1. Articles from Simon S. Gao

    25-31 of 31 « 1 2
    1. Postprocessing algorithms to minimize fixed-pattern artifact and reduce trigger jitter in swept source optical coherence tomography

      Postprocessing algorithms to minimize fixed-pattern artifact and reduce trigger jitter in swept source optical coherence tomography

      We propose methods to align interferograms affected by trigger jitter to a reference interferogram based on the information (amplitude/phase) at a fixed-pattern noise location to reduce residual fixed-pattern noise and improve the phase stability of swept source optical coherence tomography (SS-OCT) systems. One proposed method achieved this by introducing a wavenumber shift (k-shift) in the interferograms of interest and searching for the k-shift that minimized the fixed-pattern noise amplitude. The other method calculated the relative k-shift using the phase information at the residual fixed-pattern noise location. Repeating this wavenumber alignment procedure for all A-lines of interest produced fixed-pattern noise ...

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    2. Spectral fractionation detection of gold nanorod contrast agents using optical coherence tomography

      Spectral fractionation detection of gold nanorod contrast agents using optical coherence tomography

      We demonstrate the proof of concept of a novel Fourier-domain optical coherence tomography contrast mechanism using gold nanorod contrast agents and a spectral fractionation processing technique. The methodology detects the spectral shift of the backscattered light from the nanorods by comparing the ratio between the short and long wavelength halves of the optical coherence tomography signal intensity. Spectral fractionation further divides the halves into sub-bands to improve spectral contrast and suppress speckle noise. Herein, we show that this technique can detect gold nanorods in intralipid tissue phantoms. Furthermore, cellular labeling by gold nanorods was demonstrated using retinal pigment epithelial cells ...

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    3. In vivo vibrometry inside the apex of the mouse cochlea using spectral domain optical coherence tomography

      In vivo vibrometry inside the apex of the mouse cochlea using spectral domain optical coherence tomography

      Sound transduction within the auditory portion of the inner ear, the cochlea, is a complex nonlinear process. The study of cochlear mechanics in large rodents has provided important insights into cochlear function. However, technological and experimental limitations have restricted studies in mice due to their smaller cochlea. These challenges are important to overcome because of the wide variety of transgenic mouse strains with hearing loss mutations that are available for study. To accomplish this goal, we used spectral domain optical coherence tomography to visualize and measure sound-induced vibrations of intracochlear tissues. We present, to our knowledge, the first vibration measurements ...

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    4. Methodology for assessment of structural vibrations by spectral domain optical coherence tomography

      Methodology for assessment of structural vibrations by spectral domain optical coherence tomography

      Clinical diagnosis of cochlear dysfunction typically remains incomplete due to a lack of proper diagnostic methods. Medical imaging modalities can only detect gross changes in the cochlea, and non-invasive in vivo cochlear measurements are scarce. As a result, extensive efforts have been made to adapt optical coherence tomography (OCT) techniques to analyze and study the cochlea. Herein, we detail the methods for measuring vibration using OCT. We used spectral domain OCT with ~950 nm as the center wavelength and a bandwidth of ~80 nm. The custom spectrometer used was based on a high speed line scan camera which is capable ...

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    5. Imaging high-frequency periodic motion in the mouse ear with coherently interleaved optical coherence tomography

      Imaging high-frequency periodic motion in the mouse ear with coherently interleaved optical coherence tomography

      Vibratory measurements of the structures of the ear are key to understanding much of the pathology in mouse models of hearing loss. Unfortunately the high-speed sampling required to interrogate the high end of the mouse hearing spectrum is beyond the reach of most optical coherence tomography (OCT) systems. To address this issue, we have developed an algorithm that enables phase-sensitive OCT measurements over the full range of the mouse hearing spectrum (4–90 kHz). The algorithm phase-locks the line-trigger to the acoustic stimulation and then uses interleaved sampling to reconstruct the signal with higher temporal sampling. The algorithm was evaluated ...

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    6. Biophysical Mechanisms Underlying Hearing Loss Associated with a Shortened Tectorial Membrane

      Biophysical Mechanisms Underlying Hearing Loss Associated with a Shortened Tectorial Membrane

      The tectorial membrane (TM) connects to the stereociliary bundles of outer hair cells (OHCs). Herein, we summarize key experimental data and modeling analyses that describe how biophysical alterations to these connections underlie hearing loss. The heterozygous C1509G mutation in alpha tectorin produces partial congenital hearing loss that progresses in humans. We engineered this mutation in mice, and histology revealed that the TM was shortened. DIC imaging of freshly-dissected cochlea as well as imaging with optical coherence tomography indicated that the TM is malformed and only stimulates the first row of OHCs. Noise exposure produced acute threshold shifts that fully recovered ...

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    7. Quantitative imaging of cochlear soft tissues in wild-type and hearing-impaired transgenic mice by spectral domain optical coherence tomography

      Quantitative imaging of cochlear soft tissues in wild-type and hearing-impaired transgenic mice by spectral domain optical coherence tomography

      Human hearing loss often occurs as a result of damage or malformations to the functional soft tissues within the cochlea, but these changes are not appreciable with current medical imaging modalities. We sought to determine whether optical coherence tomography (OCT) could assess the soft tissue structures relevant to hearing using mouse models. We imaged excised cochleae with an altered tectorial membrane and during normal development. The soft tissue structures and expected anatomical variations were visible using OCT, and quantitative measurements confirmed the ability to detect critical changes relevant to hearing.

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    25-31 of 31 « 1 2
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    1. (26 articles) Oregon Health & Science University
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    Quantitative imaging of cochlear soft tissues in wild-type and hearing-impaired transgenic mice by spectral domain optical coherence tomography Biophysical Mechanisms Underlying Hearing Loss Associated with a Shortened Tectorial Membrane Imaging high-frequency periodic motion in the mouse ear with coherently interleaved optical coherence tomography Methodology for assessment of structural vibrations by spectral domain optical coherence tomography In vivo vibrometry inside the apex of the mouse cochlea using spectral domain optical coherence tomography Postprocessing algorithms to minimize fixed-pattern artifact and reduce trigger jitter in swept source optical coherence tomography Quantitative optical coherence tomography angiography of vascular abnormalities in the living human eye Automated choroidal neovascularization detection algorithm for optical coherence tomography angiography OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY FEATURES OF DIABETIC RETINOPATHY Automated Quantification of Capillary Nonperfusion Using Optical Coherence Tomography Angiography in Diabetic Retinopathy Beating Cancer - One Patient at a Time Conavi Medical and Japan Lifeline Announce MHLW Approval of Novasight Hybrid Intravascular Imaging System for Japanese Market