David Sampson

Toward the discrimination of early melanoma from common and dysplastic nevus using fiber optic diffuse reflectance spectroscopy

Publisher: SPIE-Intl Soc Optical Eng

Date: 2005

DOI: 10.1117/1.2135799

Abstract: We describe a study of the discrimination of early melanoma from common and dysplastic nevus using fiber optic diffuse reflectance spectroscopy. Diffuse reflectance spectra in the wavelength range 550 to 1000 nm are obtained using 400-microm core multimode fibers arranged in a six-illumination-around-one-collection geometry with a single fiber-fiber spacing of 470 microm. Spectra are collected at specific locations on 120 pigmented lesions selected by clinicians as possible melanoma, including 64 histopathologically diagnosed as melanoma. These locations are carried through to the histopathological diagnosis, permitting a spatially localized comparison with the corresponding spectrum. The variations in spectra between groups of lesions with different diagnoses are examined and reduced to features suitable for discriminant analysis. A classifier distinguishing between benign and malignant lesions performs with sensitivity/specificity of between 6469% and 7278%. Classifiers between pairs of the group common nevus, dysplastic nevus, in situ melanoma, and invasive melanoma show better or similar performance than the benign/malignant classifier, and analysis provides evidence that different spectral features are needed for each pair of groups. This indicates that multiple discriminant systems are likely to be required to distinguish between melanoma and similar lesions.

Semiconductor line source for low-coherence interferometry

Publisher: Optica Publishing Group

Date: 20-02-2001

DOI: 10.1364/AO.40.000913

Abstract: The suitability for low-coherence interferometry of a high-power, semiconductor laser line source operated at a forward bias current below threshold is demonstrated. Measurements of the important characteristics of the source are presented. For ex le, the source produces an output power of 1.3 mW and a spatially uniform coherence length of 16 mum at a bias current of 86% of threshold (250 mA) at 20 degrees C. The usefulness of the source is verified by measurement of the line profile of a contact lens.

Two-photon polymerisation 3D printed freeform micro-optics for optical coherence tomography fibre probes

Publisher: Springer Science and Business Media LLC

Date: 04-10-2018

DOI: 10.1038/S41598-018-32407-0

Abstract: Miniaturised optical coherence tomography (OCT) fibre-optic probes have enabled high-resolution cross-sectional imaging deep within the body. However, existing OCT fibre-optic probe fabrication methods cannot generate miniaturised freeform optics, which limits our ability to fabricate probes with both complex optical function and dimensions comparable to the optical fibre diameter. Recently, major advances in two-photon direct laser writing have enabled 3D printing of arbitrary three-dimensional micro/nanostructures with a surface roughness acceptable for optical applications. Here, we demonstrate the feasibility of 3D printing of OCT probes. We evaluate the capability of this method based on a series of characterisation experiments. We report fabrication of a micro-optic containing an off-axis paraboloidal total internal reflecting surface, its integration as part of a common-path OCT probe, and demonstrate proof-of-principle imaging of biological s les.

Imaging of human lymph nodes using optical coherence tomography: potential for staging cancer

Publisher: American Association for Cancer Research (AACR)

Date: 31-03-2010

DOI: 10.1158/0008-5472.CAN-09-4062

Abstract: Histologic assessment is the gold standard technique for the identification of metastatic involvement of lymph nodes in malignant disease, but can only be performed ex vivo and often results in the unnecessary excision of healthy lymph nodes, leading to complications such as lymphedema. Optical coherence tomography (OCT) is a high-resolution, near-IR imaging modality capable of visualizing microscopic features within tissue. OCT has the potential to provide in vivo assessment of tissue involvement by cancer. In this morphologic study, we show the capability of OCT to image nodal microarchitecture through an assessment of fresh, unstained ex vivo lymph node s les. Ex les include both benign human axillary lymph nodes and nodes containing metastatic breast carcinoma. Through accurate correlation with the histologic gold standard, OCT is shown to enable differentiation of lymph node tissue from surrounding adipose tissue, reveal nodal structures such as germinal centers and intranodal vessels, and show both diffuse and well circumscribed patterns of metastatic node involvement. Cancer Res 70(7) 2579–84

Volumetric quantitative optical coherence elastography with an iterative inversion method

Publisher: The Optical Society

Date: 03-01-2019

DOI: 10.1364/BOE.10.000384

Computational optical palpation: a finite-element approach to micro-scale tactile imaging using a compliant sensor

Publisher: The Royal Society

Date: 03-2017

DOI: 10.1098/RSIF.2016.0878

Abstract: High-resolution tactile imaging, superior to the sense of touch, has potential for future biomedical applications such as robotic surgery. In this paper, we propose a tactile imaging method, termed computational optical palpation, based on measuring the change in thickness of a thin, compliant layer with optical coherence tomography and calculating tactile stress using finite-element analysis. We demonstrate our method on test targets and on freshly excised human breast fibroadenoma, demonstrating a resolution of up to 15–25 µm and a field of view of up to 7 mm. Our method is open source and readily adaptable to other imaging modalities, such as ultrasonography and confocal microscopy.

Optical coherence elastography for cellular-scale stiffness imaging of mouse aorta

Publisher: SPIE

Date: 29-04-2017

DOI: 10.1117/12.2269903

Mapping the mechanical heterogeneity of human breast tissue using optical coherence elastography

Publisher: OSA

Date: 2016

DOI: 10.1364/CANCER.2016.JM2A.3

In vivo dynamic optical coherence elastography using a ring actuator

Publisher: Optica Publishing Group

Date: 12-11-2009

DOI: 10.1364/OE.17.021762

Fibrin phantom for use in optical coherence tomography

Publisher: SPIE-Intl Soc Optical Eng

Date: 2010

DOI: 10.1117/1.3427249

Abstract: This work presents a novel tissue-mimicking phantom for use in a range of optical coherence tomography (OCT) experiments. Such phantoms are critical in the development and assessment of new OCT techniques, but no previously published phantoms have become universally accepted. We present the first description of a phantom based on a fibrin matrix, which improves key attributes of previously published methods. It provides a biocompatible, optically transparent scaffold in which to incorporate organic and/or inorganic optical scattering materials. Its fabrication time is markedly shorter than many common phantoms, and its lifetime is longer than other biocompatible phantoms. The potential of fibrin phantoms incorporating Intralipid() to introduce uniform optical scattering is demonstrated. The measured attenuation coefficient as a function of Intralipid concentration confirms the ability to control optical scattering. A bilayer phantom with distinct optical scattering in each layer is also presented.

Age-Dependent Decline in Common Femoral Artery Flow-Mediated Dilation and Wall Shear Stress in Healthy Subjects

Publisher: MDPI AG

Date: 04-12-2022

DOI: 10.3390/LIFE12122023

Abstract: Femoral artery (FA) endothelial function is a promising biomarker of lower extremity vascular health for peripheral artery disease (PAD) prevention and treatment however, the impact of age on FA endothelial function has not been reported in healthy adults. Therefore, we evaluated the reproducibility and acceptability of flow-mediated dilation (FMD) in the FA and brachial artery (BA) (n = 20) and performed cross-sectional FA- and BA-FMD measurements in healthy non-smokers aged 22–76 years (n = 50). FMD protocols demonstrated similar good reproducibility. Leg occlusion was deemed more uncomfortable than arm occlusion thigh occlusion was less tolerated than forearm and calf occlusion. FA-FMD with calf occlusion was lower than BA-FMD (6.0 ± 1.1% vs 6.4 ± 1.3%, p = 0.030). Multivariate linear regression analysis indicated that age (−0.4%/decade) was a significant independent predictor of FA-FMD (R2 = 0.35, p = 0.002). The age-dependent decline in FMD did not significantly differ between FA and BA (pinteraction agexlocation = 0.388). In older participants, 40% of baseline FA wall shear stress (WSS) values were dyne/cm2, which is regarded as pro-atherogenic. In conclusion, endothelial function declines similarly with age in the FA and the BA in healthy adults. The age-dependent FA enlargement results in a critical decrease in WSS that may explain part of the age-dependent predisposition for PAD.

High-sensitivity anastigmatic imaging needle for optical coherence tomography

Publisher: The Optical Society

Date: 14-12-2012

DOI: 10.1364/OL.37.005247

Optical coherence tomography as a novel tool for non-destructive measurement of the hull thickness of lupin seeds

Publisher: Wiley

Date: 06-2004

DOI: 10.1111/J.1439-0523.2004.00989.X

In vivo 4D imaging of the human lower airway using anatomical optical coherence tomography

Publisher: SPIE

Date: 05-10-2009

DOI: 10.1117/12.835797

Parametric imaging of viscoelasticity using optical coherence elastography

Publisher: IOP Publishing

Date: 26-02-2015

DOI: 10.1088/0031-9155/60/6/2293

Abstract: We demonstrate imaging of soft tissue viscoelasticity using optical coherence elastography. Viscoelastic creep deformation is induced in tissue using step-like compressive loading and the resulting time-varying deformation is measured using phase-sensitive optical coherence tomography. From a series of co-located B-scans, we estimate the local strain rate as a function of time, and parameterize it using a four-parameter Kelvin-Voigt model of viscoelastic creep. The estimated viscoelastic strain and time constant are used to visualize viscoelastic creep in 2D, dual-parameter viscoelastograms. We demonstrate our technique on six silicone tissue-simulating phantoms spanning a range of viscoelastic parameters. As an ex le in soft tissue, we report viscoelastic contrast between muscle and connective tissue in fresh, ex vivo rat gastrocnemius muscle and mouse abdominal transection. Imaging viscoelastic creep deformation has the potential to provide complementary contrast to existing imaging modalities, and may provide greater insight into disease pathology.

Correlation of static speckle with sample properties in optical coherence tomography

Publisher: The Optical Society

Date: 15-01-2006

DOI: 10.1364/OL.31.000190

Abstract: We present theoretical calculations, based on a random phasor sum model, which show that the optical coherence tomography speckle contrast ratio is dependent on the local density of scattering particles in a s le, provided that the effective number of scatterers in the probed volume is less than about five. We confirm these theoretical predictions experimentally, using suspensions of microspheres in water. The observed contrast ratios vary in value from the Rayleigh limit of 0.52 to in excess of 2, suggesting that the contrast ratio could be useful in optical coherence tomography, particularly when imaging in ultrahigh-resolution regimes.

Birefringence imaging for optical sensing of tissue damage

Publisher: IEEE

Date: 04-2013

DOI: 10.1109/ISSNIP.2013.6529762

In vivo label-free lymphangiography of cutaneous lymphatic vessels in human burn scars using optical coherence tomography

Publisher: The Optical Society

Date: 02-11-2016

DOI: 10.1364/BOE.7.004886

Motion correction of in vivo three-dimensional optical coherence tomography of human skin using a fiducial marker

Publisher: The Optical Society

Date: 29-06-2012

DOI: 10.1364/BOE.3.001774

In vivo imaging of the depth-resolved optic axis of birefringence in human skin

Publisher: Optica Publishing Group

Date: 31-08-2020

DOI: 10.1364/OL.400855

Abstract: Recent progress has enabled the reconstruction of the local (i.e., depth-resolved) optic axis (OAx) of biological tissue from measurements made with polarization-sensitive optical coherence tomography (PS-OCT). Here we demonstrate local OAx imaging in healthy human skin in vivo . The images reveal dense, weaving patterns that are imperceptible in OCT intensity tomograms or conventional PS-OCT metrics and that suggest a mesh-like tissue organization, consistent with the morphology of dermal collagen. Using co-registered polarization-sensitive optical coherence microscopy, we furthermore investigated the impact of spatial resolution on the recovered OAx patterns and confirmed their consistency. OAx orientation as a contrast mechanism merits further exploration for applications in dermatology.

Speckle reduction in optical coherence tomography images using tissue viscoelasticity

Publisher: SPIE-Intl Soc Optical Eng

Date: 2011

DOI: 10.1117/1.3548239

Abstract: We present a technique to reduce speckle in optical coherence tomography images of soft tissues. An average is formed over a set of B-scans that have been decorrelated by viscoelastic creep strain. The necessary correction for the deformation-induced spatial distortions between B-scans is achieved through geometrical co-registration using an affine transformation. Speckle reduction by up to a factor of 1.65 is shown in images of tissue-mimicking soft fibrin phantoms and excised human lymph node tissue with no observable loss of spatial resolution.

Simplifying the assessment of human breast cancer by mapping a micro‐scale heterogeneity index in optical coherence elastography

Publisher: Wiley

Date: 12-09-2016

DOI: 10.1002/JBIO.201600092

Abstract: Surgical treatment of breast cancer aims to identify and remove all malignant tissue. Intraoperative assessment of tumor margins is, however, not exact thus, re-excision is frequently needed, or excess normal tissue is removed. Imaging methods applicable intraoperatively could help to reduce re-excision rates whilst minimizing removal of excess healthy tissue. Optical coherence elastography (OCE) has been proposed for use in breast-conserving surgery however, intraoperative interpretation of complex OCE images may prove challenging. Observations of breast cancer on multiple length scales, by OCE, ultrasound elastography, and atomic force microscopy, have shown an increase in the mechanical heterogeneity of malignant breast tumors compared to normal breast tissue. In this study, a micro-scale mechanical heterogeneity index is introduced and used to form heterogeneity maps from OCE scans of 10 ex vivo human breast tissue s les. Through comparison of OCE, optical coherence tomography images, and corresponding histology, malignant tissue is shown to possess a higher heterogeneity index than benign tissue. The heterogeneity map simplifies the contrast between tumor and normal stroma in breast tissue, facilitating the rapid identification of possible areas of malignancy, which is an important step towards intraoperative margin assessment using OCE.

Retinal Differential Light Sensitivity Variation Across the Macula in Healthy Subjects: Importance of Cone Separation and Loci Eccentricity

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 11-05-2021

DOI: 10.1167/TVST.10.6.16

Delay and dispersion characteristics of a frequency-domain optical delay line for scanning interferometry

Publisher: Optica Publishing Group

Date: 02-2003

DOI: 10.1364/JOSAA.20.000333

Abstract: The reflective frequency-domain optical delay line employing a diffraction grating, a lens, and a tiltable mirror has emerged as a device particularly suitable for interferometry and optical coherence tomography. The device is comprehensively described, both theoretically and experimentally, in the context of interferometry. The variations of phase and group delay produced by the device as well as its dispersive properties are described and demonstrated experimentally.

Towards standardizing retinal optical coherence tomography angiography: a review

Publisher: Springer Science and Business Media LLC

Date: 18-03-2022

DOI: 10.1038/S41377-022-00740-9

Abstract: The visualization and assessment of retinal microvasculature are important in the study, diagnosis, monitoring, and guidance of treatment of ocular and systemic diseases. With the introduction of optical coherence tomography angiography (OCTA), it has become possible to visualize the retinal microvasculature volumetrically and without a contrast agent. Many lab-based and commercial clinical instruments, imaging protocols and data analysis methods and metrics, have been applied, often inconsistently, resulting in a confusing picture that represents a major barrier to progress in applying OCTA to reduce the burden of disease. Open data and software sharing, and cross-comparison and pooling of data from different studies are rare. These inabilities have impeded building the large databases of annotated OCTA images of healthy and diseased retinas that are necessary to study and define characteristics of specific conditions. This paper addresses the steps needed to standardize OCTA imaging of the human retina to address these limitations. Through review of the OCTA literature, we identify issues and inconsistencies and propose minimum standards for imaging protocols, data analysis methods, metrics, reporting of findings, and clinical practice and, where this is not possible, we identify areas that require further investigation. We hope that this paper will encourage the unification of imaging protocols in OCTA, promote transparency in the process of data collection, analysis, and reporting, and facilitate increasing the impact of OCTA on retinal healthcare delivery and life science investigations.

Airway narrowing assessed by anatomical optical coherence tomography in vitro: Dynamic airway wall morphology and function

Publisher: American Physiological Society

Date: 02-2010

DOI: 10.1152/JAPPLPHYSIOL.00511.2009

Abstract: Regulation of airway caliber by lung volume or bronchoconstrictor stimulation is dependent on physiological, structural, and mechanical events within the airway wall, including airway smooth muscle (ASM) contraction, deformation of the mucosa and cartilage, and tensioning of elastic matrices linking wall components. Despite close association between events in the airway wall and the resulting airway caliber, these have typically been studied separately: the former primarily using histological approaches, the latter with a range of imaging modalities. We describe a new optical technique, anatomical optical coherence tomography ( aOCT), which allows changes at the luminal surface (airway caliber) to be temporally related to corresponding dynamic movements within the airway wall. A fiber-optic aOCT probe was inserted into the lumen of isolated, liquid-filled porcine airways. It was used to image the response to ASM contraction induced by neural stimulation and to airway inflation and deflation. Comparisons with histology indicated that aOCT provided high-resolution images of the airway lumen including mucosal folds, the entire inner wall (mucosa and ASM), and partially the cartilaginous outer wall. Airway responses assessed by aOCT revealed several phenomena in “live” airways (i.e., not fixed) previously identified by histological investigations of fixed tissue, including a geometric relationship between ASM shortening and luminal narrowing, and sliding and bending of cartilage plates. It also provided direct evidence for distensibility of the epithelial membrane and anisotropic behavior of the airway wall. Findings suggest that aOCT can be used to relate changes in airway caliber to dynamic events in the wall of airways.

Anatomical optical coherence tomography: a safe and effective tool for quantitative long-term monitoring of upper airway size and shape

Publisher: SPIE

Date: 07-02-2008

DOI: 10.1117/12.774887

Needle-probe system for the measurement of tissue refractive index

Publisher: SPIE

Date: 08-02-2007

DOI: 10.1117/12.700955

Local polarization properties of human anterior segment with single-measurement, full-range polarization-sensitive OCT

Publisher: IEEE

Date: 10-2017

DOI: 10.1109/IPCON.2017.8116111

Effect of Body Posture on Pharyngeal Shape and Size in Adults With and Without Obstructive Sleep Apnea

Publisher: Oxford University Press (OUP)

Date: 11-2008

DOI: 10.1093/SLEEP/31.11.1543

Imaging true 3D endoscopic anatomy by incorporating magnetic tracking with optical coherence tomography: proof-of-principle for airways

Publisher: The Optical Society

Date: 09-12-2010

DOI: 10.1364/OE.18.027173

Distribution of airway narrowing responses across generations and at branching points, assessed in vitro by anatomical optical coherence tomography

Publisher: Springer Science and Business Media LLC

Date: 22-01-2010

DOI: 10.1186/1465-9921-11-9

Ultrahigh-resolution optical coherence elastography

Publisher: The Optical Society

Date: 16-12-2015

DOI: 10.1364/OL.41.000021

Jones matrix‐based speckle‐decorrelation angiography using polarization‐sensitive optical coherence tomography

Publisher: Wiley

Date: 23-06-2020

DOI: 10.1002/JBIO.202000007

OCTAVA: An open-source toolbox for quantitative analysis of optical coherence tomography angiography images

Publisher: Public Library of Science (PLoS)

Date: 09-12-2021

DOI: 10.1371/JOURNAL.PONE.0261052

Abstract: Optical coherence tomography angiography (OCTA) performs non-invasive visualization and characterization of microvasculature in research and clinical applications mainly in ophthalmology and dermatology. A wide variety of instruments, imaging protocols, processing methods and metrics have been used to describe the microvasculature, such that comparing different study outcomes is currently not feasible. With the goal of contributing to standardization of OCTA data analysis, we report a user-friendly, open-source toolbox, OCTAVA (OCTA Vascular Analyzer), to automate the pre-processing, segmentation, and quantitative analysis of en face OCTA maximum intensity projection images in a standardized workflow. We present each analysis step, including optimization of filtering and choice of segmentation algorithm, and definition of metrics. We perform quantitative analysis of OCTA images from different commercial and non-commercial instruments and s les and show OCTAVA can accurately and reproducibly determine metrics for characterization of microvasculature. Wide adoption could enable studies and aggregation of data on a scale sufficient to develop reliable microvascular biomarkers for early detection, and to guide treatment, of microvascular disease.

Applying anatomical optical coherence tomography to quantitative 3D imaging of the lower airway

Publisher: The Optical Society

Date: 15-10-2008

DOI: 10.1364/OE.16.017521

Abstract: Endoscopic treatment of lower airway pathologies requires accurate quantification of airway dimensions. We demonstrate the application of a real-time endoscopic optical coherence tomography system that can image lower airway anatomy and quantify airway lumen dimensions intra-operatively. Results demonstrate the ability to acquire 3D scans of airway anatomy and include comparison against a pre-operative X-ray CT. The paper also illustrates the capability of the system to assess the real-time dynamic changes within the airway that occur during respiration.

Ultrasound-Guided Optical Coherence Tomography Needle Probe for the Assessment of Breast Cancer Tumor Margins

Publisher: American Roentgen Ray Society

Date: 10-2012

DOI: 10.2214/AJR.11.7284

Mapping Tissue Optical Attenuation to Identify Cancer Using Optical Coherence Tomography

Publisher: Springer Berlin Heidelberg

Date: 2009

DOI: 10.1007/978-3-642-04271-3_80

Abstract: The lymphatic system is a common route for the spread of cancer and the identification of lymph node metastases is a key task during cancer surgery. This paper demonstrates the use of optical coherence tomography to construct parametric images of lymph nodes. It describes a method to automatically estimate the optical attenuation coefficient of tissue. By mapping the optical attenuation coefficient at each location in the scan, it is possible to construct a parametric image indicating variations in tissue type. The algorithm is applied to ex vivo s les of human axillary lymph nodes and validated against a histological gold standard. Results are shown illustrating the variation in optical properties between cancerous and healthy tissue.

Feedforward noise reduction of incoherent light for spectrum-sliced transmission at 2.5 Gb/s

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 12-1995

DOI: 10.1109/68.477299

Optical Coherence Tomography in Respiratory Science and Medicine: From Airways to Alveoli

Publisher: American Physiological Society

Date: 09-2014

DOI: 10.1152/PHYSIOL.00002.2014

Abstract: Optical coherence tomography is a rapidly maturing optical imaging technology, enabling study of the in vivo structure of lung tissue at a scale of tens of micrometers. It has been used to assess the layered structure of airway walls, quantify both airway lumen caliber and compliance, and image in idual alveoli. This article provides an overview of the technology and reviews its capability to provide new insights into respiratory disease.

A compact source condition for modelling focused fields using the pseudospectral time-domain method

Publisher: The Optical Society

Date: 04-03-2014

DOI: 10.1364/OE.22.005599

Anatomical Optical Coherence Tomography for Long-Term, Portable, Quantitative Endoscopy

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 04-2008

DOI: 10.1109/TBME.2007.913409

Erratum

Publisher: SPIE-Intl Soc Optical Eng

Date: 19-12-2013

DOI: 10.1117/1.JBO.18.6.069801

Effect of the velopharynx on intraluminal pressures in reconstructed pharynges derived from individuals with and without sleep apnea

Publisher: Elsevier BV

Date: 09-2013

DOI: 10.1016/J.JBIOMECH.2013.07.007

Abstract: The most collapsible part of the upper airway in the majority of in iduals is the velopharynx which is the segment positioned behind the soft palate. As such it is an important morphological region for consideration in elucidating the pathogenesis of obstructive sleep apnea (OSA). This study compared steady flow properties during inspiration in the pharynges of nine male subjects with OSA and nine body-mass index (BMI)- and age-matched control male subjects without OSA. The k-ωSST turbulence model was used to simulate the flow field in subject-specific pharyngeal geometric models reconstructed from anatomical optical coherence tomography (aOCT) data. While analysis of the geometry of reconstructed pharynges revealed narrowing at velopharyngeal level in subjects with OSA, it was not possible to clearly distinguish them from subjects without OSA on the basis of pharyngeal size and shape alone. By contrast, flow simulations demonstrated that pressure fields within the narrowed airway segments were sensitive to small differences in geometry and could lead to significantly different intraluminal pressure characteristics between subjects. The ratio between velopharyngeal and total pharyngeal pressure drops emerged as a relevant flow-based criterion by which subjects with OSA could be differentiated from those without.

Bifocal optical coherenc refractometry of turbid media

Publisher: Optica Publishing Group

Date: 15-01-2003

DOI: 10.1364/OL.28.000117

Abstract: We propose and demonstrate a novel technique, which we term bifocal optical coherence refractometry, for the rapid determination of the refractive index of a turbid medium. The technique is based on the simultaneous creation of two closely spaced confocal gates in a s le. The optical path-length difference between the gates is measured by means of low-coherence interferometry and used to determine the refractive index. We present experimental results for the refractive indices of milk solutions and of human skin in vivo. As the axial scan rate determines the acquisition time, which is potentially of the order of tens of milliseconds, the technique has potential for in vivo refractive-index measurements of turbid biological media under dynamic conditions.

Assessment of repeated reference measurements to inform the validity of optical breast spectroscopy

Publisher: AIP Publishing

Date: 04-2022

DOI: 10.1063/5.0072223

Abstract: Mammographic breast density is a strong breast cancer risk factor, and its routine clinical measurement could potentially be used to identify women at higher risk of breast cancer and/or monitor primary prevention strategies. Previous reports of optical breast spectroscopy (OBS), a novel approach to measuring breast density, demonstrated that it is safe (no ionizing radiation), portable, low-cost, and does not require image interpretation but have been limited to small, single-center studies. Reference measurements taken on a phantom breast prior to and after each woman’s OBS assessment are required for the calibration of the system transfer function as a part of processing participant data. To inform the validity of participant data, a detailed description of the reference measurements and a repeatability analysis of these measurements taken before and after participant assessment is presented. Reference measurements for OBS from 539 women aged 18–40 years were obtained as a part of a high-throughput epidemiological pilot study. Of these, measurements from 20 women with no useable data due to device failure (3.7%) were excluded and from another 12 women due to user error. The intra-class correlation (ICC) within complete pairs of reference data (taken before and after assessment) was high (all ICC & 0.84). The analysis presented here confirms the OBS participant data as valid for use in ongoing epidemiological research, providing further supporting evidence of OBS as a measure of breast density. A novel method of measuring breast density is needed to bridge large gaps in the knowledge of breast density in younger women and its relation to later-life breast cancer risk.

Optical coherence tomography in the assessment of acute changes in cutaneous vascular diameter induced by heat stress

Publisher: American Physiological Society

Date: 10-2016

DOI: 10.1152/JAPPLPHYSIOL.00918.2015

Abstract: There are limited imaging technologies available that can accurately assess or provide surrogate markers of the in vivo cutaneous microvessel network in humans. In this study, we establish the use of optical coherence tomography (OCT) as a novel imaging technique to assess acute changes in cutaneous microvessel area density and diameter in humans. OCT speckle decorrelation images of the skin on the ventral side of the forearm up to a depth of 500 μm were obtained prior to and following 20-25 min of lower limb heating in eight healthy men [30.3 ± 7.6 (SD) yr]. Skin red blood cell flux was also collected using laser Doppler flowmetry probes immediately adjacent to the OCT skin sites, along with skin temperature. OCT speckle decorrelation images were obtained at both baseline and heating time points. Forearm skin flux increased significantly (0.20 ± 0.15 to 1.75 ± 0.38 cutaneous vascular conductance, P 0.01), along with forearm skin temperature (32.0 ± 1.2 to 34.3 ± 1.0°C, P 0.01). Quantitative differences in the automated calculation of vascular area densities (26 ± 9 to 49 ± 19%, P 0.01) and in idual microvessel diameters (68 ± 17 to 105 ± 25 μm, P 0.01) were evident following the heating session. This is the first in vivo within-subject assessment of acute changes in the cutaneous microvasculature in response to heating in humans and highlights the use of OCT as an exciting new imaging approach for skin physiology and clinical research.

Refractive index tomography of turbid media by bifocal optical coherence refractometry

Publisher: Optica Publishing Group

Date: 15-12-2003

DOI: 10.1364/OE.11.003503

Abstract: We demonstrate tomographic imaging of the refractive index of turbid media using bifocal optical coherence refractometry (BOCR). The technique, which is a variant of optical coherence tomography, is based on the measurement of the optical pathlength difference between two foci simultaneously present in a medium of interest. We describe a new method to axially shift the bifocal optical pathlength that avoids the need to physically relocate the objective lens or the s le during an axial scan, and present an experimental realization based on an adaptive liquid-crystal lens. We present experimental results, including video clips, which demonstrate refractive index tomography of a range of turbid liquid phantoms, as well as of human skin in vivo.

Iron Oxide-Induced Thermal Effects on Solid-State Upconversion Emissions in NaYF₄:Yb,Er Nanocrystals

Publisher: American Chemical Society (ACS)

Date: 13-08-2013

DOI: 10.1021/AM401837H

Abstract: Multifunctional materials exhibiting photon upconversion show promising applications for biological imaging and sensing. In this study, we examine the solid-state upconversion emission of NaYF4:Yb,Er nanoparticles in the presence of iron oxide nanoparticles. Fe3O4 nanoparticles (6 nm) were mixed with NaYF4:Yb,Er nanoparticles (either 10 or 50 nm) in varying proportions by drying chloroform solutions of nanoparticles onto glass slides. Upconversion spectra were acquired, and a laser power-dependent emission was observed and correlated with the iron oxide content in the mixture. Changes in the lattice temperature of the upconverting particles were monitored by careful observation of the relative intensities of the (2)H11/2 and (4)S3/2 →( 4)I15/2 transitions. The emission characteristics observed are consistent with an iron oxide-induced thermal effect that is dependent on both the laser power and the proportion of iron oxide. The results highlight that the thermal effects of mixed nanoparticle systems should be considered in the design of luminescent upconverting hybrid materials.

Parametric imaging of cancer with optical coherence tomography

Publisher: SPIE-Intl Soc Optical Eng

Date: 2010

DOI: 10.1117/1.3479931

Abstract: We present a parametric optical coherence tomography (OCT) technique to improve contrast between malignant and healthy non-neoplastic tissue. The technique incorporates a fully automated method to extract tissue attenuation characteristics. Results are represented visually as a parametric en face image, where the parameter used for contrast is indicative of the relative optical attenuation coefficient of the tissue. We present the first parametric OCT images of human lymph nodes containing malignant cells, and demonstrate improved tissue contrast over en face OCT images.

Analysis of image formation in optical coherence elastography using a multiphysics approach

Publisher: The Optical Society

Date: 08-2014

DOI: 10.1364/BOE.5.002913

Microscope-in-a-needle technology for deep-tissue 3D imaging

Publisher: IEEE

Date: 05-2011

DOI: 10.1109/ICO-IP.2011.5953752

Assessment of human burn scars with optical coherence tomography by imaging the attenuation coefficient of tissue after vascular masking

Publisher: SPIE-Intl Soc Optical Eng

Date: 05-11-2014

DOI: 10.1117/1.JBO.19.2.021111

Optofluidic needle probe integrating targeted delivery of fluid with optical coherence tomography imaging

Publisher: The Optical Society

Date: 08-05-2014

DOI: 10.1364/OL.39.002888

Biophotonics tools for characterising tissues using optical coherence tomography: Detecting mechanics, motion and birefringence

Publisher: OSA

Date: 2016

DOI: 10.1364/ACPC.2016.AF4J.1

Measurement, Reconstruction, and Flow-Field Computation of the Human Pharynx With Application to Sleep Apnea

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 10-2010

DOI: 10.1109/TBME.2010.2052808

Accurate Representation of Microscopic Scatterers in Realistic Simulation of OCT Image Formation

Publisher: IEEE

Date: 09-2018

DOI: 10.1109/IPCON.2018.8527134

Reduction of excess intensity noise in spectrum-sliced incoherent light for WDM applications

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 1997

DOI: 10.1109/50.552113

A review of optical coherence tomography in breast cancer

Publisher: Walter de Gruyter GmbH

Date: 2014

DOI: 10.1515/PLM-2014-0013

Abstract: Optical coherence tomography (OCT) is a medical imaging modality that opens up new opportunities for imaging in breast cancer. It provides two- and three-dimensional micro-scale images of tissue structure from bulk tissue,

Investigating the utility of refractive index tomography based on OCT (Invited Paper)

Publisher: SPIE

Date: 22-06-2005

DOI: 10.1117/12.634775

The emergence of optical elastography in biomedicine

Publisher: Springer Science and Business Media LLC

Date: 04-2017

DOI: 10.1038/NPHOTON.2017.6

Detection of multiple scattering in optical coherence tomography using the spatial distribution of Stokes vectors

Publisher: The Optical Society

Date: 18-12-2007

DOI: 10.1364/OE.15.018033

Abstract: Multiple scattering is one of the main degrading influences in optical coherence tomography, but to date its presence in an image can only be indirectly inferred. We present a polarization-sensitive method that shows the potential to detect it more directly, based on the degree to which the detected polarization state at any given image point is correlated with the mean state over the surrounding region. We report the validation of the method in microsphere suspensions, showing a strong dependence of the degree of correlation upon the extent to which multiply scattered light is coherently detected. We demonstrate the method's utility in various tissues, including chicken breast ex vivo and human skin and nailfold in vivo.

Elastic Properties of the Central Airways in Obstructive Lung Diseases Measured Using Anatomical Optical Coherence Tomography

Publisher: American Thoracic Society

Date: 03-2011

DOI: 10.1164/RCCM.201002-0178OC

Optical coherence tomography can assess skeletal muscle tissue from mouse models of muscular dystrophy by parametric imaging of the attenuation coefficient

Publisher: The Optical Society

Date: 19-03-2014

DOI: 10.1364/BOE.5.001217

Detection of multiple scattering in optical coherence tomography by speckle correlation of angle-dependent B-scans

Publisher: Optica Publishing Group

Date: 08-06-2010

DOI: 10.1364/OL.35.001998

HIGH-SPEED GATED SURFACE PROFILING WITH CLOSED-LOOP OPTICAL COHERENCE TOPOGRAPHY

Publisher: Walter de Gruyter GmbH

Date: 2002

DOI: 10.1515/BMTE.2002.47.S1A.189

Abstract: The here presented work describes a surface profiling technique, for which the term closed-loop optical coherence topography (CLOCT) was proposed [1]. This technique is a scanning beam, servo-locked variation of low-coherence interferometry. It allows for the sub-wavelength-resolution tracking of a weakly scattering macroscopic-scale surface with the absence of significant real-time computational overhead and is thus particularly well suited to real-time surface profiling of in vivo, macroscopic biological surfaces.

Energy-efficient low-Fresnel-number Bessel beams and their application in optical coherence tomography

Publisher: The Optical Society

Date: 23-01-2014

DOI: 10.1364/OL.39.000548

Full wave model of image formation in optical coherence tomography applicable to general samples

Publisher: The Optical Society

Date: 29-01-2015

DOI: 10.1364/OE.23.002541

Investigation of speckle contrast ratio in optical coherence tomography

Publisher: SPIE

Date: 09-02-2006

DOI: 10.1117/12.645700

3D visualization of tissue microstructures using optical coherence tomography needle probes

Publisher: SPIE

Date: 15-05-2011

DOI: 10.1117/12.887366

High-speed, high-sensitivity, gated surface profiling with closed-loop optical coherence topography

Publisher: Optica Publishing Group

Date: 08-04-2002

DOI: 10.1364/AO.41.002179

Abstract: We describe and experimentally demonstrate a novel (to our knowledge) surface profiling technique, for which we propose the term closed-loop optical coherence topography. This technique is a scanning beam, servo-locked variation of low-coherence interferometry. It allows for the sub-wavelength-resolution tracking of a weakly scattering macroscopic-scale surface, with the surface profile being directly output by the controlling electronics. The absence of significant real-time computational overhead makes the technique well suited to high-speed tracking. The use of a micrometer-scale coherence gate efficiently suppresses signals arising from structures not associated with the surface. These features make the technique particularly well suited to real-time surface profiling of in vivo, macroscopic biological surfaces.

Structured three-dimensional optical phantom for optical coherence tomography

Publisher: The Optical Society

Date: 22-09-2011

DOI: 10.1364/OE.19.019480

Optical coherence tomography angiography for longitudinal monitoring of vascular changes in human cutaneous burns

Publisher: Wiley

Date: 13-07-2016

DOI: 10.1111/EXD.13053

Abstract: Assessment of vasculature is an important aspect of monitoring healing of cutaneous burn injuries. Recent advances in optical coherence tomography (OCT) have enabled it to be used to perform high-resolution imaging of the cutaneous vasculature in vivo, with the potential to provide a superior alternative to the conventional assessment of scoring skin color. The goal of this study is to investigate the feasibility of OCT angiography for longitudinal monitoring of vasculature and identification of vascular features in human cutaneous burns. We integrate several OCT imaging protocols and image-processing techniques into a systematic method for longitudinal monitoring and automatic quantification. The demonstration of this method on a partial-thickness burn shows the accurate co-location of longitudinal scans characteristic vascular features in different healing phases and eventual decrease of the elevated vasculature area density and vessel diameter to normal levels. Such a method holds promise for longitudinal monitoring of vasculature in burn injures as well as in other cutaneous vascular pathologies and responses to treatment.

Three-dimensional optical coherence tomography of whole-muscle autografts as a precursor to morphological assessment of muscular dystrophy in mice

Publisher: SPIE-Intl Soc Optical Eng

Date: 2008

DOI: 10.1117/1.2870170

Abstract: Three-dimensional optical coherence tomography (3D-OCT) is used to evaluate the structure and pathology of regenerating mouse skeletal muscle autografts for the first time. The death of myofibers with associated inflammation and subsequent new muscle formation in this graft model represents key features of necrosis and inflammation in the human disease Duchenne muscular dystrophy. We perform 3D-OCT imaging of excised autografts and compare OCT images with coregistered histology. The OCT images readily distinguish the necrotic and inflammatory tissue of the graft from the intact healthy muscle fibers in the underlying host tissue. These preliminary findings suggest that, with further development, 3D-OCT could be used as a tool for the evaluation of small-animal muscle morphology and pathology, in particular, for analysis of mouse models of muscular dystrophy.

Cocoa flavanol consumption improves lower extremity endothelial function in healthy individuals and people with type 2 diabetes

Publisher: Royal Society of Chemistry (RSC)

Date: 2022

DOI: 10.1039/D2FO02017C

Abstract: T2DM in iduals exhibit macro- and microvascular dysfunction that is pronounced in the legs. Cocoa acutely increases endothelial function of the brachial and the femoral arteries and dilation of microvasculature in the feet of T2DM and healthy in iduals.

Axial length variation impacts on retinal vessel density and foveal avascular zone area measurement using optical coherence tomography angiography

Publisher: SPIE

Date: 29-04-2017

DOI: 10.1117/12.2270134

Flexible needle with integrated optical coherence tomography probe for imaging during transbronchial tissue aspiration

Publisher: SPIE-Intl Soc Optical Eng

Date: 11-10-2017

DOI: 10.1117/1.JBO.22.10.106002

Optical coherence tomography for longitudinal monitoring of vasculature in scars treated with laser fractionation

Publisher: Wiley

Date: 11-08-2016

DOI: 10.1002/JBIO.201500157

Abstract: This study presents the first in vivo longitudinal assessment of scar vasculature in ablative fractional laser treatment using optical coherence tomography (OCT). A method based on OCT speckle decorrelation was developed to visualize and quantify the scar vasculature over the treatment period. Through reliable co-location of the imaging field of view across multiple imaging sessions, and compensation for motion artifact, the study was able to track the same scar tissue over a period of several months, and quantify changes in the vasculature area density. The results show incidences of occlusion of in idual vessels 3 days after the first treatment. The subsequent responses ˜20 weeks after the initial treatment show differences between immature and mature scars. Image analysis showed a distinct decrease (25 ± 13%, mean ± standard deviation) and increase (19 ± 5%) of vasculature area density for the immature and mature scars, respectively. This study establishes the feasibility of OCT imaging for quantitative longitudinal monitoring of vasculature in scar treatment. En face optical coherence tomography vasculature images pre-treatment (top) and ˜20 weeks after the first laser treatment (bottom) of a mature burn scar. Arrows mark the same vessel pattern.

Deep tissue volume imaging of birefringence through fibre-optic needle probes for the delineation of breast tumour

Publisher: Springer Science and Business Media LLC

Date: 07-2016

DOI: 10.1038/SREP28771

Abstract: Identifying tumour margins during breast-conserving surgeries is a persistent challenge. We have previously developed miniature needle probes that could enable intraoperative volume imaging with optical coherence tomography. In many situations, however, scattering contrast alone is insufficient to clearly identify and delineate malignant regions. Additional polarization-sensitive measurements provide the means to assess birefringence, which is elevated in oriented collagen fibres and may offer an intrinsic biomarker to differentiate tumour from benign tissue. Here, we performed polarization-sensitive optical coherence tomography through miniature imaging needles and developed an algorithm to efficiently reconstruct images of the depth-resolved tissue birefringence free of artefacts. First ex vivo imaging of breast tumour s les revealed excellent contrast between lowly birefringent malignant regions, and stromal tissue, which is rich in oriented collagen and exhibits higher birefringence, as confirmed with co-located histology. The ability to clearly differentiate between tumour and uninvolved stroma based on intrinsic contrast could prove decisive for the intraoperative assessment of tumour margins.

Respiratory gating of endoscopic OCT images of the upper airway

Publisher: SPIE

Date: 14-04-2008

DOI: 10.1117/12.786827

Evaluation of changes in birefringence for samples subjected to various stress sources measured with polarization-sensitive OCT

Publisher: SPIE

Date: 29-04-2017

DOI: 10.1117/12.2270131

Quantifying the influence of Bessel beams on image quality in optical coherence tomography

Publisher: Springer Science and Business Media LLC

Date: 24-03-2016

DOI: 10.1038/SREP23483

Abstract: Light scattered by turbid tissue is known to degrade optical coherence tomography (OCT) image contrast progressively with depth. Bessel beams have been proposed as an alternative to Gaussian beams to image deeper into turbid tissue. However, studies of turbid tissue comparing the image quality for different beam types are lacking. We present such a study, using numerically simulated beams and experimental OCT images formed by Bessel or Gaussian beams illuminating phantoms with optical properties spanning a range typical of soft tissue. We demonstrate that, for a given scattering parameter, the higher the scattering anisotropy the lower the OCT contrast, regardless of the beam type. When focusing both beams at the same depth in the s le, we show that, at focus and for equal input power and resolution, imaging with the Gaussian beam suffers less reduction of contrast. This suggests that, whilst Bessel beams offer extended depth of field in a single depth scan, for low numerical aperture (NA 0.1) and typical soft tissue properties (scattering coefficient, μ s = 3.7 mm −1 and high scattering anisotropy, g 0.95), superior contrast (by up to ~40%) may be obtained over an extended depth range by a Gaussian beam combined with dynamic focusing.

Parametric imaging of the local attenuation coefficient in human axillary lymph nodes assessed using optical coherence tomography

Publisher: The Optical Society

Date: 27-01-2012

DOI: 10.1364/BOE.3.000366

Stem cell migration and mechanotransduction on linear stiffness gradient hydrogels

Publisher: Proceedings of the National Academy of Sciences

Date: 15-05-2017

DOI: 10.1073/PNAS.1618239114

Abstract: Mechanobiology is receiving an increasing amount of focus, but the mechanics of cell-substrate behavior are often neglected in cell biology. As such, novel materials and systems that are simple to build and share in a nonengineering laboratory are sorely needed. We have fabricated gradient hydrogels with continuous linear gradients above and below the durotactic threshold, making it possible to pinpoint optimal stiffness values for a wide range of biological phenomena without the confounding effects of durotaxis. This system has the potential for wide adoption in the cell biology community because of its ease of fabrication, simple material ingredients, and wide gradient possibilities in a single well.

Automated quantification of lung structures from optical coherence tomography images

Publisher: The Optical Society

Date: 09-10-2013

DOI: 10.1364/BOE.4.002383

<title>Quantitative imaging of the human upper airway: instrument design and clinical studies</title>

Publisher: SPIE

Date: 08-2006

DOI: 10.1117/12.696987

Ultrahigh resolution optical coherence elastography using a Bessel beam for extended depth of field

Publisher: SPIE

Date: 08-03-2016

DOI: 10.1117/12.2214684

Spectroscopic optical coherence elastography

Publisher: The Optical Society

Date: 22-11-2010

DOI: 10.1364/OE.18.025519

Near Video-Rate Optical Coherence Elastography by Acceleration With a Graphics Processing Unit

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 15-08-2015

DOI: 10.1109/JLT.2015.2413402

Feasibility of applying real-time optical imaging during bronchoscopic interventions for central airway obstruction

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 10-2010

DOI: 10.1097/LBR.0B013E3181F9EAAE

Parametric imaging of attenuation by optical coherence tomography: review of models, methods, and clinical translation

Publisher: SPIE-Intl Soc Optical Eng

Date: 03-04-2020

DOI: 10.1117/1.JBO.25.4.040901

Dynamics of the human upper airway: On the development of a three-dimensional computational model

Publisher: Springer Berlin Heidelberg

Date: 2007

DOI: 10.1007/978-3-540-36841-0_872

Axial Length Variation Impacts on Superficial Retinal Vessel Density and Foveal Avascular Zone Area Measurements Using Optical Coherence Tomography Angiography

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 20-06-2017

DOI: 10.1167/IOVS.17-21551

Abstract: To evaluate the impact of image magnification correction on superficial retinal vessel density (SRVD) and foveal avascular zone area (FAZA) measurements using optical coherence tomography angiography (OCTA). Participants with healthy retinas were recruited for ocular biometry, refraction, and RTVue XR Avanti OCTA imaging with the 3 × 3-mm protocol. The foveal and parafoveal SRVD and FAZA were quantified with custom software before and after correction for magnification error using the Littman and the modified Bennett formulae. Relative changes between corrected and uncorrected SRVD and FAZA were calculated. Forty subjects were enrolled and the median (range) age of the participants was 30 (18-74) years. The mean (range) spherical equivalent refractive error was -1.65 (-8.00 to +4.88) diopters and mean (range) axial length was 24.42 mm (21.27-28.85). Images from 13 eyes were excluded due to poor image quality leaving 67 for analysis. Relative changes in foveal and parafoveal SRVD and FAZA after correction ranged from -20% to +10%, -3% to +2%, and -20% to +51%, respectively. Image size correction in measurements of foveal SRVD and FAZA was greater than 5% in 51% and 74% of eyes, respectively. In contrast, 100% of eyes had less than 5% correction in measurements of parafoveal SRVD. Ocular biometry should be performed with OCTA to correct image magnification error induced by axial length variation. We advise caution when interpreting interocular and interin idual comparisons of SRVD and FAZA derived from OCTA without image size correction.

In situ 3D imaging of alveoli with a 30 gauge side-facing optical needle probe

Publisher: IEEE

Date: 12-2011

DOI: 10.1109/ISSNIP.2011.6146625

In vivo three-dimensional optical coherence elastography

Publisher: The Optical Society

Date: 23-03-2011

DOI: 10.1364/OE.19.006623

En faceparametric imaging of tissue birefringence using polarization-sensitive optical coherence tomography

Publisher: SPIE-Intl Soc Optical Eng

Date: 03-06-2013

DOI: 10.1117/1.JBO.18.6.066005

Measuring airway dimensions during bronchoscopy using anatomical optical coherence tomography

Publisher: European Respiratory Society (ERS)

Date: 18-06-2010

DOI: 10.1183/09031936.00041809

Ultrahigh-Resolution Optical Coherence Elastography Images Cellular-Scale Stiffness of Mouse Aorta

Publisher: Elsevier BV

Date: 12-2017

DOI: 10.1016/J.BPJ.2017.09.022

Multiwavelength source for spectrum-sliced WDM access networks and LAN's

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 07-1997

DOI: 10.1109/68.593384

Dual-modality needle probe for combined fluorescence imaging and three-dimensional optical coherence tomography

Publisher: The Optical Society

Date: 16-01-2013

DOI: 10.1364/OL.38.000266

In vivo size and shape measurement of the human upper airway using endoscopic long-range optical coherence tomography

Publisher: Optica Publishing Group

Date: 28-07-2003

DOI: 10.1364/OE.11.001817

Abstract: We describe a long-range optical coherence tomography system for size and shape measurement of large hollow organs in the human body. The system employs a frequency-domain optical delay line of a configuration that enables the combination of high-speed operation with long scan range. We compare the achievable maximum delay of several delay line configurations, and identify the configurations with the greatest delay range. We demonstrate the use of one such long-range delay line in a catheter-based optical coherence tomography system and present profiles of the human upper airway and esophagus in vivo with a radial scan range of 26 millimeters. Such quantitative upper airway profiling should prove valuable in investigating the pathophysiology of airway collapse during sleep (obstructive sleep apnea).

Clinical applications of fiber-optic probes in optical coherence tomography

Publisher: Elsevier BV

Date: 12-2010

DOI: 10.1016/J.YOFTE.2010.09.013

Anatomical Optical Coherence Tomography: Endoscopic Quantitative Imaging of the Upper Airway

Publisher: OSA

Date: 2006

DOI: 10.1364/OFS.2006.WA7

Superior Imaging Performance of All-Fiber, Two-Focusing-Element Microendoscopes

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 10-2022

DOI: 10.1109/JPHOT.2022.3203219

Quantifying tracheobronchial tree dimensions: methods, limitations and emerging techniques

Publisher: European Respiratory Society (ERS)

Date: 30-06-2009

DOI: 10.1183/09031936.00020408

Abstract: The ability to measure airway dimensions is important for clinicians, interventional bronchoscopists and researchers in order to accurately quantify structural abnormalities and track their changes over time or in response to treatment. Most quantitative airway measurements are based on X-ray computed tomography and, more recently, on multidetector computed tomography. Quantitative bronchoscopic techniques have also been developed, although these are less widely employed. Emerging techniques, including magnetic resonance imaging, endoscopic optical coherence tomography, endobronchial ultrasound and confocal endomicroscopy, provide new research tools with potential clinical applications. An understanding of issues related to the acquisition, processing and analysis of images, and how such issues impact on imaging the tracheobronchial tree, is essential in order to assess measurement accuracy and to make effective use of the newer methods. This article contributes to this understanding by providing a comprehensive review of current and emerging techniques for quantifying airway dimensions.

Reduction of image artifacts in three-dimensional optical coherence tomography of skin in vivo

Publisher: SPIE-Intl Soc Optical Eng

Date: 2011

DOI: 10.1117/1.3652710

Abstract: This paper presents results of in vivo studies on the effect of refractive index-matching media on image artifacts in optical coherence tomography (OCT) images of human skin. These artifacts present as streaks of artificially low backscatter and displacement or distortion of features. They are primarily caused by refraction and scattering of the OCT light beam at the skin surface. The impact of the application of glycerol and ultrasound gel is assessed on both novel skin-mimicking phantoms and in vivo human skin, including assessment of the epidermal thickening caused by the media. Based on our findings, recommendations are given for optimal OCT imaging of skin in vivo.

Enabling freehand lateral scanning of optical coherence tomography needle probes with a magnetic tracking system

Publisher: The Optical Society

Date: 08-06-2012

DOI: 10.1364/BOE.3.001565

Real-time dispersion compensation in scanning interferometry

Publisher: Optica Publishing Group

Date: 15-11-2002

DOI: 10.1364/OL.27.001998

Abstract: We propose and demonstrate a method of real-time dispersion compensation suitable for scanning interferometry and optical coherence tomography. Static grating tilt in a scanning frequency-domain optical delay line is shown to produce dispersion that is linearly proportional to scan position, and we use this property to achieve depth-dependent dispersion compensation during an interferometric scan through a dispersive s le.

Ultrathin side-viewing needle probe for optical coherence tomography

Publisher: The Optical Society

Date: 28-09-2011

DOI: 10.1364/OL.36.003894

Needle-based refractive index measurement using low-coherence interferometry

Publisher: The Optical Society

Date: 26-01-2007

DOI: 10.1364/OL.32.000385

Abstract: We present a novel needle-based device for the measurement of refractive index and scattering using low-coherence interferometry. Coupled to the s le arm of an optical coherence tomography system, the device detects the scattering response of, and optical path length through, a s le residing in a fixed-width channel. We report use of the device to make near-infrared measurements of tissues and materials with known optical properties. The device could be used to exploit the refractive index variations of tissue for medical and biological diagnostics accessible by needle insertion.

Depth-encoded optical coherence elastography for simultaneous volumetric imaging of two tissue faces

Publisher: The Optical Society

Date: 17-03-2017

DOI: 10.1364/OL.42.001233

Investigation of optical attenuation imaging using optical coherence tomography for monitoring of scars undergoing fractional laser treatment

Publisher: Wiley

Date: 31-05-2017

DOI: 10.1002/JBIO.201500342

Abstract: We demonstrate the use of the near-infrared attenuation coefficient, measured using optical coherence tomography (OCT), in longitudinal assessment of hypertrophic burn scars undergoing fractional laser treatment. The measurement method incorporates blood vessel detection by speckle decorrelation and masking, and a robust regression estimator to produce 2D en face parametric images of the attenuation coefficient of the dermis. Through reliable co-location of the field of view across pre- and post-treatment imaging sessions, the study was able to quantify changes in the attenuation coefficient of the dermis over a period of ∼20 weeks in seven patients. Minimal variation was observed in the mean attenuation coefficient of normal skin and control (untreated) mature scars, as expected. However, a significant decrease (13 ± 5%, mean ± standard deviation) was observed in the treated mature scars, resulting in a greater distinction from normal skin in response to localized damage from the laser treatment. By contrast, we observed an increase in the mean attenuation coefficient of treated (31 ± 27%) and control (27 ± 20%) immature scars, with numerical values incrementally approaching normal skin as the healing progressed. This pilot study supports conducting a more extensive investigation of OCT attenuation imaging for quantitative longitudinal monitoring of scars. En face 2D OCT attenuation coefficient map of a treated immature scar derived from the pre-treatment (top) and the post-treatment (bottom) scans. (Vasculature (black) is masked out.) The scale bars are 0.5 mm.

The influence of NaYF₄:Yb,Er size/phase on the multimodality of co-encapsulated magnetic photon-upconverting polymeric nanoparticles

Publisher: Royal Society of Chemistry (RSC)

Date: 2014

DOI: 10.1039/C4DT01597E

Abstract: Assessment of polymeric nanoparticles incorporating NaYF 4 :Yb,Er and Fe 3 O 4 as multimodal imaging probes in vitro .

Room temperature synthesis of upconversion fluorescent nanocrystals

Publisher: Royal Society of Chemistry (RSC)

Date: 2011

DOI: 10.1039/C1CC12385H

Abstract: Synthesis of nanocrystals that exhibit strong upconversion (UC) luminescence upon infrared excitation has been challenging due to the stringent control needed over experimental variables. Herein, we report a method to synthesize nanocrystals demonstrating high UC at room temperature in aqueous solution on graphene.

Immune‐mediated ECM depletion improves tumour perfusion and payload delivery

Publisher: EMBO

Date: 11-11-2019

DOI: 10.15252/EMMM.201910923

Imaging the small with the small: Prospects for photonics in micro-endomicroscopy for minimally invasive cellular-resolution bioimaging

Publisher: AIP Publishing

Date: 06-2021

DOI: 10.1063/5.0052258

Abstract: Many bioimaging studies, including those in engineered tissue constructs, intravital microscopy in animal models, and medical imaging in humans, require cellular-resolution imaging of structures deep within a s le. Yet, many of the current approaches are limited in terms of resolution, but also in invasiveness, repeatable imaging of the same location, and accessible imaging depth. We coin the term micro-endomicroscope to describe the emerging class of small, cellular-resolution endoscopic imaging systems designed to image cells in situ while minimizing perturbation of the s le. In this Perspective, we motivate the need for further development of micro-endomicroscopes, highlighting applications that would greatly benefit, reviewing progress, and considering how photonics might contribute. We identify areas ripe for technological development, such as micro-scanners and small lens systems, that would advance micro-endomicroscope performance. With the right developments in photonics, many possibilities exist for new minimally invasive translatable imaging tools across the scientific, pre-clinical, and clinical spectrum: from longitudinal studies of engineered tissue constructs, to tracking disease progression in animal models, to expanding the ability to diagnose and develop treatments for diseases without the need for invasive medical procedures.

Vectorial birefringence imaging by optical coherence microscopy for assessing fibrillar microstructures in the cornea and limbus

Publisher: Optica Publishing Group

Date: 24-01-2020

DOI: 10.1364/BOE.382755

Abstract: The organization of fibrillar tissue on the micrometer scale carries direct implications for health and disease but remains difficult to assess in vivo . Polarization-sensitive optical coherence tomography measures birefringence, which relates to the microscopic arrangement of fibrillar tissue components. Here, we demonstrate a critical improvement in leveraging this contrast mechanism by employing the improved spatial resolution of focus-extended optical coherence microscopy (1.4 µm axially in air and 1.6 µm laterally, over more than 70 µm depth of field). Vectorial birefringence imaging of sheep cornea ex vivo reveals its lamellar organization into thin sections with distinct local optic axis orientations, paving the way to resolving similar features in vivo .

Static and dynamic imaging of alveoli using optical coherence tomography needle probes

Publisher: American Physiological Society

Date: 15-09-2012

DOI: 10.1152/JAPPLPHYSIOL.00051.2012

Abstract: Imaging of alveoli in situ has for the most part been infeasible due to the high resolution required to discern in idual alveoli and limited access to alveoli beneath the lung surface. In this study, we present a novel technique to image alveoli using optical coherence tomography (OCT). We propose the use of OCT needle probes, where the distal imaging probe has been miniaturized and encased within a hypodermic needle (as small as 30-gauge, outer diameter 310 μm), allowing insertion deep within the lung tissue with minimal tissue distortion. Such probes enable imaging at a resolution of ∼12 μm within a three-dimensional cylindrical field of view with diameter ∼1.5 mm centered on the needle tip. The imaging technique is demonstrated on excised lungs from three different species: adult rats, fetal sheep, and adult pigs. OCT needle probes were used to image alveoli, small bronchioles, and blood vessels, and results were matched to histological sections. We also present the first dynamic OCT images acquired with an OCT needle probe, allowing tracking of in idual alveoli during simulated cyclical lung inflation and deflation.

Robust reconstruction of local optic axis orientation with fiber-based polarization-sensitive optical coherence tomography

Publisher: The Optical Society

Date: 15-10-2018

DOI: 10.1364/BOE.9.005437

Local birefringence of the anterior segment of the human eye in a single capture with a full range polarisation-sensitive optical coherence tomography

Publisher: SPIE

Date: 29-04-2017

DOI: 10.1117/12.2270230

Refractive index tomography of turbid media by bifocal optical coherence refractometry

Publisher: SPIE

Date: 07-2012

DOI: 10.1117/12.531272

A model of optical coherence tomography image formation based on Maxwell's equations

Publisher: IEEE

Date: 10-2016

DOI: 10.1109/IPCON.2016.7831012

Pilot study of optical coherence tomography angiography-derived microvascular metrics in hands and feet of healthy and diabetic people

Publisher: Springer Science and Business Media LLC

Date: 20-01-2023

DOI: 10.1038/S41598-022-26871-Y

Abstract: Optical coherence tomography angiography (OCTA) is a non-invasive, high-resolution imaging modality with growing application in dermatology and microvascular assessment. Accepted reference values for OCTA-derived microvascular parameters in skin do not yet exist but need to be established to drive OCTA into the clinic. In this pilot study, we assess a range of OCTA microvascular metrics at rest and after post-occlusive reactive hyperaemia (PORH) in the hands and feet of 52 healthy people and 11 people with well-controlled type 2 diabetes mellitus (T2DM). We calculate each metric, measure test–retest repeatability, and evaluate correlation with demographic risk factors. Our study delivers extremity-specific, age-dependent reference values and coefficients of repeatability of nine microvascular metrics at baseline and at the maximum of PORH. Significant differences are not seen for age-dependent microvascular metrics in hand, but they are present for several metrics in the foot. Significant differences are observed between hand and foot, both at baseline and maximum PORH, for most of the microvascular metrics with generally higher values in the hand. Despite a large variability over a range of in iduals, as is expected based on heterogeneous ageing phenotypes of the population, the test–retest repeatability is 3.5% to 18% of the mean value for all metrics, which highlights the opportunities for OCTA-based studies in larger cohorts, for longitudinal monitoring, and for assessing the efficacy of interventions. Additionally, branchpoint density in the hand and foot and changes in vessel diameter in response to PORH stood out as good discriminators between healthy and T2DM groups, which indicates their potential value as biomarkers. This study, building on our previous work, represents a further step towards standardised OCTA in clinical practice and research.

Extracting something from nothing

Publisher: IEEE

Date: 10-2017

DOI: 10.1109/IPCON.2016.7831014

Quantitative assessment of muscle damage in the mdx mouse model of Duchenne muscular dystrophy using polarization-sensitive optical coherence tomography

Publisher: American Physiological Society

Date: 11-2013

DOI: 10.1152/JAPPLPHYSIOL.00265.2013

Abstract: Minimally invasive, high-resolution imaging of muscle necrosis has the potential to aid in the assessment of diseases such as Duchenne muscular dystrophy. Undamaged muscle tissue possesses high levels of optical birefringence due to its anisotropic ultrastructure, and this birefringence decreases when the tissue undergoes necrosis. In this study, we present a novel technique to image muscle necrosis using polarization-sensitive optical coherence tomography (PS-OCT). From PS-OCT scans, our technique is able to quantify the birefringence in muscle tissue, generating an image indicative of the tissue ultrastructure, with areas of abnormally low birefringence indicating necrosis. The technique is demonstrated on excised skeletal muscles from exercised dystrophic mdx mice and control C57BL/10ScSn mice with the resulting images validated against colocated histological sections. The technique additionally gives a measure of the proportion (volume fraction) of necrotic tissue within the three-dimensional imaging field of view. The percentage necrosis assessed by this technique is compared against the percentage necrosis obtained from manual assessment of histological sections, and the difference between the two methods is found to be comparable to the interobserver variability of the histological assessment. This is the first published demonstration of PS-OCT to provide automated assessment of muscle necrosis.

Imaging of skin birefringence for human scar assessment using polarization-sensitive optical coherence tomography aided by vascular masking

Publisher: SPIE-Intl Soc Optical Eng

Date: 24-12-2014

DOI: 10.1117/1.JBO.19.12.126014

Real-time detection technique for Doppler optical coherence tomography

Publisher: Optica Publishing Group

Date: 15-11-2000

DOI: 10.1364/OL.25.001645

Abstract: We propose and demonstrate a novel detection technique, based on a modified electronic phase-locked loop, for Doppler optical coherence tomography. The technique permits real-time simultaneous reflectivity and continuous, bidirectional velocity mapping in turbid media over a wide velocity range with minimal sensitivity penalty compared with conventional optical coherence tomography, which is a major advance over current postprocessing and discrete parallel detection techniques.

Imaging deep skeletal muscle structure using a high-sensitivity ultrathin side-viewing optical coherence tomography needle probe

Publisher: The Optical Society

Date: 15-10-2011

DOI: 10.1364/BOE.5.000136

In vivo assessment of human burn scars through automated quantification of vascularity using optical coherence tomography

Publisher: SPIE-Intl Soc Optical Eng

Date: 22-11-2013

DOI: 10.1117/1.JBO.18.6.061213

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

Publisher: SPIE-Intl Soc Optical Eng

Date: 07-07-2014

DOI: 10.1117/1.JBO.19.7.076006

Wide-field optical coherence micro-elastography for intraoperative assessment of human breast cancer margins

Publisher: The Optical Society

Date: 19-09-2016

DOI: 10.1364/BOE.7.004139

Label‐free volumetric imaging of conjunctival collecting lymphatics ex vivo by optical coherence tomography lymphangiography

Publisher: Wiley

Date: 13-07-2018

DOI: 10.1002/JBIO.201800070

Abstract: We employ optical coherence tomography (OCT) and optical coherence microscopy (OCM) to study conjunctival lymphatics in porcine eyes ex vivo. This study is a precursor to the development of in vivo imaging of the collecting lymphatics for potentially guiding and monitoring glaucoma filtration surgery. OCT scans at 1300 nm and higher‐resolution OCM scans at 785 nm reveal the lymphatic vessels via their optical transparency. Equivalent signal characteristics are also observed from blood vessels largely free of blood (and devoid of flow) in the ex vivo conjunctiva. In our lymphangiography, vessel networks were segmented by compensating the depth attenuation in the volumetric OCT/OCM signal, projecting the minimum intensity in two dimensions and thresholding to generate a three‐dimensional vessel volume. Vessel segmentation from multiple locations of a range of porcine eyes ( n = 21) enables visualization of the vessel networks and indicates the varying spatial distribution of patent lymphatics. Such visualization provides a new tool to investigate conjunctival vessels in tissue ex vivo without need for histological tissue processing and a valuable reference on vessel morphology for the in vivo label‐free imaging studies of lymphatics to follow.

Short-time series optical coherence tomography angiography and its application to cutaneous microvasculature

Publisher: The Optical Society

Date: 19-12-2018

DOI: 10.1364/BOE.10.000293

Molecular imaging needles: dual-modality optical coherence tomography and fluorescence imaging of labeled antibodies deep in tissue

Publisher: The Optical Society

Date: 21-04-2015

DOI: 10.1364/BOE.6.001767

Audio frequencyin vivooptical coherence elastography

Publisher: IOP Publishing

Date: 06-05-2009

DOI: 10.1088/0031-9155/54/10/011

Abstract: We present a new approach to optical coherence elastography (OCE), which probes the local elastic properties of tissue by using optical coherence tomography to measure the effect of an applied stimulus in the audio frequency range. We describe the approach, based on analysis of the Bessel frequency spectrum of the interferometric signal detected from scatterers undergoing periodic motion in response to an applied stimulus. We present quantitative results of sub-micron excitation at 820 Hz in a layered phantom and the first such measurements in human skin in vivo.

Imaging of Breast Cancer With Optical Coherence Tomography Needle Probes: Feasibility and Initial Results

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 05-2012

DOI: 10.1109/JSTQE.2011.2166757

Multiple scattering detection in optical coherence tomography using speckle statistics

Publisher: IEEE

Date: 2010

DOI: 10.1109/PHOTWTM.2010.5421964

Depth-resolved birefringence imaging of collagen fiber organization in the human oral mucosa in vivo

Publisher: The Optical Society

Date: 22-03-2019

DOI: 10.1364/BOE.10.001942

Does smooth muscle in an intact airway undergo length adaptation during a sustained change in transmural pressure?

Publisher: American Physiological Society

Date: 03-2015

DOI: 10.1152/JAPPLPHYSIOL.00724.2014

Abstract: In isolated airway smooth muscle (ASM) strips, an increase or decrease in ASM length away from its current optimum length causes an immediate reduction in force production followed by a gradual time-dependent recovery in force, a phenomenon termed length adaptation. In situ, length adaptation may be initiated by a change in transmural pressure (P tm ), which is a primary physiological determinant of ASM length. The present study sought to determine the effect of sustained changes in P tm and therefore, ASM perimeter, on airway function. We measured contractile responses in whole porcine bronchial segments in vitro before and after a sustained inflation from a baseline P tm of 5 cmH 2 O to 25 cmH 2 O, or deflation to −5 cmH 2 O, for ∼50 min in each case. In one group of airways, lumen narrowing and stiffening in response to electrical field stimulation (EFS) were assessed from volume and pressure signals using a servo-controlled syringe pump with pressure feedback. In a second group of airways, lumen narrowing and the perimeter of the ASM in situ were determined by anatomical optical coherence tomography. In a third group of airways, active tension was determined under isovolumic conditions. Both inflation and deflation reduced the contractile response to EFS. Sustained P tm change resulted in a further decrease in contractile response, which returned to baseline levels upon return to the baseline P tm . These findings reaffirm the importance of P tm in regulating airway narrowing. However, they do not support a role for ASM length adaptation in situ under physiological levels of ASM lengthening and shortening.

Respiratory gating of anatomical optical coherence tomography images of the human airway

Publisher: Optica Publishing Group

Date: 06-04-2009

DOI: 10.1364/OE.17.006568

Abstract: Anatomical optical coherence tomography (aOCT) is a long-range endoscopic imaging modality capable of quantifying size and shape of the human airway. A challenge to its in vivo application is motion artifact due to respiratory-related movement of the airway walls. This paper represents the first demonstration of respiratory gating of aOCT airway data, and introduces a novel error measure to guide appropriate parameter selection. Results indicate that at least four gates per respiratory cycle should be used, with only minor improvements as the number of gates is further increased. It is shown that respiratory gating can substantially improve the quality of aOCT images and reveal events and features that are otherwise obscured by blurring.

Identification of muscle necrosis in the mdx mouse model of Duchenne muscular dystrophy using three-dimensional optical coherence tomography

Publisher: SPIE-Intl Soc Optical Eng

Date: 2011

DOI: 10.1117/1.3598842

Abstract: Three-dimensional optical coherence tomography (3D-OCT) was used to image the structure and pathology of skeletal muscle tissue from the treadmill-exercised mdx mouse model of human Duchenne muscular dystrophy. Optical coherence tomography (OCT) images of excised muscle s les were compared with co-registered hematoxylin and eosin-stained and Evans blue dye fluorescence histology. We show, for the first time, structural 3D-OCT images of skeletal muscle dystropathology well correlated with co-located histology. OCT could identify morphological features of interest and necrotic lesions within the muscle tissue s les based on intrinsic optical contrast. These findings demonstrate the utility of 3D-OCT for the evaluation of small-animal skeletal muscle morphology and pathology, particularly for studies of mouse models of muscular dystrophy.

Quantitative Upper Airway Imaging with Anatomic Optical Coherence Tomography

Publisher: American Thoracic Society

Date: 15-01-2006

DOI: 10.1164/RCCM.200507-1148OC

Deciphering Cell-to-Cell Communication in Acquisition of Cancer Traits: Extracellular Membrane Vesicles Are Regulators of Tissue Biomechanics

Publisher: Mary Ann Liebert Inc

Date: 08-2016

DOI: 10.1089/OMI.2016.0072

Abstract: Deciphering the role of cell-to-cell communication in acquisition of cancer traits such as metastasis is one of the key challenges of integrative biology and clinical oncology. In this context, extracellular vesicles (EVs) are important vectors in cell-to-cell communication and serve as conduits in the transfer of cellular constituents required for cell function and for the establishment of cellular phenotypes. In the case of malignancy, they have been shown to support the acquisition of common traits defined as constituting the hallmarks of cancer. Cellular biophysics has contributed to our understanding of some of these central traits with changes in tissue biomechanics reflective of cell state. Indeed, much is known about stiffness of the tissue scaffold in the context of cell invasion and migration. This article advances this knowledge frontier by showing for the first time that EVs are mediators of tissue biomechanical properties and, importantly, demonstrates a link between the acquisition of cancer multidrug resistance and increased tissue stiffness of the malignant mass. The methodology used in the study employed optical coherence elastography and atomic force microscopy on breast cancer cell monolayers and tumor spheroids. Specifically, we show here that the acquired changes in tissue stiffness can be attributed to the intracellular transfer of a protein complex comprising ezrin, radixin, moesin, CD44, and P-glycoprotein. This has important implications in facilitating mechano-transduced signaling cascades that regulate the acquisition of cancer traits, such as invasion and metastasis. Finally, this study also introduces novel targets and strategies for diagnostic and therapeutic innovation in oncology, with a view to prevention of metastatic spread and personalized medicine in cancer treatment.

In situ imaging of lung alveoli with an optical coherence tomography needle probe

Publisher: SPIE-Intl Soc Optical Eng

Date: 03-2023

DOI: 10.1117/1.3556719

Abstract: In situ imaging of alveoli and the smaller airways with optical coherence tomography (OCT) has significant potential in the assessment of lung disease. We present a minimally invasive imaging technique utilizing an OCT needle probe. The side-facing needle probe comprises miniaturized focusing optics consisting of no-core and GRIN fiber encased within a 23-gauge needle. 3D-OCT volumetric data sets were acquired by rotating and retracting the probe during imaging. The probe was used to image an intact, fresh (not fixed) sheep lung filled with normal saline, and the results validated against a histological gold standard. We present the first published images of alveoli acquired with an OCT needle probe and demonstrate the potential of this technique to visualize other anatomical features such as bifurcations of the bronchioles.

Functional Reactive Polymer Electrospun Matrix

Publisher: American Chemical Society (ACS)

Date: 11-02-2016

DOI: 10.1021/ACSAMI.5B11447

Abstract: Synthetic multifunctional electrospun composites are a new class of hybrid materials with many potential applications. However, the lack of an efficient, reactive large-area substrate has been one of the major limitations in the development of these materials as advanced functional platforms. Herein, we demonstrate the utility of electrospun poly(glycidyl methacrylate) films as a highly versatile platform for the development of functional nanostructured materials anchored to a surface. The utility of this platform as a reactive substrate is demonstrated by grafting poly(N-isopropylacrylamide) to incorporate stimuli-responsive properties. Additionally, we demonstrate that functional nanocomposites can be fabricated using this platform with properties for sensing, fluorescence imaging, and magneto-responsiveness.

Using Optical Coherence Tomography To Improve Diagnostic and Therapeutic Bronchoscopy

Publisher: Elsevier BV

Date: 07-2009

DOI: 10.1378/CHEST.08-2800

Abstract: Flexible bronchoscopy is a common procedure that is used in both diagnostic and therapeutic settings but does not readily permit measurement of central airway dimensions. Anatomic optical coherence tomography (a OCT), a modification of conventional optical coherence tomography (OCT), is a novel light-based imaging tool with the capacity to measure the diameter and lumen area of the central airways accurately during bronchoscopy. This study describes the first clinical use of aOCT imaging in the lower airways in three in iduals with common endobronchial pathologies. During bronchoscopy, a specialized fiberoptic probe was passed through the biopsy channel of a standard flexible bronchoscope to the site of airway pathology. Airway dimensions were measured from the generated cross-sectional images in three subjects, one with subglottic tracheal stenosis (subject 1), one with malignant left main bronchus (LMB) obstruction (subject 2), and another with severe tracheomalacia (subject 3). Measured dimensions included internal airway diameter, cross-sectional area, and, in subject 1, stenosis length. Tracheal stenosis dimensions, measured using aOCT imaging, correlated with chest CT scan findings and guided the choice of airway stent (subject 1). The airway beyond a malignant obstruction of the LMB, and beyond bronchoscopic view, could be imaged using aOCT, and the distal extent of obstructing tumor identified (subject 2). The severity of newly diagnosed tracheomalacia was able to be quantified using aOCT imaging (subject 3). aOCT imaging during bronchoscopy allows accurate real-time airway measurements and may assist bronchoscopic assessment.

Speckle reduction in optical coherence tomography by strain compounding

Publisher: Optica Publishing Group

Date: 13-07-2010

DOI: 10.1364/OL.35.002445

Extended range, rapid scanning optical delay line for biomedical interferometric imaging

Publisher: Institution of Engineering and Technology (IET)

Date: 1999

DOI: 10.1049/EL:19990989

Ultrahigh-resolution optical coherence elastography through a micro-endoscope: towards in vivo imaging of cellular-scale mechanics

Publisher: The Optical Society

Date: 20-10-2017

DOI: 10.1364/BOE.8.005127

Achromatic optical phase shifter–modulator

Publisher: Optica Publishing Group

Date: 15-03-1224

DOI: 10.1364/OL.26.000187

Abstract: We propose and demonstrate, theoretically and experimentally, a novel achromatic optical phase shifter-modulator based on a frequency-domain optical delay line configured to maintain zero group delay as variable phase delay is generated by means of tilting a mirror. Compared with previously reported phase shifter-modulators, e.g., based on the Pancharatnam (geometric) phase, our device is high speed and polarization insensitive and produces a large, bounded phase delay that, uniquely, is one-to-one mapped to a measurable parameter, the tilt angle.

Special Section Guest Editorial: Optical Elastography and Measurement of Tissue Biomechanics

Publisher: SPIE-Intl Soc Optical Eng

Date: 19-12-2013

DOI: 10.1117/1.JBO.18.12.121501

Preliminary results on in-vivo imaging of upper airway inhalation injuries using anatomical optical coherence tomography

Publisher: SPIE

Date: 29-04-2017

DOI: 10.1117/12.2270588

Evaluation of pharyngeal shape and size using anatomical optical coherence tomography in individuals with and without obstructive sleep apnoea

Publisher: Wiley

Date: 15-04-2008

DOI: 10.1111/J.1365-2869.2008.00647.X

Abstract: This study compared shape, size and length of the pharyngeal airway in in iduals with and without obstructive sleep apnoea (OSA) using a novel endoscopic imaging technique, anatomical optical coherence tomography (aOCT). The study population comprised a preliminary study group of 20 OSA patients and a subsequent controlled study group of 10 OSA patients and 10 body mass index (BMI)-, gender- and age-matched control subjects without OSA. All subjects were scanned using aOCT while awake, supine and breathing quietly. Measurements of airway cross-sectional area (CSA) and anteroposterior (A-P) and lateral diameters were obtained from the hypo-, oro- and velopharyngeal regions. A-P : lateral diameter ratios were calculated to provide an index of regional airway shape. In all subjects, pharyngeal CSA was lowest in the velopharynx. Patients with OSA had a smaller velopharyngeal CSA than controls (maximum CSA 91 +/- 40 versus 153 +/- 84 mm(2) P < 0.05) but comparable oro- (318 +/- 80 versus 279 +/- 129 mm(2) P = 0.48) and hypopharyngeal CSA (250 +/- 105 versus 303 +/- 112 mm(2) P = 0.36). In each pharyngeal region, the long axis of the airway was oriented in the lateral diameter. Airway shape was not different between the groups. Pharyngeal airway length was similar in both groups, although the OSA group had longer uvulae than the control group (16.8 +/- 6.2 versus 11.2 +/- 5.2 mm P < 0.05). This study has shown that in iduals with OSA have a smaller velopharyngeal CSA than BMI-, gender- and age-matched control volunteers, but comparable shape: a laterally oriented ellipse. These findings suggest that it is an abnormality in size rather than shape that is the more important anatomical predictor of OSA.

Realistic simulation and experiment reveals the importance of scatterer microstructure in optical coherence tomography image formation

Publisher: The Optical Society

Date: 13-06-2018

DOI: 10.1364/BOE.9.003122

University Of Surrey

Location: United Kingdom of Great Britain and Northern Ireland

View Organisation

Discovery Projects - Grant ID: DP110104789

Start Date: 2011

End Date: 12-2013

Amount: $680,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0208390

Start Date: 03-2002

End Date: 03-2005

Amount: $240,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0221428

Start Date: 2001

End Date: 12-2002

Amount: $530,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP140104443

Start Date: 2014

End Date: 12-2017

Amount: $635,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0989649

Start Date: 04-2009

End Date: 07-2010

Amount: $800,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP160104969

Start Date: 2016

End Date: 03-2019

Amount: $500,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0559408

Start Date: 2005

End Date: 07-2010

Amount: $425,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP1096178

Start Date: 2010

End Date: 12-2013

Amount: $390,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0771111

Start Date: 02-2007

End Date: 02-2011

Amount: $798,478.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0775672

Start Date: 2007

End Date: 12-2007

Amount: $150,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0454017

Start Date: 01-2004

End Date: 12-2004

Amount: $582,598.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0452405

Start Date: 02-2004

End Date: 12-2007

Amount: $375,000.00

Funder: Australian Research Council

Special Research Initiatives - Grant ID: SR0354734

Start Date: 2004

End Date: 12-2004

Amount: $10,000.00

Funder: Australian Research Council

Linkage - International - Grant ID: LX0775892

Start Date: 2007

End Date: 07-2008

Amount: $84,530.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE110100146

Start Date: 2011

End Date: 12-2012

Amount: $500,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE130100030

Start Date: 2013

End Date: 12-2013

Amount: $980,000.00

Funder: Australian Research Council

Research Networks - Grant ID: RN0460002

Start Date: 08-2004

End Date: 08-2009

Amount: $2,000,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE100100217

Start Date: 2010

End Date: 05-2011

Amount: $450,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE160100086

Start Date: 05-2016

End Date: 12-2016

Amount: $850,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE120100095

Start Date: 01-2012

End Date: 12-2013

Amount: $620,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0989782

Start Date: 10-2009

End Date: 10-2010

Amount: $524,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE150100006

Start Date: 2015

End Date: 12-2015

Amount: $1,060,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE150100066

Start Date: 2015

End Date: 12-2015

Amount: $440,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE130100011

Start Date: 2013

End Date: 12-2014

Amount: $470,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE140100036

Start Date: 2014

End Date: 12-2015

Amount: $771,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP180103757

Start Date: 2018

End Date: 01-2018

Amount: $423,052.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE110100114

Start Date: 2011

End Date: 06-2012

Amount: $360,000.00

Funder: Australian Research Council