1. Articles in category: Otolaryngology

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    1. Stanford University Receives a NIH Grant for Optical Coherence Tomography for 3D Measurements of Cochlear Mechanics In Vivo

      Stanford University Receives a  NIH Grant for Optical Coherence Tomography for 3D Measurements of Cochlear Mechanics In Vivo

      Stanford University Receives a 2015 NIH Grant for $448,758 for Optical Coherence Tomography for 3D Measurements of Cochlear Mechanics In Vivo. The principal investigator is John Oghalai. The program began in 2015 and ends in 2020. Below is a summary of the proposed work. The function of the cochlea is to transduce complex sound pressure waves into electrical signals. Organ of Corti vibration is based upon a complex interplay between passive mechanical structures and active OHC- based processes. While laser Doppler vibrometry has added tremendously to our understanding of cochlear physiology, this technique is limited. Only motion from one ...

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    2. Feature Of The Week 04/05/15: Noninvasive in vivo Imaging Reveals Differences Between Tectorial Membrane and Basilar Membrane Traveling Waves in the Mouse Cochlea

      Feature Of The Week 04/05/15: Noninvasive in vivo Imaging Reveals Differences Between Tectorial Membrane and Basilar Membrane Traveling Waves in the Mouse Cochlea

      Sound is encoded within the auditory portion of the inner ear, the cochlea, after propagating down its length as a traveling wave. For over half a century, vibratory measurements to study cochlear traveling waves have been made using invasive approaches such as laser Doppler vibrometry. While these studies have provided critical information regarding the non-linear processes within the living cochlea that increase the amplitude of vibration and sharpen frequency tuning, the data have typically been limited to point measurements of basilar membrane vibration. In addition, opening the cochlea may alter its function and affect the findings. Here we describe volumetric ...

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    3. Evaluation of the usefulness of three-dimensional optical coherence tomography in a guinea pig model of endolymphatic hydrops induced by surgical obliteration of the endolymphatic duct

      Evaluation of the usefulness of three-dimensional optical coherence tomography in a guinea pig model of endolymphatic hydrops induced by surgical obliteration of the endolymphatic duct

      Optical coherence tomography (OCT) has advanced significantly over the past two decades and is currently used extensively to monitor the internal structures of organs, particularly in ophthalmology and dermatology. We used ethylenediamine tetra-acetic acid (EDTA) to decalcify the bony walls of the cochlea and investigated the inner structures by deep penetration of light into the cochlear tissue using OCT on a guinea pig model of endolymphatic hydrops (EH), induced by surgical obliteration of the endolymphatic duct. The structural and functional changes associated with EH were identified using OCT and auditory brainstem response tests, respectively. We also evaluated structural alterations in ...

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    4. Elasticity measurement of nasal cartilage as a function of temperature using optical coherence elastography

      Elasticity measurement of nasal cartilage as a function of temperature using optical coherence elastography

      Current clinical methods of reconstruction surgery involve laser reshaping of nasal cartilage. The process of stress relaxation caused by laser heating is the primary method to achieve nasal cartilage reshaping. Based on this, a rapid, non-destructive and accurate elasticity measurement would allow for a more robust reshaping procedure. In this work, we have utilized a phase-stabilized swept source optical coherence elastography (PhSSSOCE) to quantify the Young’s modulus of porcine nasal septal cartilage during the relaxation process induced by heating. The results show that PhS-SSOCE was able to monitor changes in elasticity of hyaline cartilage, and this method could potentially ...

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    5. In vivo microvascular imaging of human oral and nasal cavities using swept-source optical coherence tomography with a single forward/side viewing probe

      In vivo microvascular imaging of human oral and nasal cavities using swept-source optical coherence tomography with a single forward/side viewing probe

      We report three-dimensional (3D) imaging of microcirculation within human cavity tissues in vivo using a high-speed swept-source optical coherence tomography (SS-OCT) at 1.3 μm with a modified probe interface. Volumetric structural OCT images of the inner tissues of oral and nasal cavities are acquired with a field of view of 2 mm x 2 mm. Two types of disposable and detachable probe attachments are devised and applied to the port of the imaging probe of OCT system, enabling forward and side imaging scans for selective and easy access to specific cavity tissue sites. Blood perfusion is mapped with OCT-based ...

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    6. Noninvasive in vivo imaging reveals differences between tectorial membrane and basilar membrane traveling waves in the mouse cochlea

      Noninvasive in vivo imaging reveals differences between tectorial membrane and basilar membrane traveling waves in the mouse cochlea

      Sound is encoded within the auditory portion of the inner ear, the cochlea, after propagating down its length as a traveling wave. For over half a century, vibratory measurements to study cochlear traveling waves have been made using invasive approaches such as laser Doppler vibrometry. Although these studies have provided critical information regarding the nonlinear processes within the living cochlea that increase the amplitude of vibration and sharpen frequency tuning, the data have typically been limited to point measurements of basilar membrane vibration. In addition, opening the cochlea may alter its function and affect the findings. Here we describe volumetric ...

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    7. Two dimensional vibrations of the guinea pig apex organ of Corti measured in vivo using phase sensitive Fourier domain optical coherence tomography

      Two dimensional vibrations of the guinea pig apex organ of Corti measured in vivo using phase sensitive Fourier domain optical coherence tomography

      In this study, we measure the in vivo apical-turn vibrations of the guinea pig organ of Corti in both axial and radial directions using phase-sensitive Fourier domain optical coherence tomography. The apical turn in guinea pig cochlea has best frequencies around 100 – 500 Hz which are relevant for human speech. Prior measurements of vibrations in the guinea pig apex involved opening the otic capsule, which has been questioned on the basis of the resulting changes to cochlear hydrodynamics. Here this limitation is overcome by measuring the vibrations through bone without opening the otic capsule. Furthermore, we have significantly reduced the ...

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    8. Optical coherence tomography for the diagnosis and evaluation of human otitis media

      Optical coherence tomography for the diagnosis and evaluation of human otitis media

      We report the application of optical coherence tomography (OCT) to the diagnosis and evaluation of otitis media (OM). Whereas conventional diagnostic modalities for OM, including standard and pneumatic otoscopy, are limited to visualizing the surface of the tympanic membrane (TM), OCT effectively reveals the depth-resolved microstructure below the TM with very high spatial resolution, with the potential advantage of its use for diagnosing different types of OM. We examined the use of 840-nm spectral domain-OCT (SD-OCT) clinically, using normal ears and ears with the adhesive and effusion types of OM. Specific features were identified in two-dimensional OCT images of abnormal ...

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    9. 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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    10. 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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    11. Optical coherence tomography and autofluorescence imaging of human tonsil

      Optical coherence tomography and autofluorescence imaging of human tonsil

      For the first time, we present co-registered autofluorescence imaging and optical coherence tomography (AF/OCT) of excised human palatine tonsils to evaluate the capabilities of OCT to visualize tonsil tissue components. Despite limited penetration depth, OCT can provide detailed structural information about tonsil tissue with much higher resolution than that of computed tomography, magnetic resonance imaging, and Ultrasound. Different tonsil tissue components such as epithelium, dense connective tissue, lymphoid nodules, and crypts can be visualized by OCT. The co-registered AF imaging can provide matching biochemical information. AF/OCT scans may provide a non-invasive tool for detecting tonsillar cancers and for ...

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    12. Intraoperative long range optical coherence tomography as a novel method of imaging the pediatric upper airway before and after adenotonsillectomy

      Intraoperative long range optical coherence tomography as a novel method of imaging the pediatric upper airway before and after adenotonsillectomy

      Background/Objectives While upper airway obstruction is a common problem in the pediatric population, the first-line treatment, adenotonsillectomy, fails in up to 20% of patients. The decision to proceed to surgery is often made without quantitative anatomic guidance. We evaluated the use of a novel technique, long-range optical coherence tomography (LR-OCT), to image the upper airway of children under general anesthesia immediately before and after tonsillectomy and/or adenoidectomy. We investigated the feasibility of LR-OCT to identify both normal anatomy and sites of airway narrowing and to quantitatively compare airway lumen size in the oropharyngeal and nasopharyngeal regions pre- and ...

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    13. Intraoperative optical coherence tomography imaging to identify parathyroid glands

      Intraoperative optical coherence tomography imaging to identify parathyroid glands

      Objective Optical coherence tomography (OCT) is a non-invasive high-resolution imaging technique that permits characterization of microarchitectural features in real time. Previous ex vivo studies have shown that the technique is capable of distinguishing between parathyroid tissue, thyroid tissue, lymph nodes, and adipose tissue. The purpose of this study was to evaluate the practicality of OCT during open and minimally invasive parathyroid and thyroid surgery. Methods During parathyroid and thyroid surgery, OCT images were generated from parathyroid glands, thyroid tissue, lymph nodes, and adipose tissue. The images were immediately assessed by the operating team using the previously defined criteria. Second, the ...

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    14. Long-range Fourier domain optical coherence tomography of the pediatric subglottis

      Long-range Fourier domain optical coherence tomography of the pediatric subglottis

      Background Acquired subglottic stenosis (SGS) most commonly results from prolonged endotracheal intubation and is a diagnostic challenge in the intubated child. At present, no imaging modality allows for in vivo characterization of subglottic microanatomy to identify early signs of acquired SGS while the child remains intubated. Fourier domain optical coherence tomography (FD-OCT) is a minimally invasive, light-based imaging modality which provides high resolution, three dimensional (3D) cross-sectional images of biological tissue. We used long-range FD-OCT to image the subglottis in intubated pediatric patients undergoing minor head and neck surgical procedures in the operating room. Methods A long-range FD-OCT system and ...

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    15. Method and apparatus for cochlear implant surgery

      Method and apparatus for cochlear implant surgery

      A system for cochlear implant surgery includes a reference device having at least a portion adapted to be arranged at a fixed position relative to a cochlea of a patient to provide a reference position, an image acquisition and processing system adapted to acquire an image of at least a portion of the cochlea relative to the reference position and to provide an implant plan based at least partially on the acquired image, and an implant system adapted for implanting a cochlear lead array using the reference position and the implant plan.

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    16. Phase-sensitive optical coherence tomography using an Vernier-tuned distributed Bragg reflector swept laser in the mouse middle ear

      Phase-sensitive optical coherence tomography using an Vernier-tuned distributed Bragg reflector swept laser in the mouse middle ear

      Phase-sensitive optical coherence tomography (PhOCT) offers exquisite sensitivity to mechanical vibration in biological tissues. There is growing interest in using PhOCT for imaging the nanometer scale vibrations of the ear in animal models of hearing disorders. Swept-source-based systems offer fast acquisition speeds, suppression of common mode noise via balanced detection, and good signal roll-off. However, achieving high phase stability is difficult due to nonlinear laser sweeps and trigger jitter in a typical swept laser source. Here, we report on the initial application of a Vernier-tuned distributed Bragg reflector (VT-DBR) swept laser as the source for a fiber-based PhOCT system. The ...

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    17. Optical coherence tomography guided laser cochleostomy: towards the accuracy on tens of micrometer scale

      Optical coherence tomography guided laser cochleostomy: towards the accuracy on tens of micrometer scale

      Lasers have been proven to be precise tools for bone ablation. Applying no mechanical stress to the patient, they are potentially very suitable for microsurgery on fragile structures such as the inner ear. However, it remains challenging to control the laser-bone ablation without injuring embedded soft tissue. In this work, we demonstrate a closed-loop control of a short-pulsed CO 2 laser to perform laser cochleostomy under the monitoring of an optical coherence tomography (OCT) system. A foresighted detection of the bone-endosteum-perilymph boundary several hundred micrometers before its exposure has been realized. Position and duration of the laser pulses are planned ...

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    18. The role of physics in inner-ear physiology and auditory perception

      The role of physics in inner-ear physiology and auditory perception

      Auditory analysis of acoustical stimuli has mainly been connected with Fourier analysis. This touches the basic link between auditory perception and the operation of the hearing organs, namely, physics and mathematics. This relation has amply been demonstrated by the work and ideas of Georg von Békésy. Later, the healthy cochlea (inner ear) was found to contain amplifying elements that boost frequency selectivity. Associated with this there is a pronounced nonlinearity. Furthermore, the ear does not only absorb and process sounds, it also emits sound waves. Mathematical models of all these processes must contain subsets serving them all, a ...

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    19. Visualization of Maculae and Membranous Semicircular Ducts in the Otic Capsule by Optical Coherence Tomography

      Visualization of Maculae and Membranous Semicircular Ducts in the Otic Capsule by Optical Coherence Tomography

      Objectives: (1) Show the possibility of using optical coherence tomography (OCT) to visualize the internal structure of the vestibule and semicircular canals with the bony capsule intact. (2) Study the effect of the decalcification. OCT is a nondestructive imaging modality that uses infrared light as it penetrates turbid biological tissue. Previously, OCT has been successfully used to visualize inside the cochlea in normal and abnormal inner ears. Methods: The OCT system, OCS-1300SS (Thorlabs, Inc, NJ) with a central wavelength of 1300 nm and a theoretical axial resolution of 9 µm, was employed for image acquisition. Normal and Slc26a4 mutant mice ...

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    20. First Use of Long-Range Optical Coherence Tomography to Image Airway Structure in Awake Children

      First Use of Long-Range Optical Coherence Tomography to Image Airway Structure in Awake Children

      Objectives: Identifying the appropriate operation(s) for children with sleep-disordered breathing (SDB) remains a challenge, and current imaging modalities have major shortcomings. We have pioneered the use of long-range optical coherence tomography (LR-OCT) to provide real-time images of the upper airway (UA) during sleep and wakefulness. Here we present our first use of LR-OCT to image the UA of awake children. (1) Understand how LR-OCT produces high-resolution structural images by acting as an optical range-finder. (2) Recognize how LR-OCT can identify strictures and real-time collapse of the airway. Methods: This study builds upon our experience using LR-OCT to image 58 ...

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    21. Experimental and Modeling Study of Human Tympanic Membrane Motion in the Presence of Middle Ear Liquid

      Experimental and Modeling Study of Human Tympanic Membrane Motion in the Presence of Middle Ear Liquid

      Vibration of the tympanic membrane (TM) has been measured at the umbo using laser Doppler vibrometry and analyzed with finite element (FE) models of the human ear. Recently, full-field TM surface motion has been reported using scanning laser Doppler vibrometry, holographic interferometry, and optical coherence tomography. Technologies for imaging human TM motion have the potential to lead to using a dedicated clinical diagnosis tool for identification of middle ear diseases. However, the effect of middle ear fluid (liquid) on TM surface motion is still not clear. In this study, a scanning laser Doppler vibrometer was used to measure the full-field ...

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    22. Do You Hear That? It Sounds Like a Technology Breakthrough

      Do You Hear That? It Sounds Like a Technology Breakthrough

      The inner workings of the ear have been a mystery for decades. However, that’s all about to change thanks to the efforts of a team of researchers determined to shed some light on the hearing process. Researchers from Stanford University and Texas A&M are working on mapping the tissues of the cochlea, the portion of the inner ear responsible for hearing. To map the cochlea, they used a technique known as optical coherence tomography (OCT) on animal models. OCT is similar to ultrasound but generates very high-resolution images, along with terabytes of measurement data. This data must be ...

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    23. High-resolution images of inner ear could lead to new hearing loss therapies

      High-resolution images of inner ear could lead to new hearing loss therapies

      Understanding how hearing works has long been hampered by challenges associated with seeing inside the inner ear, but technology being developed by a team of researchers that includes a biomedical engineer from Texas A&M University is generating some of the most detailed images of the inner ear to date while offering new insight into the mechanics of hearing that could lead to new therapies for hearing loss. Employing a technique that generates high-resolution, three-dimensional images, Brian Applegate, associate professor in the Department of Biomedical Engineering at Texas A&M, and colleagues from Stanford University are mapping the tissues within ...

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    24. Observing cochlear function

      Observing cochlear function

      Phase-sensitive optical coherence tomography measures the morphology and functional vibratory response in the mouse cochlea and helps decipher the complex mechanical processes responsible for hearing.  Hearing loss is the most common sensory health issue due to the multiple effects of noise, aging, disease, and heredity. According to the World Health Organization, more than 360 million people worldwide suffer from disabling hearing loss. 1 Current therapies for hearing loss treat some of the symptoms by providing volume amplification, but there are no curative therapies. The development of effective therapies significantly depends upon a detailed understanding of the complex mechanisms of the ...

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