Capability Of Optical Coherence Tomography Research Articles

Percutaneous coronary intervention for bifurcation coronary lesions using optimised angiographic guidance: the 18th consensus document from the European Bifurcation Club.

The 2023 European Bifurcation Club (EBC) meeting took place in Warsaw in October, and the latest evidence for the use of intravascular ultrasound (IVUS) and optical coherence tomography (OCT) to optimise percutaneous coronary interventions (PCI) on coronary bifurcation lesions (CBLs) was a major focus. The topic generated deep discussions and general appraisal on the potential benefits of IVUS and OCT in PCI procedures. Nevertheless, despite an increasing recognition of IVUS and OCT capabilities and their recognised central role for guidance in complex CBL and left main PCI, it is expected that angiography will continue to be the primary guidance modality for CBL PCI, principally due to educational and economic barriers. Mindful of the restricted access/adoption of intracoronary imaging for CBL PCI, the EBC board decided to review and describe a series of tips and tricks which can help to optimise angiography-guided PCI for CBLs. The identified key points for achieving an optimal angiography-guided PCI include a thorough analysis of pre-PCI images (computed tomography angiography, multiple angiographic views, quantitative coronary angiography vessel estimation), a systematic application of the technical steps suggested for a given selected technique, an intraprocedural or post-PCI use of stent enhancement and a low threshold for bailout use of intravascular imaging.

In vivo burn scar assessment with speckle decorrelation and joint spectral and time domain optical coherence tomography.

Post-burn scars and scar contractures present significant challenges in burn injury management, necessitating accurate evaluation of the wound healing process to prevent or minimize complications. Non-invasive and accurate assessment of burn scar vascularity can offer valuable insights for evaluations of wound healing. Optical coherence tomography (OCT) and OCT angiography (OCTA) are promising imaging techniques that may enhance patient-centered care and satisfaction by providing detailed analyses of the healing process. Our study investigates the capabilities of OCT and OCTA for acquiring information on blood vessels in burn scars and evaluates the feasibility of utilizing this information to assess burn scars. Healthy skin and neighboring scar data from nine burn patients were obtained using OCT and processed with speckle decorrelation, Doppler OCT, and an enhanced technique based on joint spectral and time domain OCT. These methods facilitated the assessment of vascular structure and blood flow velocity in both healthy skin and scar tissues. Analyzing these parameters allowed for objective comparisons between normal skin and burn scars. Our study found that blood vessel distribution in burn scars significantly differs from that in healthy skin. Burn scars exhibit increased vascularization, featuring less uniformity and lacking the intricate branching network found in healthy tissue. Specifically, the density of the vessels in burn scars is 67% higher than in healthy tissue, while axial flow velocity in burn scar vessels is 25% faster than in healthy tissue. Our research demonstrates the feasibility of OCT and OCTA as burn scar assessment tools. By implementing these technologies, we can distinguish between scar and healthy tissue based on its vascular structure, providing evidence of their practicality in evaluating burn scar severity and progression.

Enhancement of Optical Coherence Tomography for Early Diagnostics Through Ag-Decorated ZnO Quantum Dots-Induced Motion Analysis

Optical Coherence Tomography (OCT) stands as a pivotal imaging modality in medical diagnostics, providing intricate insights into microstructural alterations within biological tissues. This research delves into the augmentative impact of nanostructures on OCT, with a specific emphasis on their potential applications in early diagnostic scenarios. The article introduces a novel composite material, Silver-Zinc Oxide (Ag-ZnO) nano-structures, synthesized through the amalgamation of zinc oxide (ZnO) quantum dots and silver (Ag) particles. The study scrutinizes the enhancement effect of these nanostructures on the depth imaging capability and diagnostic precision of OCT. Employing the finite difference time domain method, the research simulates and calculates the extinction spectrum enhancement effect of Ag-ZnO quantum dots in OCT. Comparative analyses are conducted to evaluate the effectiveness and diagnostic accuracy of OCT imaging when enhanced with Ag-ZnO quantum dots against Magnetic Resonance Imaging (MRI) technology. The outcomes manifest a noteworthy improvement in diagnostic accuracy with the integration of Ag-ZnO quantum dots in OCT, underscoring their efficacy in heightening imaging depth and diagnostic precision for early diagnostic applications. This study not only accentuates the pivotal role played by quantum dots in amplifying the capabilities of OCT but also paves the way for the advancement of sophisticated diagnostic tools within the realm of medical imaging.

Imaging human macular pigments with visible light optical coherence tomography and superluminescent diodes.

We demonstrate superluminescent diodes (SLDs) for visible light optical coherence tomography (OCT) of the human retina. SLDs are less costly than supercontinuum sources and have lower intrinsic excess noise, enabling imaging closer to the shot noise limit. While single SLDs are not broadband, they provide power concentrated at specific wavelengths relevant to retinal function. As a new, to the best of our knowledge, application, we image human macular pigments (MPs), which are thought to both aid vision and protect against advanced age-related macular degeneration. Using the unique depth-resolved capabilities of OCT, we localize MPs in depth to Henle's fibers beneath the foveal pit in the living human retina. Our approach reduces the cost of visible light OCT to nearly that of near-infrared (NIR) OCT while also providing information about clinically relevant MPs which cannot be measured in the NIR.

Reed microstructure detection by optical coherence tomography, an efficient andnon-invasive method.

Woodwind instrument reeds are commonly made from Arundo donax Linn (ADL) material. The mechanical properties of ADL significantly influence the acoustic behavior of the reed, thereby affecting the instrument's overall performance. Current investigations into the internal microstructure of reeds are primarily conducted through optical microscopy, a method that involves cutting open the sample and observing its morphological features, thereby causing irreversible damage to the specimen. To address this issue, we employed optical coherence tomography (OCT) to examine the interior microstructure of reeds in both two and three dimensions, thus providing a non-invasive and real-time technique for characterizing reeds. The optical data gathered through backscattering is used to reveal microstructural variations and determine the reed's lifespan. Our findings indicate that, with increasing degrees of vibratory load excitation, the microstructure of the vessel wall degrades while the width of the vessel lumen appears to expand. Over extended periods of usage, the backscattered signal intensity of the parenchymal tissue diminishes. Additionally, the 3D imaging capabilities of OCT can be employed to rapidly establish the spatial volume of defects within the reed. In light of these results, optical coherence tomography shows its promise as a powerful, real-time, and noninvasive technique for the identification of reeds.

Angular contrastive distillation driven self-supervised scanner independent screening and grading of retinopathy

Retinopathy is a group of retinal diseases that causes severe retinal damage, resulting in partial visual impairment or complete vision loss. Due to the capability of optical coherence tomography in revealing early retinal abnormalities, many researchers have utilized it to develop autonomous retinal screening systems. However, to the best of our knowledge, the majority of these systems are vulnerable against diversified scanner specifications, hence, requiring extensive training supervision (on large-scale datasets) to accurately learn retinal screening tasks. In this paper, we present a novel self-supervised segmentation-driven classification pipeline that employs a proposed angular contrastive distillation scheme to extract retinal lesions (from the multi-vendor data) in order to give lesion-aware scanner independent screening and grading of retinopathy. The diagnostic capacity of the proposed framework is further enhanced by the integration of a novel co-attention mechanism, which enables the underlying network to focus its attention on retinal abnormalities to effectively grade retinal diseases without incurring supervision from the ground truth labels. The proposed framework is rigorously validated on seven public datasets, acquired with four different scanners, where it outperforms its competitors by achieving 9.22% improvement in terms of mean intersection-over-union for extracting retinal lesions and 10.71% improvement in terms of F1 score for grading retinopathy.

Effect of an Anaerobic Fermentation Process on 3D-Printed PLA Materials of a Biogas-Generating Reactor.

3D-printed materials are present in numerous applications, from medicine to engineering. The aim of this study is to assess their suitability for an application of interest today, that of testing of 3D-printed polylactic acid (PLA)-based reactors for biogas production using anaerobic digestion. The impact of temperature, pH, and aqueous phase on the tested bioreactor is investigated, together with the effect of the gaseous phase (i.e., produced biogas). Two batches of materials used separately, one after another inside the bioreactor were considered, in a realistic situation. Two essential parameters inside the reactor (i.e., pH and temperature) were continuously monitored during a time interval of 25 to 30 days for each of the two biogas-generating processes. To understand the impact of these processes on the walls of the bioreactor, samples of 3D-printed material were placed at three levels: at the top (i.e., outside the substrate), in the middle, and at the bottom of the bioreactor. The samples were analyzed using a non-destructive imaging method, Optical Coherence Tomography (OCT). An in-house developed swept-source (SS) OCT system, master-slave (MS) enhanced, operating at a central wavelength of 1310 nm was utilized. The 3D OCT images related to the degradation level of the material of the PLA samples were validated using Scanning Electron Microscopy (SEM). The differences between the impact of the substrate on samples situated at the three considered levels inside the reactor were determined and analyzed using their OCT B-scans (optical cross-section images). Thus, the impact of the biogas-generating process on the interior of the bioreactor was demonstrated and quantified, as well as the capability of OCT to perform such assessments. Therefore, future work may target OCT for in situ investigations of such bioreactors.

Diagnostic capabilities of optical coherence tomography and optical coherence tomography angiography in the diagnosis of primary open-angle glaucoma

Abstract. to assess the features of the retinal nerve fiber layer (RNFL), ganglion complex (GC) and the microcirculatory bed of the retina in patients with primary open-angle glaucoma (POAG) using optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA).
 Materials and methods: The study involved 20 people (11 females, 9 males). Patients were divided into 2 groups. The first group included 10 clinically healthy individuals, the second group - 10 patients with POAG. All patients underwent standard ophthalmic examination, OCT / OCTA examination of the RNFL, GC and retinal microcirculatory bed.
 Results: The study identified the most sensitive indicators to the progression of the glaucoma process. It was found that the RNFL thickness and the density of the retinal vascular progressively decrease with the development of glaucoma opticopathy. Compared with the group of healthy individuals in patients with POAG, the RNFL thickness in the lower temporal sector of the peripapillary zone was reduced by 44.04% (p <0,01). Compared with healthy individuals, the density of the superficial vascular plexus decreased by 16.3%, deep - by 12.5% ​​(p <0,01). The perimeter of the foveolar avascular zone in patients with glaucoma increased by 31.01%, the area of ​​the foveolar avascular zone increased 1.6 times (p <0.01).
 Conclusions: OCT and OCTA are effective methods for assessing the state of GC, RNFL and microcirculatory bed of the retina, which allow for non-invasive monitoring and evaluation of these indicators in patients with POAG.

In Situ Characterization of Melt–Electrowritten Scaffolds in 3D Using Optical Coherence Tomography

Recent developments in melt electrowriting (MEW), a high‐resolution additive manufacturing technology, have led to increases in scaffold complexity. However, MEW scaffolds are currently characterized ex situ, which causes time–consuming iterations of characterization and fabrication that limit scaffold throughput and more widespread use of the technology. For the first time, an in situ method to characterize the 3D microstructure of MEW scaffolds using optical coherence tomography (OCT) is described. Calculations of microstructural features are performed on OCT data using a custom algorithm, demonstrating close correspondence with scanning electron microscopy (SEM). For example, OCT calculations of fiber diameter and scaffold thickness are within an average of 0.31 and 1.79 μm, respectively, of corresponding SEM–derived calculations. Additionally, the 3D capabilities of OCT enable the nondestructive characterization of scaffolds with depth–varying microstructures, overcoming some main limitations of SEM. Finally, in situ characterization is achieved by integrating the OCT scanner within an MEW printer, enabling the scaffold microstructure to be evaluated and optimized during manufacture. This new capability represents an important step toward achieving an efficient fabrication–characterization cycle with the guaranteed scaffold quality and reproducibility required to validate the manufacturing process.

Capabilities of optical coherence tomography in examination of senile scleral plaques

To assess the morphological characteristics of SSP using spectral optical coherence tomography (OCT). The study examined 13 patients (21 eyes) with average age of 77.1±6.3 years. OCT scanning was performed to determine OCT signs of SSP, the length (parallel to the limb), the width and height of the SSP, as well as the depth and thickness of the overlying sclera. A combination of nasal and temporal SSP was observed in 14 eyes, and nasal only SSP was detected in 6 eyes. In all cases, OCT presented a characteristic picture of SSP observed as an intrascleral cavity with hyperreflective content with lower reflectivity than the surrounding tissues, and clear borders represented by unchanged scleral fibers. The length of the SSP parallel to the limb was 3296±820 µm, the width - 2312±436 µm, the height of the SSP cavity - 482±89 µm. The depth of SSP site was 213±36 µm, the thickness of the overlying sclera - 125±29 µm. Updated information about SSP structure can be used in the development of standard surgical algorithms contributing to prevention of postoperative complications.

Potential Imaging Capability of Optical Coherence Tomography as Dental Optical Probe: A Mini-Review

Optical coherence tomography (OCT) has been emerging in the dental field as an alternative diagnostic imaging for “optical probes” owing to its micro-meter resolution and non-invasiveness. This review aims to answer the following question: what is the imaging capability of OCT to visualize the subgingival area? Online searches were performed on PubMed and SPIE digital library databases, followed by a manual screening of references listed in relevant studies. The feasibility and imaging performance of OCT to visualize the subgingival area, including the periodontal, peri-implant, and crown margins, are discussed. All of the literature reviewed in this study demonstrated that OCT has the ability to visualize periodontal, including hard and soft tissues, and peri-implant conditions with high resolution. Gingival sulcus depth, periodontal pocket, and calculus deposition can also be depicted. However, clinical evidence that support the imaging capability of OCT as a dental optical probe to visualize subgingival area is lacking. Limited availability, portability, and usability of OCT for clinical experiments in dentistry, particularly for the subgingival area, might be contributed to its limitations. Hence, further development of handheld OCT systems and controlled clinical trials are needed to confirm the imaging capability of OCT reported in this review.

Detection of intracranial hypertension in children using optical coherence tomography: a systematic review

ObjectivesTo evaluate the diagnostic capability of optical coherence tomography (OCT) in children aged under 18 years old with intracranial hypertension (IH).DesignSystematic review.MethodsWe conducted a systematic review using the following platforms...

Sm-Net OCT: a deep-learning-based speckle-modulating optical coherence tomography.

Speckle imposes obvious limitations on resolving capabilities of optical coherence tomography (OCT), while speckle-modulating OCT can efficiently reduce speckle arbitrarily. However, speckle-modulating OCT seriously reduces the imaging sensitivity and temporal resolution of the OCT system when reducing speckle. Here, we proposed a deep-learning-based speckle-modulating OCT, termed Sm-Net OCT, by deeply integrating conventional OCT setup and generative adversarial network trained with a customized large speckle-modulating OCT dataset containing massive speckle patterns. The customized large speckle-modulating OCT dataset was obtained from the aforementioned conventional OCT setup rebuilt into a speckle-modulating OCT and performed imaging using different scanning parameters. Experimental results demonstrated that the proposed Sm-Net OCT can effectively obtain high-quality OCT images without the electronic noise and speckle, and conquer the limitations of reducing the imaging sensitivity and temporal resolution which conventional speckle-modulating OCT has. The proposed Sm-Net OCT can significantly improve the adaptability and practicality capabilities of OCT imaging, and expand its application fields.

New capabilities of optical coherence tomography in the diagnostics of primary angle-closure glaucoma

INTRODUCTION. Recently, posterior vitreous detachment (PVD) was suggested as a fundamental pathologic process in primary angle-closure glaucoma (PACG) in morphologically predisposed patients with anatomically narrow anterior chamber angle.PURPOSE. To study the role of PVD in the development and clinical manifestation of PACG in anatomically predisposed eyes and to assess the capabilities of posterior segment optical coherence tomography (PS-OCT) in PACG diagnostics.MATERIALS AND METHODS. Thirty eyes with newly diagnosed stage I-II PACG and thirty eyes predisposed to PACG (with narrow anterior chamber angle without glaucoma signs) were enrolled in the study. All patients underwent ophthalmological examination, Hyams test, ocular ultrasound (OU) and PS-OCT.RESULTS. PVD with retrohyaloid space (RHS) formation was revealed in all PACG eyes. Positive Hyams test was in 86.67% eyes with PACG, and 13.33% were negative. All the eyes with PVD as a result of Hyams test experienced RHS enhancement correlating with IOP rise. Despite the negative results of Hyams test in some PACG eyes with PVD — glaucomatous optic neuropathy signs were present. Possible causes are discussed.PVD with RHS formation was revealed in 53.33% predisposed to PACG eyes — all with positive result of Hyams test. The other 46.67% eyes predisposed to PACG had negative Hyams test, no PVD and no RHS.CONCLUSION. Obtained results confirm a new theory of PACG etiopathogenesis suggesting PVD with PGS to be the essential mechanism of POAG development in morphologically predisposed eyes. PS-OCT appears to be crucial in PACG early diagnostics.

Adaptive compounding speckle-noise-reduction filter for optical coherence tomography images.

.Significance: Speckle noise limits the diagnostic capabilities of optical coherence tomography (OCT) images, causing both a reduction in contrast and a less accurate assessment of the microstructural morphology of the tissue.Aim: We present a speckle-noise reduction method for OCT volumes that exploits the advantages of adaptive-noise wavelet thresholding with a wavelet compounding method applied to several frames acquired from consecutive positions. The method takes advantage of the wavelet representation of the speckle statistics, calculated properly from a homogeneous sample or a region of the noisy volume.Approach: The proposed method was first compared quantitatively with different state-of-the-art approaches by being applied to three different clinical dermatological OCT volumes with three different OCT settings. The method was also applied to a public retinal spectral-domain OCT dataset to demonstrate its applicability to different imaging modalities.Results: The results based on four different metrics demonstrate that the proposed method achieved the best performance among the tested techniques in suppressing noise and preserving structural information.Conclusions: The proposed OCT denoising technique has the potential to adapt to different image OCT settings and noise environments and to improve image quality prior to clinical diagnosis based on visual assessment.

Application of OCT-Derived Attenuation Coefficient in Acute Burn-Damaged Skin.

There remains a need to objectively monitor burn wound healing within a clinical setting, and optical coherence tomography (OCT) is proving itself one of the ideal modalities for just such a use. The aim of this study is to utilize the noninvasive and multipurpose capabilities of OCT, along with its cellular-level resolution, to demonstrate the application of optical attenuation coefficient (OAC), as derived from OCT data, to facilitate the automatic digital segmentation of the epidermis from scan images and to work as an objective indicator for burn wound healing assessment. A simple, yet efficient, method was used to estimate OAC from OCT images taken over multiple time points following acute burn injury. This method enhanced dermal-epidermal junction (DEJ) contrast, which facilitated the automatic segmentation of the epidermis for subsequent thickness measurements. In addition, we also measured and compared the average OAC of the dermis within said burns for correlative purposes. Compared with unaltered OCT maps, enhanced DEJ contrast was shown in OAC maps, both from single A-lines and completed B-frames. En face epidermal thickness and dermal OAC maps both demonstrated significant changes between imaging sessions following burn injury, such as a loss of epidermal texture and decreased OAC. Quantitative analysis also showed that OAC of acute burned skin decreased below that of healthy skin following injury. Our study has demonstrated that the OAC estimated from OCT data can be used to enhance imaging contrast to facilitate the automatic segmentation of the epidermal layer, as well as help elucidate our understanding of the pathological changes that occur in human skin when exposed to acute burn injury, which could serve as an objective indicator of skin injury and healing.

Longitudinal optical coherence tomography to visualize the in vivo response of middle ear biofilms to antibiotic therapy

Studying the impact of antibiotic treatment on otitis media (OM), the leading cause of primary care office visits during childhood, is critical to develop appropriate treatment strategies. Tracking dynamic middle ear conditions during antibiotic treatment is not readily applicable in patients, due to the limited diagnostic techniques available to detect the smaller amount and variation of middle ear effusion (MEE) and middle ear bacterial biofilm, responsible for chronic and recurrent OM. To overcome these challenges, a handheld optical coherence tomography (OCT) system has been developed to monitor in vivo response of biofilms and MEEs in the OM-induced chinchilla model, the standard model for human OM. As a result, the formation of MEE as well as biofilm adherent to the tympanic membrane (TM) was longitudinally assessed as OM developed. Various types of MEEs and biofilms in the chinchilla model were identified, which showed comparable features as those in humans. Furthermore, the effect of antibiotics on the biofilm as well as the amount and type of MEEs was investigated with low-dose and high-dose treatment (ceftriaxone). The capability of OCT to non-invasively track and examine middle ear conditions is highly beneficial for therapeutic OM studies and will lead to improved management of OM in patients.

Diagnostic accuracy of optical coherence tomography for the identification of in-stent fibroatheroma following stent implantation: an ex vivo histological validation study.

The accurate identification of in-stent fibroatheroma by in vivo imaging is clinically important to preventing the late catch-up phenomenon after stent deployment. This study investigated the diagnostic accuracy of optical coherence tomography (OCT) for the detection of "in-stent fibroatheroma" following stent implantation.Fifty stented coronary arteries from the 31 autopsy hearts were examined to compare OCT and histological image findings. A histological in-stent fibroatheroma was defined as a neointima containing an acellular necrotic core generated by macrophage infiltration. OCT-derived in-stent fibroatheroma comprised a heterogeneous pattern with an invisible stent strut behind the low-signal-intensity region.A total of 122 matched OCT and histology cross-sections were evaluated. Using histological findings as the gold standard, the sensitivity, specificity, positive predictive value, and negative predictive value for OCT-derived in-stent fibroatheroma were 100%, 99%, 80%, and 100%, respectively. The only histological finding underlying the false-positive diagnosis of OCT-derived in-stent fibroatheroma was foam cell accumulation without a necrotic core on the neointimal surface. No false-negative diagnosis of OCT for in-stent fibroatheroma was apparent in this analysis.This study demonstrated the potential capability of OCT based on stent strut visualization behind low-signal-intensity regions to discriminate in-stent fibroatheroma from other neointimal tissues.

Handheld optical coherence tomography for clinical assessment of dental plaque and gingiva.

.Significance: Optical coherence tomography (OCT) offers high spatial resolution and contrast for imaging intraoral structures, yet few studies have investigated its clinical feasibility for dental plaque and gingiva imaging in vivo. Furthermore, the accessibility is often limited to anterior teeth due to bulky imaging systems and probes.Aim: A custom-designed, handheld probe-based, spectral-domain OCT system with an interchangeable attachment was developed to assess dental plaque and gingival health in a clinical setting.Approach: Healthy volunteers and subjects with gingivitis and sufficient plaque were recruited. The handheld OCT system was operated by trained dental hygienists to acquire images of dental plaque and gingiva at various locations and after one-week use of oral hygiene products.Results: The handheld OCT can access premolars, first molars, and lingual sides of teeth to visualize the plaque distribution. OCT intensity-based texture analysis revealed lower intensity from selected sites in subjects with gingivitis. The distribution of the dental plaque after one-week use of the oral hygiene products was compared, showing the capability of OCT as a longitudinal tracking tool.Conclusions: OCT has a strong potential to display and assess dental plaque and gingiva in a clinical setting. Meanwhile, technological challenges remain to perform systematic longitudinal tracking and comparative analyses.

Optical coherence tomography for fast bedside imaging, assessment and monitoring of autoimmune inflammatory skin diseases?

Optical coherence tomography (OCT) is a non-invasive, high-resolution imaging technique with a growing impact in dermatology. The principle of OCT is comparable to that of sonography, except that it uses infrared laser light instead of ultrasound waves. It has been clinically demonstrated that OCT is suitable for discriminating between different types of non-melanoma skin cancer at an early stage of disease. Optical coherence tomography generates two- or three-dimensional images of up to 2mm penetration depth, a field of view of 6mm × 6mm, and an acquisition time of seconds. The resolution capability of OCT is more than 3 to 100 times higher than that of ultrasound imaging. It is of particular interest that the additional information on vasculature provided by OCT angiography enables the assessment and monitoring of inflammatory skin diseases. The use of OCT to locate exact blister levels was demonstrated for diagnosing autoimmune bullous diseases. It is anticipated that detection of subclinical lesions could indicate a relapse of the disease. In the future, this could enable intervention and early treatment. Furthermore, the development of high-speed OCT could allow fast scanning and bedside imaging of large body sites.