retinopathy and recently diagnosed untreated DMO. Investigations included microperimetry, fluorescein angiography, colour fundus photography, and OCT. All measures and gradings were made for each of the nine fields of an early treatment diabetic retinopathy study macula template. Statistical analysis was made using Spearman’s nonparametric test including field and mean values within fields. Comparisons were made within the study ...

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    19. In vivo measurement of the human epidermal thickness in different localizations by multiphoton laser tomography

      In vivo measurement of the human epidermal thickness in different localizations by multiphoton laser tomography
      Background: The in vivo measurement of epidermal thickness is still challenging. While ultrasound, optical coherence tomography and confocal laser microscopy are used with moderate success, this issue has not been addressed by multiphoton laser tomography. Objectives: In the present study, an in vivo measurement of four different morphometric epidermal parameters is performed. Methods: Thirty healthy volunteers aged 21–82 years were included in the study after informed consent and approval of the local ethics committee. At the dorsal forearm and the dorsum of the hand, the thicknesses of the total epidermis, viable epidermis and stratum corneum and the depth of ...
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    20. Spatially Resolved Stress Measurements in Materials With Polarisation-Sensitive Optical Coherence Tomography: Image Acquisition and Processing Aspects

      Spatially Resolved Stress Measurements in Materials With Polarisation-Sensitive Optical Coherence Tomography: Image Acquisition and Processing Aspects
      We demonstrate that polarisation-sensitive optical coherence tomography (PS-OCT) is suitable for mapping the stress distribution within materials in a contact-free and non-destructive way. In contrast to transmission photoelasticity measurements, the samples do not have to be transparent but can be of scattering nature. Denoising and analysis of fringe patterns in single PS-OCT retardation images are demonstrated to be the bases for a quantitative whole-field evaluation of the internal stress state of samples under investigation.
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    21. New approach to cross-polarized optical coherence tomography based on orthogonal arbitrarily polarized modes

      New approach to cross-polarized optical coherence tomography based on orthogonal arbitrarily polarized modes
      A novel cross-polarized optical coherence tomography (CP OCT) system is developed, which is based on standard isotropic single-mode fiber. We exploit the property of an arbitrary pair of orthogonal waves propagating in a singlemode fiber to maintain their orthogonality in the absence of anisotropy losses, regardless of the induced phase anisotropy. The well-known isotropic fiber based OCT scheme that commonly comprises an optical probe with a Fizeau interferometer and a compensating Michelson interferometer with Faraday mirrors is modified. We introduce an additional optical element to form the initial radiation into two mutually time-delayed and coherent waves that have strictly orthogonal ...
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