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Comparative Study of Optical Coherence Tomography Angiography and Phase-Resolved Doppler Optical Coherence Tomography for Measurement of Retinal Blood Vessels Caliber
摘要： Purpose: To compare the accuracy of Doppler optical coherence tomography (DOCT) and OCT angiography (OCTA) for measuring retinal blood vessel caliber at different flow rates. Methods: A research-grade 1060-nm OCT system with 3.5-lm axial resolution in retinal tissue and 92,000 A scan/s image acquisition rate was used in this study. DOCT and OCTA measurements were acquired both from a flow phantom and in vivo from retinal blood vessels in six male Brown Norway rats. The total retinal blood flow (TRBF) was modified from baseline to 70% and 20% of baseline by reducing the ocular perfusion pressure (OPP). The retinal blood vessel caliber (RBVC) was measured from OCTA and DOCT images. The caliber measurements were conducted by two separate graders using a custom MATLAB-based image processing algorithm. Results: The RBVC measured with OCTA and DOCT for normal blood flow rates were not significantly different (56.69 6 12.17 and 57.17 6 9.46 lm, P ? 0.27, respectively). However, significant differences were detected when TRBF was reduced to 70% (55.69 6 11.56 vs. 50.62 6 8.85 lm, P , 0.01) and 20% (50.29 6 9.29 vs. 44.88 6 7.13 lm, P , 0.01) of baseline. Conclusions: Reduced TRBF resulted in inaccuracy of the RBVC measurements with DOCT in both the phantom and animal study. This result suggests that OCTA is a more accurate tool for RBVC evaluation when applied to retinal diseases associated with reduced TRBF, such as glaucoma and diabetic retinopathy. Translational Relevance: Results from this study are directly applicable to clinical studies of retinal blood flow measured with OCTA and DOCT.
关键词： optical coherence tomography angiography,ocular perfusion pressure,retinal imaging,doppler optical coherence tomography
更新于2025-09-23 15:22:29
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Spectral versus Time-Domain OCT in Detecting Preoperative Epiretinal Membranes that Accompany Macular Holes
摘要： Purpose: To compare the sensitivities of spectral-domain optical coherence tomography (SD-OCT) versus time-domain OCT (TD-OCT) in identifying epiretinal membranes (ERM) preoperatively in patients who underwent surgery for full-thickness macular holes (FTMH). Methods: This is an interventional retrospective case series of 59 eyes diagnosed with FTMHs who underwent 25-G pars plana vitrectomy with internal limiting membrane peeling between 2009 and 2015. Preoperative OCTs were obtained by SD-OCT (Spectralis, Heidelberg, Germany) or TD-OCT (Stratus, Carl Zeiss Meditec, Dublin, CA, USA). Volume scans were reviewed for ERM accompanying the FTMH. This was compared to indocyanine green-negative staining and intraoperative findings of ERM as the gold standard. Results: Baseline characteristics between the SD-OCT and TD-OCT groups were comparable. Mean duration of postoperative follow-up was 41.4 weeks (±49.0). Of 59 eyes, 33 (55.9%) exhibited an ERM intraoperatively. Four ERMs (SD-OCT group) compared to 12 (TD-OCT group) were not visualized on preoperative OCT (p = 0.003). Sensitivity and specificity of SD-OCT in ERM detection was 79% and 100% compared to 14% and 91% for TD-OCT. Visual acuity improved in both arms (0.5 and 0.3 logMAR units in SD-OCT and TD-OCT, respectively (p = 0.002, 0.0002). Conclusions: We found that SD-OCT was superior to TD-OCT in identifying the presence of ERM preoperatively in patients who underwent macular hole surgery. Since ERMs may decrease the chance of successful pharmacologic vitreolysis, we recommend using SD-OCT over TD-OCT in the evaluation of patients with FTMH to more accurately identify ERMs and allow more comprehensive treatment decisions (pharmacologic versus surgical).
关键词： Epiretinal membrane,Spectral-domain optical coherence tomography,Macular hole,Time-domain optical coherence tomography
更新于2025-09-23 15:22:29
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[IEEE 2018 International Multi-Conference on Industrial Engineering and Modern Technologies (FarEastCon) - Vladivostok, Russia (2018.10.3-2018.10.4)] 2018 International Multi-Conference on Industrial Engineering and Modern Technologies (FarEastCon) - Numerical Simulation of Low-Coherence Radiation Propagation in Turbid Media and Structural Image Reconstruction in Endoscopic Optical Coherence Tomography with Allowance for Speckle Fluctuations
摘要： A method of Monte Carlo simulation of low-coherence radiation propagation in turbid media with consideration of speckle noise (the result of mutual interference of secondary spherical waves) is described. The process of photon propagation within investigated object, such as biological tissue, includes the following steps: the photon injection, mean free path determination, the verification of the fulfillment of the boundary condition, the absorption and scattering. Structural image reconstruction in optical coherence tomography (OCT) with consideration of speckle fluctuations is made by summation the statistical weight of the beam coming out of the investigated object inside the detector area with the intensity of a series of pixels of the current A-scan. The key feature of the presented method is the description of the investigated object geometry. Three-dimensional array of voxels combined into parallelograms, and the border cross checking is carried out by using an improved Smith algorithm. The described method can be used to obtain high-quality endoscopic structural OCT images of body cavities and tracts (diagnosis of the respiratory tract, cardiovascular system, gastrointestinal tract, genitourinary system, etc.).
关键词： coherence probing depth,Monte Carlo simulation,optical coherence tomography,voxel based model,speckle fluctuations,structural image
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Symposium on Medical Measurements and Applications (MeMeA) - Rome, Italy (2018.6.11-2018.6.13)] 2018 IEEE International Symposium on Medical Measurements and Applications (MeMeA) - Extracting Features from Optical Coherence Tomography for Measuring Optical Nerve Thickness
摘要： Neurological pathologies, especially optical neuropathologies, can be studied by means of OCT (optical coherence tomography). Tomography generally allows to investigate inner structures of a tissue such as mass, and profiles of liquid flow. OCT is intended as an interferometry-based imaging technique that provides cross-sectional views of substrates. It allows to measure micro-scale cross-sectional imaging of biological tissue. While ultrasound uses sound waves, it acts like it but with a low coherence light. Optical nerve thickness has an impact on different neurological pathologies, and in particular as an indicator of epilepsy. We propose a dedicated technique for measuring optical nerve thickness and identifying its quality by means of processing front eye image in nanoscale. Experimental measurements have been performed, and a database of 10 teenagers has been used for that.
关键词： Micro and Nanotechnology,Optical nerve thickness measurement,Optical coherence Tomography,Neuro-disorders,Epilepsy,Atomic Force Microscopy,EEG
更新于2025-09-23 15:22:29
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Optical coherence tomography and its use in optical neuritis and multiple sclerosis
摘要： Optical coherence tomography is a relatively new non-invasive imaging technique used for obtaining the images and quantifying the layers of the retina. It also provides information about optic nerve head topography, peripapillary retinal nerve fiber layer thickness, and macular volume which correlates with axonal loss. Until now, this method was used mainly in ophthalmology; now it has emerged as relevant in neurology as well. RNFL thickness is of particular interest in optic neuropathies and in multiple sclerosis. In sclerosis multiplex, axonal loss occurs as early as the first stages and the quantification of the RNFL thickness by OCT provides an indirect measure of axonal and neuronal loss in the anterior visual pathways. Because OCT is noninvasive, easy to obtain, and highly reproducible, it can be used as a marker of axonal loss and as an endpoint in clinical trials. This paper presents a comprehensive summary of the use of this new diagnostic method in multiple sclerosis patients (Fig. 1, Ref. 58). Text in PDF www.elis.sk.
关键词： multiple sclerosis,optical neuritis,optical coherence tomography
更新于2025-09-23 15:22:29
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Polarization-Sensitive Optical Coherence Tomography for Brain Tumor Characterization
摘要： Complete removal of brain tumor is of the most interest to a surgeon because the resection area directly relates to recurrence rate. Although there are many biomedical imaging modalities applied to locate the positions of tumors, they lack the spatial resolution to precisely delineate the boundary between brain tumor and normal brain tissues and are also inconvenient to be used intraoperatively. This study aims to examine the feasibility of label-free, polarization-sensitive optical coherence tomography (PS-OCT) for distinguishing brain tumors from normal brain tissues. Ex vivo samples were obtained from two patients with grade II and II-III glioma; healthy porcine brain tissues were utilized as the control group. In the results obtained from normal porcine brain, white matter contains significantly higher birefringent property over grey matter indicated by phase retardation. Based on the knowledge obtained from porcine brain experiment, a similar high-birefringent tissue is observed partially on the edge of the sliced glioma, and such tissue is considered as white matter because glioma originates through the mutation of the healthy white matter's glia cells. Additionally, differences between grey matter and brain tumor are not apparent based on phase retardation images and further histogram analysis. The capability of PS-OCT for distinguishing glioma from white matter is demonstrated. It could be a potential system to facilitate safe and maximum resection area, and finally, lead to ameliorated outcomes.
关键词： optical polarization,white matter,Brain tumor,optical coherence tomography
更新于2025-09-23 15:22:29
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Impact of procedural characteristics on coronary vessel wall healing following implantation of second-generation drug-eluting absorbable metal scaffold in patients with de novo coronary artery lesions: an optical coherence tomography analysis
摘要： Aims Second-generation drug-eluting absorbable metal scaffold (DREAMS 2G) is an alternative novel device for treating coronary lesions. However, the relationship between in-scaffold dimensions after implantation of DREAMS 2G and vessel healing and luminal results at follow-up is unknown. The aim of this study is, therefore, to investigate whether the expansion index after implantation of DREAMS 2G as assessed by optical coherence tomography (OCT) impacts late luminal status and healing of the vessel wall. Methods and results This study comprises of a total 65 out of 123 patients who were enrolled in the BIOSOLVE-II trial. We assessed both qualitative and quantitative OCT findings and the expansion index of DREAMS 2G after implantation frame by frame using OCT. Expansion index was defined as minimum scaffold area/mean reference lumen area. The over-expansion group was also defined with expansion index >1.0. The total number of analysed frames at post-procedure and 6-month follow-up was 8243 and 8263 frames, respectively. At 6-month follow-up, in-scaffold healing was documented by the reduction of 82% in dissections, 93% in attached intra-luminal mass (ILM), 65% in non-attached ILM, and 76% in jailed side branch. The over-expansion group had significantly greater in-scaffold luminal volume loss (LVL) compared with the non-over-expansion group [over-expansion: 35.0 (18.5–52.1) mm3 vs. non-over-expansion: 21.0 (11.6–37.9) mm3, P = 0.039]. Conclusion Excellent in vivo healing process after implantation of DREAMS 2G was observed at 6 months. We found that higher expansion indices were associated with higher in-scaffold LVL at 6 months assessed by OCT.
关键词： optical coherence tomography,drug-eluting absorbable metal scaffold,luminal volume loss
更新于2025-09-23 15:22:29
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Intracoronary Imaging
摘要： Coronary angiography represents both the gold standard for diagnosis of coronary artery disease and the main guidance for percutaneous coronary intervention (PCI). Yet, coronary angiography is well known to not be optimal in appreciating the whole spectrum of lesions that may cause clinical problems in patients with coronary artery disease. Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) represent the 2 contemporary invasive intracoronary imaging modalities aimed at improving the detection of coronary details. Their potential is extraordinary but their use for improving coronary disease diagnosis is not standardized. Moving from diagnosis to treatment, PCI based on drug-eluting stent (DES) implantation often requires a series of manipulations with different techniques and devices. Last generation DES types have similar technical features and share a comparable ability to scaffold coronary lesions. Not surprisingly, lesion complexity is known to be associated with increased procedure challenges that may be tackled by different strategies. The selection of devices and the assessment of appropriate DES implantation may be based on either angiography or intracoronary imaging techniques like IVUS or OCT. Both techniques have evolved over time and offer the possibility to see details of coronary lesions and stent/vessel interactions that are impossible to be captured and measured by angiography. So far, thousands of studies with different designs have been performed, but they have not been able to make interventional cardiologists act in a homogeneous way. Consequently, intravascular imaging is selected on the basis of individual yield, with an impressive variability across different countries and operators. Reimbursement issues are part of the game but do not entirely explain the overall underutilization of intravascular imaging (especially in Western countries where a lot of expensive devices are routinely incorporated in interventional practice). In reality, the application of intracoronary imaging adds complexity to PCI, requires adequate technical skills, and by itself does not necessarily improve the clinical outcome. As compared with angiography guidance, IVUS and OCT are able to provide (in real time) many more coronary details. Such angiographically invisible details need to be recognized by the operator to properly react to improve the clinical outcome of treated patients. Because of the impressive amount of details and possible measures/cutoffs, the identification of both impactful features (deserving attention) and best reactions (additional technical steps with corrective efficacy) is pivotal. Yet, data collected by IVUS studies have not been concordant and this has resulted in overall limited clinical penetration: many catheterization laboratories are actually working without any access to intracoronary imaging. Furthermore, although rare, imaging catheter-related complications may occur so that a safety issue has to be considered any time the expected benefit is not well established in clinical practice. On the bases of these concepts, it is evident that the intracoronary imaging clinical impact may come from the correct identification and appropriate processing of those details that may help (1) to improve the PCI strategy (technique/device selection, that is, PCI planning) and (2) to facilitate the achievement of improved stenting result (ie, PCI optimization). As shown in the Figure, among all the information captured by intracoronary imaging, a limited series of imaging-based pre-PCI findings can be easily incorporated in the PCI planning (lesion preparation and stent selection). Similarly, some key intra-PCI findings (stent underexpansion, stent edge dissections, and strut malapposition) can be searched in order to optimize the stent implantation result. The feasibility of this approach is supported by the daily experience of many high volume centers. Yet, the overall clinical impact of image guidance in PCI is still unrecognized, and large studies in the field are needed. Recently-collected data started shedding new light on both IVUS and OCT. The large study by Maehara et al, although not randomized, allowed to run a propensity-matched comparison between thousands of IVUS-guided and angiography-guided procedures. IVUS use was associated with different procedure conduction and reduced major adverse events incidence at up to 2 years. Of note, the clinical benefit comprised significant improvements of hard end points, namely stent thrombosis, myocardial infarction, and cardiac mortality. Such results fit well with the recent ULTIMATE prospective randomized trial (Intravascular Ultrasound Guided Drug Eluting Stents Implantation in 'All-Comers' Coronary Lesions). The ULTIMATE investigators randomized 1448 all-comer patients who required DES implantation to either IVUS guidance or angiography guidance. As compared with angiography, randomization to IVUS guidance was associated with different procedure course (higher contrast administration, larger and longer stents, and higher inflation pressures) and warranted lower target vessel failures with IVUS at 12 months. OCT, as compared with IVUS, represents a younger technique, but data are growingly been collected because it has the appeal of offering higher resolution. The specific image generation process of OCT translates into the need of dedicated experience but has the potential for shorter learning curve. The possible clinical impact of OCT use in PCI guidance has been started to be highlighted by the results of the CLI-OPCI II study (Centro per la Lotta Contro l'Infarto-Optimisation of Percutaneous Coronary Intervention II). In this large registry, specific definitions for OCT features of suboptimal stent results were found to be independently associated with adverse clinical outcome after PCI. For sure, more complex PCIs (where the risk of stent thrombosis and restenosis is higher), are expected to benefit more from PCI refinements. Thus, two large prospectively randomized trials (OCTOBER, and ILUMIEN IV, and URL: https://www.clinicaltrials.gov. Unique identifier: NCT03507777) comparing OCT and angiographic guidance are actually ongoing and have been powered to explore the benefit of OCT guidance (using rigorous OCT-based PCI optimization algorithms) in, respectively, bifurcated lesions and complex patients. In conclusion, intravascular imaging modalities are entering a new era because the recently collected data seem to show new thresholds and targets for PCI planning and optimization. Thus, IVUS and OCT are going to become the ideal glasses that interventional cardiologists should wear anytime something looks unclear before, during or after PCI. Appropriate education, standardization of operative protocols and definitions of best clinical settings for application represent the future challenges for the intravascular imaging clinical implementation.
关键词： intravascular ultrasound,angiography,myocardial infarction,Editorials,diagnosis,optical coherence tomography,coronary artery disease,percutaneous coronary intervention
更新于2025-09-23 15:22:29
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Repeatability and reproducibility of retinal nerve fibre layer thickness measurements with the iVue-100 optical coherence tomographer
摘要： Background: Accurate and repeatable measurements of the retinal nerve fibre layer (RNFL) thickness are important in the diagnosis and management of glaucoma and other disorders. Objective: To assess the repeatability and reproducibility of the iVue-100 optical coherence tomographer (OCT). Methods: The thickness of the RNFL was measured for 50 healthy participants using the iVue-100 OCT. Although both eyes per participant were measured, only right eyes were analysed here. Repeatability and reproducibility of the iVue-100 OCT were assessed using the intraclass correlation coefficient (ICC), coefficient of variation (CoV), paired t-tests and Bland-Altman analysis. Results: Good intra-observer repeatability was obtained as indicated by the ICC of observer 1 (range: 0.941 - 0.976) and observer 2 (range: 0.829 – 0.953) as well by the CoV of observer 1 (range: 0.098 – 0.137) and observer 2 (0.091 – 0.132). In terms of inter-observer reproducibility, significant differences (p< 0.05) in mean measurements between the observers were noted for the average RNFL readings and in the superior and inferior quadrants as assessed with paired t-tests. Even though significant inter-session differences were found for the average RNFL thickness and the superior quadrant (p = 0.003 and p = 0.013, respectively), excellent ICCs were obtained for inter-session reproducibility (range: 0.914 – 0.979). Conclusion: The iVue-100 OCT demonstrated good repeatability and reproducibility for RNFL thickness measurements.
关键词： Retinal nerve fibre layer thickness,optical coherence tomography,repeatability,iVue-100 OCT,reproducibility
更新于2025-09-23 15:22:29
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Fully automated detection of retinal disorders by image-based deep learning
摘要： Purpose With the aging population and the global diabetes epidemic, the prevalence of age-related macular degeneration (AMD) and diabetic macular edema (DME) diseases which are the leading causes of blindness is further increasing. Intravitreal injections with anti-vascular endothelial growth factor (anti-VEGF) medications are the standard of care for their indications. Optical coherence tomography (OCT), as a noninvasive imaging modality, plays a major part in guiding the administration of anti-VEGF therapy by providing detailed cross-sectional scans of the retina pathology. Fully automating OCT image detection can significantly decrease the tedious clinician labor and obtain a faithful pre-diagnosis from the analysis of the structural elements of the retina. Thereby, we explore the use of deep transfer learning method based on the visual geometry group 16 (VGG-16) network for classifying AMD and DME in OCT images accurately and automatically. Method A total of 207,130 retinal OCT images between 2013 and 2017 were selected from retrospective cohorts of 5319 adult patients from the Shiley Eye Institute of the University of California San Diego, the California Retinal Research Foundation, Medical Center Ophthalmology Associates, the Shanghai First People’s Hospital, and the Beijing Tongren Eye Center, with 109,312 images (37,456 with choroidal neovascularization, 11,599 with diabetic macular edema, 8867 with drusen, and 51,390 normal) for the experiment. After images preprocessing, 1000 images (250 images from each category) from 633 patients were selected as validation dataset while the rest images from another 4686 patients were used as training dataset. We used deep transfer learning method to fine-tune the VGG-16 network pre-trained on the ImageNet dataset, and evaluated its performance on the validation dataset. Then, prediction accuracy, sensitivity, specificity, and receiver-operating characteristic (ROC) were calculated. Results Experimental results proved that the proposed approach had manifested superior performance in retinal OCT images detection, which achieved a prediction accuracy of 98.6%, with a sensitivity of 97.8%, a specificity of 99.4%, and introduced an area under the ROC curve of 100%. Conclusion Deep transfer learning method based on the VGG-16 network shows significant effectiveness on classification of retinal OCT images with a relatively small dataset, which can provide assistant support for medical decision-making. Moreover, the performance of the proposed approach is comparable to that of human experts with significant clinical experience. Thereby, it will find promising applications in an automatic diagnosis and classification of common retinal diseases.
关键词： Diabetic macular edema,Visual geometry group 16 network,Age-related macular degeneration,Optical coherence tomography,Deep transfer learning
更新于2025-09-23 15:22:29