1. Articles from Ryan L. Shelton

    1-20 of 20
    1. Magnetomotive Displacement of the Tympanic Membrane using Magnetic Nanoparticles: Toward Enhancement of Sound Perception

      Magnetomotive Displacement of the Tympanic Membrane using Magnetic Nanoparticles: Toward Enhancement of Sound Perception

      Objective: A novel hearing-aid scheme using magnetomotive nanoparticles (MNPs) as transducers in the tympanic membrane (TM) is proposed, aiming to noninvasively and directly induce a modulated vibration on the TM. Methods: In this feasibility study, iron-oxide (Fe<sub>3</sub>O<sub>4</sub>) nanoparticles were applied on ex vivo rat TM tissues and allowed to diffuse over ~2 hr. Subsequently, magnetic force was exerted on the MNP-laden TM via a programmable electromagnetic solenoid to induce the magnetomotion. Optical coherence tomography (OCT), along with its phase-sensitive measurement capabilities, was utilized to visualize and quantify the nanometer-scale vibrations generated on the ...

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    2. Noninvasive in vivo optical coherence tomography tracking of chronic otitis media in pediatric subjects after surgical intervention

      Noninvasive in vivo optical coherence tomography tracking of chronic otitis media in pediatric subjects after surgical intervention

      In an institutional review board-approved study, 25 pediatric subjects diagnosed with chronic or recurrent otitis media were observed over a period of six months with optical coherence tomography (OCT). Subjects were followed throughout their treatment at the initial patient evaluation and preoperative consultation, surgery (intraoperative imaging), and postoperative follow-up, followed by an additional six months of records-based observation. At each time point, the tympanic membrane (at the light reflex region) and directly adjacent middle-ear cavity were observed in vivo with a handheld OCT probe and portable system. Imaging results were compared with clinical outcomes to correlate the clearance of symptoms ...

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    3. Ratiometric analysis of optical coherence tomography–measured in vivo retinal layer thicknesses for the detection of early diabetic retinopathy

      Ratiometric analysis of optical coherence tomography–measured in vivo retinal layer thicknesses for the detection of early diabetic retinopathy

      Influence of diabetes mellitus (DM) and diabetic retinopathy (DR) on parafoveal retinal thicknesses and their ratios was evaluated. Six retinal layer boundaries were segmented from spectral-domain optical coherence tomography images using open-source software. Five study groups: (1) healthy control (HC) subjects, and subjects with (2) controlled DM, (3) uncontrolled DM, (4) controlled DR and (5) uncontrolled DR, were identified. The one-way analyses of variance (ANOVA) between adjacent study groups (i. e. 1 with 2, 2 with 3, etc) indicated differences in retinal thicknesses and ratios. Overall retinal thickness, ganglion cell layer (GCL) thickness, inner plexiform layer (IPL) thickness, and their ...

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    4. Quantitative characterization of mechanically indented in vivo human skin in adults and infants using optical coherence tomography

      Quantitative characterization of mechanically indented in vivo human skin in adults and infants using optical coherence tomography

      Influenced by both the intrinsic viscoelasticity of the tissue constituents and the time-evolved redistribution of fluid within the tissue, the biomechanical response of skin can reflect not only localized pathology but also systemic physiology of an individual. While clinical diagnosis of skin pathologies typically relies on visual inspection and manual palpation, a more objective and quantitative approach for tissue characterization is highly desirable. Optical coherence tomography (OCT) is an interferometry-based imaging modality that enables in vivo assessment of cross-sectional tissue morphology with micron-scale resolution, which surpasses those of most standard clinical imaging tools, such as ultrasound imaging and magnetic resonance ...

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    5. Low-cost hand-held probe for depth-resolved low-coherence interferometry

      Low-cost hand-held probe for depth-resolved low-coherence interferometry

      We report on the development of a low-cost hand-held low-coherence interferometric imaging system based on the principle of linear optical coherence tomography (Linear OCT), a technique which was first proposed in the early 2000s as a simpler alternative to the conventional time-domain and Fourier-domain OCT. A bench-top implementation of the proposed technique is first presented and validated. The axial resolution, SNR, and sensitivity roll-of of the system was estimated to be 5.2 μm and 80 dB, and 3.7 dB over a depth of 0.15 mm, respectively. After validating the bench-top system, two hand-held probe implementations for contact-based ...

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    6. A Mosaicking Approach for In Vivo Thickness Mapping of the Human Tympanic Membrane Using Low Coherence Interferometry

      A Mosaicking Approach for In Vivo Thickness Mapping of the Human Tympanic Membrane Using Low Coherence Interferometry

      The thickness of the human tympanic membrane (TM) is known to vary considerably across different regions of the TM. Quantitative determination of the thickness distribution and mapping of the TM is of significant importance in hearing research, particularly in mathematical modeling of middle-ear dynamics. Change in TM thickness is also associated with several middle-ear pathologies. Determination of the TM thickness distribution could therefore also enable a more comprehensive diagnosis of various otologic diseases. Despite its importance, very limited data on human TM thickness distribution, obtained almost exclusively from ex vivo samples, are available in the literature. In this study, the ...

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    7. Detection of retinal blood vessel changes in multiple sclerosis with optical coherence tomography

      Detection of retinal blood vessel changes in multiple sclerosis with optical coherence tomography

      Although retinal vasculitis is common in multiple sclerosis (MS), it is not known if MS is associated with quantitative abnormalities in retinal blood vessels (BVs). Optical coherence tomography (OCT) is suitable for examining the integrity of the anterior visual pathways in MS. In this paper we have compared the size and number of retinal blood vessels in patients with MS, with and without a history of optic neuritis (ON), and control subjects from the cross-sectional retinal images from OCT. Blood vessel diameter (BVD), blood vessel number (BVN), and retinal nerve fiber layer thickness (RNFL T ) were extracted from OCT images ...

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    8. Non-Invasive Optical Assessment of Viscosity of Middle Ear Effusions in Otitis Media

      Non-Invasive Optical Assessment of Viscosity of Middle Ear Effusions in Otitis Media

      In vivo Optical Coherence Tomography (OCT) image of a human tympanic membrane and Middle Ear Effusion (MEE) (top), with a CCD image of the tympanic membrane surface (inset). Below is the corresponding time-lapse M-mode OCT data acquired along the white dotted line over time, which can be analyzed to determine the Stokes–Einstein diffusion coefficient of the effusion. Eustachian tube dysfunction can cause fluid to collect within the middle ear cavity and form a middle ear effusion (MEE). MEEs can persist for weeks or months and cause hearing loss as well as speech and learning delays in young children. The ...

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    9. Non-invasive optical assessment of viscosity of middle ear effusions in otitis media

      Non-invasive optical assessment of viscosity of middle ear effusions in otitis media

      In vivo Optical Coherence Tomography (OCT) image of a human tympanic membrane and Middle Ear Effusion (MEE) (top), with a CCD image of the tympanic membrane surface (inset). Below is the corresponding time-lapse M-mode OCT data acquired along the white dotted line over time, which can be analyzed to determine the Stokes–Einstein diffusion coefficient of the effusion. Eustachian tube dysfunction can cause fluid to collect within the middle ear cavity and form a middle ear effusion (MEE). MEEs can persist for weeks or months and cause hearing loss as well as speech and learning delays in young children. The ...

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    10. Intraoperative optical coherence tomography for assessing human lymph nodes for metastatic cancer

      Intraoperative optical coherence tomography for assessing human lymph nodes for metastatic cancer

      Background Evaluation of lymph node (LN) status is an important factor for detecting metastasis and thereby staging breast cancer. Currently utilized clinical techniques involve the surgical disruption and resection of lymphatic structure, whether nodes or axillary contents, for histological examination. While reasonably effective at detection of macrometastasis , the majority of the resected lymph nodes are histologically negative. Improvements need to be made to better detect micrometastasis , minimize or eliminate lymphatic disruption complications, and provide immediate and accurate intraoperative feedback for in vivo cancer staging to better guide surgery. Methods We evaluated the use of optical coherence tomography (OCT), a high-resolution ...

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    11. Noninvasive depth-resolved optical measurements of the tympanic membrane and middle ear for differentiating otitis media

      Noninvasive depth-resolved optical measurements of the tympanic membrane and middle ear for differentiating otitis media

      Objective/Hypothesis In this study, optical coherence tomography (OCT) is used to noninvasively and quantitatively determine tympanic membrane (TM) thickness and the presence and thickness of any middle-ear biofilm located behind the TM. These new metrics offer the potential to differentiate normal, acute, and chronic otitis media (OM) infections in pediatric subjects. Study Design Case series with comparison group. Methods The TM thickness of 34 pediatric subjects was acquired using a custom-built, handheld OCT system following a traditional otoscopic ear exam. Results Overall thickness (TM and any associated biofilm) was shown to be statistically different for normal, acute, and chronic ...

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    12. Real-time automated thickness measurement of the in vivo human tympanic membrane using optical coherence tomography

      Real-time automated thickness measurement of the in vivo human tympanic membrane using optical coherence tomography

      Background: Otitis media (OM), an infection in the middle ear, is extremely common in the pediatric population. Current gold-standard methods for diagnosis include otoscopy for visualizing the surface features of the tympanic membrane (TM) and making qualitative assessments to determine middle ear content. OM typically presents as an acute infection, but can progress to chronic OM, and after numerous infections and antibiotic treatments over the course of many months, this disease is often treated by surgically inserting small tubes in the TM to relieve pressure, enable drainage, and provide aeration to the middle ear. Diagnosis and monitoring of OM is ...

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    13. Implementation and evaluation of Google Glass for visualizing real-time image and patient data in the primary care office

      Implementation and evaluation of Google Glass for visualizing real-time image and patient data in the primary care office

      Primary care physicians must conduct a staggering number of comprehensive physical exams and medical record reviews, resulting in demanding daily schedules. Few commercial technologies have been marketed towards the primary care market, which has stifled improvements in disease screening and detection, work flow, and records management, taking time away from interactions with patients. In efforts to improve the quality of care in primary care medicine, we integrated our handheld primary care optical imaging system with Google Glass©, a commercial heads-up display (HUD). The integration of a HUD allows the physician to focus on the patient during the medical history review ...

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    14. Feature Of The Week 2/23/14: Texas A&M University Reports on In vivo Pump-Probe Optical Coherence Tomography Imaging in Xenopus Laevis

      Feature Of The Week 2/23/14: Texas A&M University Reports on In vivo Pump-Probe Optical Coherence Tomography Imaging in Xenopus Laevis

      Currently, optical coherence tomography (OCT), is not capable of obtaining molecular information often crucial for identification of disease. To enable molecular imaging with OCT, we have further developed a technique that harnesses transient changes in light absorption in the sample to garner molecular information. A Fourier-domain Pump-Probe OCT (PPOCT) system utilizing a 532 nm pump and 830 nm probe has been developed for imaging hemoglobin. Methylene blue, a biological dye with well-known photophysics, was used to characterize the system before investigating the origin of the hemoglobin PPOCT signal. The first in vivo PPOCT images were recorded of the vasculature in ...

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    15. In vivo pump-probe optical coherence tomography imaging in Xenopus laevis

      In vivo pump-probe optical coherence tomography imaging in Xenopus laevis

      Currently, optical coherence tomography (OCT), is not capable of obtaining molecular information often crucial for identification of disease. To enable molecular imaging with OCT, we have further developed a technique that harnesses transient changes in light absorption in the sample to garner molecular information. A Fourier-domain Pump-Probe OCT (PPOCT) system utilizing a 532 nm pump and 830 nm probe has been developed for imaging hemoglobin. Methylene blue, a biological dye with well-know photophysics, was used to characterize the system before investigating the origin of the hemoglobin PPOCT signal. The first in vivo PPOCT images were recorded of the vasculature in ...

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    16. Optical coherence tomography for advanced screening in the primary care office

      Optical coherence tomography for advanced screening in the primary care office

      Optical coherence tomography (OCT) has long been used as a diagnostic tool in the field of ophthalmology. The ability to observe microstructural changes in the tissues of the eye has proved very effective in diagnosing ocular disease. However, this technology has yet to be introduced into the primary care office, where indications of disease are first encountered. We have developed a portable, handheld imaging probe for use in the primary care setting and evaluated its tissue site accessibility, ability to observe diseased tissue, and screening capabilities in in vivo human patients, particularly for pathologies related to the eye, ear and ...

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    17. 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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    18. 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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    19. Feature Of The Week 6/20/10: Fourier Domain Pump-Probe Optical Coherence Tomography Imaging

      Feature Of The Week 6/20/10: Fourier Domain Pump-Probe Optical Coherence Tomography Imaging

      Feature Of The Week 6/20/10: Researchers from the Laboratory for Optical and Molecular Imaging at Texas A&M; University have recently published on a fusing Optical Coherence Tomography (OCT) imaging with pump-probe spectroscopy. Shown here is a summary of some of their recent work. Contrast in Optical Coherence Tomography (OCT) is primarily derived from local variations in the scattering coefficient, which does not vary widely among different molecular species. As a consequence, the ability to resolve specific molecular species with OCT is very limited. However, the extraction of molecular information is highly desirable because it could provide valuable ...

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    20. Fourier Domain Pump-Probe Optical Coherence Tomography Imaging of Melanin

      Fourier Domain Pump-Probe Optical Coherence Tomography Imaging of Melanin
      We report the development of a two-color Fourier domain Pump-Probe Optical Coherence Tomography (PPOCT) system. Tissue phantom experiments to characterize the system performance demonstrated imaging depths in excess of 725 μm, nearly comparable to the base Optical Coherence Tomography system. PPOCT A-line rates were also demonstrated in excess of 1 kHz. The physical origin of the PPOCT signal was investigated with a series of experiments which revealed that the signal is a mixture of short and long lifetime component signals. The short lifetime component was attributed to transient absorption while the long lifetime component may be due to a mixture ...
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    1-20 of 20
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    1. (20 articles) Ryan L. Shelton
    2. (14 articles) University of Illinois at Urbana-Champaign
    3. (14 articles) Stephen A. Boppart
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    5. (6 articles) Texas A&M University
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    Fourier Domain Pump-Probe Optical Coherence Tomography Imaging of Melanin Feature Of The Week 6/20/10: Fourier Domain Pump-Probe Optical Coherence Tomography Imaging Quantitative imaging of cochlear soft tissues in wild-type and hearing-impaired transgenic mice by spectral domain optical coherence tomography Imaging high-frequency periodic motion in the mouse ear with coherently interleaved optical coherence tomography Optical coherence tomography for advanced screening in the primary care office In vivo pump-probe optical coherence tomography imaging in Xenopus laevis Feature Of The Week 2/23/14: Texas A&M University Reports on In vivo Pump-Probe Optical Coherence Tomography Imaging in Xenopus Laevis Implementation and evaluation of Google Glass for visualizing real-time image and patient data in the primary care office Non-Invasive Optical Assessment of Viscosity of Middle Ear Effusions in Otitis Media Low-cost hand-held probe for depth-resolved low-coherence interferometry IMAGING TECHNIQUE FROM BECKMAN LAB NAMED TOP 10 MICROSCOPY INNOVATION Optical coherence refraction tomography