Special Issue "Optical Coherence Tomography and its Applications"

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Optics and Lasers".

Deadline for manuscript submissions: closed (30 April 2019).

Special Issue Editor

Prof. Dr. Yaochun Shen
E-Mail Website
Guest Editor
Department of Electrical and Electronic Engineering, University of Liverpool, Liverpool, UK
Interests: optical coherence tomography; terahertz imaging; non-destructive testing; imaging method; process analytical technology; coating
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Optical coherence tomography (OCT) is a powerful non-invasive optical imaging technique that acquires real-time cross-sectional images with micron-scale resolution. Since its invention in 1991, OCT soon became an indispensable tool for the diagnosis and management of many eye diseases. Because of the technology's capabilities and inherent practicality, OCT continues to move into new biomedical applications including cardiovascular research, dermatology and dental diagnosis, small animal imaging and many more. In addition, with the advances in new light source (swept light source, supercontinuum light source, for example) and development in new imaging modalities (high-resolution OCT microscope, high-speed OCT angiography etc.), OCT has also expanded into non-medical application areas particularly in the non-destructive evaluation field including both off-line inspection and in-line process monitoring. This Special Issue of the journal Applied Sciences, “Optical Coherence Tomography and Its Applications” is dedicated to cover some recent advances in novel technology, as well as medical and non-medical applications of OCT. 

Prof. Dr. Yaochun Shen
Guest Editor

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Keywords

  • Optical coherence tomography
  • Optical coherence angiography
  • Optical coherence microscopy
  • Polarization sensitive OCT
  • Doppler OCT
  • Swept light source
  • Supercontinuum light source
  • Ophthalmic imaging
  • Dermatology and dental application
  • Non-destructive evaluation

Published Papers (21 papers)

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Research

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Open AccessArticle
Review on Retrospective Procedures to Correct Retinal Motion Artefacts in OCT Imaging
Appl. Sci. 2019, 9(13), 2700; https://doi.org/10.3390/app9132700 - 02 Jul 2019
Abstract
Motion artefacts from involuntary changes in eye fixation remain a major imaging issue in optical coherence tomography (OCT). This paper reviews the state-of-the-art of retrospective procedures to correct retinal motion and axial eye motion artefacts in OCT imaging. Following an overview of motion [...] Read more.
Motion artefacts from involuntary changes in eye fixation remain a major imaging issue in optical coherence tomography (OCT). This paper reviews the state-of-the-art of retrospective procedures to correct retinal motion and axial eye motion artefacts in OCT imaging. Following an overview of motion induced artefacts and correction strategies, a chronological survey of retrospective approaches since the introduction of OCT until the current days is presented. Pre-processing, registration, and validation techniques are described. The review finishes by discussing the limitations of the current techniques and the challenges to be tackled in future developments. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Open AccessArticle
En-Face Optical Coherence Tomography Angiography for Longitudinal Monitoring of Retinal Injury
Appl. Sci. 2019, 9(13), 2617; https://doi.org/10.3390/app9132617 - 28 Jun 2019
Abstract
A customized Optical Coherence Tomography Angiography (OCTA) algorithm and Orthogonal OCT (en-face and B-Scans) were used for longitudinal assessment of retina murine vascular and tissue remodeling comparing photoreceptor ablation and laser-induced Choroidal Neovascularization (CNV). In the mouse model, we utilized a combined OCTA/OCT [...] Read more.
A customized Optical Coherence Tomography Angiography (OCTA) algorithm and Orthogonal OCT (en-face and B-Scans) were used for longitudinal assessment of retina murine vascular and tissue remodeling comparing photoreceptor ablation and laser-induced Choroidal Neovascularization (CNV). In the mouse model, we utilized a combined OCTA/OCT technique to image and quantify morphological and vascular features of laser lesions over time. This approach enabled us to monitor and correlate the dynamics of retina vascular and tissue remodeling as evidenced by swelling, edema, and scarring. From the OCT B-Scans, three stages of inflammatory progression were identified: the early response occurring within hours to day 3, the transition phase from 3–7 days, and the late stage of 7–21 days entering either the resolving phase or chronic phase, respectively. For the case of CNV, en-face OCTA revealed a transient non-perfusion of inner retina capillaries, specifically Deep Vascular Plexus (DVP), which corresponded to growth in lesions of a height of 200 µm or greater. Non-perfusion first occurred at 24 hours, persisted during edema and CNV formation days 7–14. In contrast, the acute inflammation induced photoreceptor damage, but no detectable alterations to the microvasculature were observed. We demonstrated that the en-face OCTA system is capable of visualizing capillary networks (∼5 µm) and the corresponding tissue remodeling and growth dynamics allowing for separating acute injury from CNV. For the first time, by using OCTA we observed the presence of the 5–10 μm capillary non-perfusion present in DVP as part of CNV formation and the associated wound healing in the retina. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Open AccessArticle
Ensemble of Deep Convolutional Neural Networks for Classification of Early Barrett’s Neoplasia Using Volumetric Laser Endomicroscopy
Appl. Sci. 2019, 9(11), 2183; https://doi.org/10.3390/app9112183 - 28 May 2019
Abstract
Barrett’s esopaghagus (BE) is a known precursor of esophageal adenocarcinoma (EAC). Patients with BE undergo regular surveillance to early detect stages of EAC. Volumetric laser endomicroscopy (VLE) is a novel technology incorporating a second-generation form of optical coherence tomography and is capable of [...] Read more.
Barrett’s esopaghagus (BE) is a known precursor of esophageal adenocarcinoma (EAC). Patients with BE undergo regular surveillance to early detect stages of EAC. Volumetric laser endomicroscopy (VLE) is a novel technology incorporating a second-generation form of optical coherence tomography and is capable of imaging the inner tissue layers of the esophagus over a 6 cm length scan. However, interpretation of full VLE scans is still a challenge for human observers. In this work, we train an ensemble of deep convolutional neural networks to detect neoplasia in 45 BE patients, using a dataset of images acquired with VLE in a multi-center study. We achieve an area under the receiver operating characteristic curve (AUC) of 0.96 on the unseen test dataset and we compare our results with previous work done with VLE analysis, where only AUC of 0.90 was achieved via cross-validation on 18 BE patients. Our method for detecting neoplasia in BE patients facilitates future advances on patient treatment and provides clinicians with new assisting solutions to process and better understand VLE data. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Open AccessFeature PaperArticle
Comparison of Intensity- and Polarization-based Contrast in Amyloid-beta Plaques as Observed by Optical Coherence Tomography
Appl. Sci. 2019, 9(10), 2100; https://doi.org/10.3390/app9102100 - 22 May 2019
Abstract
One key hallmark of Alzheimer’s disease (AD) is the accumulation of extracellular amyloid-beta protein in cortical regions of the brain. For a definitive diagnosis of AD, post-mortem histological analysis, including sectioning and staining of different brain regions, is required. Here, we present optical [...] Read more.
One key hallmark of Alzheimer’s disease (AD) is the accumulation of extracellular amyloid-beta protein in cortical regions of the brain. For a definitive diagnosis of AD, post-mortem histological analysis, including sectioning and staining of different brain regions, is required. Here, we present optical coherence tomography (OCT) as a tissue-preserving imaging modality for the visualization of amyloid-beta plaques and compare their contrast in intensity- and polarization-sensitive (PS) OCT. Human brain samples of eleven patients diagnosed with AD were imaged. Three-dimensional PS-OCT datasets were acquired and plaques were manually segmented in 500 intensity and retardation cross-sections per patient using the freely available ITK-SNAP software. The image contrast of plaques was quantified. Histological staining of tissue sections from the same specimens was performed to compare OCT findings against the gold standard. Furthermore, the distribution of plaques was evaluated for intensity-based OCT, PS-OCT and the corresponding histological amyloid-beta staining. Only 5% of plaques were visible in both intensity and retardation segmentations, suggesting that different types of plaques may be visualized by the two OCT contrast channels. Our results indicate that multicontrast OCT imaging might be a promising approach for a tissue-preserving visualization of amyloid-beta plaques in AD. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Open AccessArticle
Acceleration of OCT Signal Processing with Lookup Table Method for Logarithmic Transformation
Appl. Sci. 2019, 9(7), 1278; https://doi.org/10.3390/app9071278 - 27 Mar 2019
Abstract
Real-time Fourier domain optical coherence tomography (FDOCT) has been widely used in clinical applications. In order to accelerate the imaging processing and display of FDOCT, an alternative lookup table-based strategy for logarithmic transformation was presented. In this paper, real-time and high-quality FDOCT imaging [...] Read more.
Real-time Fourier domain optical coherence tomography (FDOCT) has been widely used in clinical applications. In order to accelerate the imaging processing and display of FDOCT, an alternative lookup table-based strategy for logarithmic transformation was presented. In this paper, real-time and high-quality FDOCT imaging display of biological tissues at an A-line rate of 62 kHz was demonstrated by optimizing the logarithmic calculation. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Open AccessArticle
Multi-Imaging Investigation to Evaluate the Relationship between Serum Cystatin C and Features of Atherosclerosis in Non-ST-Segment Elevation Acute Coronary Syndrome
Appl. Sci. 2019, 9(4), 657; https://doi.org/10.3390/app9040657 - 15 Feb 2019
Abstract
Objectives: High cystatin C(CysC) levels are associated with impaired cardiovascular outcome. Whether CysC levels are independently related to the atherosclerosis burden is still controversial. Methods: We enrolled 31 non-ST-segment elevation acute coronary syndrome patients undergoing percutaneous coronary intervention. Patients were divided into 2 [...] Read more.
Objectives: High cystatin C(CysC) levels are associated with impaired cardiovascular outcome. Whether CysC levels are independently related to the atherosclerosis burden is still controversial. Methods: We enrolled 31 non-ST-segment elevation acute coronary syndrome patients undergoing percutaneous coronary intervention. Patients were divided into 2 groups on the basis of median value of serum CysC. Using the high CysC group as a dependent variable, univariable and multivariable analyses were used to evaluate the association between CysC and three different features of atherosclerosis: 1) coronary plaque vulnerability as assessed by optical coherence tomography (OCT), 2) coronary artery calcium (CAC) by means of computed tomography scan, and 3) aortic wall metabolic activity, as assessed using 18F-Fluorodeoxyglucose-positron emission tomography (18F-FDG-PET). Results: After univariable and multivariable analyses, 18F-FDG uptake in the descending aorta (DA) was independently associated with a low level of CysC [(Odds Ratio = 0.02; 95%CI 0.0004–0.89; p = 0.044; 18F-FDG uptake measured as averaged maximum target to blood ratio); (Odds Ratio = 0.89; 95%CI 0.82–0.98, p = 0.025; 18F-FDG uptake measured as number of active slices)]. No trend was found for the association between CysC and characteristics of OCT-assessed coronary plaque vulnerability or CAC score. Conclusions: In patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS), 18F-FDG uptake in the DA was associated with a low level of serum CysC. There was no relation between CysC levels and OCT-assessed coronary plaque vulnerability or CAC score. These findings suggest that high levels of CysC may not be considered as independent markers of atherosclerosis. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Open AccessArticle
In Vivo Rat Brain Imaging through Full-Field Optical Coherence Microscopy Using an Ultrathin Short Multimode Fiber Probe
Appl. Sci. 2019, 9(2), 216; https://doi.org/10.3390/app9020216 - 09 Jan 2019
Abstract
We demonstrate full-field optical coherence microscopy (OCM) using an ultrathin forward-imaging short multimode fiber (SMMF) probe with a core diameter of 50 μm, outer diameter of 125 μm, and length of 7.4 mm, which is a typical graded-index multimode fiber used for optical [...] Read more.
We demonstrate full-field optical coherence microscopy (OCM) using an ultrathin forward-imaging short multimode fiber (SMMF) probe with a core diameter of 50 μm, outer diameter of 125 μm, and length of 7.4 mm, which is a typical graded-index multimode fiber used for optical communications. The axial and lateral resolutions were measured to be 2.14 μm and 2.3 μm, respectively. By inserting the SMMF 4 mm into the cortex of an in vivo rat brain, scanning was performed to a depth of 147 μm from the SMMF facet with a field of view of 47 μm. Three-dimensional (3D) OCM images were obtained at depths ranging from approximately 20 μm to 90 μm. Based on the morphological information of the resliced 3D images and the dependence of the integration of the OCM image signal on the insertion length, the obtained 3D information of nerve fibers has been presented. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Open AccessArticle
Non-Contact Measurement of Small-Module Gears Using Optical Coherence Tomography
Appl. Sci. 2018, 8(12), 2490; https://doi.org/10.3390/app8122490 - 04 Dec 2018
Abstract
Due to the small size and harsh transmission conditions of small-module gears, it is very difficult to measure gear characteristics with a modulus smaller than 1 mm. We proposed an optical coherence tomography (OCT) method for measuring small-module gears. Testing of a 30-tooth [...] Read more.
Due to the small size and harsh transmission conditions of small-module gears, it is very difficult to measure gear characteristics with a modulus smaller than 1 mm. We proposed an optical coherence tomography (OCT) method for measuring small-module gears. Testing of a 30-tooth copper gear with a small modulus of 0.5 mm was carried out for the measurement of its modulus, tooth parameter, tooth number, pressure angle, modification coefficient, and tooth thickness by using OCT. In addition, the influencing factors on the measurement were discussed. The whole teeth profile of a 0.2 mm modulus gear was imaged by processing of the data collected from different clamping angles. Compared with the visual imaging without depth information and small-scale microscopic imaging, the OCT method has shown its superiority, and it has potential in the application of the measurement of micro gears with a small modulus of less than 0.2 mm. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Open AccessArticle
Computer-Aided Analysis of Gland-Like Subsurface Hyposcattering Structures in Barrett’s Esophagus Using Optical Coherence Tomography
Appl. Sci. 2018, 8(12), 2420; https://doi.org/10.3390/app8122420 - 28 Nov 2018
Cited by 2
Abstract
(1) Background: Barrett’s esophagus (BE) is a complication of chronic gastroesophageal reflux disease and is a precursor to esophageal adenocarcinoma. The clinical implication of subsurface glandular structures of Barrett’s esophagus is not well understood. Optical coherence tomography (OCT), also known as volumetric laser [...] Read more.
(1) Background: Barrett’s esophagus (BE) is a complication of chronic gastroesophageal reflux disease and is a precursor to esophageal adenocarcinoma. The clinical implication of subsurface glandular structures of Barrett’s esophagus is not well understood. Optical coherence tomography (OCT), also known as volumetric laser endomicroscopy (VLE), can assess subsurface glandular structures, which appear as subsurface hyposcattering structures (SHSs). The aim of this study is to develop a computer-aided algorithm and apply it to investigate the characteristics of SHSs in BE using clinical VLE data; (2) Methods: SHSs were identified with an initial detection followed by machine learning. Comprehensive SHS characteristics including the number, volume, depth, size and shape were quantified. Clinical VLE datasets collected from 35 patients with a history of dysplasia undergoing BE surveillance were analyzed to study the general SHS distribution and characteristics in BE. A subset of radiofrequency ablation (RFA) patient data were further analyzed to investigate the pre-RFA SHS characteristics and post-RFA treatment response; (3) Results: SHSs in the BE region were significantly shallower, more vertical, less eccentric, and more regular, as compared with squamous SHSs. SHSs in the BE region which became neosquamous epithelium after RFA were shallower than those in the regions that remained BE. Pre-ablation squamous SHSs with higher eccentricity correlated strongly with larger reduction of post-ablation BE length for less elderly patients; (4) Conclusions: The computer algorithm is potentially a valuable tool for studying the roles of SHSs in BE. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Open AccessArticle
Demonstration of Triband Multi-Focal Imaging with Optical Coherence Tomography
Appl. Sci. 2018, 8(12), 2395; https://doi.org/10.3390/app8122395 - 26 Nov 2018
Abstract
We demonstrate an extended depth of focus optical coherence tomography (OCT) system based on the use of chromatic aberration to create displaced focal planes in the sample. The system uses a wavelength-swept source tuning over three spectral bands and three separate interferometers, each [...] Read more.
We demonstrate an extended depth of focus optical coherence tomography (OCT) system based on the use of chromatic aberration to create displaced focal planes in the sample. The system uses a wavelength-swept source tuning over three spectral bands and three separate interferometers, each of which interfaces to a single illumination/collection fiber. The resulting three imaged volumes are merged in post-processing to generate an image with a larger depth of focus than is obtained from each band individually. The improvements are demonstrated in structural imaging of a porous phantom and a lipid-cleared murine brain, and by angiographic imaging of human skin. By using a coaxial approach with Gaussian beams, this approach enables an extended focus with relatively simple microscope optics and data-merging algorithms. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Open AccessArticle
Combination of High-Resolution Optical Coherence Tomography and Raman Spectroscopy for Improved Staging and Grading in Bladder Cancer
Appl. Sci. 2018, 8(12), 2371; https://doi.org/10.3390/app8122371 - 23 Nov 2018
Cited by 3
Abstract
We present a combination of optical coherence tomography (OCT) and Raman spectroscopy (RS) for improved diagnosis and discrimination of different stages and grades of bladder cancer ex vivo by linking the complementary information provided by these two techniques. Bladder samples were obtained from [...] Read more.
We present a combination of optical coherence tomography (OCT) and Raman spectroscopy (RS) for improved diagnosis and discrimination of different stages and grades of bladder cancer ex vivo by linking the complementary information provided by these two techniques. Bladder samples were obtained from biopsies dissected via transurethral resection of the bladder tumor (TURBT). As OCT provides structural information rapidly, it was used as a red-flag technology to scan the bladder wall for suspicious lesions with the ability to discriminate malignant tissue from healthy urothelium. Upon identification of degenerated tissue via OCT, RS was implemented to determine the molecular characteristics via point measurements at suspicious sites. Combining the complementary information of both modalities allows not only for staging, but also for differentiation of low-grade and high-grade cancer based on a multivariate statistical analysis. OCT was able to clearly differentiate between healthy and malignant tissue by tomogram inspection and achieved an accuracy of 71% in the staging of the tumor, from pTa to pT2, through texture analysis followed by k-nearest neighbor classification. RS yielded an accuracy of 93% in discriminating low-grade from high-grade lesions via principal component analysis followed by k-nearest neighbor classification. In this study, we show the potential of a multi-modal approach with OCT for fast pre-screening and staging of cancerous lesions followed by RS for enhanced discrimination of low-grade and high-grade bladder cancer in a non-destructive, label-free and non-invasive way. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Open AccessArticle
Design Considerations for Murine Retinal Imaging Using Scattering Angle Resolved Optical Coherence Tomography
Appl. Sci. 2018, 8(11), 2159; https://doi.org/10.3390/app8112159 - 05 Nov 2018
Cited by 1
Abstract
Optical coherence tomography (OCT), an optical imaging approach enabling cross-sectional analysis of turbid samples, is routinely used for retinal imaging in human and animal models of diseases affecting the retina. Scattering angle resolved (SAR-)OCT has previously been demonstrated as offering additional contrast in [...] Read more.
Optical coherence tomography (OCT), an optical imaging approach enabling cross-sectional analysis of turbid samples, is routinely used for retinal imaging in human and animal models of diseases affecting the retina. Scattering angle resolved (SAR-)OCT has previously been demonstrated as offering additional contrast in human studies, but no SAR-OCT system has been reported in detail for imaging the retinas of mice. An optical model of a mouse eye was designed and extended for validity at wavelengths of light around 1310 nm; this model was then utilized to develop a SAR-OCT design for murine retinal imaging. A Monte Carlo technique simulates light scattering from the retina, and the simulation results are confirmed with SAR-OCT images. Various images from the SAR-OCT system are presented and utility of the system is described. SAR-OCT is demonstrated as a viable and robust imaging platform to extend utility of retinal OCT imaging by incorporating scattering data into investigative ophthalmologic analysis. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Open AccessArticle
Impact of Combination Therapy with Ezetimibe/Simvastatin Treatment on the Neointimal Response to Biodegradable Polymer Biolimus-Eluting Stent Implantation in Patients with Acute Myocardial Infarction: Serial Assessment with Optical Coherence Tomography
Appl. Sci. 2018, 8(10), 1968; https://doi.org/10.3390/app8101968 - 18 Oct 2018
Cited by 1
Abstract
The aim of this study was to compare the neointimal response at 12-month follow-up between ezetimibe/simvastatin (Vytorin, manufactured by Merck) 10/10 mg and Vytorin 10/40 mg after biodegradable polymer Biolimus-eluting stent (BP-BES) implantation in patients with acute myocardial infarction (AMI). A total of [...] Read more.
The aim of this study was to compare the neointimal response at 12-month follow-up between ezetimibe/simvastatin (Vytorin, manufactured by Merck) 10/10 mg and Vytorin 10/40 mg after biodegradable polymer Biolimus-eluting stent (BP-BES) implantation in patients with acute myocardial infarction (AMI). A total of 20 patients requiring revascularization were randomly assigned to receive either Vytorin 10/10 mg (n = 9) or Vytorin 10/40 mg (n = 11). Baseline optical coherence tomography (OCT) was performed after stent implantation, and follow-up OCT was scheduled at 12 months. We performed follow-up OCT in 18 patients (Vytorin 10/10 mg (n = 9) or Vytorin 10/40 mg (n = 9)). A total of 842 frames and 8552 struts were analyzed at initial and follow-up OCT. At follow-up, the percentage of uncovered struts was not significantly different between both groups (6.61 ± 10.29% vs. 7.57 ± 6.45%, p = 0.815). The percentage of malapposed struts was also similar between both groups (0.69 ± 1.58% vs. 1.55 ± 2.72%, respectively, p = 0.422). Mean percent neointimal hyperplasia area was not significantly different between both groups (6.53 ± 3.26% vs. 6.37 ± 8.96%, p = 0.961). This OCT study showed that both high- and moderate-intensity dosing of Vytorin was associated with relatively lower percentages of uncovered struts and malapposed struts after Biolimus A9-eluting stent implantation in patients with AMI. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Open AccessArticle
Five-Frame Variable Phase-Shifting Method for Full-Range Spectral-Domain Optical Coherence Tomography
Appl. Sci. 2018, 8(9), 1580; https://doi.org/10.3390/app8091580 - 07 Sep 2018
Abstract
In order to achieve a better complex conjugate artifacts (CCA) suppression, we propose a five-frame variable phase-shifting (FVP) method for spectral domain optical coherence tomography (SD-OCT). The traditional five-frame invariant phase-shifting (FIP) method employs five phase shifts correlate with the center wavelength. However, [...] Read more.
In order to achieve a better complex conjugate artifacts (CCA) suppression, we propose a five-frame variable phase-shifting (FVP) method for spectral domain optical coherence tomography (SD-OCT). The traditional five-frame invariant phase-shifting (FIP) method employs five phase shifts correlate with the center wavelength. However, due to the effects of polychromatic errors, the FIP method cannot get excellent CCA suppression. In the present work, we employ FVP method using variable phase shifts which is dependent on all the wavelengths and therefore, theoretically, the system would have no effects of polychromatic errors. This is the reason why the FVP method would achieve better CCA suppression than the FIP method. Comparative studies between FIP and FVP methods are investigated in the work. Subsequently, we develop a homemade SD-OCT system involving a homemade spectrometer, by which the anterior segment of a rat’s eyeball is measured. The experimental results demonstrate that the quality of OCT images is significantly improved by using FVP method with an increase by a factor of 1.7 on the CCA suppression of SD-OCT. FVP provides a new strategy for complex conjugate artifacts suppression for spectral domain optical coherence tomography. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Open AccessArticle
A Patient-Specific Study Investigating the Relation between Coronary Hemodynamics and Neo-Intimal Thickening after Bifurcation Stenting with a Polymeric Bioresorbable Scaffold
Appl. Sci. 2018, 8(9), 1510; https://doi.org/10.3390/app8091510 - 01 Sep 2018
Cited by 1
Abstract
We present an application of a validated reconstruction methodology for the comparison between patient-specific hemodynamics and neo-intimal thickening at nine months from the intervention. (1) Background: Coronary bifurcation stenting alters the vessel geometry, influencing the local hemodynamics. The evaluation of wall shear stress [...] Read more.
We present an application of a validated reconstruction methodology for the comparison between patient-specific hemodynamics and neo-intimal thickening at nine months from the intervention. (1) Background: Coronary bifurcation stenting alters the vessel geometry, influencing the local hemodynamics. The evaluation of wall shear stress (WSS) relies on the application of computational fluid dynamics to model its distribution along the coronary tree. The endothelium actively responds to WSS, which triggers eventual cell proliferation to cover the stent struts. (2) Methods: Baseline optical coherence tomography and angiographic data were combined to reconstruct a patient-specific coronary bifurcation with an implanted bioresorbable scaffold and to simulate the hemodynamics. Results were linked with the neo-intimal thickening after nine months from the intervention. (3) Results: Blood velocity patterns were disrupted at the bifurcation due to the presence of the stent. It was observed that 55.6% of the scaffolded lumen surface was exposed to values of time-averaged WSS lower than 0.4 Pa. Follow-up images showed a luminal narrowing of 19% in the main branch. There was also a complete coverage in 99% of struts. (4) Conclusions: This approach provided valuable complementary information that might improve the clinical outcomes in this subset of coronary diseases. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Open AccessArticle
Rheological and Flocculation Analysis of Microfibrillated Cellulose Suspension Using Optical Coherence Tomography
Appl. Sci. 2018, 8(5), 755; https://doi.org/10.3390/app8050755 - 10 May 2018
Cited by 3
Abstract
A sub-micron resolution optical coherence tomography device was used together with a pipe rheometer to analyze the rheology and flocculation dynamics of a 0.5% microfibrillated cellulose (MFC) suspension. The bulk behavior of the MFC suspension showed typical shear thinning (power-law) behavior. This was [...] Read more.
A sub-micron resolution optical coherence tomography device was used together with a pipe rheometer to analyze the rheology and flocculation dynamics of a 0.5% microfibrillated cellulose (MFC) suspension. The bulk behavior of the MFC suspension showed typical shear thinning (power-law) behavior. This was reflected in a monotonously decreasing floc size when the shear stress exceeded the yield stress of the suspension. The quantitative viscous behavior of the MFC suspension changed abruptly at the wall shear stress of 10 Pa, which was reflected in a simultaneous abrupt drop of the floc size. The flocs were strongly elongated with low shear stresses. With the highest shear stresses, the flocs were almost spherical, indicating a good level of fluidization of the suspension. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Review

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Open AccessReview
Developments in Contact Lens Imaging: New Applications of Optical Coherence Tomography
Appl. Sci. 2019, 9(13), 2580; https://doi.org/10.3390/app9132580 - 26 Jun 2019
Abstract
Optical coherence tomography (OCT) is a high-speed and non-contact optical imaging technology widely used for noninvasive cross-sectional imaging of biological objects. Two main OCT technologies have been developed: time domain and Fourier domain technologies. The latter can be further divided into spectral domain [...] Read more.
Optical coherence tomography (OCT) is a high-speed and non-contact optical imaging technology widely used for noninvasive cross-sectional imaging of biological objects. Two main OCT technologies have been developed: time domain and Fourier domain technologies. The latter can be further divided into spectral domain OCT, which uses a broadband light source and a spectrometer as a detector, and swept source OCT, which employs a quickly-rotating laser source. Advances in OCT technology have made it one of the most helpful devices in ophthalmic practice. Fourier OCT has revolutionized imaging of the posterior segment of the eye, as well as of anterior structures and has enhanced the ability to diagnose and manage patients. It provides high-resolution information about the tear film, contact lens (CL), a qualitative and quantitative assessment of the anterior eye that is important in CL fitting, and allows possible eye surface changes while wearing CLs to be monitored. Potential swept source OCT technology applications include industrial processes of lens design and quality control. In this paper, we describe clinical applications ant outline a variety of multifunctional uses of OCT in the field of refractive error correction with CLs. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Open AccessReview
Clinical Applications of Optical Coherence Angiography Imaging in Ocular Vascular Diseases
Appl. Sci. 2019, 9(12), 2577; https://doi.org/10.3390/app9122577 - 25 Jun 2019
Abstract
Optical coherence tomography angiography (OCTA) provides us with a non-invasive and efficient means of imaging anterior and posterior segment vasculature in the eye. OCTA has been shown to be effective in imaging diseases such as diabetic retinopathy; retinal vein occlusions; retinal artery occlusions; [...] Read more.
Optical coherence tomography angiography (OCTA) provides us with a non-invasive and efficient means of imaging anterior and posterior segment vasculature in the eye. OCTA has been shown to be effective in imaging diseases such as diabetic retinopathy; retinal vein occlusions; retinal artery occlusions; ocular ischemic syndrome; and neovascularization of the iris. It is especially useful with depth-resolved imaging of the superficial, intermediate, and deep capillary plexi in the retina, which enables us to study and closely monitor disease progression and response to treatment. With further advances in technology, OCTA has the potential to become a more widely used tool in the clinical setting and may even supersede ocular angiography in some areas. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Open AccessReview
Ten Years of Gabor-Domain Optical Coherence Microscopy
Appl. Sci. 2019, 9(12), 2565; https://doi.org/10.3390/app9122565 - 24 Jun 2019
Abstract
Gabor-domain optical coherence microscopy (GDOCM) is a high-definition imaging technique leveraging principles of low-coherence interferometry, liquid lens technology, high-speed imaging, and precision scanning. GDOCM achieves isotropic 2 μm resolution in 3D, effectively breaking the cellular resolution limit of optical coherence tomography (OCT). In [...] Read more.
Gabor-domain optical coherence microscopy (GDOCM) is a high-definition imaging technique leveraging principles of low-coherence interferometry, liquid lens technology, high-speed imaging, and precision scanning. GDOCM achieves isotropic 2 μm resolution in 3D, effectively breaking the cellular resolution limit of optical coherence tomography (OCT). In the ten years since its introduction, GDOCM has been used for cellular imaging in 3D in a number of clinical applications, including dermatology, oncology and ophthalmology, as well as to characterize materials in industrial applications. Future developments will enhance the structural imaging capability of GDOCM by adding functional modalities, such as fluorescence and elastography, by estimating thicknesses on the nano-scale, and by incorporating machine learning techniques. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Open AccessReview
A Review of the Applications of OCT for Analysing Pharmaceutical Film Coatings
Appl. Sci. 2018, 8(12), 2700; https://doi.org/10.3390/app8122700 - 19 Dec 2018
Cited by 1
Abstract
Optical coherence tomography (OCT) has recently attracted a lot of interest in the pharmaceutical manufacturing industry as a fast, contactless and non-destructive modality for quantifying thin film coatings on pharmaceutical dosage forms, which cannot be resolved easily with other techniques. In this topical [...] Read more.
Optical coherence tomography (OCT) has recently attracted a lot of interest in the pharmaceutical manufacturing industry as a fast, contactless and non-destructive modality for quantifying thin film coatings on pharmaceutical dosage forms, which cannot be resolved easily with other techniques. In this topical review, we present an overview of the research that has been performed to date, highlighting key differences between systems and outlining major challenges ahead. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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Open AccessReview
OCT Angiography: A Technique for the Assessment of Retinal and Optic Nerve Diseases in the Pediatric Population
Appl. Sci. 2018, 8(12), 2441; https://doi.org/10.3390/app8122441 - 01 Dec 2018
Abstract
Optical coherence tomography angiography (OCT-A) is a novel, rapidly evolving, non-invasive imaging technique that allows images of the retinal vasculature to be obtained in a few seconds. Blood vessels of different retinal vascular plexuses and the foveal avascular zone (FAZ) can be examined [...] Read more.
Optical coherence tomography angiography (OCT-A) is a novel, rapidly evolving, non-invasive imaging technique that allows images of the retinal vasculature to be obtained in a few seconds. Blood vessels of different retinal vascular plexuses and the foveal avascular zone (FAZ) can be examined without the administration of any contrast or dye. Due to these characteristics, OCT-A could be an excellent complementary test to study retinal vascularization in children. Until now, most of the studies with OCT-A have been conducted in adults and only a few have been carried out in children. In this review, we describe the principles and advantages of OCT-A over traditional imaging methods and provide a summary of the OCT-A findings in retinopathy of prematurity and other retinal and optic disc pathologies in children. In view of the promising results from studies, the advantages of a relatively rapid and non-invasive method to assess the retinal vasculature makes OCT-A a tool of which applications in the field of pediatric ophthalmology will be expanded in the near future for patient diagnosis and follow-up in every day clinical practice. Full article
(This article belongs to the Special Issue Optical Coherence Tomography and its Applications)
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