1. Articles from Stephen A. Boppart

    1-24 of 176 1 2 3 4 5 6 7 8 »
    1. Diagnostic accuracy of optical coherence tomography for surgical margin assessment of feline injection-site sarcoma

      Diagnostic accuracy of optical coherence tomography for surgical margin assessment of feline injection-site sarcoma

      The invasive, locally aggressive nature of feline injection-site sarcomas (FISS) pose a unique challenge for surgeons to obtain complete margins with surgical excision. Optical coherence tomography (OCT), an imaging technology that uses light waves to generate real-time views of tissue architecture, provides an emerging solution to this dilemma by allowing fast, high-resolution scanning of surgical margins. The purpose of this study was to use OCT to assess surgical margins of FISS and to evaluate the diagnostic accuracy of OCT for detecting residual cancer using six evaluators of varying experience. Five FISS were imaged with OCT to create a training set ...

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    2. Synthetic polarization-sensitive optical coherence tomography by deep learning

      Synthetic polarization-sensitive optical coherence tomography by deep learning

      Polarization-sensitive optical coherence tomography (PS-OCT) is a high-resolution label-free optical biomedical imaging modality that is sensitive to the microstructural architecture in tissue that gives rise to form birefringence, such as collagen or muscle fibers. To enable polarization sensitivity in an OCT system, however, requires additional hardware and complexity. We developed a deep-learning method to synthesize PS-OCT images by training a generative adversarial network (GAN) on OCT intensity and PS-OCT images. The synthesis accuracy was first evaluated by the structural similarity index (SSIM) between the synthetic and real PS-OCT images. Furthermore, the effectiveness of the computational PS-OCT images was validated by ...

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    3. Differentiation of breast tissue types for surgical margin assessment using machine learning and polarization-sensitive optical coherence tomography

      Differentiation of breast tissue types for surgical margin assessment using machine learning and polarization-sensitive optical coherence tomography

      We report an automated differentiation model for classifying malignant tumor, fibro-adipose, and stroma in human breast tissues based on polarization-sensitive optical coherence tomography (PS-OCT). A total of 720 PS-OCT images from 72 sites of 41 patients with H&E histology-confirmed diagnoses as the gold standard were employed in this study. The differentiation model is trained by the features extracted from both one standard OCT-based metric (i.e., intensity) and four PS-OCT-based metrics (i.e., phase difference between two channels ( PD ), phase retardation ( PR ), local phase retardation ( LPR ), and degree of polarization uniformity ( DOPU )). Further optimized by forward searching and validated ...

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    4. Biomechanical sensing of in vivo magnetic nanoparticle hyperthermia-treated melanoma using magnetomotive optical coherence elastography

      Biomechanical sensing of in vivo magnetic nanoparticle hyperthermia-treated melanoma using magnetomotive optical coherence elastography

      Rationale: Magnetic nanoparticle hyperthermia (MH) therapy is capable of thermally damaging tumor cells, yet a biomechanically-sensitive monitoring method for the applied thermal dosage has not been established. Biomechanical changes to tissue are known indicators for tumor diagnosis due to its association with the structural organization and composition of tissues at the cellular and molecular level. Here, by exploiting the theranostic functionality of magnetic nanoparticles (MNPs), we aim to explore the potential of using stiffness-based metrics that reveal the intrinsic biophysical changes of in vivo melanoma tumors after MH therapy. Methods: A total of 14 melanoma-bearing mice were intratumorally injected with ...

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    5. Compressive sensing for polarization sensitive optical coherence tomography

      Compressive sensing for polarization sensitive optical coherence tomography

      In this work, we reported on the implementation of compressive sensing (CS) and sparse sampling in polarization - sensitive optical coherence tomography (PS-OCT) to reduce the number of B-scans (frames consisting of an array of A-scans, where each represents a single depth profile of reflections) required for effective volumetric (3D dataset composed of an array of B-scans) PS-OCT mea surements (i.e., OCT intensity, and phase retardation) reconstruction. Sparse sampling of PS-OCT is achieved through randomization of step sizes along slow-axis of PS-OCT imaging, covering the same spatial ranges as those with equal slow-axis step sizes, but with a reduced number ...

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    6. Computational adaptive optics for polarization-sensitive optical coherence tomography

      Computational adaptive optics for polarization-sensitive optical coherence tomography

      Defocus aberration in optical systems, including optical coherence tomography (OCT) systems employing Gaussian illumination, gives rise to the well-known compromise between transverse resolution and depth-of-field. This results in blurry images when out-of-focus, whilst other low-order aberrations (e.g., astigmatism, coma, etc.) present in both the OCT system and biological samples further reduce image resolution and contrast. Computational adaptive optics (CAO) is a computed optical interferometric imaging technique that modifies the phase of the OCT data in the spatial frequency domain to correct optical aberrations and provide improvement of the image quality throughout the three-dimensional (3D) volume. In this Letter, we ...

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    7. Longitudinal optical coherence tomography to visualize the in vivo response of middle ear biofilms to antibiotic therapy

      Longitudinal optical coherence tomography to visualize the in vivo response of middle ear biofilms to antibiotic therapy

      Studying the impact of antibiotic treatment on otitis media (OM), the leading cause of primary care office visits during childhood, is critical to develop appropriate treatment strategies. Tracking dynamic middle ear conditions during antibiotic treatment is not readily applicable in patients, due to the limited diagnostic techniques available to detect the smaller amount and variation of middle ear effusion (MEE) and middle ear bacterial biofilm, responsible for chronic and recurrent OM. To overcome these challenges, a handheld optical coherence tomography (OCT) system has been developed to monitor in vivo response of biofilms and MEEs in the OM-induced chinchilla model, the ...

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    8. Simultaneous 4-phase-shifted full-field optical coherence microscopy

      Simultaneous 4-phase-shifted full-field optical coherence microscopy

      A new method is presented for full-field optical coherence tomography imaging, which permits capturing single shot phase sensitive imaging through simultaneous acquisition of four phase-shifted images with a single camera using unpolarized light for object illumination. Our method retains the full dynamic range of the camera by using different areas of a single camera sensor to capture each image. We demonstrate the performance of our method by imaging phantoms and live cultures of fibroblast, cancer, and macrophage cells to achieve 59 dB sensitivity with isotropic resolution down to 1 μm, and displacement sensitivity down to 0.1 nm. Our method ...

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    9. In vivo dynamic characterization of the human tympanic membrane using pneumatic optical coherence tomography

      In vivo dynamic characterization of the human tympanic membrane using pneumatic optical coherence tomography

      Decreased mobility of the human eardrum, the tympanic membrane (TM), is an essential indicator of a prevalent middle ear infection. The current diagnostic method to assess TM mobility is via pneumatic otoscopy, which provides subjective and qualitative information of subtle motion. In this study, a handheld spectral-domain pneumatic optical coherence tomography system was developed to simultaneously measure the displacement of the TM, air pressure inputs applied to a sealed ear canal, and to perform digital pneumatic otoscopy. A novel approach based on quantitative parameters is presented to characterize spatial and temporal variations of the dynamic TM motion. Furthermore, the TM ...

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    10. Efficacy of endotracheal tube suctioning in intubated intensive care unit patients determined by in vivo catheter-based optical coherence tomography—a pilot study

      Efficacy of endotracheal tube suctioning in intubated intensive care unit patients determined by in vivo catheter-based optical coherence tomography—a pilot study

      Background: Mechanical ventilation using an endotracheal tube (ETT) is one of the critical interventions given to patients in the intensive care unit (ICU). ETTs are associated with the formation of biofilms, placing patients at increased risk for developing ventilator-associated pneumonia (VAP). ETT suctioning is used to remove secretions, reduce bacterial colonization, and reduce the rate of biofilm formation. However, current standard-of-care suctioning procedures do not adequately eliminate all secretions from the ETT. Methods: This observational study was conducted in a cohort of 4 subjects admitted to the ICU and intubated with an ETT, irrespective of ethnicity, gender, or race. A ...

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    11. Handheld optical coherence tomography for clinical assessment of dental plaque and gingiva

      Handheld optical coherence tomography for clinical assessment of dental plaque and gingiva

      Significance: Optical coherence tomography (OCT) offers high spatial resolution and contrast for imaging intraoral structures, yet few studies have investigated its clinical feasibility for dental plaque and gingiva imaging in vivo. Furthermore, the accessibility is often limited to anterior teeth due to bulky imaging systems and probes. Aim: A custom-designed, handheld probe-based, spectral-domain OCT system with an interchangeable attachment was developed to assess dental plaque and gingival health in a clinical setting. Approach: Healthy volunteers and subjects with gingivitis and sufficient plaque were recruited. The handheld OCT system was operated by trained dental hygienists to acquire images of dental plaque ...

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    12. Statistical evaluation of reader variability in assessing the diagnostic performance of optical coherence tomography

      Statistical evaluation of reader variability in assessing the diagnostic performance of optical coherence tomography

      Significance: Optical coherence tomography (OCT) is widely used as a potential diagnostic tool for a variety of diseases including various types of cancer. However, sensitivity and specificity analyses of OCT in different cancers yield results varying from 11% to 100%. Hence, there is a need for more detailed statistical analysis of blinded reader studies. Aim: Extensive statistical analysis is performed on results from a blinded study involving OCT of breast tumor margins to assess the impact of reader variability on sensitivity and specificity. Approach: Five readers with varying levels of experience reading OCT images assessed 50 OCT images of breast ...

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    13. The feasibility and utility of optical coherence tomography directed histopathology for surgical margin assessment of canine mast cell tumors

      The feasibility and utility of optical coherence tomography directed histopathology for surgical margin assessment of canine mast cell tumors

      Histopathologic surgical margin assessment in veterinary patients is an imprecise science with assessment limited to a small proportion of the surgical margin due to time and finances. Incomplete excision of canine mast cell tumors (MCTs) alters treatment recommendations and prognosis. Optical coherence tomography (OCT) is a novel imaging modality that has been reported in a single veterinary study for surgical margin assessment. Twenty‐five dogs with 34 MCTs were enrolled in a prospective pilot‐study to assess the imaging characteristics of canine MCTs with OCT and to evaluate the feasibility and utility of OCT‐guided histopathology. All dogs underwent routine ...

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    14. Automated fast computational adaptive optics for optical coherence tomography based on a stochastic parallel gradient descent algorithm

      Automated fast computational adaptive optics for optical coherence tomography based on a stochastic parallel gradient descent algorithm

      The transverse resolution of optical coherence tomography is decreased by aberrations introduced from optical components and the tested samples. In this paper, an automated fast computational aberration correction method based on a stochastic parallel gradient descent (SPGD) algorithm is proposed for aberration-corrected imaging without adopting extra adaptive optics hardware components. A virtual phase filter constructed through combination of Zernike polynomials is adopted to eliminate the wavefront aberration, and their coefficients are stochastically estimated in parallel through the optimization of the image metrics. The feasibility of the proposed method is validated by a simulated resolution target image, in which the introduced ...

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    15. Single-shot two-dimensional spectroscopic magnetomotive optical coherence elastography with graphics processing unit acceleration

      Single-shot two-dimensional spectroscopic magnetomotive optical coherence elastography with graphics processing unit acceleration

      Biomechanical contrast within tissues can be assessed based on the resonant frequency probed by spectroscopic magnetomotive optical coherence elastography (MM-OCE). However, to date, in vivo MM-OCE imaging has not been achieved, mainly due to the constraints on imaging speed. Previously, spatially-resolved spectroscopic contrast was achieved in a “multiple-excitation, multiple-acquisition” manner, where seconds of coil cooling time set between consecutive imaging frames lead to total acquisition times of tens of minutes. Here, we demonstrate an improved data acquisition speed by providing a single chirped force excitation prior to magnetomotion imaging with a BM-scan configuration. In addition, elastogram reconstruction was accelerated by ...

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    16. Optical coherence tomography imaging of excised canine apocrine gland anal sac adenocarcinoma tumors

      Optical coherence tomography imaging of excised canine apocrine gland anal sac adenocarcinoma tumors

      Optical coherence tomography (OCT) is an optical imaging modality that has been investigated for real‐time surgical margin evaluation in human breast cancer patients. Previous veterinary OCT studies have been limited to surgical margin imaging for soft tissue sarcoma (STS) tumors. To the authors knowledge, OCT has never been used to characterize or evaluate other types of neoplasia in dogs. The goal of this study was to characterize the OCT imaging appearance of apocrine gland anal sac adenocarcinoma (AGASACA) in excised ex vivo specimens from five client‐owned dogs. All excised tissue surgical margins were imaged using a clinical spectral ...

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    17. Evaluating optical coherence tomography for surgical margin assessment of canine mammary tumors

      Evaluating optical coherence tomography for surgical margin assessment of canine mammary tumors

      Optical coherence tomography (OCT) uses near‐infrared light waves to generate real‐time, high‐resolution images on the microscopic scale similar to low power histopathology. Previous studies have demonstrated the use of OCT for real‐time surgical margin assessment for human breast cancer. The use of OCT for canine mammary tumors (CMT) could allow intra‐operative visualization of residual tumor at surgical margins. The purpose of this study was to assess OCT imaging for the detection of incomplete tumor resection following CMT surgery. We hypothesized that OCT images would have comparable features to histopathological images of tissues at the surgical ...

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    18. Otitis Media Middle Ear Effusion Identification and Characterization Using an Optical Coherence Tomography Otoscope

      Otitis Media Middle Ear Effusion Identification and Characterization Using an Optical Coherence Tomography Otoscope

      Objective To determine the feasibility of detecting and differentiating middle ear effusions (MEEs) using an optical coherence tomography (OCT) otoscope. Study Design Cross-sectional study. Setting US tertiary care children’s hospital. Subjects and Methods Seventy pediatric patients undergoing tympanostomy tube placement were preoperatively imaged using an OCT otoscope. A blinded reader quiz was conducted using 24 readers from 4 groups of tiered medical expertise. The primary outcome assessed was reader ability to detect presence/absence of MEE. A secondary outcome assessed was reader ability to differentiate serous vs nonserous MEE. Results OCT image data sets were analyzed from 45 of ...

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    19. Assessing the Effect of Middle Ear Effusions on Wideband Acoustic Immittance Using Optical Coherence Tomography

      Assessing the Effect of Middle Ear Effusions on Wideband Acoustic Immittance Using Optical Coherence Tomography

      Objectives: Wideband acoustic immittance (WAI) noninvasively assesses middle ear function by measuring the sound conduction over a range of audible frequencies. Although several studies have shown the potential of WAI for detecting the presence of middle ear effusions (MEEs), determining the effects of MEE type and amount on WAI in vivo has been challenging due to the anatomical location of middle ear cavity. The purpose of this study is to correlate WAI measurements with physical characteristics of the middle ear and MEEs determined by optical coherence tomography (OCT), a noninvasive optical imaging technique. Design: Sixteen pediatric subjects (average age of ...

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    20. Comparison between optical coherence tomographic and histopathologic appearances of artifacts caused by common surgical conditions and instrumentation

      Comparison between optical coherence tomographic and histopathologic appearances of artifacts caused by common surgical conditions and instrumentation

      Objective To document the appearance of artifacts created by commonly encountered surgical conditions and instrumentation on optical coherence tomography (OCT) and to compare these findings with histopathology. Study design Ex vivo study. Animals Five canine cadavers. Methods Skin, subcutaneous fat, skeletal muscle, and fascia samples were obtained from fresh canine cadavers. Blood pooling, hemostatic crushing, scalpel blade cut, monopolar electrosurgery, bipolar vessel sealing device, and ultrasonic energy surgical artifacts were induced on each tissue type. Each specimen was imaged with OCT and subsequently histologically processed. Results Most surgical instrumentation used for tumor excision created a high‐scattering region with local ...

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    21. Method and apparatus for OCT-based viscometry

      Method and apparatus for OCT-based viscometry

      Methods and apparatus for ascertaining a relative viscosity characterizing a fluid sample. The fluid sample is illuminated through a scattering membrane adjacent to the fluid with broadband radiation. Scattering from particles within the fluid sample characterized by a distribution of characteristic dimensions spanning at least two orders of magnitude is detected, generating a detector signal as a function of depth relative to a specified surface of the scattering membrane at a plurality of temporal delays. A cross-correlation function of at least one of amplitude, phase and intensity of a scattered optical field is derived for a plurality of depths relative ...

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    22. Automated classification platform for the identification of otitis media using optical coherence tomography

      Automated classification platform for the identification of otitis media using optical coherence tomography

      The diagnosis and treatment of otitis media (OM), a common childhood infection, is a significant burden on the healthcare system. Diagnosis relies on observer experience via otoscopy, although for non-specialists or inexperienced users, accurate diagnosis can be difficult. In past studies, optical coherence tomography (OCT) has been used to quantitatively characterize disease states of OM, although with the involvement of experts to interpret and correlate image-based indicators of infection with clinical information. In this paper, a flexible and comprehensive framework is presented that automatically extracts features from OCT images, classifies data, and presents clinically relevant results in a user-friendly platform ...

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    23. Local wavefront mapping in tissue using computational adaptive optics OCT

      Local wavefront mapping in tissue using computational adaptive optics OCT

      The identification and correction of wavefront aberrations is often necessary to achieve high-resolution optical images of biological tissues, as imperfections in the optical system and the tissue itself distort the imaging beam. Measuring the localized wavefront aberration provides information on where the beam is distorted and how severely. We have recently developed a method to estimate the single-pass wavefront aberrations from complex optical coherence tomography (OCT) data. Using this method, localized wavefront measurement and correction using computational OCT was performed in ex vivo tissues. The computationally measured wavefront varied throughout the imaged OCT volumes and, therefore, a local wavefront correction ...

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    24. Interstitial magnetic thermotherapy dosimetry based on shear wave magnetomotive optical coherence elastography

      Interstitial magnetic thermotherapy dosimetry based on shear wave magnetomotive optical coherence elastography

      While magnetic thermoseeds are often utilized in interstitial magnetic thermotherapy (iMT) to enable localized tumor ablation, we propose to extend their use as the perturbative source in magnetomotive optical coherence elastography (MM-OCE) so that the heat-induced elasticity alterations can be ‘theranostically’ probed. MM-OCE measurements were found to agree with indentation results. Tissue stiffening was visualized on iMT-treated porcine liver and canine soft tissue sarcoma specimens, where histology confirmed thermal damages. Additionally, the elasticity was found to increase exponentially and linearly with the conventional thermal dosage metrics and the deposited thermal energy, respectively. Collectively, a physiologically-meaningful, MM-OCE-based iMT dosimetry is feasible.

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