1. Articles from Zhongping Chen

    1-24 of 206 1 2 3 4 5 6 7 8 9 »
    1. Coupling Pressure Sensing with Optical Coherence Tomography to Evaluate the Internal Nasal Valve

      Coupling Pressure Sensing with Optical Coherence Tomography to Evaluate the Internal Nasal Valve

      Purpose: To evaluate endoscopic long-range optical coherence tomography system combined with a pressure sensor to concurrently measure internal nasal valve cross-sectional area and intraluminal pressure. Methods: A pressure sensor was constructed using an Arduino platform and calibrated using a limiter-controlled vacuum system and industrial absolute pressure gauge. Long-range optical coherence tomography imaging and pressure transduction were performed concurrently in the naris of eight healthy adult subjects during normal respiration and forced inspiration. The internal nasal valve was manually segmented using Mimics software and cross-sectional area was measured. Internal nasal valve cross-sectional area measurements were correlated with pressure recordings. Results: Mean ...

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    2. Ultrahigh-sensitive optical coherence elastography

      Ultrahigh-sensitive optical coherence elastography

      The phase stability of an optical coherence elastography (OCE) system is the key determining factor for achieving a precise elasticity measurement, and it can be affected by the signal-to-noise ratio (SNR), timing jitters in the signal acquisition process, and fluctuations in the optical path difference (OPD) between the sample and reference arms. In this study, we developed an OCE system based on swept-source optical coherence tomography (SS-OCT) with a common-path configuration (SS-OCECP). Our system has a phase stability of 4.2 mrad without external stabilization or extensive post-processing, such as averaging. This phase stability allows us to detect a ...

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    3. Optical Vaginal Biopsy Using Optical Coherence Tomography

      Optical Vaginal Biopsy Using Optical Coherence Tomography

      Objective Optical coherence tomography is a noninvasive technology that visualizes tissue microstructure with high spatial resolution. We designed a novel vaginal system that demonstrates a clear distinction between vaginal tissues planes. In this study, we sought to compare vaginal tomographic images of premenopausal, perimenopausal, and postmenopausal women, demonstrate feasibility of tracking vaginal tissue changes after treatment with fractional-pixel CO 2 laser therapy, and obtain a histologic correlation of these findings. Methods Enrolled subjects underwent imaging and were divided into 3 groups based on menopausal status. Women with genitourinary syndrome of menopause who received fractional-pixel CO 2 laser therapy were assessed ...

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    4. Extended imaging depth of en-face optical coherence tomography based on fast measurement of a reflection matrix by wide-field heterodyne detection

      Extended imaging depth of en-face optical coherence tomography based on fast measurement of a reflection matrix by wide-field heterodyne detection

      Multiple light scattering in biomedical tissue limits the penetration depth of optical imaging systems such as optical coherence tomography. To increase the imaging depth in scattering media, a computational method based on coherent reflection matrix measurement has been developed using low coherence interferometry. The complex reflection matrix is obtained via point-by-point scanning followed by a phase-shifting method; then singular value decomposition is used to retrieve the singly back-scattered light. However, the in vivo application of the current reported method is limited due to the slow acquisition speed of the matrix. In this Letter, a wide-field heterodyne-detection method is adopted to ...

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    5. In vivo evaluation of posterior eye elasticity using shaker-based optical coherence elastography

      In vivo evaluation of posterior eye elasticity using shaker-based optical coherence elastography

      Age-related macular degeneration (AMD) is a progressive retinal disease and becomes the leading cause of blindness. It is well established that early detection is the key to preservation of functional vision. However, it is very difficult to diagnose AMD in very early stages, before structural changes are evident. Consequently, investigating the biomechanical properties of the retina maybe essential for understanding its physiological function. In this study, we present a shear wave-based quantitative method for estimating the elasticity of the posterior eye using shaker-based optical coherence elastography. This technique has been developed and validated on both a homogeneous phantom and a ...

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    6. Spatiotemporal dynamics of pial collateral blood flow following permanent middle cerebral artery occlusion in a rat model of sensory-based protection: a Doppler optical coherence tomography study

      Spatiotemporal dynamics of pial collateral blood flow following permanent middle cerebral artery occlusion in a rat model of sensory-based protection: a Doppler optical coherence tomography study

      There is a growing recognition regarding the importance of pial collateral flow in the protection from impending ischemic stroke both in preclinical and clinical studies. Collateral flow is also a major player in sensory stimulation-based protection from impending ischemic stroke. Doppler optical coherence tomography has been employed to image spatiotemporal patterns of collateral flow within the dorsal branches of the middle cerebral artery (MCA) as it provides a powerful tool for quantitative in vivo flow parameters imaging (velocity, flux, direction of flow, and radius of imaged branches). It was employed prior to and following dorsal permanent MCA occlusion (pMCAo) in ...

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    7. The Use of Optical Coherence Tomography and Convolutional Neural Networks to Distinguish Normal and Abnormal Oral Mucosa

      The Use of Optical Coherence Tomography and Convolutional Neural Networks to Distinguish Normal and Abnormal Oral Mucosa

      Incomplete surgical resection of head and neck squamous cell carcinoma (HNSCC) is the most common cause of local HNSCC recurrence. Currently, surgeons rely on pre‐operative imaging, direct visualization, palpation, and frozen section to determine the extent of tissue resection. It has been demonstrated that optical coherence tomography (OCT), a minimally invasive, non‐ionizing near infrared mesoscopic imaging modality can resolve subsurface differences between normal and abnormal head and neck mucosa. Previous work has utilized 2‐D OCT imaging which is limited to the evaluation of a small regions of interest generated frame by frame. OCT technology is capable of ...

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    8. Method to characterize cut gemstones using optical coherence tomography

      Method to characterize cut gemstones using optical coherence tomography

      The invention includes an improvement in a method of assessing a gemstone having at least one planar face with an internally reflecting surface including the steps of optically modifying the at least one planar face of the gemstone to return a sample beam from an internally reflecting plane corresponding to the at least one planar face to an optical coherence tomography (OCT) system; selectively directing the sample beam from an optical coherence tomography (OCT) system onto the gemstone; and generating an OCT image map of the gemstone to determine volume, gem carat weight and/or quality.

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    9. Acoustic Radiation Force Optical Coherence Elastography

      Acoustic Radiation Force Optical Coherence Elastography

      Mechanical properties, such as the elasticity and viscosity, are often major indicators of diseases. Over the years, tissue mechanical properties have been demonstrated to be an early indicator for cardiovascular disease. Mechanical imaging technologies have been quickly evolving with a goal to effectively diagnose coronary artery disease and atherosclerosis in their early stages. By combining the advantages of acoustic and optical properties, acoustic radiation force optical coherence elastography (ARF-OCE) has become an imaging tool with a high potential for translation into clinics. In this chapter, we review the principles of OCE and describe the development of ARF-OCE systems for imaging ...

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    10. Endoscopic Optical Coherence Tomography for Assessing Inhalation Airway Injury: A Technical Review

      Endoscopic Optical Coherence Tomography for Assessing Inhalation Airway Injury: A Technical Review

      Diagnosis of inhalation injury has been clinically challenging. Currently, assessment of inhalation injury relies on subjective clinical exams and bronchoscopy, which provides little understanding of tissue conditions and results in limited prognostics. Endoscopic Optical coherence tomography (OCT) technology has been recently utilized in the airway for direct assessment of respiratory tract disorders and injuries. Endoscopic OCT is capable of capturing highresolution images of tissue morphology 1-3 mm beneath the surface as well as the complex 3D anatomical shape. Previous studies indicate that changes in airway histopathology can be found in the OCT image almost immediately after inhalation of smoke and ...

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    11. Dynamic programming and automated segmentation of optical coherence tomography images of the neonatal subglottis: enabling efficient diagnostics to manage subglottic stenosis

      Dynamic programming and automated segmentation of optical coherence tomography images of the neonatal subglottis: enabling efficient diagnostics to manage subglottic stenosis

      Subglottic stenosis (SGS) is a challenging disease to diagnose in neonates. Long-range optical coherence tomography (OCT) is an optical imaging modality that has been described to image the subglottis in intubated neonates. A major challenge associated with OCT imaging is the lack of an automated method for image analysis and micrometry of large volumes of data that are acquired with each airway scan (1 to 2 Gb). We developed a tissue segmentation algorithm that identifies, measures, and conducts image analysis on tissue layers within the mucosa and submucosa and compared these automated tissue measurements with manual tracings. We noted small ...

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    12. Assessment of blood coagulation using an acoustic radiation force based optical coherence elastography (ARF-OCE)

      Assessment of blood coagulation using an acoustic radiation force based optical coherence elastography (ARF-OCE)

      An apparatus and method of using an optical coherence elastography (OCE) under acoustic radiation force (ARF) excitation includes the steps of inducing an excitation wave in a blood sample by use of an ultrasound beam from an ultrasonic transducer; measuring an elastic property of the blood sample by use of an optical coherence tomography (OCT) beam transverse to the ultrasound beam to dynamically measure the elastic property of the blood sample during coagulation and assessing the clot formation/dissolution kinetics and strength.

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    13. Fiber-based polarization-sensitive optical coherence tomography of a minimalistic system configuration

      Fiber-based polarization-sensitive optical coherence tomography of a minimalistic system configuration

      We present a very simple method of constructing a polarization-sensitive optical coherence tomography (PS-OCT) system. An ordinary fiber-based swept-source OCT system was reconfigured for PS-OCT by adding a long section of polarization-maintaining fiber in the sample arm. Two polarization modes of a large group-delay difference formed spatially distinguished polarization channels. The depth-encoded information on the polarization states was retrieved by an amplitude-based analysis. We found that our method provides an economic scheme of PS-OCT. It demonstrates that an ordinary OCT system can be easily reconfigured for PS-OCT imaging if it has sufficient margins in the imaging range.

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    14. Multimodal endoscopy for colorectal cancer detection by optical coherence tomography and near-infrared fluorescence imaging

      Multimodal endoscopy for colorectal cancer detection by optical coherence tomography and near-infrared fluorescence imaging

      While colonoscopy is the gold standard for diagnosis and classification of colorectal cancer (CRC), its sensitivity and specificity are operator-dependent and are especially poor for small and flat lesions. Contemporary imaging modalities, such as optical coherence tomography (OCT) and near-infrared (NIR) fluorescence, have been investigated to visualize microvasculature and morphological changes for detecting early stage CRC in the gastrointestinal (GI) tract. In our study, we developed a multimodal endoscopic system with simultaneous co-registered OCT and NIR fluorescence imaging. By introducing a contrast agent into the vascular network, NIR fluorescence is able to highlight the cancer-suspected area based on significant change ...

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    15. Automatic Proximal Airway Volume Segmentation Using Optical Coherence Tomography for Assessment of Inhalation Injury

      Automatic Proximal Airway Volume Segmentation Using Optical Coherence Tomography for Assessment of Inhalation Injury

      Background Acute respiratory distress syndrome (ARDS) is a severe form of acute lung injury with a mortality rate of up to 40%. Early management of ARDS has been difficult due to the lack of sensitive imaging tools and robust analysis software. We previously designed an optical coherence tomography (OCT) system to evaluate mucosa thickness (MT) post smoke inhalation, but the analysis relied on manual segmentation. The aim of this study is to assess in vivo proximal airway volume (PAV) after inhalation injury using automated OCT segmentation and correlate the PAV to lung function for rapid indication of ARDS. Methods Anesthetized ...

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    16. The effect of melanin on in vivo optical coherence tomography of the skin in a multiethnic cohort

      The effect of melanin on in vivo optical coherence tomography of the skin in a multiethnic cohort

      Background Noninvasive real‐time assessment of living tissue is quickly becoming invaluable for bolstering histologic and dermatoscopic measures of cutaneous conditions. While many skin researchers have explored the utility of noninvasive imaging in inflammatory and malignant skin conditions, there is yet to be a definitive and direct assessment of the effects of melanin on the quality of optical coherence tomography (OCT) imaging and its accuracy in multiethnic patient populations. We conducted a study to evaluate the effects of melanin on the quality of in vivo OCT imaging. Methods Volunteers of all Fitzpatrick skin types were imaged once in five skin ...

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    17. Intra-operative point-of-procedure delineation of oral cancer margins using optical coherence tomography

      Intra-operative point-of-procedure delineation of oral cancer margins using optical coherence tomography

      Objectives Surgical margin status is a significant determinant of treatment outcome in oral cancer. Negative surgical margins can decrease the loco-regional recurrence by five-fold. The current standard of care of intraoperative clinical examination supplemented by histological frozen section, can result in a risk of positive margins from 5 to 17 percent. In this study, we attempted to assess the utility of intraoperative optical coherence tomography (OCT) imaging with automated diagnostic algorithm to improve on the current method of clinical evaluation of surgical margin in oral cancer. Materials and methods We have used a modified handheld OCT device with automated algorithm ...

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    18. Integrated ultrasound, OCT, PA and/or florescence imaging endoscope for diagnosing cancers in gastrointestinal, respiratory, and urogenital tracts

      Integrated ultrasound, OCT, PA and/or florescence imaging endoscope for diagnosing cancers in gastrointestinal, respiratory, and urogenital tracts

      A multimodality imaging system including ultrasound, optical coherence tomography (OCT), photoacoustic (PA) imaging, florescence imaging and endoscopic catheter for imaging inside the gastrointestinal tract with real-time automatic image co-registration capability, including: an ultrasound subsystem for imaging; an optical coherence tomography (OCT) subsystem for imaging, a PA microscopy or tomography subsystem for imaging and a florescence imaging subsystem for imaging. An invasive interventional imaging device is included with an instrumentality to take a tissue biopsy from a location visible on the ultrasound subsystem for imaging, on the optical coherence tomography (OCT) subsystem for imaging, photoacoustic (PA) subsystem for imaging and florescence ...

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    19. Perspective: Current challenges and solutions of Doppler optical coherence tomography and angiography for neuroimaging

      Perspective: Current challenges and solutions of Doppler optical coherence tomography and angiography for neuroimaging

      The nervous system, based on a complex network of nerves and cells, carries messages by transmitting signals to and from different parts of the body. The supply of blood flow in the nervous system is critical to maintain physiological functions. Optical coherence tomography (OCT) has the ability to noninvasively image the microvascular networks and accurately quantify the blood flow in vivo with high spatial and temporal resolutions in three dimensions. It has been used to measure changes in blood supplies and assess physiological functions before and after occurrences of diseases, drug administration, and external stimulation in the nervous system, especially ...

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    20. Point-of-care endoscopic optical coherence tomography detects changes in mucosal thickness in ARDS due to smoke inhalation and burns

      Point-of-care endoscopic optical coherence tomography detects changes in mucosal thickness in ARDS due to smoke inhalation and burns

      Background The prevalence of acute respiratory distress syndrome (ARDS) in mechanically ventilated burn patients is 33%, with mortality varying from 11–46% depending on ARDS severity. Despite the new Berlin definition for ARDS, prompt bedside diagnosis is lacking. We developed and tested a bedside technique of fiberoptic-bronchoscopy-based optical coherence tomography (OCT) measurement of airway mucosal thickness (MT) for diagnosis of ARDS following smoke inhalation injury (SII) and burns. Methods 16 female Yorkshire pigs received SII and 40% thermal burns. OCT MT and PaO 2 -to-FiO 2 ratio (PFR) measurements were taken at baseline, after injury, and at 24, 48, and ...

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    21. Phase-stability optimization of swept-source optical coherence tomography

      Phase-stability optimization of swept-source optical coherence tomography

      Phase-resolved imaging of swept-source optical coherence tomography (SS-OCT) is subject to phase measurement instabilities involved with the sweep variation of a frequency-swept source. In general, optically generated timing references are utilized to track the variations imposed on OCT signals. But they might not be accurately synchronized due to relative time delays. In this research, we investigated the impact of the signal delays on the timing instabilities and the consequent deviations of the measured phases. We considered two types of timing signals utilized in a popular digitizer operation mode: a sweep trigger from a fiber Bragg grating (FBG) that initiates a ...

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    22. Optical Coherence Tomography as an Oral Cancer Screening Adjunct in a Low Resource Settings

      Optical Coherence Tomography as an Oral Cancer Screening Adjunct in a Low Resource Settings

      Oral cancer is the sixth most common cancer worldwide, predominantly seen in low and middle-income countries (LMIC). Two thirds of all cases are detected at a late stage when prognosis and treatment outcomes are poor. Oral lesions are commonly detected by visual inspection, followed by invasive surgical biopsy and time consuming histopathological analysis. Optical Coherence Tomography (OCT), a minimally invasive tomographic imaging technology, can be used to non-invasively identify premalignant or malignant change in the oral mucosa. In this study, a mobile OCT imaging system was designed, constructed and tested for its performance as a point-of-care oral diagnostic device. Twenty ...

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    23. 1.7 micron optical coherence tomography for vaginal tissue characterization in vivo

      1.7 micron optical coherence tomography for vaginal tissue characterization in vivo

      Objectives Optical coherence tomography (OCT) can noninvasively visualize in vivo tissue microstructure with high spatial resolution that approaches the histologic level. Currently, OCT studies in gynecology are few and limited to a conventional 1.3 μm center wavelength swept light source which provides high spatial resolution but limited penetration depth. Here, we present a novel endoscopic OCT system with improved penetration depth and high resolution. Methods A novel endoscopic OCT system was developed based on a 1.7 µm swept source laser, which is capable of deeper tissue penetration due to its longer wavelength. To evaluate the performance of system ...

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    24. Upper airway reconstruction using long‐range optical coherence tomography: Effects of airway curvature on airflow resistance

      Upper airway reconstruction using long‐range optical coherence tomography: Effects of airway curvature on airflow resistance

      Objectives Adenotonsillectomy (AT) is commonly used to treat upper airway obstruction in children, but selection of patients who will benefit most from AT is challenging. The need for diagnostic evaluation tools without sedation, radiation, or high costs has motivated the development of long‐range optical coherence tomography (LR‐OCT), providing real‐time cross‐sectional airway imaging during endoscopy. Since the endoscope channel location is not tracked in conventional LR‐OCT, airway curvature must be estimated and may affect predicted airway resistance. The study objective was to assess effects of three realistic airway curvatures on predicted airway resistance using computational fluid ...

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    1-24 of 206 1 2 3 4 5 6 7 8 9 »
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    1. (205 articles) Zhongping Chen
    2. (197 articles) UC Irvine
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