1. Articles from Vadim Backman

    1-20 of 20
    1. Spectral contrast optical coherence tomography angiography enables single-scan vessel imaging

      Spectral contrast optical coherence tomography angiography enables single-scan vessel imaging

      Optical coherence tomography angiography relies on motion for contrast and requires at least two data acquisitions per pointwise scanning location. We present a method termed spectral contrast optical coherence tomography angiography using visible light that relies on the spectral signatures of blood for angiography from a single scan using endogenous contrast. We demonstrate the molecular sensitivity of this method, which enables lymphatic vessel, blood, and tissue discrimination. Optical coherence tomography (OCT) is a noninvasive optical imaging modality that provides micron-scale resolution of three-dimensional (3D) tissue morphology 1 . In addition to providing structural information, enhanced processing of an OCT signal can ...

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    2. Quantitative quality-control metrics for in vivo oximetry in small vessels by visible light optical coherence tomography angiography

      Quantitative quality-control metrics for in vivo oximetry in small vessels by visible light optical coherence tomography angiography

      Biological functions rely on local microvasculature to deliver oxygen and nutrients and carry away metabolic waste. Alterations to local oxygenation levels are manifested in diseases including cancer, diabetes mellitus, etc. The ability to quantify oxygen saturation (sO 2 ) within microvasculature in vivo to assess local tissue oxygenation and metabolic function is highly sought after. Visible light optical coherence tomography (vis-OCT) angiography has shown promise in reaching this goal. However, achieving reliable measurements in small vessels can be challenging due to the reduced contrast and requires data averaging to improve the spectral data quality. Therefore, a method for quality-control of the ...

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    3. Spectral Contrast Optical Coherence Tomography Angiography Enables Single-Scan Vessel Imaging

      Spectral Contrast Optical Coherence Tomography Angiography Enables Single-Scan Vessel Imaging

      Optical Coherence Tomography angiography relies on motion for contrast and requires at least two data acquisitions per point-wise scanning location. We present a method termed Spectral Contrast Optical Coherence Tomography Angiography using visible light which relies on the spectral signatures of blood to obtain angiography from a single scan using endogenous contrast. We demonstrate the molecular sensitivity of this method enabling lymphatic, blood, and tissue discrimination.

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    4. Single capillary oximetry and tissue ultrastructural sensing by dual-band dual-scan inverse spectroscopic optical coherence tomography

      Single capillary oximetry and tissue ultrastructural sensing by dual-band dual-scan inverse spectroscopic optical coherence tomography

      Measuring capillary oxygenation and the surrounding ultrastructure can allow one to monitor a microvascular niche and better understand crucial biological mechanisms. However, capillary oximetry and pericapillary ultrastructure are challenging to measure in vivo. Here, we demonstrate a novel optical imaging system, Dual-band Dual-scan Inverse Spectroscopic Optical Coherence Tomography (D2- ISOCT), that, for the first time, can simultaneously obtain the following metrics in vivo using endogenous contrast: (1) capillary-level oxygen saturation and arteriolar-level blood flow rates, oxygen delivery rates, and oxygen metabolic rates; (2) spatial characteristics of tissue structures at length scales down to 30 nm; and (3) morphological images up ...

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    5. In vivo broadband visible light optical coherence tomography probe enables inverse spectroscopic analysis

      In vivo broadband visible light optical coherence tomography probe enables inverse spectroscopic analysis

      We report the design and characterization of a 6 mm outer diameter pull-back circumferential scanning visible optical coherence tomography probe. The probe’s large visible bandwidth (500–695 nm) allowed for inverse spectroscopic analysis and an axial resolution of ∼ 1.1    μm ∼1.1  μm in tissue. We verify spectral imaging capabilities by measuring microsphere backscattering spectra and demonstrate in vivo spatial nanoscale characterization of tissue.

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    6. Devices, methods, and systems of functional optical coherence tomography

      Devices, methods, and systems of functional optical coherence tomography

      The present disclosure provides systems and methods for the determining a rate of change of one or more analyte concentrations in a target using non invasive non contact imaging techniques such as OCT. Generally, OCT data is acquired and optical information is extracted from OCT scans to quantitatively determine both a flow rate of fluid in the target and a concentration of one or more analytes. Both calculations can provide a means to determine a change in rate of an analyte over time. Example methods and systems of the disclosure may be used in assessing metabolism of a tissue, where ...

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    7. Detection of extracellular matrix modification in cancer models with inverse spectroscopic optical coherence tomography

      Detection of extracellular matrix modification in cancer models with inverse spectroscopic optical coherence tomography

      In cancer biology, there has been a recent effort to understand tumor formation in the context of the tissue microenvironment. In particular, recent progress has explored the mechanisms behind how changes in the cell-extracellular matrix ensemble influence progression of the disease. The extensive use of in vitro tissue culture models in simulant matrix has proven effective at studying such interactions, but modalities for non-invasively quantifying aspects of these systems are scant. We present the novel application of an imaging technique, Inverse Spectroscopic Optical Coherence Tomography, for the non-destructive measurement of in vitro biological samples during matrix remodeling. Our findings indicate ...

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    8. Devices, Methods, And Systems Of Functional Optical Coherence Tomography

      Devices, Methods, And Systems Of Functional Optical Coherence Tomography

      The present disclosure provides systems and methods for the determining a rate of change of one or more analyte concentrations in a target using non invasive non contact imaging techniques such as OCT. Generally, OCT data is acquired and optical information is extracted from OCT scans to quantitatively determine both a flow rate of fluid in the target and a concentration of one or more analytes. Both calculations can provide a means to determine a change in rate of an analyte over time.

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    9. Visible light optical coherence tomography measures retinal oxygen metabolic response to systemic oxygenation

      Visible light optical coherence tomography measures retinal oxygen metabolic response to systemic oxygenation

      The lack of capability to quantify oxygen metabolism noninvasively impedes both fundamental investigation and clinical diagnosis of a wide spectrum of diseases including all the major blinding diseases such as age-related macular degeneration, diabetic retinopathy, and glaucoma. Using visible light optical coherence tomography (vis-OCT), we demonstrated accurate and robust measurement of retinal oxygen metabolic rate (rMRO 2 ) noninvasively in rat eyes. We continuously monitored the regulatory response of oxygen consumption to a progressive hypoxic challenge. We found that both oxygen delivery, and rMRO 2 increased from the highly regulated retinal circulation (RC) under hypoxia, by 0.28 ± 0.08 µL ...

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    10. Monte Carlo Investigation of Optical Coherence Tomography Retinal Oximetry

      Monte Carlo Investigation of Optical Coherence Tomography Retinal Oximetry

      Optical coherence tomography (OCT) oximetry explores the possibility to measure retinal hemoglobin oxygen saturation level (sO2). We investigated the accuracy of OCT retinal oximetry using Monte Carlo simulation in a commonlyused four-layer retinal model. After we determined the appropriate number of simulated photon packets, we studied the effects of blood vessel diameter, signal sampling position, physiological sO2 level, and the blood packing factor on the accuracy of sO2 estimation in OCT retinal oximetry . The simulation results showed that a packing factor between 0.2 and 0.4 yields a reasonably accurate estimation of sO2 within a 5% error tolerance, which ...

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    11. Two electric field Monte Carlo models of coherent backscattering of polarized light

      Two electric field Monte Carlo models of coherent backscattering of polarized light

      Modeling of coherent polarized light propagation in turbid scattering medium by the Monte Carlo method provides an ultimate understanding of coherent effects of multiple scattering, such as enhancement of coherent backscattering and peculiarities of laser speckle formation in dynamic light scattering (DLS) and optical coherence tomography (OCT) diagnostic modalities. In this report, we consider two major ways of modeling the coherent polarized light propagation in scattering tissue-like turbid media. The first approach is based on tracking transformations of the electric field along the ray propagation. The second one is developed in analogy to the iterative procedure of the solution of ...

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    12. In vivo functional microangiography by visible-light optical coherence tomography

      In vivo functional microangiography by visible-light optical coherence tomography

      Although hemoglobin oxygen saturation (sO 2 ) in the microvasculature is an essential physiological parameter of local tissue functions, non-invasive measurement of microvascular sO 2 is still challenging. Here, we demonstrated that visible-light optical coherence tomography (vis-OCT) can simultaneously provide three-dimensional anatomical tissue morphology, visualize microvasculature at the capillary level, and measure sO 2 from the microvasculature in vivo . We utilized speckle contrast caused by the moving blood cells to enhance microvascular imaging. We applied a series of short-time inverse Fourier transforms to obtain the spectroscopic profile of blood optical attenuation, from which we quantified sO 2 . We validated the sO ...

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

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

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

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    14. Visible-light optical coherence tomography for retinal oximetry

      Visible-light optical coherence tomography for retinal oximetry

      We applied a visible-light spectroscopic optical coherence tomography (vis-OCT) for in vivo retinal oximetry. To extract hemoglobin oxygen saturation (sO2) in individual retinal vessels, we established a comprehensive analytical model to describe optical absorption, optical scattering, and blood cell packing factor in the whole blood and fit the acquired vis-OCT signals from the bottom of each imaged vessel. We found that averaged sO2 values in arterial and venous bloods were 95% and 72%, respectively.

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    15. Can OCT be sensitive to nanoscale structural alterations in biological tissue?

      Can OCT be sensitive to nanoscale structural alterations in biological tissue?

      Exploration of nanoscale tissue structures is crucial in understanding biological processes. Although novel optical microscopy methods have been developed to probe cellular features beyond the diffraction limit, nanometer-scale quantification remains still inaccessible for in situ tissue. Here we demonstrate that, without actually resolving specific geometrical feature, OCT can be sensitive to tissue structural properties at the nanometer length scale. The statistical mass-density distribution in tissue is quantified by its autocorrelation function modeled by the Whittle-Mateŕn functional family. By measuring the wavelength-dependent backscattering coefficient μb(λ) and the scattering coefficient μs, we introduce a technique called inverse spectroscopic OCT (ISOCT) to quantify ...

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    16. Imaging a full set of optical scattering properties of biological tissue by inverse spectroscopic optical coherence tomography

      Imaging a full set of optical scattering properties of biological tissue by inverse spectroscopic optical coherence tomography

      We here develop a method to measure and image the full optical scattering properties by inverse spectroscopic optical coherence tomography (ISOCT). Tissue is modelled as a medium with continuous refractive index (RI) fluctuation and such a fluctuation is described by the RI correlation functions. Under the first-order Born approximation, the forward model is established for ISOCT. By measuring optical quantities of tissue including the scattering power of the OCT spectrum, the reflection albedo α defined as the ratio of scattering coefficient μ s , and the backscattering coefficient μ b , we are able to inversely deduce the RI correlation function and image the full ...

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    17. Structured interference optical coherence tomography

      Structured interference optical coherence tomography

      We developed a structured interference optical coherence tomography (SIOCT) to enhance the lateral resolution beyond the diffraction limit. A sinusoidal pattern is created on the interferometric beam with the reference intensity temporally modulated. In the Fourier domain, the high spatial frequencies are shifted into the detectable range, which enhances the lateral resolution beyond the diffraction limit by a factor of 2. The lateral resolution of SIOCT was characterized in our study as ∼5.5  μm , surpassing the diffraction limit ∼9.6  μm as in conventional Fourier-domain optical coherence tomography. SIOCT was demonstrated on phantoms and ex vivo adipose tissues

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    18. Measurement of optical scattering properties with low-coherence enhanced backscattering spectroscopy

      Measurement of optical scattering properties with low-coherence enhanced backscattering spectroscopy
      Low-coherence enhanced backscattering (LEBS) is a depth selective technique that allows noninvasive characterization of turbid media such as biological tissue. LEBS provides a spectral measurement of the tissue reflectance distribution as a function of distance between incident and reflected ray pairs through the use of partial spatial coherence broadband illumination. We present LEBS as a new depth-selective technique to measure optical properties of tissue in situ. Because LEBS enables measurements of reflectance due to initial scattering events, LEBS is sensitive to the shape of the phase function in addition to the reduced scattering coefficient (μs*). We introduce a simulation of ...
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    19. Method for identifying refractive-index fluctuations of a target

      Method for identifying refractive-index fluctuations of a target
      Systems and methods for identifying refractive-index fluctuations of a target are described in this application. One embodiment includes identifying one or more properties of emergent light, the emergent light to be emergent from a target, and determining refractive-index fluctuations of the target based on the one or more properties of the emergent light. The determining refractive-index fluctuations further comprises determining one or more of the variance of the refractive-index fluctuations and the spatial correlation length of the refractive-index fluctuations. The determining refractive-index fluctuations further comprises determining one or more of the variance of the refractive-index fluctuations and the spatial correlation ...
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    20. System for identifying refractive-index fluctuations of a target

      System for identifying refractive-index fluctuations of a target
      Systems and methods for identifying refractive-index fluctuations of a target are described in this application. One embodiment includes identifying one or more properties of emergent light, the emergent light to be emergent from a target, and determining refractive-index fluctuations of the target based on the one or more properties of the emergent light. The determining refractive-index fluctuations further comprises determining one or more of the variance of the refractive-index fluctuations and the spatial correlation length of the refractive-index fluctuations. The determining refractive-index fluctuations further comprises determining one or more of the variance of the refractive-index fluctuations and the spatial correlation ...
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    1-20 of 20
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  2. Topics in the News

    1. (20 articles) Northwestern University
    2. (20 articles) Vadim Backman
    3. (14 articles) Ji Yi
    4. (7 articles) Hao F. Zhang
    5. (3 articles) Boston University
    6. (1 articles) University of Minnesota
    7. (1 articles) University of Otago
    8. (1 articles) University of Wisconsin
    9. (1 articles) Igor V. Meglinski
    10. (1 articles) Fudan University
    11. (1 articles) UCLA
    12. (1 articles) University of Miami
    13. (1 articles) Capital Medical University
    14. (1 articles) VU University Amsterdam
    15. (1 articles) Srinivas R. Sadda
    16. (1 articles) Johannes F. de Boer
    17. (1 articles) Frank D. Verbraak
    18. (1 articles) Apollo Medical Optics
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    System for identifying refractive-index fluctuations of a target Method for identifying refractive-index fluctuations of a target Measurement of optical scattering properties with low-coherence enhanced backscattering spectroscopy Structured interference optical coherence tomography Imaging a full set of optical scattering properties of biological tissue by inverse spectroscopic optical coherence tomography Can OCT be sensitive to nanoscale structural alterations in biological tissue? Visible-light optical coherence tomography for retinal oximetry Spatially resolved optical and ultrastructural properties of colorectal and pancreatic field carcinogenesis observed by inverse spectroscopic optical coherence tomograph In vivo functional microangiography by visible-light optical coherence tomography Monte Carlo Investigation of Optical Coherence Tomography Retinal Oximetry Optical Coherence Tomography: Critical Tool to Manage Expectations after Cataract Extraction Improving the characterization of ex vivo human brain optical properties using high numerical aperture optical coherence tomography by spatially constraining the confocal parameters