Localization of cortical tissue optical changes during seizure activity in vivo with optical coherence tomography.
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ABSTRACT:
SUBMITTER: Eberle MM
PROVIDER: S-EPMC4467710 | biostudies-other | 2015 May
REPOSITORIES: biostudies-other
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Project description: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??m 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, we imaged the human vaginas in vivo with both conventional 1.3 and 1.7??m endoscopic OCT systems. RESULTS:With the 1.7??m endoscopic OCT system, imaging depth was improved by more than 25%, allowing better visualization of the lamina propria and clear contrast of the epithelial layer from the surrounding tissues. CONCLUSION:The significantly improved performance of the novel 1.7??m OCT imaging system demonstrates its potential use as a minimally-invasive monitoring tool of vaginal health in gynecologic practice. Lasers Surg. Med. 51:120-126, 2019. © 2018 Wiley Periodicals, Inc.
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Project description:PurposeThe purpose of this study was to develop an in vivo optical coherence tomography (OCT) system capable of imaging the developing mouse retina and its associated morphometric and microstructural changes.MethodsThirty-four wild-type mice (129S1/SvlmJ) were anesthetized and imaged between postnatal (P) day 7 and P21. OCT instrumentation was developed to optimize signal intensity and image quality. Semi-automatic segmentation tools were developed to quantify the retinal thickness of the nerve fiber layer (NFL), inner plexiform layer (IPL), inner nuclear layer (INL), and the outer retinal layers (ORL), in addition to the total retina. The retinal maturation was characterized by comparing layer thicknesses between consecutive time points.ResultsFrom P7 to P10, the IPL increased significantly, consistent with retinal synaptogenesis. From P10 to P12, the IPL and ORL also increased, which is coherent with synaptic connectivity and photoreceptor maturation. In contrast, during these periods, the INL decreased significantly, consistent with cellular densification and selective apoptotic "pruning" of the tissue during nuclear migration. Thereafter from P12 to P21, the INL continued to thin (significantly from P17 to P21) whereas the other layers remained unchanged. No time-dependent changes were observed in the NFL. Overall, changes in the total retina were attributed to those in the IPL, INL, and ORL. Regions of the retina adjacent to the optic nerve head were thinner than distal regions during maturation.ConclusionsChanges in retinal layer thickness are consistent with retinal developmental mechanisms. Accordingly, this report opens new horizons in using our system in the mouse to characterize longitudinally developmental digressions in models of human diseases.
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Project description:Application of optical coherence tomography (OCT) for in vivo imaging of tissue and skeleton structure of intact living corals enabled the non-invasive visualization of coral tissue layers (endoderm versus ectoderm), skeletal cavities and special structures such as mesenterial filaments and mucus release from intact living corals. Coral host chromatophores containing green fluorescent protein-like pigment granules appeared hyper-reflective to near-infrared radiation allowing for excellent optical contrast in OCT and a rapid characterization of chromatophore size, distribution and abundance. In vivo tissue plasticity could be quantified by the linear contraction velocity of coral tissues upon illumination resulting in dynamic changes in the live coral tissue surface area, which varied by a factor of 2 between the contracted and expanded state of a coral. Our study provides a novel view on the in vivo organization of coral tissue and skeleton and highlights the importance of microstructural dynamics for coral ecophysiology.
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Project description:This study investigates the feasibility of in vivo quantitative optical coherence tomography (OCT) of human brain tissue during glioma resection surgery in six patients. High-resolution detection of glioma tissue may allow precise and thorough tumor resection while preserving functional brain areas, and improving overall survival. In this study, in vivo 3D OCT datasets were collected during standard surgical procedure, before and after partial resection of the tumor, both from glioma tissue and normal parenchyma. Subsequently, the attenuation coefficient was extracted from the OCT datasets using an automated and validated algorithm. The cortical measurements yield a mean attenuation coefficient of 3.8?±?1.2 mm-1 for normal brain tissue and 3.6?±?1.1 mm-1 for glioma tissue. The subcortical measurements yield a mean attenuation coefficient of 5.7?±?2.1 and 4.5?±?1.6 mm-1 for, respectively, normal brain tissue and glioma. Although the results are inconclusive with respect to trends in attenuation coefficient between normal and glioma tissue due to the small sample size, the results are in the range of previously reported values. Therefore, we conclude that the proposed method for quantitative in vivo OCT of human brain tissue is feasible during glioma resection surgery.
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Project description:Intravascular optical coherence tomography (IVOCT) is rapidly becoming the method of choice for the in vivo investigation of coronary artery disease. While IVOCT visualizes atherosclerotic plaques with a resolution <20µm, image analysis in terms of tissue composition is currently performed by a time-consuming manual procedure based on the qualitative interpretation of image features. We illustrate an algorithm for the automated and systematic characterization of IVOCT atherosclerotic tissue. The proposed method consists in a supervised classification of image pixels according to textural features combined with the estimated value of the optical attenuation coefficient. IVOCT images of 64 plaques, from 49 in vivo IVOCT data sets, constituted the algorithm's training and testing data sets. Validation was obtained by comparing automated analysis results to the manual assessment of atherosclerotic plaques. An overall pixel-wise accuracy of 81.5% with a classification feasibility of 76.5% and per-class accuracy of 89.5%, 72.1% and 79.5% for fibrotic, calcified and lipid-rich tissue respectively, was found. Moreover, measured optical properties were in agreement with previous results reported in literature. As such, an algorithm for automated tissue characterization was developed and validated using in vivo human data, suggesting that it can be applied to clinical IVOCT data. This might be an important step towards the integration of IVOCT in cardiovascular research and routine clinical practice.
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Project description:SignificanceOptical coherence tomography (OCT) has proven useful for detecting various oral maxillofacial abnormalities. To apply it to clinical applications including biopsy guidance and routine screening, a handheld imaging probe is indispensable. OCT probes reported for oral maxillofacial imaging were either based on a bulky galvanometric mirror pair (not compact or long enough) or a distal-end microelectromechanical systems (MEMS) scanner (raised safety concerns), or adapted from fiber-optic catheters (ill-suited for oral cavity geometry).AimTo develop a handheld probe featuring great compactness and excellent maneuverability for oral maxillofacial tissue imaging.ApproachA dual-axis MEMS scanner was deployed at the proximal end of the probe and the scanned beam was relayed to the distal end through a 4f configuration. Such design provides both a perfect dual-axis telecentric scan and excellent compactness.ResultsA handheld probe with a rigid part 70 mm in length and 7 mm in diameter and weighing 25 g in total was demonstrated through both ex vivo and in vivo experiments, including structural visualization of various oral maxillofacial tissues and monitoring the recovery process of an oral mucosa canker sore.ConclusionsThe proposed probe exhibits excellent maneuverability and imaging performance showing great potential in clinical applications.
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Project description:Leaf senescence provides a unique window to explore the age-dependent programmed degradation at organ label in plants. Here, spectral domain optical coherence tomography (SD-OCT) has been used to study in vivo senescing leaf microstructural changes in the deciduous plant Acer serrulatum Hayata. Hayata leaves show autumn phenology and change color from green to yellow and finally red. SD-OCT image analysis shows distinctive features among different layers of the leaves; merging of upper epidermis and palisade layers form thicker layers in red leaves compared to green leaves. Moreover, A-scan analysis showed a significant (p?<?0.001) decrease in the attenuation coefficient (for wavelength range: 1100-1550?nm) from green to red leaves. In addition, the B-scan analysis also showed significant changes in 14 texture parameters extracted from second-order spatial gray level dependence matrix (SGLDM). Among these parameters, a set of three features (energy, skewness, and sum variance), capable of quantitatively distinguishing difference in the microstructures of three different colored leaves, has been identified. Furthermore, classification based on k-nearest neighbors algorithm (k-NN) was found to yield 98% sensitivity, 99% specificity, and 95.5% accuracy. Following the proposed technique, a portable noninvasive tool for quality control in crop management can be anticipated.
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Project description:Computational models and experimental optical mapping of cardiac electrophysiology serve as powerful tools to investigate the underlying mechanisms of arrhythmias. Modeling can also aid the interpretation of optical mapping signals, which may have different characteristics with respect to the underlying electrophysiological signals they represent. However, despite the prevalence of atrial arrhythmias such as atrial fibrillation, models of optical electrical mapping incorporating realistic structure of the atria are lacking. Therefore, we developed image-based models of atrial tissue using structural information extracted from optical coherence tomography (OCT), which can provide volumetric tissue characteristics in high resolution. OCT volumetric data of four swine atrial tissue samples were used to develop models incorporating tissue geometry, tissue-specific myofiber orientation, and ablation lesion regions. We demonstrated the use of these models through electrophysiology and photon scattering simulations. Changes in transmural electrical conduction were observed with the inclusion of OCT-derived, depth-resolved fiber orientation. Additionally, the amplitude of optical mapping signals were not found to correspond with lesion transmurality because of lesion geometry and electrical propagation occurring beyond excitation light penetration. This work established a framework for the development of tissue-specific models of atrial tissue derived from OCT imaging data, which can be useful in future investigations of electrophysiology and optical mapping signals with respect to realistic atrial tissue structure.
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