1. 1-24 of 567 1 2 3 4 ... 22 23 24 »
    1. Higher-order regression three-dimensional motion-compensation method for real-time optical coherence tomography volumetric imaging of the cornea

      Higher-order regression three-dimensional motion-compensation method for real-time optical coherence tomography volumetric imaging of the cornea

      Significance: Optical coherence tomography (OCT) allows high-resolution volumetric three-dimensional (3D) imaging of biological tissues in vivo. However, 3D-image acquisition can be time-consuming and often suffers from motion artifacts due to involuntary and physiological movements of the tissue, limiting the reproducibility of quantitative measurements. Aim: To achieve real-time 3D motion compensation for corneal tissue with high accuracy. Approach: We propose an OCT system for volumetric imaging of the cornea, capable of compensating both axial and lateral motion with micron-scale accuracy and millisecond-scale time consumption based on higher-order regression. Specifically, the system first scans three reference B-mode images along the C-axis before ...

      Read Full Article
    2. Methods and applications of full-filed optical coherence tomography: a review

      Methods and applications of full-filed optical coherence tomography: a review

      Significance: Full-field optical coherence tomography (FF-OCT) enables en face views of scattering samples at a given depth with subcellular resolution, similar to biopsy without the need of sample slicing or other complex preparation. This noninvasive, high-resolution, three-dimensional (3D) imaging method has the potential to become a powerful tool in biomedical research, clinical applications, and other microscopic detection. Aim: Our review provides an overview of the disruptive innovations and key technologies to further improve FF-OCT performance, promoting FF-OCT technology in biomedical and other application scenarios. Approach: A comprehensive review of state-of-the-art accomplishments in OCT has been performed. Methods to improve performance ...

      Read Full Article
    3. Differentiation of primary central nervous system lymphoma from glioblastoma using optical coherence tomography based on attention ResNet

      Differentiation of primary central nervous system lymphoma from glioblastoma using optical coherence tomography based on attention ResNet

      Significance: Differentiation of primary central nervous system lymphoma from glioblastoma is clinically crucial to minimize the risk of treatments, but current imaging modalities often misclassify glioblastoma and lymphoma. Therefore, there is a need for methods to achieve high differentiation power intraoperatively. Aim: The aim is to develop and corroborate a method of classifying normal brain tissue, glioblastoma, and lymphoma using optical coherence tomography with deep learning algorithm in an ex vivo experimental design. Approach: We collected tumor specimens from ordinal surgical operations and measured them with optical coherence tomography. An attention ResNet deep learning model was utilized to differentiate glioblastoma ...

      Read Full Article
    4. Signal-carrying speckle in optical coherence tomography: a methodological review on biomedical applications

      Signal-carrying speckle in optical coherence tomography: a methodological review on biomedical applications

      Significance: Speckle has historically been considered a source of noise in coherent light imaging. However, a number of works in optical coherence tomography (OCT) imaging have shown that speckle patterns may contain relevant information regarding subresolution and structural properties of the tissues from which it is originated. Aim: The objective of this work is to provide a comprehensive overview of the methods developed for retrieving speckle information in biomedical OCT applications. Approach: PubMed and Scopus databases were used to perform a systematic review on studies published until December 9, 2021. From 146 screened studies, 40 were eligible for this review ...

      Read Full Article
    5. Assessing corneal cross-linking with reverberant 3D optical coherence elastography

      Assessing corneal cross-linking with reverberant 3D optical coherence elastography

      Significance: Corneal cross-linking (CXL) is a well-known procedure for treating certain eye disorders such as keratoconus. However, characterization of the biomechanical changes in the cornea as a result of this procedure is still under active research. Specifically, there is a clinical need for high-resolution characterization of individual corneal layers. Aim: A high-resolution elastography method in conjunction with a custom optical coherence tomography system is used to track these biomechanical changes in individual corneal layers. Pre- and post-treatment analysis for both low-dose and high-dose CXL experiments are performed. Approach: A recently developed elastography technique that utilizes the theory of reverberant shear ...

      Read Full Article
    6. Blood vessel tail artifacts suppression in optical coherence tomography angiography

      Blood vessel tail artifacts suppression in optical coherence tomography angiography

      Significance: A long-standing challenge of the blood vessel tail artifacts along the axial direction prevents optical coherence tomography angiography (OCTA) for a comprehensive three-dimensional (3D) vascular mapping. Addressing the blood vessel tail artifacts issue will make OCTA to be a real 3D blood vessel structural imaging technique, which in combination with OCT-based blood flow velocity measurements will pave the way for a simpler and robust 3D imaging of the capillary transit time, one important parameter for the evaluation of micro circulation. Approach: We first described the basic principles of OCTA imaging, discussed the origin of blood vessel tail artifacts in ...

      Read Full Article
    7. Automatic Assessment of Calcified Plaque and Nodule by Optical Coherence Tomography Adopting Deep Learning Mode

      Automatic Assessment of Calcified Plaque and Nodule by Optical Coherence Tomography Adopting Deep Learning Mode

      Significance: Detection and characterization of coronary atherosclerotic plaques often need reviews of a large number of optical coherence tomography (OCT) imaging slices to make a clinical decision. However, it is a challenge to manually review all the slices and consider the interrelationship between adjacent slices. Approach : Inspired by the recent success of deep convolutional network on the classification of medical images, we proposed a ResNet-3D network for classification of coronary plaque calcification in OCT pullbacks. The ResNet-3D network was initialized with a trained ResNet-50 network and a three-dimensional convolution filter filled with zeros padding and non-zeros padding with a convolutional ...

      Read Full Article
    8. Multicontrast investigation of in vivo wildtype zebrafish in three development stages using polarization-sensitive optical coherence tomography

      Multicontrast investigation of in vivo wildtype zebrafish in three development stages using polarization-sensitive optical coherence tomography

      Significance: The scattering and polarization characteristics of various organs of in vivo wildtype zebrafish in three development stages were investigated using a non-destructive and label-free approach. The presented results showed a promising first step for the usability of Jones-matrix optical coherence tomography (JM-OCT) in zebrafish-based research. Aim: We aim to visualize and quantify the scatter and polarization signatures of various zebrafish organs for larvae, juvenile, and young adult animals in vivo in a non-invasive and label-free way. Approach: A custom-built polarization-sensitive JM-OCT setup in combination with a motorized translation stage was utilized to investigate live zebrafish. Depth-resolved scattering (intensity and ...

      Read Full Article
    9. Birefringent tissue-mimicking phantom for polarization-sensitive optical coherence tomography imaging

      Birefringent tissue-mimicking phantom for polarization-sensitive optical coherence tomography imaging

      Significance: Tissue birefringence is an important parameter to consider when designing realistic, tissue-mimicking phantoms. Options for suitable birefringent materials that can be used to accurately represent tissue scattering are limited. Aim: To introduce a method of fabricating birefringent tissue phantoms with a commonly used material-polydimethylsiloxane (PDMS)-for imaging with polarization-sensitive optical coherence tomography (PS-OCT). Approach: Stretch-induced birefringence was characterized in PDMS phantoms made with varying curing ratios, and the resulting phantom birefringence values were compared with those of biological tissues. Results: We showed that, with induced birefringence levels up to 2.1 × 10 - 4, PDMS can be used to resemble ...

      Read Full Article
    10. Deep-learning approach for automated thickness measurement of epithelial tissue and scab using optical coherence tomography

      Deep-learning approach for automated thickness measurement of epithelial tissue and scab using optical coherence tomography

      Significance: In order to elucidate therapeutic treatment to accelerate wound healing, it is crucial to understand the process underlying skin wound healing, especially re-epithelialization. Epidermis and scab detection is of importance in the wound healing process as their thickness is a vital indicator to judge whether the re-epithelialization process is normal or not. Since optical coherence tomography (OCT) is a real-time and non-invasive imaging technique that can perform a cross-sectional evaluation of tissue microstructure, it is an ideal imaging modality to monitor the thickness change of epidermal and scab tissues during wound healing processes in micron-level resolution. Traditional segmentation on ...

      Read Full Article
    11. 3D retinal imaging and measurement using light field technology

      3D retinal imaging and measurement using light field technology

      Significance: Light-field fundus photography has the potential to be a new milestone in ophthalmology. Up-to-date publications show only unsatisfactory image quality, preventing the use of depth measurements. We show that good image quality and, consequently, reliable depth measurements are possible, and we investigate the current challenges of this novel technology. Aim: We investigated whether light field (LF) imaging of the retina provides depth information, on which structures the depth is estimated, which illumination wavelength should be used, whether deeper layers are measurable, and what kinds of artifacts occur. Approach: The technical setup, a mydriatic fundus camera with an LF imager ...

      Read Full Article
    12. Enhanced medical diagnosis for dOCTors: a perspective of optical coherence tomography

      Enhanced medical diagnosis for dOCTors: a perspective of optical coherence tomography

      Significance: After three decades, more than 75,000 publications, tens of companies being involved in its commercialization, and a global market perspective of about USD 1.5 billion in 2023, optical coherence tomography (OCT) has become one of the fastest successfully translated imaging techniques with substantial clinical and economic impacts and acceptance. Aim: Our perspective focuses on disruptive forward-looking innovations and key technologies to further boost OCT performance and therefore enable significantly enhanced medical diagnosis. Approach: A comprehensive review of state-of-the-art accomplishments in OCT has been performed. Results: The most disruptive future OCT innovations include imaging resolution and speed (single-beam ...

      Read Full Article
    13. Optical coherence tomography of small intestine allograft biopsies using a handheld surgical probe

      Optical coherence tomography of small intestine allograft biopsies using a handheld surgical probe

      Significance: The current gold standard for monitoring small intestinal transplant (IT) rejection is endoscopic visual assessment and biopsy of suspicious lesions; however, these lesions are only superficially visualized by endoscopy. Invasive biopsies provide a coarse sampling of tissue health without depicting the true presence and extent of any pathology. Optical coherence tomography (OCT) presents a potential alternative approach with significant advantages over traditional white-light endoscopy. Aim: The aim of our investigation was to evaluate OCT performance in distinguishing clinically relevant morphological features associated with IT graft failure. Approach: OCT was applied to evaluate the small bowel tissues of two rhesus ...

      Read Full Article
    14. OCT particle tracking velocimetry of biofluids in a microparallel plate strain induction chamber

      OCT particle tracking velocimetry of biofluids in a microparallel plate strain induction chamber

      Significance: Imaging biofluid flow under physiologic conditions aids in understanding disease processes and health complications. We present a method employing a microparallel plate strain induction chamber (MPPSIC) amenable to optical coherence tomography to track depth-resolved lateral displacement in fluids in real time while under constant and sinusoidal shear. Aim: Our objective is to track biofluid motion under shearing conditions found in the respiratory epithelium, first validating methods in Newtonian fluids and subsequently assessing the capability of motion-tracking in bronchial mucus. Approach: The motion of polystyrene microspheres in aqueous glycerol is tracked under constant and sinusoidal applied shear rates in the ...

      Read Full Article
    15. Automatic focus method using interference fringes magnitudes in retinal optical coherence tomography

      Automatic focus method using interference fringes magnitudes in retinal optical coherence tomography

      In retinal optical coherence tomography (OCT), it is significant to focus the scan beam on the retina layers of the human eye fast to acquire high-quality OCT images. The refrac- tive errors of the human eye are usually compensated by shifting the optical lens in the sample arm manually or electrically. Otherwise, refractive errors of the human eye will cause axial focal shift of the scanning beam and blur the OCT images. We propose a fast automatic focus method using the interference fringes magnitudes of the whole retinal layers to determine the best refrac- tive correction position of motor-driven optical ...

      Read Full Article
    16. MEMS-VCSEL as a tunable light source for OCT imaging of long working distance

      MEMS-VCSEL as a tunable light source for OCT imaging of long working distance

      We present a wavelength tunable vertical-cavity surface-emitting laser (VCSEL) constructed by die-bonding a half-cavity InGaAs laser diode (LD) chip onto a silicon-on-insulator chip with a microelectromechanical system electrostatic diaphragm mirror that functions as a Fabry–Perot interferometer. As a result of the short cavity length, the integrated tunable LD has single-mode lasing characteristics with an extremely large coherence length of 150 m or more. The developed wavelength tunable LD is used to perform swept-source optical coherence tomography with a large scan depth, which is applicable to ophthalmic observation for the diagnosis of pathologic nearsightedness based on the measurement of the ...

      Read Full Article
      Mentions: Santec
    17. Automatic quantitative analysis of structure parameters in the growth cycle of artificial skin using optical coherence tomography

      Automatic quantitative analysis of structure parameters in the growth cycle of artificial skin using optical coherence tomography

      Significance: Artificial skin (AS) is widely used in dermatology, pharmacology, and toxicology, and has great potential in transplant medicine, burn wound care, and chronic wound treatment. There is a great demand for high-quality AS product and a non-invasive detection method is highly desirable. Aim: To quantify the constructure parameters (i.e., thickness and surface roughness) of AS samples in the culture cycle and explore the growth regularities using optical coherent tomography (OCT). Approach: An adaptive interface detection algorithm is developed to recognize surface points in each A-scan, offering a rapid method to calculate parameters without constructing OCT B-scan pictures and ...

      Read Full Article
    18. Surface kinematic and depth-resolved analysis of human vocal folds in vivo during phonation using optical coherence tomography

      Surface kinematic and depth-resolved analysis of human vocal folds in vivo during phonation using optical coherence tomography

      Significance: The human vocal fold (VF) oscillates in multiple vectors and consists of distinct layers with varying viscoelastic properties that contribute to the mucosal wave. Office-based and operative laryngeal endoscopy are limited to diagnostic evaluation of the VF epithelial surface only and are restricted to axial-plane characterization of the horizontal mucosal wave. As such, understanding of the biomechanics of human VF motion remains limited. Aim: Optical coherence tomography (OCT) is a micrometer-resolution, high-speed endoscopic imaging modality which acquires cross-sectional images of tissue. Our study aimed to leverage OCT technology and develop quantitative methods for analyzing the anatomy and kinematics of ...

      Read Full Article
    19. Looking for a perfect match: multimodal combinations of Raman spectroscopy for biomedical applications

      Looking for a perfect match: multimodal combinations of Raman spectroscopy for biomedical applications

      Raman spectroscopy has shown very promising results in medical diagnostics by providing label-free and highly specific molecular information of pathological tissue ex vivo and in vivo . Nevertheless, the high specificity of Raman spectroscopy comes at a price, i.e., low acquisition rate, no direct access to depth information, and limited sampling areas. However, a similar case regarding advantages and disadvantages can also be made for other highly regarded optical modalities, such as optical coherence tomography, autofluorescence imaging and fluorescence spectroscopy, fluorescence lifetime microscopy, second-harmonic generation, and others. While in these modalities the acquisition speed is significantly higher, they have no ...

      Read Full Article
    20. Concurrent OCT and OCT angiography of retinal neurovascular degeneration in the 5XFAD Alzheimer’s disease mice

      Concurrent OCT and OCT angiography of retinal neurovascular degeneration in the 5XFAD Alzheimer’s disease mice

      Significance : As one part of the central nervous system, the retina manifests neurovascular defects in Alzheimer’s disease (AD). Quantitative imaging of retinal neurovascular abnormalities may promise a new method for early diagnosis and treatment assessment of AD. Previous imaging studies of transgenic AD mouse models have been limited to the central part of the retina. Given that the pathological hallmarks of AD frequently appear in different peripheral quadrants, a comprehensive regional investigation is needed for a better understanding of the retinal degeneration associated with AD-like pathology. Aim : We aim to demonstrate concurrent optical coherence tomography (OCT) and OCT angiography ...

      Read Full Article
    21. Label-free detection of brain tumors in a 9L gliosarcoma rat model using stimulated Raman scattering-spectroscopic optical coherence tomography

      Label-free detection of brain tumors in a 9L gliosarcoma rat model using stimulated Raman scattering-spectroscopic optical coherence tomography

      Significance: In neurosurgery, it is essential to differentiate between tumor and healthy brain regions to maximize tumor resection while minimizing damage to vital healthy brain tissue. However, conventional intraoperative imaging tools used to guide neurosurgery are often unable to distinguish tumor margins, particularly in infiltrative tumor regions and low-grade gliomas. Aim: The aim of this work is to assess the feasibility of a label-free molecular imaging tool called stimulated Raman scattering-spectroscopic optical coherence tomography (SRS-SOCT) to differentiate between healthy brain tissue and tumor based on (1) structural biomarkers derived from the decay rate of signals as a function of depth ...

      Read Full Article
      Mentions: Emory University
    22. Small airway dilation measured by endoscopic optical coherence tomography correlates with chronic lung allograft dysfunction

      Small airway dilation measured by endoscopic optical coherence tomography correlates with chronic lung allograft dysfunction

      Significance: Chronic lung allograft dysfunction (CLAD) is the leading cause of death in transplant patients who survive past the first year post-transplant. Current diagnosis is based on sustained decline in lung function; there is a need for tools that can identify CLAD onset. Aim: Endoscopic optical coherence tomography (OCT) can visualize structural changes in the small airways, which are of interest in CLAD progression. We aim to identify OCT features in the small airways of lung allografts that correlate with CLAD status. Approach: Imaging was conducted with an endoscopic rotary pullback OCT catheter during routine bronchoscopy procedures (n = 54), collecting ...

      Read Full Article
    23. CNN-based CP-OCT sensor integrated with a subretinal injector for retinal boundary tracking and injection guidance

      CNN-based CP-OCT sensor integrated with a subretinal injector for retinal boundary tracking and injection guidance

      Significance: Subretinal injection is an effective way of delivering transplant genes and cells to treat many degenerative retinal diseases. However, the technique requires high-dexterity and microscale precision of experienced surgeons, who have to overcome the physiological hand tremor and limited visualization of the subretinal space. Aim: To automatically guide the axial motion of microsurgical tools (i.e., a subretinal injector) with microscale precision in real time using a fiber-optic common-path swept-source optical coherence tomography distal sensor. Approach: We propose, implement, and study real-time retinal boundary tracking of A-scan optical coherence tomography (OCT) images using a convolutional neural network (CNN) for ...

      Read Full Article
    24. Fiber-based photoacoustic remote sensing microscopy and spectral-domain optical coherence tomography with a dual-function 1050-nm interrogation source

      Fiber-based photoacoustic remote sensing microscopy and spectral-domain optical coherence tomography with a dual-function 1050-nm interrogation source

      Significance: Spectral-domain optical coherence tomography (SD-OCT) offers depth-resolved imaging of optical scattering contrast but is limited in sensitivity to optical absorption. Dual-modality imaging combined with the noncontact absorption contrast of photoacoustic remote sensing (PARS) microscopy can augment SD-OCT applications with specific molecular and functional contrasts in an all-optical, fiber-based platform. Aim: To develop a fiber-based multimodal PARS and SD-OCT imaging system, which efficiently uses a common 1050-nm light source for SD-OCT and PARS interrogation. Approach: PARS microscopy has predominantly utilized a 1310-nm interrogation light source to date. Hence, a recent dual-modality PARS and 1050-nm SD-OCT imaging system required three distinct ...

      Read Full Article
    1-24 of 567 1 2 3 4 ... 22 23 24 »
  1. Categories

    1. Applications:

      Art, Cardiology, Dentistry, Dermatology, Developmental Biology, Gastroenterology, Gynecology, Microscopy, NDE/NDT, Neurology, Oncology, Ophthalmology, Other Non-Medical, Otolaryngology, Pulmonology, Urology
    2. Business News:

      Acquisition, Clinical Trials, Funding, Other Business News, Partnership, Patents
    3. Technology:

      Broadband Sources, Probes, Tunable Sources
    4. Miscellaneous:

      Jobs & Studentships, Student Theses, Textbooks