The role of optical coherence tomography in coronary intervention

Visualization of Atherosclerotic Plaques Paired with Joheksol 350 (Omnipaque)

Background: Cardiovascular disease is one of the leading causes of death around the globe. Atherosclerosis, a chronic inflammatory blood vessel disease that takes years to develop, is its primary cause. Instability and further plaque buildup are caused by chronic inflammation, which creates the conditions for possible rupture. The visualization of arterial lesions in situ can enhance understanding of atherosclerosis progression and potentially improve experimental therapies. Conventional histology methods for assessing atherosclerotic lesions are robust but are destructive and may prevent further tissue analysis. Objectives: The objective of the current study was to evaluate a novel, nondestructive method for the visualization and characterization of atherosclerotic lesions. Methods and Results: Thus, we tested the hypothesis that MRI paired with an iodine-based radiopaque stain would effectively characterize atherosclerotic plaques in a manner comparable to routine histology while maintaining sample integrity and providing whole-volume data.

Dynamics-aware deep predictive adaptive scanning optical coherence tomography

Conventional scanned optical coherence tomography (OCT) suffers from the frame rate/resolution tradeoff, whereby increasing image resolution leads to decreases in the maximum achievable frame rate. To overcome this limitation, we propose two variants of machine learning (ML)-based adaptive scanning approaches: one using a ConvLSTM-based sequential prediction model and another leveraging a temporal attention unit (TAU)-based parallel prediction model for scene dynamics prediction. These models are integrated with a kinodynamic path planner based on the clustered traveling salesperson problem to create two versions of ML-based adaptive scanning pipelines. Through experimental validation with novel deterministic phantoms based on a digital light processing board, our techniques achieved mean frame rate speed-ups of up to 40% compared to conventional raster scanning and the probabilistic adaptive scanning method without compromising image quality. Furthermore, these techniques reduced scene-dependent manual tuning of system parameters to demonstrate better generalizability across scenes of varying types, including those of intrasurgical relevance. In a real-time surgical tool tracking experiment, our technique achieved an average speed-up factor of over 3.2× compared to conventional scanning methods, without compromising image quality.

Bioresorbable stent unloading during percutaneous coronary intervention: Early detection and management

In this letter, we comment on a recent case report by Sun et al in the World Journal of Cardiology. The report describes the successful management of a rare complication: The unloading or detachment of a bioresorbable stent (BRS) during percutaneous coronary intervention (PCI) in a male patient. The unloading of BRS was detected via angiography and intravascular ultrasound (IVUS) imaging of the left coronary artery and left anterior descending artery. Although this case is interesting, the authors' report lacked crucial details. Specifically, insufficient information about the type of BRS used, potential causes of BRS unloading, or whether optical coherence tomography (OCT) imaging for coronary arteries was performed before, during, or after PCI. The OCT imaging of coronary arteries before PCI can potentially prevent BRS unloading due to its higher resolution compared to IVUS. In addition, despite detecting myocardial bridging during the PCI, the authors did not provide any details regarding this variation. Here we discuss the various types of BRS, the importance of OCT in PCI, and the clinical relevance of myocardial bridging.

Optical Coherence Tomography in the Evaluation of Suspected Carotid Webs

BACKGROUND

Carotid web (CaW) is a subtype of fibromuscular dysplasia that predominantly involves the intimal layer of the arterial wall and is commonly overlooked as a separate causative entity for recurrent strokes. CaW is defined as a shelf-like lesion at the carotid bulb, although different morphological features have been reported. Optical coherence tomography (OCT) has been described in the literature as a useful microscopic and cross-sectional tomographic imaging tool. This study aimed to evaluate the potential utility of OCT in characterizing the wall structure features of patients with suspected CaW.

METHODS

Retrospective analysis of patients with suspected CaW who underwent digital subtraction angiography (DSA) coupled with OCT of the carotid bulb from 2018 to 2021 in a single comprehensive stroke center.

RESULTS

Sixteen patients were included. The median age was 56 years (IQR 46-61) and 50% were women. OCT corroborated the diagnosis of CaW in 12/16 (75%) cases and ruled it out in 4/16 (25%) patients in whom atherosclerotic disease was demonstrated. Five of the 12 lesions demonstrated a thick fibrotic ridge consistent with CaW but also showed atherosclerotic changes in the vicinity of the carotid bulb (labeled as "CaW+"). In 4/16 (25%) patients, microthrombi adhered to the vessel wall were noted on OCT (inside the CaW pocket or just distal to the web), none of which were observed on CT angiography or DSA.

CONCLUSIONS

OCT may have value as a complementary imaging tool in the investigation of patients with suspected CaW and atypical morphological features. Further studies are warranted.

Update on cardiac imaging: A critical analysis

Imaging is instrumental in diagnosing and directing the management of atherosclerosis. In 1958 the first diagnostic coronary angiography (CA) was performed, and since then further development has led to new methods such as coronary CT angiography (CTA), optical coherence tomography (OCT), positron tomography (PET), and intravascular ultrasound (IVUS). Currently, CA remains powerful for visualizing coronary arteries; however, recent studies show the benefits of using other non-invasive techniques. This review identifies optimum imaging techniques for diagnosing and monitoring plaque stability. This becomes even direr now, given the rapidly rising incidence of atherosclerosis in society today. Many acute coronary events, including acute myocardial infarctions and sudden deaths, are attributable to plaque rupture. Although fatal, these events can be preventable. We discuss the factors affecting plaque integrity, such as increased inflammation, medications like statins, and increased lipid content. Some of these precipitating factors are identifiable through imaging. However, we also highlight significant complications arising in some modalities; in CA this can include ventricular arrhythmia and even death. Extending this, we elucidated from the literature that risk can also vary based on the location of arteries and their plaques. Promisingly, there are less invasive methods being trialled for assessing plaque stability, such as Cardiac Magnetic Resonance Imaging (CMR), which is already in use for other cardiac diseases like cardiomyopathies. Therefore, future research focusing on using imaging modalities in conjunction may be sensible, to bridge between the effectiveness of modalities, at the expense of increased complications, and vice versa.

Challenges and Advances in Interventional Cardiology for Coronary Artery Disease Management

The development of percutaneous coronary intervention (PCI) has been one of the greatest advances in cardiology and has changed clinical practice for patients with coronary artery disease (CAD). Despite continuous improvements in operators' experience, techniques, and the development of new-generation devices, significant challenges remain in improving the efficacy of PCI, including calcification, bifurcation, multivascular disease, stent restenosis, and stent thrombosis, among others. The present review aims to provide an overview of the current status of knowledge of endovascular revascularization in CAD, including relevant trials, therapeutic strategies, and new technologies addressing particular scenarios that can impact the prognosis of this vulnerable population.

Innovations in Intracoronary Imaging: Present Clinical Practices and Future Outlooks

Engaging intracoronary imaging (IC) techniques such as intravascular ultrasound or optical coherence tomography enables the precise description of vessel architecture. These imaging modalities have well-established roles in providing guidance and optimizing percutaneous coronary intervention (PCI) outcomes. Furthermore, IC is increasingly recognized for its diagnostic capabilities, as it has the unique capacity to reveal vessel wall characteristics that may not be apparent through angiography alone. This manuscript thoroughly reviews the contemporary landscape of IC in clinical practice. Focused on current methodologies, the review explores the utility and advancements in IC techniques. Emphasizing their role in clarifying coronary pathophysiology, guiding PCI, and optimizing patient outcomes, the manuscript critically evaluates the strengths and limitations of each modality. Additionally, the integration of IC into routine clinical workflows and its impact on decision-making processes are discussed. By synthesizing the latest evidence, this review provides valuable insights for clinicians, researchers, and healthcare professionals involved in the dynamic field of interventional cardiology.

Application of optical coherence tomography in cardiovascular diseases: bibliometric and meta-analysis

Significance

Since the advent of Optical Coherence Tomography (OCT) two decades ago, there has been substantial advancement in our understanding of intravascular biology. Identifying culprit lesion pathology through OCT could precipitate a paradigm shift in the treatment of patients with Acute Coronary Syndrome. Given the technical prowess of OCT in the realm of cardiology, bibliometric analysis can reveal trends and research focal points in the application of OCT for cardiovascular diseases. Concurrently, meta-analyses provide a more comprehensive evidentiary base, supporting the clinical efficacy of OCT-guided Percutaneous Coronary Intervention (PCI).

Design

This study employs a dual approach of Bibliometric and Meta-analysis.

Methods

Relevant literature from 2003 to 2023 was extracted from the Web of Science Core Collection (WoSCC) and analyzed using VOSviewer, CiteSpace, and R for publication patterns, countries, institutions, authors, and research hotspots. The study compares OCT-guided and coronary angiography-guided PCI in treating adult coronary artery disease through randomized controlled trials (RCTs) and observational studies. The study has been reported in the line with PRISMA and AMSTAR Guidelines.

Results

Adhering to inclusion and exclusion criteria, 310 publications were incorporated, demonstrating a continual rise in annual output. Chinese researchers contributed the most studies, while American research wielded greater influence. Analysis of trends indicated that research on OCT and angiography-guided PCI has become a focal topic in recent cohort studies and RCTs. In 11 RCTs (n = 5,277), OCT-guided PCI was not significantly associated with a reduction in the risk of Major Adverse Cardiac Events (MACE) (Odds ratio 0.84, 95% CI 0.65-1.10), cardiac death (0.61, 0.36-1.02), all-cause death (0.7, 0.49-1.02), myocardial infarction (MI) (0.88, 0.69-1.13), target lesion revascularization (TLR) (0.94, 0.7-1.27), target vessel revascularization (TVR) (1.04, 0.76-1.43), or stent thrombosis (0.72, 0.38-1.38). However, in 7 observational studies (n = 4,514), OCT-guided PCI was associated with a reduced risk of MACE (0.66, 0.48-0.91) and TLR (0.39, 0.22-0.68).

Conclusion

Our comprehensive review of OCT in cardiovascular disease literature from 2004 to 2023, encompassing country and institutional origins, authors, and publishing journals, suggests that OCT-guided PCI does not demonstrate significant clinical benefits in RCTs. Nevertheless, pooled results from observational studies indicate a reduction in MACE and TLR.

Integrating Computational and Biological Hemodynamic Approaches to Improve Modeling of Atherosclerotic Arteries

Atherosclerosis is the primary cause of cardiovascular disease, resulting in mortality, elevated healthcare costs, diminished productivity, and reduced quality of life for individuals and their communities. This is exacerbated by the limited understanding of its underlying causes and limitations in current therapeutic interventions, highlighting the need for sophisticated models of atherosclerosis. This review critically evaluates the computational and biological models of atherosclerosis, focusing on the study of hemodynamics in atherosclerotic coronary arteries. Computational models account for the geometrical complexities and hemodynamics of the blood vessels and stenoses, but they fail to capture the complex biological processes involved in atherosclerosis. Different in vitro and in vivo biological models can capture aspects of the biological complexity of healthy and stenosed vessels, but rarely mimic the human anatomy and physiological hemodynamics, and require significantly more time, cost, and resources. Therefore, emerging strategies are examined that integrate computational and biological models, and the potential of advances in imaging, biofabrication, and machine learning is explored in developing more effective models of atherosclerosis.

Viewing early life without labels: optical approaches for imaging the early embryo†

Embryo quality is an important determinant of successful implantation and a resultant live birth. Current clinical approaches for evaluating embryo quality rely on subjective morphology assessments or an invasive biopsy for genetic testing. However, both approaches can be inherently inaccurate and crucially, fail to improve the live birth rate following the transfer of in vitro produced embryos. Optical imaging offers a potential non-invasive and accurate avenue for assessing embryo viability. Recent advances in various label-free optical imaging approaches have garnered increased interest in the field of reproductive biology due to their ability to rapidly capture images at high resolution, delivering both morphological and molecular information. This burgeoning field holds immense potential for further development, with profound implications for clinical translation. Here, our review aims to: (1) describe the principles of various imaging systems, distinguishing between approaches that capture morphological and molecular information, (2) highlight the recent application of these technologies in the field of reproductive biology, and (3) assess their respective merits and limitations concerning the capacity to evaluate embryo quality. Additionally, the review summarizes challenges in the translation of optical imaging systems into routine clinical practice, providing recommendations for their future development. Finally, we identify suitable imaging approaches for interrogating the mechanisms underpinning successful embryo development.

Contemporary status of diagnostic endoluminal ultrasound and optical coherence tomography in the ureter

Objective

To evaluate via a review of published literature, the efficacy of endoluminal ultrasound (ELUS) and optical coherence tomography (OCT) in the following ureteric diseases: urolithiasis, upper tract urothelial carcinoma, stricture disease and pelvic-ureteric junction obstruction (PUJO).

Patients and methods

Ureteric high-frequency ELUS provides 360° imaging, to a depth of 20 mm, and has been demonstrated to assess ureteric stricture length, degree of fibrosis and aetiology. OCT produces high-quality images with a penetration depth of 2 mm. ELUS has proven to be useful at the time of endopyelotomy for PUJO as it can identify crossing vessels, some not detectable on CT angiography, allowing the urologist to avoid these when making their incision. Ureteric ELUS may be utilised for submucosal ureteric stones as they are highly visible. Endoluminal ultrasound may be deployed in the case of known sub-mucosal urolithiasis when the ureter appears stone-free. It may help identify sub-mucosal stones or stones within diverticulum.

Results

Endoluminal ultrasound has been analysed for its use in determining muscle-invasive urothelial carcinoma of the ureter. The PPV for ≥pT2 was only 16.7% in one study of six patients with MIBC and 76.2% in 21 patients with

Conclusions

Ureteric ELUS has been reported to be a useful tool in endopyelotomy, urolithiasis and stricture disease. The staging of ureteric urothelial carcinoma remains unsatisfactory with current imaging techniques and biopsy methods, and, based on the current literature, ELUS does not appear to have a strong enough PPV to determine muscle invasion. Ureteric OCT may be a useful tool in the future staging of upper tract urothelial carcinoma, particularly in differentiating the stage of small tumours. Further studies are needed in this area.

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Key Words

• endoluminal ultrasound
• optical coherence tomography
• ureter

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Affiliation(s)

Samuel Sii Department of SurgeryUniversity of Melbourne, Austin HealthMelbourneVictoriaAustralia
Jeremy Bolton Monash UniversityMelbourneVictoriaAustralia
Jake Tempo Department of SurgeryUniversity of Melbourne, Austin HealthMelbourneVictoriaAustralia
Damien Bolton Department of SurgeryUniversity of Melbourne, Austin HealthMelbourneVictoriaAustralia

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Visualization Materials Using Silicon-Based Optical Nanodisks (ViSiON) for Enhanced NIR Imaging in Ophthalmology

ViSiON (visualization materials composed of silicon-based optical nanodisks) is presented, which offers a unique optical combination of near-infrared (NIR) optical properties and biodegradability. Initially, numerical simulations are conducted to calculate the total extinction and scattering effects of ViSiON by the diameter-to-thickness ratio, predicting precise control over its scattering properties in the NIR region. A top-down patterning technique is employed to synthesize ViSiON with accurate diameter and thickness control. ViSiON with a 50 nm thickness exhibits scattering properties over 400 times higher than that of 30 nm, rendering it suitable as a contrast agent for optical coherence tomography (OCT), especially in ophthalmic applications. Furthermore, ViSiON possesses inherent biodegradability in media, with ≈95% degradation occurring after 48 h, and the degradation rate can be finely tuned based on the quantity of protein coating applied to the surface. Subsequently, the OCT imaging capability is validated even within vessels smaller than 300 µm, simulating retinal vasculature using a retinal phantom. Then, using an ex ovo chick embryo model, it is demonstrated that ViSiON enhances the strength of protein membranes by 6.17 times, thereby presenting the potential for ViSiON as an OCT imaging probe capable of diagnosing retinal diseases.

Monolithic Integration of Ultraslim Flow Sensor and Medical Guidewire by Laser Filament Scanning Sintering for In Vivo Diagnostics of Cardiovascular Diseases

In this study, an ultraslim thermal flow sensor system integrated onto a 340 μm diameter medical guidewire was developed using a laser filament scanning sintering method for the early diagnosis of cardiovascular diseases. The proposed system is a calorimetric-based micro thermal flow sensor comprising a microheater and two thermistors. Prior to fabrication, the sensor design was optimized through flow simulation, and the patterned sensor was successfully implemented on a thin and curved surface of the medical guidewire using a laser patterning method with Ag nanoparticles. The performance of the ultraslim thermal flow sensor-on-guidewire system (SoW) was evaluated under pulsatile flow by using an artificial heartbeat simulator with differentially induced fluid flow velocities of up to 60 cm/s. The resulting electrical signals generated by the temperature difference between the two thermistors caused by the fluid flow were measured across different velocity ranges. Based on the obtained data, a calibration curve was derived to establish the relationship between the fluid velocity and the sensor output voltage. Furthermore, the SoW was tested on living animals, whereby the measured blood flow velocities were 60-90 cm/s in the left coronary artery of pigs. This research demonstrates the potential of ultraslim microsensors, such as the developed thermal flow sensor system, for various industries, particularly in the medical field.

Advanced nanomaterials for imaging of eye diseases

Background and purpose

Vision impairment and blindness present significant global challenges, with common causes including age-related macular degeneration, diabetes, retinitis pigmentosa, and glaucoma. Advanced imaging tools, such as optical coherence tomography, fundus photography, photoacoustic microscopy, and fluorescence imaging, play a crucial role in improving therapeutic interventions and diagnostic methods. Contrast agents are often employed with these tools to enhance image clarity and signal detection. This review aims to explore the commonly used contrast agents in ocular disease imaging.

Experimental approach

The first section of the review delves into advanced ophthalmic imaging techniques, outlining their importance in addressing vision-related issues. The emphasis is on the efficacy of therapeutic interventions and diagnostic methods, establishing a foundation for the subsequent exploration of contrast agents.

Key results

This review focuses on the role of contrast agents, with a specific emphasis on gold nanoparticles, particularly gold nanorods. The discussion highlights how these contrast agents optimize imaging in ocular disease diagnosis and monitoring, emphasizing their unique properties that enhance signal detection and imaging precision.

Conclusion

The final section, we explores both organic and inorganic contrast agents and their applications in specific conditions such as choroidal neovascularization, retinal neovascularization, and stem cell tracking. The review concludes by addressing the limitations of current contrast agent usage and discussing potential future clinical applications. This comprehensive exploration contributes to advancing our understanding of contrast agents in ocular disease imaging and sets the stage for further research and development in the field.

Role of intravascular ultrasound and optical coherence tomography in intracoronary imaging for coronary artery disease: a systematic review

Coronary angiography has long been the standard for coronary imaging, but it has limitations in assessing vessel wall anatomy and guiding percutaneous coronary intervention (PCI). Intracoronary imaging techniques like intravascular ultrasound (IVUS) and optical coherence tomography (OCT) can overcome these limitations. IVUS uses ultrasound and OCT uses near-infrared light to visualize coronary pathology in unique ways due to differences in temporal and spatial resolution. These techniques have evolved to offer clinical utility in plaque characterization and vessel assessment during PCI. Meta-analyses and adjusted observational studies suggest that both IVUS and OCT-guided PCI correlate with reduced cardiovascular risks compared to angiographic guidance alone. While IVUS demonstrates consistent clinical outcome benefits, OCT evidence is less robust. IVUS has progressed from early motion detection to high-resolution systems, with smaller compatible catheters. OCT utilizes near infrared light to achieve unparalleled resolutions, but requires temporary blood clearance for optimal imaging. Enhanced visualization and guidance make IVUS and OCT well-suited for higher risk PCI in patients with diabetes and chronic kidney disease by allowing detailed visualization of complex lesions and ensuring optimal stent deployment and positioning in PCI for patients with type 2 diabetes and chronic kidney disease, improving outcomes. IVUS and recent advancements in zero- and low-contrast OCT techniques can reduce nephrotoxic contrast exposure, thus helping to minimize PCI complications in these high-risk patient groups. IVUS and OCT provide valuable insights into coronary pathophysiology and guide interventions precisely compared to angiography alone. Both have comparable clinical outcomes, emphasizing the need for tailored imaging choices based on clinical scenarios. Continued refinement and integration of intravascular imaging will likely play a pivotal role in optimizing coronary interventions and outcomes. This systematic review aims to delve into the nuances of IVUS and OCT, highlighting their strengths and limitations as PCI adjuncts.

Reproducibility of an artificial intelligence optical coherence tomography software for tissue characterization: Implications for the design of longitudinal studies

BACKGROUND

To assess the reproducibility of coronary tissue characterization by an Artificial Intelligence Optical Coherence Tomography software (OctPlus, Shanghai Pulse Medical Imaging Technology Inc.).

METHODS

74 patients presenting with multivessel ST-segment elevation myocardial infarction (STEMI) underwent optical coherence tomography (OCT) of the infarct-related artery at the end of primary percutaneous coronary intervention (PPCI) and during staged PCI (SPCI) within 7 days thereafter in the MATRIX (Minimizing Adverse Hemorrhagic Events by Transradial Access Site and angioX) Treatment-Duration study (ClinicalTrials.gov, NCT01433627). OCT films were run through the OctPlus software. The same region of interest between either side of the stent and the first branch was identified on OCT films for each patient at PPCI and SPCI, thus generating 94 pairs of segments. 42 pairs of segments were re-analyzed for intra-software difference. Five plaque characteristics including cholesterol crystal, fibrous tissue, calcium, lipid, and macrophage content were analyzed for various parameters (span angle, thickness, and area).

RESULTS

There was no statistically significant inter-catheter (between PPCI and SPCI) or intra-software difference in the mean values of all the parameters. Inter-catheter correlation for area was best seen for calcification [intraclass correlation coefficient (ICC) 0.86], followed by fibrous tissue (ICC 0.87), lipid (ICC 0.62), and macrophage (ICC 0.43). Some of the inter-catheter relative differences for area measurements were large: calcification 9.75 %; cholesterol crystal 74.10 %; fibrous tissue 5.90 %; lipid 4.66 %; and macrophage 1.23 %. By the intra-software measurements, there was an excellent correlation (ICC > 0.9) for all tissue types. The relative differences for area measurements were: calcification 0.64 %; cholesterol crystal 5.34 %; fibrous tissue 0.19 %; lipid 1.07 %; and macrophage 0.60 %. Features of vulnerable plaque, minimum fibrous cap thickness and lipid area showed acceptable reproducibility.

CONCLUSION

The present study demonstrates an overall good reproducibility of tissue characterization by the Artificial Intelligence Optical Coherence Tomography software. In future longitudinal studies, investigators may use discretion in selecting the imaging endpoints and sample size, accounting for the observed relative differences in this study.

Rapid automated lumen segmentation of coronary optical coherence tomography images followed by 3D reconstruction of coronary arteries

Purpose

Optical coherence tomography has emerged as an important intracoronary imaging technique for coronary artery disease diagnosis as it produces high-resolution cross-sectional images of luminal and plaque morphology. Precise and fast lumen segmentation is essential for efficient OCT morphometric analysis. However, due to the presence of various image artifacts, including side branches, luminal blood artifacts, and complicated lesions, this remains a challenging task.

Approach

Our research study proposes a rapid automatic segmentation method that utilizes nonuniform rational B-spline to connect limited pixel points and identify the edges of the OCT lumen. The proposed method suppresses image noise and accurately extracts the lumen border with a high correlation to ground truth images based on the area, minimal diameter, and maximal diameter.

Results

We evaluated the method using 3300 OCT frames from 10 patients and found that it achieved favorable results. The average time taken for automatic segmentation by the proposed method is 0.17 s per frame. Additionally, the proposed method includes seamless vessel reconstruction following the lumen segmentation.

Conclusions

The developed automated system provides an accurate, efficient, robust, and user-friendly platform for coronary lumen segmentation and reconstruction, which can pave the way for improved assessment of the coronary artery lumen morphology.

Effect of skin color on optical properties and the implications for medical optical technologies: a review

Significance

Skin color affects light penetration leading to differences in its absorption and scattering properties. COVID-19 highlighted the importance of understanding of the interaction of light with different skin types, e.g., pulse oximetry (PO) unreliably determined oxygen saturation levels in people from Black and ethnic minority backgrounds. Furthermore, with increased use of other medical wearables using light to provide disease information and photodynamic therapies to treat skin cancers, a thorough understanding of the effect skin color has on light is important for reducing healthcare disparities.

Aim

The aim of this work is to perform a thorough review on the effect of skin color on optical properties and the implication of variation on optical medical technologies.

Approach

Published in vivo optical coefficients associated with different skin colors were collated and their effects on optical penetration depth and transport mean free path (TMFP) assessed.

Results

Variation among reported values is significant. We show that absorption coefficients for dark skin are ∼ 6 % to 74% greater than for light skin in the 400 to 1000 nm spectrum. Beyond 600 nm, the TMFP for light skin is greater than for dark skin. Maximum transmission for all skin types was beyond 940 nm in this spectrum. There are significant losses of light with increasing skin depth; in this spectrum, depending upon Fitzpatrick skin type (FST), on average 14% to 18% of light is lost by a depth of 0.1 mm compared with 90% to 97% of the remaining light being lost by a depth of 1.93 mm.

Conclusions

Current published data suggest that at wavelengths beyond 940 nm light transmission is greatest for all FSTs. Data beyond 1000 nm are minimal and further study is required. It is possible that the amount of light transmitted through skin for all skin colors will converge with increasing wavelength enabling optical medical technologies to become independent of skin color.

State-of-art review: intravascular imaging in percutaneous coronary interventions

The history of intravascular ultrasound (IVUS) and optical coherence tomography (OCT) reflects the relentless pursuit of innovation in interventional cardiology. These intravascular imaging technologies have played a pivotal role in our understanding of coronary atherosclerosis, vascular pathology, and the interaction of coronary stents with the vessel wall. Two decades of clinical investigations demonstrating the clinical efficacy and safety of intravascular imaging modalities have established these technologies as staples in the contemporary cardiac catheterization lab's toolbox and earning their place in revascularization clinical practice guidelines. In this comprehensive review, we will delve into the historical evolution, mechanisms, and technical aspects of IVUS and OCT. We will discuss the expanding evidence supporting their use in complex percutaneous coronary interventions, emphasizing their crucial roles in optimizing patient outcomes and ensuring procedural success. Furthermore, we will explore the substantial advances that have propelled these imaging modalities to the forefront of contemporary interventional cardiology. Finally, we will survey the latest developments in the field and explore the promising future directions that have the potential to further revolutionize coronary interventions.

Treatment of left main coronary artery compression in the setting of unpalliated congenital heart disease: a case series

Background

Left main coronary artery compression syndrome (LMCS) is a well-characterized phenomenon resulting from compression of the left main coronary artery (LMCA) between the aorta and an enlarged pulmonary arterial trunk. The development of LMCS is usually described in the context of severe pulmonary arterial hypertension. Cases of LMCS, in the context of unpalliated congenital heart disease (CHD), are complex clinical scenarios that challenge traditional treatment paradigms.

Case summary

Here, we discuss two thought-provoking patients with unpalliated CHD complicated by severe pulmonary hypertension (PH). Both patients developed LMCS, one with severe non-ST elevation myocardial infarction and the other with refractory angina. Their pulmonary vascular resistance was severely elevated despite pulmonary vasodilator therapy, and concomitant surgical correction of their CHD in addition to bypass grafting was deemed high risk. They underwent successful percutaneous coronary intervention (PCI) of the LMCA with drug-eluting stents.

Discussion

Pulmonary hypertension can develop in the setting of long-standing unpalliated CHD. Surgical correction of congenital heart defects may be performed in select patients with systemic-to-pulmonary shunts, contingent on the status of PH severity. Pulmonary vasodilator therapy modulates haemodynamics to ensure surgical correction without risk of cardiopulmonary demise-termed the 'treat and repair' strategy. LMCS, an increasingly recognized phenomenon in patients with long-standing PH, is a notable complicating factor in the 'treat and repair' strategy. We introduce the concept that PCI of the LMCA may bridge patients to corrective surgery for CHD by allowing time for optimization of their pulmonary vasodilator therapy.

Intravascular Imaging versus Physiological Assessment versus Biomechanics-Which Is a Better Guide for Coronary Revascularization

Today, coronary artery disease (CAD) continues to be a prominent cause of death worldwide. A reliable assessment of coronary stenosis represents a prerequisite for the appropriate management of CAD. Nevertheless, there are still major challenges pertaining to some limitations of current imaging and functional diagnostic modalities. The present review summarizes the current data on invasive functional and intracoronary imaging assessment using optical coherence tomography (OCT), and intravascular ultrasound (IVUS). Amongst the functional parameters-on top of fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR)-we point to novel angiography-based measures such as quantitative flow ratio (QFR), vessel fractional flow reserve (vFFR), angiography-derived fractional flow reserve (FFRangio), and computed tomography-derived flow fractional reserve (FFR-CT), as well as hybrid approaches focusing on optical flow ratio (OFR), computational fluid dynamics and attempts to quantify the forces exaggerated by blood on the coronary plaque and vessel wall.

Advances in Intravascular Ultrasound

Since its inception, intravascular ultrasound (IVUS) and optical coherence tomography (OCT) have played a significant role in evaluating the pathophysiology of coronary artery disease (CAD) guiding the interventional and medical management of CAD improving outcomes in patients. Although the benefits of each of these modalities have been proven, due to some limitations, no single intravascular imaging technique has been proven to provide a detailed and complete evaluation of all CAD lesions. The use of different intravascular imaging modalities sequentially may lead to complications, which are cumbersome, consume time, and add financial burden to the patient. Recently, hybrid imaging catheters that combine OCT and IVUS benefits have been developed to limit these problems. Intravascular imaging techniques we are using currently have some drawbacks that hinder accurate assessment of plaque morphology and pathobiology as demonstrated in many histological studies, causing difficulty in identifying high-risk plaques. To overcome these limitations, great efforts have been put into developing hybrid, dual-probe catheters by combining imaging modalities to get an accurate analysis of plaque characteristics, and high-risk lesions. At present, many dual-probe catheters are available including combined IVUS-OCT, near-infrared spectroscopy-IVUS that is available commercially, the OCT-near infrared fluorescence (NIRF) molecular imaging, IVUS-NIRF, and combined fluorescence lifetime-IVUS imaging. Application of this combined multimodal imaging in clinical practice overcomes the limitations of standalone imaging and helps in providing a comprehensive and accurate visualization of plaque characteristics, composition, and plaque biology. The present article summarizes the advances in hybrid intravascular imaging, analyses the technical hindrances that should be known to have a use in the different clinical circumstances, and the till date shreds of evidence available from their first clinical application aiming to bring these modalities into the limelight and their potential role in the study of CAD.

Post-procedure micro-CT analyses of coronary artery stenting in left main vessels of reanimated and perfusion-fixed human hearts

BACKGROUND

Percutaneous coronary interventions (PCIs) within left main coronary arteries are high-risk procedures that require optimization of interactions between stent(s) and diseased vessels. Optical Coherence Tomography (OCT) is a widely accepted tool that enhances physicians' ability to assess proper stent appositions during clinical procedures. The primary aim of this study was to develop complementary post-procedure imaging methodologies to better assess and interpret outcomes of left main PCI procedures, utilizing both reanimated and perfusion-fixed human hearts.

METHODS

PCIs were performed while obtaining OCT scans within the left main anatomies of six human hearts. Subsequently, each heart was scanned with a micro-CT scanner with optimized parameters to achieve resolutions up to 20 µm. Scans were reconstructed and imported into a DICOM segmentation software to generate computational models of implanted stents and associated coronary vessels. 2D images from OCT that were obtained during PCIs were compared to the 3D models generated from micro-CT reconstructions. In addition, the 3D models were utilized to create virtual reality scenes and enlarged 3D prints for development of "mixed reality" tools relative to bifurcation stenting within human left main coronary arteries.

RESULTS

We developed reproducible methodologies for post-implant analyses of coronary artery stenting procedures. In addition, we generated high-resolution 3D computational models, with ~ 20-micron resolutions, of PCIs performed within reanimated and perfusion-fixed heart specimens.

CONCLUSIONS

Generated computational models of left main PCIs performed in isolated human hearts can be used to obtain detailed measurements that provide further clinical insights on procedural outcomes. The 3D models from these procedures are useful for generating virtual reality scenes and 3D prints for physician training and education.

Intracoronary Imaging: Current Practice and Future Perspectives

Intracoronary imaging has brought new insight in the field of interventional cardiology. Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) are the most commonly used imaging modalities. Regarding their technical characteristics IVUS and OCT have similarities as well as differences, a fact that could have significant clinical implications. Both techniques play an important role in percutaneous coronary intervention (PCI) guidance and demonstrated superiority compared to intravascular coronary angiography (ICA) guidance alone. Furthermore, their use can notably assist coronary plaque evaluation; both provide additional information of plaque characteristics, which can lead to a better understanding of the cause of an acute coronary syndrome (ACS) and better clinical outcomes. However, there is not enough clinical evidence for the superiority of one method compared to the other, something that is, also, reflected in the guidelines. In this review, we aim to compare role of IVUS and OCT in the different aspects of coronary artery disease (CAD), according to the latest scientific data. In addition, we present the future perspectives regarding the IVUS and OCT, with co-registration of the two methods or hybrid OCT-IVUS catheters.

Use of Optical Coherence Tomography (OCT) in Assessment of Diabetic Skin Wound Characteristics and Blood Flow

Optical coherence tomography allows for various measurements of skin but the utility of the device in determining properties of normal and wounded skin in diabetic patients is unknown. This single-site, non-randomized, observational study used an optical coherence tomography device to acquire skin images at 1305 nm, creating real-time image of 17 patient's skin and wounds 1 to 2 mm under the skin surface. Vertical B-scan, en-face and 3-D images were produced to calculate surface and dermal-epidermal junction roughness, the optical attenuation coefficient, a measure of light absorption and scattering, and blood flow metrics. In subjects with diabetes there was an increase in both the Ra (p < .02) and Rz (p < .001) of the wounded versus the control skin. In subjects without diabetes, there was an increase in both the Ra (p < .001) and Rz (p < .03) values of the wounded versus the control skin. At a depth of 0.6 mm across all subjects, there was an average decrease in blood flow of 63% from control to wounded skin. In subjects with diabetes, this decrease was 76%. In subjects without diabetes the decrease was 55%. The change in vasculature between control and wounded skin was associated with a p < .005. There was an increase in the Ra and Rz values and a decrease in blood flow between the wounded skin and control. The device determined a difference in the Ra and Rz values of both diabetic and healthy subjects' skin and a more pronounced decrease in blood flow in the wounds of patients with diabetes as opposed to those without.

Intramural Hematoma During a Complex Chronic Total Occlusion Intervention

We describe a patient who presented for elective percutaneous coronary intervention to treat a chronic total occlusion of the right coronary artery. An intramural hematoma resulted from the intervention and was discovered with intravenous ultrasound. The complication was successfully managed conservatively, and follow-up showed patent coronary arteries. (Level of Difficulty: Intermediate.)

Imaging in Percutaneous Coronary Intervention

Intracoronary imaging (ICI) use during percutaneous coronary intervention (PCI) has been shown to effectively improve cardiovascular outcomes, particularly for high-risk subgroups. However, data from randomized controlled trials are limited and the overall utilization rate of ICI remains variable between different countries and centers. Potential benefits of ICI include identification of appropriate lesions for PCI, improved characterization of lesions, and optimization of stent placement. Currently available modalities of ICI include intravascular ultrasound, optical coherence tomography and near infrared spectroscopy. Within this review, we summarize the contemporary evidence surrounding ICI and discuss its application in clinical practice.

Kounis syndrome secondary to nimesulide ingestion: a case report

BACKGROUND

Kounis syndrome, also known as "allergic myocardial infarction," is a rare co-occurrence of acute coronary syndrome (ACS) in the setting of hypersensitivity reaction to any agent. Non-steroidal anti-inflammatory drugs (NSAIDs) like are often implicated in causing allergic reactions. Here, we present a case of anterior wall myocardial infarction (AWMI) occurred following angioedema secondary to intake of Nimesulide, not described earlier in literature.

CASE PRESENTATION

A 45-year-old female developed generalized pruritic, erythematous maculopapular rash, facial puffiness, oral ulcers and hoarseness of voice within few hours following consumption of Nimesulide for fever and body-ache. Due to development of hypotension, electrocardiogram (ECG) was done, which revealed ST elevation in V2-V6, with marked elevation of troponin (TnI) and creatine kinase (CK-MB). He had no chest pain or shortness of breath. Echocardiography showed regional wall motion (RWMA) abnormality in left anterior descending artery (LAD) territory with an ejection fraction of 25%. Coronary angiography showed a complete thrombotic cutoff of LAD, for which Tirofiban infusion was started to decrease thrombus burden. Repeat angiography on next day showed 80% lesion in proximal LAD for which she underwent revascularization with a drug-eluting stent. The patient later showed improvement in cardiac function at 8 months of follow-up.

CONCLUSIONS

The occurrence of ACS requiring percutaneous coronary intervention (PCI) in the setting of allergic reactions is rarely reported in the literature. One should be aware of the rare possibility of Kounis syndrome in the setting of hypersensitivity reaction when accompanying features of symptoms suggestive of coronary artery disease co-exists. When indicated, ECG monitoring and cardiac biomarkers in patients with allergic responses help to identify this rare and treatable condition.

Optical coherence tomography

During the past decade, noninvasive imaging has emerged as a valuable tool in clinical dermatology and dermatologic research. Optical coherence tomography (OCT) is one such type of noninvasive imaging. OCT uses the principle of interferometry to produce real-time images. A low-power diode laser shines infrared light onto tissues, which reflects back to an optical fiber interferometer. Using time delay and the backscattered light intensity, a two-dimensional image akin to an ultrasound is rendered. We review the history, types, and modalities of OCT, plus the many applications of frequency domain, high definition, and dynamic OCT in practice, including its utility in diagnosis, monitoring, and grading disease severity in a variety of cutaneous conditions.

Toward cardiac tissue characterization using machine learning and light-scattering spectroscopy

SIGNIFICANCE

The non-destructive characterization of cardiac tissue composition provides essential information for both planning and evaluating the effectiveness of surgical interventions such as ablative procedures. Although several methods of tissue characterization, such as optical coherence tomography and fiber-optic confocal microscopy, show promise, many barriers exist that reduce effectiveness or prevent adoption, such as time delays in analysis, prohibitive costs, and limited scope of application. Developing a rapid, low-cost non-destructive means of characterizing cardiac tissue could improve planning, implementation, and evaluation of cardiac surgical procedures.

AIM

To determine whether a new light-scattering spectroscopy (LSS) system that analyzes spectra via neural networks is capable of predicting the nuclear densities (NDs) of ventricular tissues.

APPROACH

We developed an LSS system with a fiber-optics probe and applied it for measurements on cardiac tissues from an ovine model. We quantified the ND in the cardiac tissues using fluorescent labeling, confocal microscopy, and image processing. Spectra acquired from the same cardiac tissues were analyzed with spectral clustering and convolutional neural networks (CNNs) to assess the feasibility of characterizing the ND of tissue via LSS.

RESULTS

Spectral clustering revealed distinct groups of spectra correlated to ranges of ND. CNNs classified three groups of spectra with low, medium, or high ND with an accuracy of 95.00  ±  11.77  %   (mean and standard deviation). Our analyses revealed the sensitivity of the classification accuracy to wavelength range and subsampling of spectra.

CONCLUSIONS

LSS and machine learning are capable of assessing ND in cardiac tissues. We suggest that the approach is useful for the diagnosis of cardiac diseases associated with changes of ND, such as hypertrophy and fibrosis.

Noninvasive monitoring of suprachoroidal, subretinal, and intravitreal implants using confocal scanning laser ophthalmoscope (cSLO) and optical coherence tomography (OCT)

To address the need for noninvasive monitoring of injectable preformed drug delivery implants in the eye, we developed noninvasive methods to monitor such implants in different locations within the eye. Cylindrical polymeric poly(lactide-co-glycolide) or metal implants were injected into isolated bovine eyes at suprachoroidal, subretinal, and intravitreal locations and imaged noninvasively using the cSLO and OCT modes of a Heidelberg Spectralis HRA + OCT instrument after adjusting for the corneal curvature. Length and diameter of implants were obtained using cSLO images for all three locations, and the volume was calculated. Additionally, implant volume for suprachoroidal and subretinal location was estimated by integrating the cross-sectional bleb area over the implant length in multiple OCT images or using the maximum thickness of the implant based on thickness map along with length in cSLO image. Simultaneous cSLO and OCT imaging identified implants in different regions of the eye. Image-based measurements of implant dimensions mostly correlated well with the values prior to injection using blade micrometer. The accuracy (82-112%) and precision (1-19%) for noninvasive measurement of length was better than the diameter (accuracy 69-130%; precision 3-38%) using cSLO image for both types of implants. The accuracy for the measurement of volume of both types of implants from all three intraocular locations was better with cSLO imaging (42-152%) compared to those obtained using OCT cross-sectional bleb area integration (117-556%) or cSLO and thickness map (32-279%) methods. Suprachoroidal, subretinal, and intravitreal implants can be monitored for length, diameter, and volume using cSLO and OCT imaging. Such measurements may be useful in noninvasively monitoring implant degradation and drug release in the eye.

Saline as an alternative to radio-contrast for optical coherence tomography guided percutaneous coronary intervention: A prospective comparison

OBJECTIVES

To do a quantitative comparison of saline and contrast Frequency domain optical coherence tomography (FD-OCT) during percutaneous coronary intervention (PCI) optimisation.

METHODS

13 pairs of OCT runs were analysed, wherein each pair consisted of a contrast run and a heparinized saline run taken in the same coronary artery at the same position. Quantitative analysis was done comparing minimal lumen area (MLA), proximal reference diameter (PRD), distal reference diameter (DRD) and percentage area stenosis (AS) at the same anatomical location. Lesion morphologies, rendered stent view and 3D reconstruction were compared for image clarity.

RESULT

The saline OCT runs resulted in comparable MLA (3.88 ± 2.59 mm² with saline run vs 3.88 ± 2.71 mm² with contrast run; p = 0.650), PRD (3.66 ± 0.52 mm with saline vs 3.65 ± 0.52 mm with contrast; p = 0.463), DRD (2.97 ± 0.22 mm with saline vs 2.99 ± 0.88 mm with contrast; p = 0.433), and AS (59.60 ± 18.62% with saline vs 59.18 ± 19.11% with contrast; p = 0.753) with respect to the contrast runs. The Bland Altman plots of the measured parameters indicate good agreement between saline and contrast OCT. Linear regression analysis indicated the absence of proportional bias All lesion morphologies (calcified, fibrotic, thin cap fibroatheroma, macrophages, cholesterol crystals and edge dissection), 3D reconstruction and rendered stent view were clearly demonstrable in the saline OCT runs.

CONCLUSIONS

Using heparinized saline as flushing media in coronary FD-OCT may result in vessel dimensions that are comparable with contrast. Heparinized saline may be used as a contrast saving alternative for FD-OCT during PCI optimization.

THE USE OF ELECTRORETINOGRAPHY AND OPTICAL COHERENCE TOMOGRAPHY IN PATIENTS WITH SCHIZOPHRENIA

The use of electroretinography (ERG) and optical coherence tomography (OCT) has currently expanded beyond ophthalmology alone. The aim of this review is to present the results and knowledge acquired by these two methods in patients suffering from schizophrenia. Reviewing the studies applying ERG and OCT methods in the field of psychiatry, one can conclude that results of the research imply morphological and functional changes of retina in patients with schizophrenia that are not consistent. However, in most studies there was reduction of the amplitude and changes in the implicit time related parameters on ERG and thinning of the retinal nerve fiber layer on OCT. Neurons in the eye use the same neurotransmitters as neurons in the basal brain structures that are most affected in schizophrenia, according to the dopamine hypothesis of schizophrenia. Unlike neurons in the basal brain structures, the neurons in the eye are in vivo available to ERG. Using the aforementioned tests together with clinical diagnostic criteria of schizophrenia, the subgroups with different prognostic and therapeutic specificities within schizophrenia as a group of diseases might be identified more precisely.

Current status of hybrid intravascular ultrasound and optical coherence tomography catheter for coronary imaging and percutaneous coronary intervention

Both intravascular ultrasound (IVUS) and optical coherence tomography (OCT) play a crucial role in elucidating the pathophysiology of coronary artery disease (CAD) with the goal to improve patient outcomes of medical and/or interventional CAD management. However, no single intravascular imaging technique has been proven to provide complete and detailed evaluation of all CAD lesions due to some limitations. Although sequential use of multiple modalities may sometimes be performed, there may be issues related to risk, time, and cost. To overcome these problems, several hybrids involving dual-probe combined IVUS-OCT catheters have been developed. The aim of this review article is to demonstrate some limitations of stand-alone imaging devices for evaluation of CAD, summarize the advances in hybrid IVUS-OCT imaging devices, discuss the technical challenges, and present the potential value in the clinical setting, especially in patients receiving medical or interventional CAD management.

Role of Computed Tomography Angiography in Setting of Spontaneous Coronary Artery Dissection

Spontaneous coronary artery dissection (SCAD) is an infrequent cause of acute coronary syndrome, predominantly affecting young women. Catheter-based coronary angiography is the gold standard diagnostic test, especially when coupled with intracoronary imaging. Conservative management in stable patients is the preferred approach given the increased risk of complications associated with percutaneous interventions. Noninvasive coronary computed tomography angiography (CTA) has a potential role in the diagnosis and follow-up of SCAD. CTA also plays a role in screening for extracoronary vascular abnormalities frequently associated with SCAD. The goal of this article is to review the potential role of CTA in evaluating SCAD.

Contrast-free optical coherence tomography:Systematic evaluation of non-contrast media for intravascular assessment

Background

Coronary revascularization using imaging guidance is rapidly becoming the standard of care. Intravascular optical coherence tomography uses near-infrared light to obtain high resolution intravascular images. Standard optical coherence tomography imaging technique employs iodinated contrast dye to achieve the required blood clearance during acquisition. We sought to systematically evaluate the technical performance of saline as an alternative to iodinated contrast for intravascular optical coherence tomography assessment.

Methods and results

We performed bench top optical coherence tomography analysis on nylon tubing with sequential contrast/saline dilutions to empirically derive adjustment coefficients. We then applied these coefficients in vivo in an established rabbit abdominal stenting model with both saline and contrast optical coherence tomography imaging. In this model, we assessed the impact of saline on both quantitative and qualitative vessel assessment. Nylon tubing assessment demonstrated a linear relationship between saline and contrast for both area and diameter. We then derived adjustment coefficients, allowing for accurate calculation of area and diameter when converting saline into both contrast and reference dimensions. In vivo studies confirmed reduced area with saline versus contrast [7.43 (5.67–8.36) mm² versus 8.2 (6.34–9.39) mm², p = 0.001] and diameter [3.08 mm versus 3.23 mm, p = 0.001]. Following correction, a strong relationship was achieved in vivo between saline and contrast in both area and diameter without compromising image quality, artefact, or strut assessment.

Conclusion

Saline generates reduced dimensions compared to contrast during intravascular optical coherence tomography imaging. The relationship across physiologic coronary diameters is linear and can be corrected with high fidelity. Saline does not adversely impact image quality, artefact, or strut assessment.

The Role of Imaging for MINOCA (Myocardial Infarction with No Obstructive Coronary Artery Disease): a Review of Literature and Current Perspectives

Purpose of Review

The objective of this review is to summarize scientific statements on the diagnosis and management of myocardial infarction with no obstructive coronary artery disease (MINOCA); define the diagnostic role of optical coherence tomography (OCT), intravascular ultrasound (IVUS), and cardiac magnetic resonance imaging (CMR); and provide representative case examples.

Recent Findings

The majority of patients with MINOCA are evaluated by conventional coronary angiography. However, intracoronary imaging using OCT or IVUS permits more accurate understanding of the underlying pathology. These and other imaging modalities provide significant diagnostic and prognostic value.

Summary

Although nonobstructive disease is the hallmark of the disease, MINOCA is associated with significant morbidity and mortality. Every effort to define the underlying pathology is necessary and requires more standardized use of imaging in clinical practice.

Fifteen years of coronary intravascular ultrasound in percutaneous coronary intervention in Portugal

INTRODUCTION

Coronary intravascular ultrasound (IVUS) is increasingly important in catheterization laboratories due to its positive prognostic impact. This study aims to characterize the use of IVUS in percutaneous coronary intervention (PCI) in Portugal.

METHODS

A retrospective observational study was performed based on the Portuguese Registry on Interventional Cardiology of the Portuguese Society of Cardiology. The clinical and angiographic profiles of patients who underwent PCI between 2002 and 2016, the percentage of IVUS use, and the coronary arteries assessed were characterized.

RESULTS

A total of 118 706 PCIs were included, in which IVUS was used in 2266 (1.9%). Over time, use of IVUS changed from none in 2002 to generally increasing use from 2003 (0.1%) to 2016 (2.4%). The age of patients in whom coronary IVUS was used was similar to that of patients in whom IVUS was not used, but in the former group there were fewer male patients, and a higher prevalence of cardiovascular risk factors (hypertension, hypercholesterolemia and diabetes), previous myocardial infarction, previous PCI, multivessel coronary disease, C-type or bifurcated coronary lesions, and in-stent restenosis. IVUS was used in 54.8% of elective PCIs and in 19.15% of PCIs of the left main coronary artery.

CONCLUSION

Coronary IVUS has been increasingly used in Portugal since 2003. It is used preferentially in elective PCIs, and in patients with higher cardiovascular risk, with more complex coronary lesions and lesions of the left main coronary artery.

An automatic diagnostic system of coronary artery lesions in Kawasaki disease using intravascular optical coherence tomography imaging

Intravascular optical coherence tomography (IV-OCT) is a light-based imaging modality with high resolution, which employs near-infrared light to provide tomographic intracoronary images. Morbidity caused by coronary heart disease is a substantial cause of acute coronary syndrome and sudden cardiac death. The most common intracoronay complications caused by coronary artery disease are intimal hyperplasia, calcification, fibrosis, neovascularization and macrophage accumulation, which require efficient prevention strategies. OCT can provide discriminative information of the intracoronary tissues, which can be used to train a robust fully automatic tissue characterization model based on deep learning. In this study, we aimed to design a diagnostic model of coronary artery lesions. Particularly, we trained a random forest using convolutional neural network features to distinguish between normal and diseased arterial wall structure. Then, based on the arterial wall structure, fully convolutional network is designed to extract the tissue layers in normal cases, and pathological tissues regardless of lesion type in pathological cases. Then, the type of the lesions can be characterized with high precision using our previous model. The results demonstrate the robustness of the model with the approximate overall accuracy up to 90%.

Vascular response and intrastent thrombus in the early phase after drug-eluting versus bare-metal stent implantation in patients with ST-segment elevation myocardial infarction: An observational, single-center study

BACKGROUND AND OBJECTIVES

Second-generation drug-eluting stents (G2-DES) are associated with a lower rate of acute and subacute stent thrombosis compared with bare-metal stent (BMS) in the setting of ST-segment elevation myocardial infarction (STEMI). In this study, our aim was to compare the vascular response and thrombus burden between G2-DES and BMS in early-phase STEMI.

METHODS

Between May 2010 and August 2014, a total of 41 STEMI patients treated by either G2-DES (n = 26; everolimus-eluting stent [EES]: n = 15, zotarolimus-eluting stent [ZES]: n = 11) or BMS (n = 15) and, with multivessel disease requiring additional percutaneous coronary intervention (PCI), were prospectively enrolled. Optical coherence tomography (OCT) imaging was performed at 1 month after stent implantation.

RESULTS

Baseline clinical characteristics, except for age (61.5 ± 9.3 vs 69.3 ± 9.8, P = 0.01, t test), were comparable between patients with drug-eluting stent (DES) and BMS. The incidence of residual thrombus after the stent implantation for STEMI was comparable between DES and BMS (7.7% vs 6.7%, P = 0.88, χ 2 test). At 1 month, thrombus burden, defined as the mean thrombus area divided by the mean lumen area, was significantly smaller with DES than with BMS (median interquartile range (IQR), 1.2 (0.0, 1.0) vs 1.2 (0.0, 2.2), P = 0.04, Mann-Whitney U test), despite a similar percentage of malapposed (median (IQR), 6.2 (2.4, 9.0) vs 2.6 (0.0, 5.8)%, P = 0.07, Mann-Whitney U test) or uncovered struts (median (IQR), 6.8 (1.8, 13.1) vs 6.14 (2.8, 18.5)%, P = 0.45, Mann-Whitney U test). No significant difference in thrombus burden was observed between EES and ZES.

CONCLUSIONS

Thrombus burden was significantly smaller with DES than with BMS at 1-month follow-up in STEMI cases, although the percentage of malapposed or uncovered struts was similar between the groups. This may partly explain the lower rate of acute and subacute stent thrombosis in G2-DES that has previously been reported in the literature.

Intravascular imaging in neuroendovascular surgery: a brief review

Intravascular imaging has significantly contributed to the advancement of interventional cardiology. Intravascular ultrasound and optical coherence tomography have facilitated decision-making and interventional strategies in management of coronary artery lesions. Yet, applications of these modalities are limited in cerebrovascular practice. With the momentum in advancement of neuroendovascular interventions and techniques for treatment of strokes, cerebrovascular atherosclerotic diseases, aneurysms and vascular malformations, there is a need for the development of high-resolution platforms that can safely be used in cerebrovascular system, and to meet the imaging requirements in the field. In this brief review, we aim to discuss current and emerging intravascular imaging modalities and explore their potentials in field of neuroendovascular surgery.

A Survey on Coronary Atherosclerotic Plaque Tissue Characterization in Intravascular Optical Coherence Tomography

PURPOSE OF REVIEW

Atherosclerotic plaque deposition within the coronary vessel wall leads to arterial stenosis and severe catastrophic events over time. Identification of these atherosclerotic plaque components is essential to pre-estimate the risk of cardiovascular disease (CVD) and stratify them as a high or low risk. The characterization and quantification of coronary plaque components are not only vital but also a challenging task which can be possible using high-resolution imaging techniques.

RECENT FINDING

Atherosclerotic plaque components such as thin cap fibroatheroma (TCFA), fibrous cap, macrophage infiltration, large necrotic core, and thrombus are the microstructural plaque components that can be detected with only high-resolution imaging modalities such as intravascular ultrasound (IVUS) and optical coherence tomography (OCT). Light-based OCT provides better visualization of plaque tissue layers of coronary vessel walls as compared to IVUS. Three dominant paradigms have been identified to characterize atherosclerotic plaque components based on optical attenuation coefficients, machine learning algorithms, and deep learning techniques. This review (condensation of 126 papers after downloading 150 articles) presents a detailed comparison among various methodologies utilized for plaque tissue characterization, classification, and arterial measurements in OCT. Furthermore, this review presents the different ways to predict and stratify the risk associated with the CVD based on plaque characterization and measurements in OCT. Moreover, this review discovers three different paradigms for plaque characterization and their pros and cons. Among all of the techniques, a combination of machine learning and deep learning techniques is a best possible solution that provides improved OCT-based risk stratification.

Clinical translation of handheld optical coherence tomography: practical considerations and recent advancements

Since the inception of optical coherence tomography (OCT), advancements in imaging system design and handheld probes have allowed for numerous advancements in disease diagnostics and characterization of the structural and optical properties of tissue. OCT system developers continue to reduce form factor and cost, while improving imaging performance (speed, resolution, etc.) and flexibility for applicability in a broad range of fields, and nearly every clinical specialty. An extensive array of components to construct customized systems has also become available, with a range of commercial entities that produce high-quality products, from single components to full systems, for clinical and research use. Many advancements in the development of these miniaturized and portable systems can be linked back to a specific challenge in academic research, or a clinical need in medicine or surgery. Handheld OCT systems are discussed and explored for various applications. Handheld systems are discussed in terms of their relative level of portability and form factor, with mention of the supporting technologies and surrounding ecosystem that bolstered their development. Additional insight from our efforts to implement systems in several clinical environments is provided. The trend toward well-designed, efficient, and compact handheld systems paves the way for more widespread adoption of OCT into point-of-care or point-of-procedure applications in both clinical and commercial settings.