Polarization sensitive optical coherence tomography (PS-OCT) is increasingly used in a range of applications, both in bench-top and catheter-based imaging configurations. Reconstruction of tissue birefringence is subject to many system and processing-dependent artifacts. However, methods for the calibration and validation of PS-OCT are missing. Here, we report on a method to fabricate tissue-like imaging phantoms exhibiting clearly defined regions with controllable amounts of birefringence. We employed the photoelastic effect to enable the generation of controllable amounts of stress-induced birefringence in rubber samples, verified with polarized light microscopy. Pigmented ink was added to liquid latex solution to mold and cure rubber bands with controlled backscattering and transparency. Differently stretched segments were embedded in a stress-free background matrix to generate clearly defined areas with high birefringence contrast in an area of homogenous backscatter intensity. Arranged in planar geometry or on the outside of a glass capillary, the stretched rubber bands defined phantoms for bench-top and catheter-based imaging, respectively. Segmentation of the defined regions of interest in the reconstructed volumetric birefringence tomograms enabled assessing measurement consistency, between repeated imaging with a single system, or between independent imaging systems.
Consistent and durable imaging phantoms are crucial for advancing PS-OCT imaging technology. Our tissue-like imaging phantoms exhibit clearly defined regions with controlled amounts of birefringence and facilitate testing, calibration, and validation of imaging systems and reconstruction strategies.
Excessive and repetitive force applied on vocal fold tissue can induce benign vocal fold lesions. Children affected suffer from chronic hoarseness. In this instance, the vibratory ability of the folds, a complex layered microanatomy, becomes impaired. Histological findings have shown that lesions produce a remodeling of sup-epithelial vocal fold layers. However, our understanding of lesion features and development is still limited. Indeed, conventional imaging techniques do not allow a non-invasive assessment of sub-epithelial integrity of the vocal fold. Furthermore, it remains challenging to differentiate these sub-epithelial lesions (such as bilateral nodules, polyps and cysts) from a clinical perspective, as their outer surfaces are relatively similar. As treatment strategy differs for each lesion type, it is critical to efficiently differentiate sub-epithelial alterations involved in benign lesions.
In this study, we developed an optical coherence tomography (OCT) based handheld probe suitable for pediatric laryngological imaging. The probe allows for rapid three-dimensional imaging of vocal fold lesions. The system is adapted to allow for high-resolution intra-operative imaging. We imaged 20 patients undergoing direct laryngoscopy during which we looked at different benign pediatric pathologies such as bilateral nodules, cysts and laryngeal papillomatosis and compared them to healthy tissue. We qualitatively and quantitatively characterized laryngeal pathologies and demonstrated the added advantage of using 3D OCT imaging for lesion discrimination and margin assessment. OCT evaluation of the integrity of the vocal cord could yield to a better pediatric management of laryngeal diseases.
There is a strong clinical need for an optical coherence tomography (OCT) system capable of delivering concurrent
coagulation light enabling image-guided dynamic laser marking for targeted collection of biopsies, as opposed to a
random sampling, to reduce false-negative findings. Here, we present a system based on double-clad fiber (DCF)
capable of delivering pulsed laser light through the inner cladding while performing OCT through the core. A previously
clinically validated commercial OCT system (NVisionVLE, Ninepoint Medical) was adapted to enable in vivo
esophageal image-guided dynamic laser marking. An optimized DCF coupler was implemented into the system to
couple both modalities into the DCF. A DCF-based rotary joint was used to couple light to the spinning DCF-based
catheter for helical scanning. DCF-based OCT catheters, providing a beam waist diameter of 62μm at a working distance
of 9.3mm, for use with a 17-mm diameter balloon sheath, were used for ex vivo imaging of a swine esophagus. Imaging
results using the DCF-based clinical system show an image quality comparable with a conventional system with minimal
crosstalk-induced artifacts. To further optimize DCF catheter optical design in order to achieve single-pulse marking, a
Zemax model of the DCF output and its validation are presented.
Optical coherence tomography (OCT) has been previously identified as a promising tool for exploring laryngeal pathologies in adults. Here, we present an OCT handheld probe dedicated to imaging the unique geometry involved in pediatric laryngoscopy. A vertical cavity surface emitting laser-based wavelength-swept OCT system operating at 60 frames per second was coupled to the probe to acquire three-dimensional (3-D) volumes in vivo. In order to evaluate the performance of the proposed probe and system, we imaged pediatric vocal fold lesions of patients going under direct laryngoscopy. Through this in vivo study, we extracted OCT features characterizing each pediatric vocal fold lesion, which shows a great potential for noninvasive laryngeal lesion discrimination. We believe OCT vocal fold examination in 3-D will result in improved knowledge of the pediatric anatomy and could aid in managing pediatric laryngeal diseases.
KEYWORDS: Optical coherence tomography, Spine, 3D modeling, 3D image reconstruction, Image segmentation, Genetics, Tissues, Bone, 3D image processing, Algorithm development
A zebrafish model has recently been introduced to study various genetic mutations that could lead to spinal deformities
such as scoliosis. However, current imaging techniques make it difficult to perform longitudinal studies of this condition
in zebrafish, especially in the early stages of development. The goal of this project is to determine whether optical
coherence tomography (OCT) is a viable non-invasive method to image zebrafish exhibiting spinal deformities. Images
of both live and fixed malformed zebrafish (5 to 21 days postfertilization) as well as wild-type fish (5 to 29 days
postfertilization) were acquired non-invasively using a commercial SD-OCT system, with a laser source centered at
930nm (λ=100nm), permitting axial and lateral resolutions of 7 and 8μm respectively. Using two-dimensional images
and three-dimensional reconstructions, it was possible to identify the malformed notochord as well as deformities in
other major organs at different stages of formation. Visualization of the notochord was facilitated with the development
of a segmentation algorithm. OCT images were compared to HE histological sections and images obtained by calcein
staining. Because of the possibility of performing longitudinal studies on a same fish and reducing image processing
time as compared with staining techniques and histology, the use of OCT could facilitate phenotypic characterization in
studying genetic factors leading to spinal deformities in zebrafish and could eventually contribute to the identification of
the genetic causes of spinal deformities such as scoliosis.
Conference Committee Involvement (6)
Endoscopic Microscopy XX
25 January 2025 | San Francisco, California, United States
Endoscopic Microscopy XIX
27 January 2024 | San Francisco, California, United States
Endoscopic Microscopy XVIII
28 January 2023 | San Francisco, California, United States
Endoscopic Microscopy XVII
22 January 2022 | San Francisco, California, United States
Endoscopic Microscopy XVI
6 March 2021 | Online Only, California, United States
Endoscopic Microscopy XV
1 February 2020 | San Francisco, California, United States
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