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    1. Calibration procedure for enhanced mirror artifact removal in full-range optical coherence tomography using passive quadrature demultiplexing

      Calibration procedure for enhanced mirror artifact removal in full-range optical coherence tomography using passive quadrature demultiplexing

      Significance Passive quadrature demultiplexing allows full-range optical coherence tomography (FR-OCT). However, imperfections in the wavelength- and frequency-response of the demodulation circuits can cause residual mirror artifacts, which hinder high-quality imaging on both sides of zero delay. Aim We aim at achieving high mirror artifact extinction by calibrated postprocessing of the FR-OCT signal. Approach We propose a mathematical framework for the origin of the residual mirror peaks as well as a protocol allowing the precise measurement and correction of the associated errors directly from mirror measurements. Results We demonstrate high extinction of the mirror artifact over the entire imaging range, as ...

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    2. Rapid lipid-laden plaque identification in intravascular optical coherence tomography imaging based on time-series deep learning

      Rapid lipid-laden plaque identification in intravascular optical coherence tomography imaging based on time-series deep learning

      Significance Coronary heart disease has the highest rate of death and morbidity in the Western world. Atherosclerosis is an asymptomatic condition that is considered the primary cause of cardiovascular diseases. The accumulation of low-density lipoprotein triggers an inflammatory process in focal areas of arteries, which leads to the formation of plaques. Lipid-laden plaques containing a necrotic core may eventually rupture, causing heart attack and stroke. Lately, intravascular optical coherence tomography (IV-OCT) imaging has been used for plaque assessment. The interpretation of the IV-OCT images is performed visually, which is burdensome and requires highly trained physicians for accurate plaque identification. Aim ...

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    3. Methods and applications of full-field optical coherence tomography

      Methods and applications of full-field optical coherence tomography

      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 per- formed. Methods to ...

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    4. Detection and differentiation of semi-transparent materials simulating biological structures using optical coherence tomography: a phantom study

      Detection and differentiation of semi-transparent materials simulating biological structures using optical coherence tomography: a phantom study

      SignificanceLymphatic and peripheral nervous system imaging is of prime importance for monitoring various important pathologic processes including cancer development and metastasis, and response to therapy.AimOptical coherence tomography (OCT) is a promising approach for this imaging task but is challenged by the near-transparent nature of these structures. Our aim is to detect and differentiate semi-transparent materials using OCT texture analysis, toward label-free neurography and lymphography.ApproachWe have recently demonstrated an innovative OCT texture analysis-based approach that used speckle statistics to image lymphatics and nerves in-vivo that does not rely on negative contrast. However, these two near-transparent structures could not be ...

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    5. Optical coherence tomography holds promise to transform the diagnostic anatomic pathology gross evaluation process

      Optical coherence tomography holds promise to transform the diagnostic anatomic pathology gross evaluation process

      Significance : Real-time histology can close a variety of gaps in tissue diagnostics. Currently, gross pathology analysis of excised tissue is dependent upon visual inspection and palpation to identify regions of interest for histopathological processing. Such analysis is limited by the variable correlation between macroscopic and microscopic findings. The current standard of care is costly, burdensome, and inefficient. Aim : We are the first to address this gap by introducing optical coherence tomography (OCT) to be integrated in real-time during the pathology grossing process. Approach : This is achieved by our high-resolution, ultrahigh-speed, large field-of-view OCT device designed for this clinical application. Results ...

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    6. Semisupervised representative learning for measuring epidermal thickness in human subjects in optical coherence tomography by leveraging datasets from rodent models

      Semisupervised representative learning for measuring epidermal thickness in human subjects in optical coherence tomography by leveraging datasets from rodent models

      Significance: Morphological changes in the epidermis layer are critical for the diagnosis and assessment of various skin diseases. Due to its noninvasiveness, optical coherence tomography (OCT) is a good candidate for observing microstructural changes in skin. Convolutional neural network (CNN) has been successfully used for automated segmentation of the skin layers of OCT images to provide an objective evaluation of skin disorders. Such method is reliable, provided that a large amount of labeled data is available, which is very time-consuming and tedious. The scarcity of patient data also puts another layer of difficulty to make the model more generalizable. Aim ...

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    7. Mirau-based line-field confocal optical coherence tomography for three-dimensional high-resolution skin imaging

      Mirau-based line-field confocal optical coherence tomography for three-dimensional high-resolution skin imaging

      Significance: Line-field confocal optical coherence tomography (LC-OCT) is a recently introduced high-resolution imaging modality based on a combination of low-coherence optical interferometry and reflectance confocal optical microscopy with line illumination and line detection. Capable of producing three-dimensional (3D) images of the skin with cellular resolution, in vivo , LC-OCT has been mainly applied in dermatology and dermo-cosmetology. The LC-OCT devices capable of acquiring 3D images reported so far are based on a Linnik interferometer using two identical microscope objectives. In this configuration, LC-OCT cannot be designed to be a very compact and light device, and the image acquisition speed is limited ...

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      Mentions: Damae Medical
    8. Precision of attenuation coefficient measurements by optical coherence tomography

      Precision of attenuation coefficient measurements by optical coherence tomography

      Significance: Optical coherence tomography (OCT) is an interferometric imaging modality, which provides tomographic information on the microscopic scale. Furthermore, OCT signal analysis facilitates quantification of tissue optical properties (e.g., the attenuation coefficient), which provides information regarding the structure and organization of tissue. However, a rigorous and standardized measure of the precision of the OCT-derived optical properties, to date, is missing. Aim: We present a robust theoretical framework, which provides the Cramér -Rao lower bound σμOCT for the precision of OCT-derived optical attenuation coefficients. Approach: Using a maximum likelihood approach and Fisher information, we derive an analytical solution for ...

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    9. Noninvasive hemoglobin sensing and imaging: optical tools for disease diagnosis

      Noninvasive hemoglobin sensing and imaging: optical tools for disease diagnosis

      Significance: Measurement and imaging of hemoglobin oxygenation are used extensively in the detection and diagnosis of disease; however, the applied instruments vary widely in their depth of imaging, spatiotemporal resolution, sensitivity, accuracy, complexity, physical size, and cost. The wide variation in available instrumentation can make it challenging for end users to select the appropriate tools for their application and to understand the relative limitations of different methods. Aim: We aim to provide a systematic overview of the field of hemoglobin imaging and sensing. Approach: We reviewed the sensing and imaging methods used to analyze hemoglobin oxygenation, including pulse oximetry, spectral ...

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    10. Dual-modality fluorescence lifetime imaging-optical coherence tomography intravascular catheter system with freeform catheter optics

      Dual-modality fluorescence lifetime imaging-optical coherence tomography intravascular catheter system with freeform catheter optics

      Significance: Intravascular imaging is key to investigations into atherosclerotic plaque pathobiology and cardiovascular diagnostics overall. The development of multimodal imaging devices compatible with intracoronary applications has the potential to address limitations of currently available single-modality systems. Aim: We designed and characterized a robust, high performance multimodal imaging system that combines optical coherence tomography (OCT) and multispectral fluorescence lifetime imaging (FLIm) for intraluminal simultaneous assessment of structural and biochemical properties of coronary arteries. Approach: Several shortcomings of existing FLIm-OCT catheter systems are addressed by adopting key features, namely (1) a custom fiber optic rotary joint based on an air bearing, (2 ...

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      Mentions: UC Davis
    11. Multimodal imaging needle combining optical coherence tomography and fluorescence for imaging of live breast cancer cells labeled with a fluorescent analog of tamoxifen

      Multimodal imaging needle combining optical coherence tomography and fluorescence for imaging of live breast cancer cells labeled with a fluorescent analog of tamoxifen

      Significance: Imaging needles consist of highly miniaturized focusing optics encased within a hypodermic needle. The needles may be inserted tens of millimeters into tissue and have the potential to visualize diseased cells well beyond the penetration depth of optical techniques applied externally. Multimodal imaging needles acquire multiple types of optical signals to differentiate cell types. However, their use has not previously been demonstrated with live cells. Aim: We demonstrate the ability of a multimodal imaging needle to differentiate cell types through simultaneous optical coherence tomography (OCT) and fluorescence imaging. Approach: We characterize the performance of a multimodal imaging needle. This ...

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    12. 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 ...

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    13. 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 ...

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    14. 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 ...

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    15. 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 ...

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    16. 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 ...

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    17. 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 ...

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    18. 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 ...

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    19. 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 ...

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    20. 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 ...

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    21. 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 ...

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    22. Development of a portable ophthalmic OCT device and measurement of its performance

      Development of a portable ophthalmic OCT device and measurement of its performance

      A briefcase-sized ophthalmic optical coherence tomography (OCT) device was developed. Even with all components, including a PC, monitor, and eye alignment mechanism, this single-body-packaged OCT device has a volume of 36 cm x 23 cm x 7.8 cm and a weight less than 5 kg. Foldable chin and head rests and a protection cover make it conveniently movable. By plugging in a DC adapter, this device gets ready to run, which enables instantaneous installation. A pupil camera facilitates the alignment process and internal and external fixation targets help patients fix their eyes, while OCT images are taken. All the ...

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      Mentions: Philophos
    23. 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 ...

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    24. 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 ...

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