IVUS-based imaging modalities for tissue characterization: similarities and differences

Adjunctive Utilization of Intravascular Ultrasound in Peripheral Arterial Disease Treatment

BACKGROUND

The utility and benefit of intravascular ultrasound (IVUS) has been well established in coronary interventions, however widespread adoption for peripheral interventions has lagged. The objectives of this review article were to discuss the technical components of IVUS, describe key learning pearls for IVUS utilization, and review the literature describing the clinical outcomes of endovascular peripheral arterial interventions using IVUS.

METHODS

A scoping review of the current literature utilizing Pubmed. Terms used to search the literature included "intravascular ultrasound (IVUS)" in conjunction with "peripheral arterial disease (PAD)," "endovascular interventions," "chronic limb threatening ischemia," "balloon angioplasty" "stenting," "percutaneous coronary intervention," and "outcomes." All types of articles were reviewed including review articles, retrospective reviews, meta-analyses, and prospective observational and randomized studies.

RESULTS

Published literature regarding IVUS use in peripheral arterial interventions is heterogeneous and limited to mainly retrospective studies, registry analyses and metanalyses. Outcomes are generally favorable with the adjunct of IVUS compared to traditional angiography-driven peripheral interventions. The addition of IVUS improves stent expansion, stent patency, and reduces reintervention rates, particularly in infrainguinal arterial lesions. Long-term costs may also be lower with IVUS-guided procedures.

CONCLUSIONS

Expert consensus largely supports the implementation of IVUS in endovascular interventions for peripheral arterial disease. However, more robust high-quality data evaluating the efficacy, durability, and cost of IVUS in peripheral arterial disease are still needed.

Long-term outcomes of IVUS-guided and angiography-guided drug-eluting stent implantation for left main coronary artery disease: a retrospective consort study

BACKGROUND

In patients with unprotected left main coronary artery disease (ULMCAD), this study compared the long-term prognosis of drug-eluting stent insertion guided by intravascular ultrasonography (IVUS) vs. angiography.

PATIENTS AND METHODS

This retrospective consort investigation was performed in December 2021. This analysis included 199 patients who underwent IVUS-guided (IVUS group, n = 81) or angiography-guided (angiography group, n = 118) drug-eluting stent implantation at the Affiliated Hospital of Inner Mongolia Medical University between September 2013 and September 2018. Major adverse cardiac events (MACE) were defined as cardiovascular death, sudden cardiac death, myocardial infarction.

RESULTS

The IVUS group had considerably lower proportions of MACE within 1 year postoperatively (P = 0.002) and cardiac mortality within 3 years postoperatively (P = 0.018) compared to the angiography group. However, after adjusting for confounding variables, the hazard ratio for 3-year cardiac mortality was similar between the two groups (P = 0.28). In the IVUS group, there was considerably greater minimum lumen diameter (MLD) (P = 0.046), and reduced frequencies of target vessel restenosis (P < 0.050) and myocardial infarction (MI) (P = 0.024) compared to the angiography group. Cox regression analysis for 3-year cardiac mortality found that MSD was independently associated with low cardiac mortality (HR = 0.1, 95% CI: 0.01-14.92, P = 0.030).

CONCLUSION

IVUS-guided drug-eluting stent implantation may lead to better long-term prognosis in patients with ULMCAD, and MSD may be a predictor for lower cardiac mortality.

Patient-Specific Numerical Simulations of Coronary Artery Hemodynamics and Biomechanics: A Pathway to Clinical Use

PURPOSE

Numerical models that simulate the behaviors of the coronary arteries have been greatly improved by the addition of fluid-structure interaction (FSI) methods. Although computationally demanding, FSI models account for the movement of the arterial wall and more adequately describe the biomechanical conditions at and within the arterial wall. This offers greater physiological relevance over Computational Fluid Dynamics (CFD) models, which assume the walls do not move or deform. Numerical simulations of patient-specific cases have been greatly bolstered by the use of imaging modalities such as Computed Tomography Angiography (CTA), Magnetic Resonance Imaging (MRI), Optical Coherence Tomography (OCT), and Intravascular Ultrasound (IVUS) to reconstruct accurate 2D and 3D representations of artery geometries. The goal of this study was to conduct a comprehensive review on CFD and FSI models on coronary arteries, and evaluate their translational potential.

METHODS

This paper reviewed recent work on patient-specific numerical simulations of coronary arteries that describe the biomechanical conditions associated with atherosclerosis using CFD and FSI models. Imaging modality for geometry collection and clinical applications were also discussed.

RESULTS

Numerical models using CFD and FSI approaches are commonly used to study biomechanics within the vasculature. At high temporal and spatial resolution (compared to most cardiac imaging modalities), these numerical models can generate large amount of biomechanics data.

CONCLUSIONS

Physiologically relevant FSI models can more accurately describe atherosclerosis pathogenesis, and help to translate biomechanical assessment to clinical evaluation.

Intravascular Ultrasound Use in Peripheral Arterial and Deep Venous Interventions: Multidisciplinary Expert Opinion From SCAI/AVF/AVLS/SIR/SVM/SVS

Percutaneous revascularization is the primary strategy for treating lower extremity venous and arterial disease. Angiography is limited by its ability to accurately size vessels, precisely determine the degree of stenosis and length of lesions, characterize lesion morphology, or correctly diagnose postintervention complications. These limitations are overcome with use of intravascular ultrasound (IVUS). IVUS has demonstrated the ability to improve outcomes following percutaneous coronary intervention, and there is increasing evidence to support its benefits in the setting of peripheral vascular intervention. At this stage in its evolution, there remains a need to standardize the use and approach to peripheral vascular IVUS imaging. This manuscript represents considerations and consensus perspectives that emerged from a roundtable discussion including 15 physicians with expertise in interventional cardiology, interventional radiology, and vascular surgery, representing 6 cardiovascular specialty societies, held on February 3, 2023. The roundtable's aims were to assess the current state of lower extremity revascularization, identify knowledge gaps and need for evidence, and determine how IVUS can improve care and outcomes for patients with peripheral arterial and deep venous pathology.

Sensorized Endovascular Technologies: Additional Data to Enhance Decision-Making

BACKGROUND

Current endovascular procedures rely mostly on anatomic information, guided by fluoroscopy, to perform interventions (i.e. angioplasty, stent placement, coils). However, the structural parameters provided by these imaging technologies do not provide any physiological data on either the disease state or efficacy of intervention. Additional endovascular tools are needed to collect physiologic and other both anatomic and nonanatomic data to further individualize endovascular interventions with the ultimate goal of improving patient outcomes. This review details the current state of the art for these sensorized endovascular technologies and details systems under development with the aim of identifying gaps and new directions. The objective of this review was to survey the Vascular Surgery literature, engineering literature, and commercially available products to determine what exists in terms of sensor-enabled endovascular devices and where gaps and opportunities exist for further sensor integration.

METHODS

Search terms were entered into search engines such as Google and Google Scholar to identify endovascular devices containing sensors. A variety of terms were used including directly search for items such as "sensor-enabled endovascular devices" and then also completing more refined searches bases on areas of interest (i.e. fractional flow reserve, navigation, retrograde endovascular balloon occlusion of the aorta, etc.). For the most part, systems were included where the sensor was mounted directly onto the catheter and implantable sensors such as those that have been investigated for use with stents have been excluded.

RESULTS

The authors were able to identify a body of literature in the area of endovascular devices that contain sensors to measure physiologic information. However, areas where additional sensing capabilities may be useful were identified.

CONCLUSIONS

Several different types of sensors and sensing systems were identified that have been integrated with endovascular catheters. Although a great deal of work has been done in this field, there are additional useful data that could be obtained from additional novel sensing technologies. Furthermore, significant effort needs to be allocated to carefully studying how these new technologies can be employed to actually improve patient outcomes.

Multimodal imaging approach for the diagnosis of intracranial atherosclerotic disease (ICAD): Basic principles, current and future perspectives

PURPOSE

To review the different imaging modalities utilized in the diagnosis of Intracranial Atherosclerotic Disease (ICAD) including their latest development and relevance in management of ICAD.

METHODS

A review of the literature was conducted through a search in google scholar, PubMed/Medline, EMBASE, Scopus, clinical trials.gov and the Cochrane Library. Search terms included, "imaging modalities in ICAD," "ICAD diagnostic," "Neuroimaging of ICAD," "Evaluation of ICAD". A summary and comparison of each modality's basic principles, advantages and disadvantages were included.

RESULTS

A total of 144 articles were identified and reviewed. The most common imaging used in ICAD diagnoses were DSA, CTA, MRA and TCD. They all had proven accuracy, their own benefits, and limitations. Newer modalities such as VWI, IVUS, OCT, PWI and CFD provide more detailed information regarding the vessel walls, plaque characteristics, and flow dynamics, which play a tremendous role in treatment guidance. In certain clinical scenarios, using more than one modality has been shown to be helpful in ICAD identification. The rapidly evolving software related to imaging studies, such as virtual histology, are very promising for the diagnostic and management of ICAD.

CONCLUSIONS

ICAD is a common cause of recurrent ischemic stroke. Its management can be both medical and/or procedural. Many different imaging modalities are used in its diagnosis. In certain clinical scenario, a combination of two more modalities can be critical in the management of ICAD. We expect that continuous development of imaging technique will lead to individualized and less invasive management with adequate outcome.

Intravascular Ultrasound Use in Peripheral Arterial and Deep Venous Interventions: Multidisciplinary Expert Opinion From SCAI/AVF/AVLS/SIR/SVM/SVS

Percutaneous revascularization is the primary strategy for treating lower extremity venous and arterial disease. Angiography is limited by its ability to accurately size vessels, precisely determine the degree of stenosis and length of lesions, characterize lesion morphology, or correctly diagnose postintervention complications. These limitations are overcome with use of intravascular ultrasound (IVUS). IVUS has demonstrated the ability to improve outcomes following percutaneous coronary intervention, and there is increasing evidence to support its benefits in the setting of peripheral vascular intervention. At this stage in its evolution, there remains a need to standardize the use and approach to peripheral vascular IVUS imaging. This manuscript represents considerations and consensus perspectives that emerged from a roundtable discussion including 15 physicians with expertise in interventional cardiology, interventional radiology, and vascular surgery, representing 6 cardiovascular specialty societies, held on February 3, 2023. The roundtable's aims were to assess the current state of lower extremity revascularization, identify knowledge gaps and need for evidence, and determine how IVUS can improve care and outcomes for patients with peripheral arterial and deep venous pathology.

Relationship between Increased Plasma Levels of Legumain and Properties of Coronary Atherosclerotic Plaque

BACKGROUND

Many clinical studies have confirmed that legumain is closely related to atherosclerosis. Unfortunately, different conclusions have been reached, and analyses and studies on atherosclerotic plaque characteristics in patients with increased plasma levels of legumain are still lacking.

OBJECTIVES

This study aimed to investigate the correlation between legumain and coronary atherosclerotic plaque characteristics.

METHODS

A total of 81 patients with coronary atherosclerotic heart disease (CHD), including 43 patients with unstable angina (UA) and 38 patients with stable angina (SA), were screened by coronary angiography. Intravascular ultrasound (IVUS) was performed to evaluate the characteristics of coronary atherosclerotic plaques, and plasma legumain levels were also measured. Values of p < 0.05 were considered significant.

RESULTS

Legumain concentration was significantly higher in the two CHD subgroups than in the control group (all p<0.001). Legumain concentrations in the UA group were significantly higher than in the SA group (p=0.001). The plaque area, remodeling index (RI), and eccentricity index (EI) in the UA group were significantly higher than those in the SA group (p<0.001, p=0.001, p=0.001, respectively). There was a significant positive correlation between legumain levels and RI and EI in both UA and SA patients (all p<0.05).

CONCLUSIONS

High plasma levels of legumain were closely related to the occurrence and severity of CHD, and the lesions tended to be unstable. Legumain is expected to be a potential inflammatory biomarker for the diagnosis of CHD and the early identification of unstable coronary lesions.

Novel ultrasound techniques in the identification of vulnerable plaques-an updated review of the literature

Atherosclerosis is an inflammatory disease partly mediated by lipoproteins. The rupture of vulnerable atherosclerotic plaques and thrombosis are major contributors to the development of acute cardiovascular events. Despite various advances in the treatment of atherosclerosis, there has been no satisfaction in the prevention and assessment of atherosclerotic vascular disease. The identification and classification of vulnerable plaques at an early stage as well as research of new treatments remain a challenge and the ultimate goal in the management of atherosclerosis and cardiovascular disease. The specific morphological features of vulnerable plaques, including intraplaque hemorrhage, large lipid necrotic cores, thin fibrous caps, inflammation, and neovascularisation, make it possible to identify and characterize plaques with a variety of invasive and non-invasive imaging techniques. Notably, the development of novel ultrasound techniques has introduced the traditional assessment of plaque echogenicity and luminal stenosis to a deeper assessment of plaque composition and the molecular field. This review will discuss the advantages and limitations of five currently available ultrasound imaging modalities for assessing plaque vulnerability, based on the biological characteristics of the vulnerable plaque, and their value in terms of clinical diagnosis, prognosis, and treatment efficacy assessment.

Current Role of Intracoronary Imaging for Implementing Risk Stratification and Tailoring Culprit Lesion Treatment: A Narrative Review

Our understanding of the pathophysiology of acute coronary syndrome and of the vascular biology of coronary atherosclerosis has made enormous progress with the implementation of intravascular imaging. Intravascular imaging contributes to overcoming the known limitations of coronary angiography and allows for the in vivo discrimination of plaque morphology giving insight into the underlying pathology of the disease process. The possibility of using intracoronary imaging to characterize lesion morphologies and correlate them with clinical presentations may influence the treatment of patients and improve risk stratification, offering the opportunity for tailored management. This review examines the current role of intravascular imaging and describes how intracoronary imaging represents a valuable tool for modern interventional cardiology in order to improve diagnostic accuracy and offer a tailored approach to the treatment of patients with coronary artery disease, especially in the acute setting.

Diagnostics of atherosclerosis: Overview of the existing methods

Atherosclerosis was and remains an extremely common and serious health problem. Since the elderly are most at risk of cardiovascular risk, and the average life expectancy is increasing, the spread of atherosclerosis and its consequences increases as well. One of the features of atherosclerosis is its asymptomaticity. This factor makes it difficult to make a timely diagnosis. This entails the lack of timely treatment and even prevention. To date, in the arsenal of physicians, there is only a limited set of methods to suspect and fully diagnose atherosclerosis. In this review, we have tried to briefly describe the most common and effective methods for diagnosing atherosclerosis.

Invasive Intracoronary Imaging of Cardiac Allograft Vasculopathy: Established Modalities and Emerging Technologies

Despite advances in the care of heart transplant recipients during the past 5 decades, cardiac allograft vasculopathy (CAV) continues to be a major barrier to long-term survival. The early diagnosis and treatment of CAV is crucial for improving long-term outcomes. Coronary angiography, the current gold standard for CAV screening, has low sensitivity for detecting early CAV. Increasingly, invasive intracoronary imaging modalities that provide a more detailed analysis of vessel anatomy and allow for plaque characterization are being used to detect CAV earlier after transplant and uncover mechanistic insights. Studies validating these emerging imaging platforms are needed before their widespread adoption.

Development of Single-Channel Dual-Element Custom-Made Ultrasound Scanner with Miniature Optical Position Tracker for Freehand Imaging

Handheld ultrasound has great potential in resource-limited areas, and can improve healthcare for rural populations. Single-channel ultrasound has been widely used in many clinical ultrasound applications, and optical tracking is considered accurate and reliable. In this study, we developed a 10 MHz lead magnesium niobate-lead titanate (PMN-PT) dual-element ultrasound transducer combined with a miniature optical position tracker, and then measured the rectus femoris of the thigh, upper arm, and cheek muscles. Compared to single-element transducers, dual-element transducers improve the contrast of near-field signals, effectively reduce noise, and are suitable for measuring curved surfaces. The purpose of position tracking is to calculate the location of the ultrasound transducer during the measurement process. By utilizing positioning information, 2D ultrasound imaging can be achieved while maintaining structural integrity. The dual-element ultrasound scanner presented in this study can enable continuous scanning over a large area without a scanning width limitation. The custom-made dual-element ultrasound scanner has the advantage of being a portable, reliable, and low-cost ultrasound device, and is helpful in popularizing medical care for remote villages.

Role of Intracoronary Imaging in Myocardial Infarction with Non-Obstructive Coronary Disease (MINOCA): A Review

Myocardial infarction with non-obstructive coronary artery disease occurs in 6% to 15% of all presentation of myocardial infarctions. The pathophysiologic mechanisms of MINOCA include epicardial vasospasm, coronary microvascular disorder, spontaneous coronary artery dissection, and coronary thrombus/embolism. The diagnosis is challenging, supported by intracoronary imaging with intravascular ultrasound (IVUS) and optical coherent tomography (OCT), coronary physiology testing, and cardiac magnetic resonance imaging (CMR). OCT is able to identify atherosclerotic causes of MINOCA (plaque erosion, plaque rupture, and calcified nodule) and nonatherosclerotic causes (spontaneous artery dissection, and spasm). In this review, we summarize the performance of the two intracoronary imaging modalities (IVUS and OCT) in MINOCA and discuss the importance of supplementing these modalities with CMR in order to drive target therapy.

Miniaturized ultrasound detector arrays in silicon photonics using pulse transmission amplitude monitoring

Silicon photonics holds promise for a new generation of ultrasound-detection technology, based on optical resonators, with unparalleled miniaturization levels, sensitivities, and bandwidths, creating new possibilities for minimally invasive medical devices. While existing fabrication technologies are capable of producing dense resonator arrays whose resonance frequency is pressure sensitive, simultaneously monitoring the ultrasound-induced frequency modulation of numerous resonators has remained a challenge. Conventional techniques, which are based on tuning a continuous wave laser to the resonator wavelength, are not scalable due to the wavelength disparity between the resonators, requiring a separate laser for each resonator. In this work, we show that the Q-factor and transmission peak of silicon-based resonators can also be pressure sensitive, exploit this phenomenon to develop a readout scheme based on monitoring the amplitude, rather than frequency, at the output of the resonators using a single-pulse source, and demonstrate its compatibility with optoacoustic tomography.

Intravascular ultrasound guidance for lower extremity arterial and venous interventions

This review details the utility of intravascular ultrasound (IVUS) for the management of peripheral artery and venous disease. The purpose of this document is to provide an update in the use of IVUS in peripheral arterial and venous pathology and demonstrate the use of IVUS as a practical diagnostic imaging procedure to evaluate and treat peripheral vascular disorders. IVUS, a diagnostic tool that relies on sound waves to produce precise images of the vessel being evaluated, was originally introduced to the medical community for the purposes of peripheral artery imaging, though it was quickly adapted for coronary interventions with positive outcomes. The utility of IVUS includes vessel measurement, pre- and post-procedural planning, treatment optimisation, and detection of thrombus, dissection or calcium severity. While angiography remains the standard imaging approach during peripheral intervention, multiple observational studies and small prospective trials have shown that in comparison, IVUS provides more accurate imaging detail, which may improve procedural outcomes. IVUS can also address limitations of angiography, including the need to administer contrast medium and eliminate the ambiguity associated with other forms of imaging. This review provides contemporary examples of where IVUS is being used during peripheral intervention as well as representative imaging to serve as a resource for the practising clinician.

Targeted Imaging in Atherosclerosis

Atherosclerosis is a chronic inflammatory disease involved in plaque rupture, stroke, thrombosis, and heart attack (myocardial infarction), which is a leading cause of sudden cardiovascular events. In the past decades, various imaging strategies have been designed and employed for the diagnosis of atherosclerosis. Targeted imaging can accurately distinguish pathological tissues from normal tissues and reliably reveal biological information in the occurrence and development of atherosclerosis. By taking advantage of versatile imaging techniques, rationally designed imaging probes targeting biomarkers overexpressed in plaque microenvironments and targeting activated cells by modifying specific ligands accumulated in lesion regions have attracted increasing attention. This Perspective elucidates comprehensively the targeted imaging strategies, current challenges, and future development directions for precise identification and diagnosis of atherosclerosis, which is beneficial to better understand the physiological and pathological progression and exploit novel imaging strategies.

Comparative Appraisal of Intravascular Ultrasound and Optical Coherence Tomography in Invasive Coronary Imaging: 2022 Update

Although coronary angiography has been well established as a standard modality for percutaneous coronary intervention guidance, recent developments in intravascular imaging techniques, such as intravascular ultrasound and optical coherence tomography, have become increasingly adopted, enabling direct detailed lesion visualization, including lesions beyond the scope of assessment using exclusively angiography. Intravascular imaging modalities have been reported to potentially improve both short- and long-term percutaneous intervention outcomes. This review aims to provide a comparative summary of recent advancements in research regarding the clinical applications and outcomes of intravascular ultrasound and optical coherence tomography.

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.

Predicting Coronary Stenosis Progression Using Plaque Fatigue From IVUS-Based Thin-Slice Models: A Machine Learning Random Forest Approach

Introduction: Coronary stenosis due to atherosclerosis restricts blood flow. Stenosis progression would lead to increased clinical risk such as heart attack. Although many risk factors were found to contribute to atherosclerosis progression, factors associated with fatigue is underemphasized. Our goal is to investigate the relationship between fatigue and stenosis progression based on in vivo intravascular ultrasound (IVUS) images and finite element models.

Methods: Baseline and follow-up in vivo IVUS and angiography data were acquired from seven patients using Institutional Review Board approved protocols with informed consent obtained. Three hundred and five paired slices at baseline and follow-up were matched and used for plaque modeling and analysis. IVUS-based thin-slice models were constructed to obtain the coronary biomechanics and stress/strain amplitudes (stress/strain variations in one cardiac cycle) were used as the measurement of fatigue. The change of lumen area (DLA) from baseline to follow-up were calculated to measure stenosis progression. Nineteen morphological and biomechanical factors were extracted from 305 slices at baseline. Correlation analyses of these factors with DLA were performed. Random forest (RF) method was used to fit morphological and biomechanical factors at baseline to predict stenosis progression during follow-up.

Results: Significant correlations were found between stenosis progression and maximum stress amplitude, average stress amplitude and average strain amplitude (p < 0.05). After factors selection implemented by random forest (RF) method, eight morphological and biomechanical factors were selected for classification prediction of stenosis progression. Using eight factors including fatigue, the overall classification accuracy, sensitivity and specificity of stenosis progression prediction with RF method were 83.61%, 86.25% and 80.69%, respectively.

Conclusion: Fatigue correlated positively with stenosis progression. Factors associated with fatigue could contribute to better prediction for atherosclerosis progression.

Associations between circulating microRNAs and coronary plaque characteristics: potential impact from physical exercise

Background and aims MicroRNAs (miRs) are involved in different steps in the development of atherosclerosis and are proposed as promising biomarkers of coronary artery disease (CAD). We hypothesized that circulating levels of miRs were associated with coronary plaque components assessed by radiofrequency intravascular ultrasound (RF-IVUS) before and after aerobic exercise intervention. Methods 31 patients with CAD treated with percutaneous coronary intervention (PCI) previously included in a randomized trial with aerobic interval training (AIT) or moderate continuous training (MCT) as post-PCI intervention were included. Coronary plaque characteristics by grayscale and RF-IVUS and predefined circulating candidate miRs in plasma were analysed at baseline and follow-up. Associations between miRs and coronary plaque composition, and the potential effect from exercise, were analysed using linear regression. Results Circulating levels of miR-15a-5p, miR-30e-5p, miR-92a-3p, miR-199a-3p, miR-221-3p, and miR-222-3p were associated with baseline coronary necrotic core volume. Following exercise intervention, decreased levels of miR-15a-5p, miR-93-5p, and miR-451a, and increased levels of miR-146a-5p were associated with an observed regression of coronary plaque burden. A mirPath prediction tool identified that genes regulated by miR-15a-5p, miR-199a-3p, and miR-30e-5p were significantly overrepresented in pathways related to fatty acid biosynthesis and fatty acid metabolism. Conclusion This exploratory study demonstrated six miRs associated with coronary necrotic core, a marker of plaque vulnerability. In addition, changes in four miRs were associated with a regression of coronary plaque burden following exercise intervention. These novel findings may identify potential future biomarkers of CAD and coronary plaque composition.

Correlation between Characteristics of Coronary Plaque and Chinese Medicine Syndromes of Coronary Heart Disease: A Cross-Sectional Study Analysed by Intravascular Ultrasound

OBJECTIVE

To analyse the correlation between the characteristics of coronary plaque in coronary heart disease (CHD) patients with phlegm-blood stasis syndrome (PBS) and blood stasis syndrome (BSS).

METHODS

Patients were divided into different groups based on Chinese medicine (CM) syndrome differentiation. The baseline demographics and clinical variables were collected from the medical records. Additionally, the characteristics of plaque and pathological manifestations in coronary artery were evaluated using intravascular ultrasound (IVUS).

RESULTS

A total of 213 CHD patients were enrolled in two groups: 184 were diagnosed with PBS and the remaining 29 were diagnosed with BSS. There were no significant differences in age, body mass index, proportions of patients with high blood pressure, diabetes mellitus, smoking, hyperlipidemia, history of coronary artery bypass graft and percutaneous coronary intervention, medications, index from cardiac ultrasound image, blood lipids and C-reactive protein between the two groups (P>0.05), except gender, weight and proportions of IVUS observed target vessels (P<0.05 or P<0.01). More adverse events such as acute myocardial infarction (P=0.003) and unstable angina (P=0.048) were observed in BSS. Additionally, dissection, thrombus and coronary artery ectasia were significantly increased in BSS (P<0.05 or P<0.01). In contrast, PBS had more patients with stable angina and chronic total occlusion with significantly higher SYNTAX (synergy between percutaneous coronary intervention with Taxus and coronary artery bypass surgery) scores (P<0.05 or P<0.01). Moreover, dense-calcium was significantly elevated in PBS (P<0.01).

CONCLUSIONS

Coronary plaque characteristics were correlated with different CM syndromes. Patients with PBS were associated with a higher degree of calcified plaque and severe coronary artery stenosis, indicating poor clinical prognosis but with a low probability of acute coronary events. In contrast, the degree of calcified plaque in patients with BSS remained relatively low, and plaque was more vulnerable, resulting in the possibility of the occurrence of acute coronary events remaining high.

Advanced Ultrasound and Photoacoustic Imaging in Cardiology

Cardiovascular diseases (CVDs) remain the leading cause of death worldwide. An effective management and treatment of CVDs highly relies on accurate diagnosis of the disease. As the most common imaging technique for clinical diagnosis of the CVDs, US imaging has been intensively explored. Especially with the introduction of deep learning (DL) techniques, US imaging has advanced tremendously in recent years. Photoacoustic imaging (PAI) is one of the most promising new imaging methods in addition to the existing clinical imaging methods. It can characterize different tissue compositions based on optical absorption contrast and thus can assess the functionality of the tissue. This paper reviews some major technological developments in both US (combined with deep learning techniques) and PA imaging in the application of diagnosis of CVDs.

Vessel Diameter Evaluated by Intravascular Ultrasound Versus Angiography

PURPOSE

Although reference vessel diameter (RVD) is conveniently measured by angiography during femoropopliteal (FP) endovascular therapy (EVT) in clinical practice, angiography will potentially underestimate RVD. On the other hand, intravascular ultrasound (IVUS) can measure RVD precisely. The aim of this study was to reveal the difference between angiography- and IVUS-assessed RVD in patients undergoing FP-EVT for symptomatic peripheral artery disease (PAD).

METHODS

We analyzed a prospective and multicenter database including 1967 limbs of 1725 patients with symptomatic PAD undergoing IVUS-supported FP-EVT. The study outcome measure was the difference between IVUS- and angiography-assessed distal RVD (ΔRVD), calculated as angiography-assessed RVD subtracted from IVUS-assessed RVD. The clinically important difference was defined as 1 mm or larger.

RESULTS

IVUS-assessed RVD was significantly larger than angiography-assessed RVD (6.0±1.0 mm vs 5.0±1.0 mm; p<0.001). Mean ΔRVD (IVUS- minus angiography-assessed RVD) was 0.98 mm (95% CI, 0.94-1.03 mm). ΔRVD was 1 mm or larger in 48.8% (46.5%-51.0%) of the whole population. Multivariate analysis demonstrated that small angiography-assessed RVD, angiography-assessed bilateral calcification, and history of stent implantation were significantly associated with an increasing risk of ΔRVD ≥1mm, whereas presence of chronic total occlusion (CTO) was significantly associated with a decreasing risk of ΔRVD ≥1 mm.

CONCLUSION

The current study revealed the difference between angiography-assessed reference lumen diameter and IVUS-assessed reference EEM diameter of FP lesions. About half of population had ΔRVD ≥1 mm. IVUS-assessed RVD was more likely to be different by angiography in cases with small vessels, CTO, bilateral calcification, and history of stent implantation.

Stent visualization methods to guide percutaneous coronary interventions and assess long-term patency

Evaluation of acute percutaneous coronary intervention (PCI) results and long-term follow-up remains challenging with ongoing stent designs. Several imaging tools have been developed to assess native vessel atherosclerosis and stent expansion, improving overall PCI results and reducing adverse cardiac events. Quantitative coronary analysis has played a crucial role in quantifying the extent of coronary artery disease and stent results. Digital stent enhancement methods have been well validated and improved stent strut visualization. Intravascular imaging remains the gold standard in PCI guidance but adds costs and time to the procedure. With a recent shift towards non-invasive imaging assessment and coronary computed tomography angiography imaging have shown promising results. We hereby review novel stent visualization techniques used to guide PCI and assess stent patency in the modern PCI era.

Clinical Outcomes and Prevalence of Intravascular Ultrasound Use at a Tertiary Care Hospital in a South Asian Country

Objectives:

Intravascular ultrasound (IVUS) plays a pivotal role in the current era of coronary interventions. We aimed to determine the prevalence of IVUS use and clinical outcomes of IVUS-guided percutaneous treatment of coronary arteries lesions in a South Asian country.

Material and Methods:

It is a retrospective observational study, a total of 134 consecutive patients having done IVUS, was enrolled from January 2013 to March 2020 at a single center.

Results:

Out of 134 patients, 97 (72.4%) were male with a mean age of 63.1 ± 12.9 years. The prevalence of IVUS in our center was 3.0%. The most frequent comorbidity observed was dyslipidemia, n = 111 (82.8%). Non-ST-elevation myocardial infarction, n = 50 (37.3%), was the common mode of presentation. On coronary angiogram, the left main (LM) disease was found in n = 46 (34.3%), however, single-vessel disease, n = 51 (38.1%), was most commonly noted. IVUS utilization was higher in the left anterior descending, n = 94 (70.1%), followed by LM, n = 46 (34.3%). The LM mean minimal luminal area was 6.0 ± 2.6 mm² and minimal luminal diameter was 4.53 mm ± 0.6 (mean). The coronary artery dissection was noted in n = 15 (11.2%). The mean duration of follow-up in our study was 40.3 ± 30.1 months. Major adverse cardiac events (MACEs) were recorded in n = 13 (9.7%), which included heart failure, n = 4 (3%). Cardiovascular death and target vessel revascularization occurred in n = 3 (2.2%).

Conclusion:

IVUS results in a significant decrease in MACE. Our data might support the broader use of IVUS in both developed and in our part of the world.

Recent Advances in Transducers for Intravascular Ultrasound (IVUS) Imaging

As a well-known medical imaging methodology, intravascular ultrasound (IVUS) imaging plays a critical role in diagnosis, treatment guidance and post-treatment assessment of coronary artery diseases. By cannulating a miniature ultrasound transducer mounted catheter into an artery, the vessel lumen opening, vessel wall morphology and other associated blood and vessel properties can be precisely assessed in IVUS imaging. Ultrasound transducer, as the key component of an IVUS system, is critical in determining the IVUS imaging performance. In recent years, a wide range of achievements in ultrasound transducers have been reported for IVUS imaging applications. Herein, a comprehensive review is given on recent advances in ultrasound transducers for IVUS imaging. Firstly, a fundamental understanding of IVUS imaging principle, evaluation parameters and IVUS catheter are summarized. Secondly, three different types of ultrasound transducers (piezoelectric ultrasound transducer, piezoelectric micromachined ultrasound transducer and capacitive micromachined ultrasound transducer) for IVUS imaging are presented. Particularly, the recent advances in piezoelectric ultrasound transducer for IVUS imaging are extensively examined according to their different working mechanisms, configurations and materials adopted. Thirdly, IVUS-based multimodality intravascular imaging of atherosclerotic plaque is discussed. Finally, summary and perspectives on the future studies are highlighted for IVUS imaging applications.

Ultrasound Methods in the Evaluation of Atherosclerosis: From Pathophysiology to Clinic

Atherosclerosis is a key pathological process that causes a plethora of pathologies, including coronary artery disease, peripheral artery disease, and ischemic stroke. The silent progression of the atherosclerotic disease prompts for new surveillance tools that can visualize, characterize, and provide a risk evaluation of the atherosclerotic plaque. Conventional ultrasound methods-bright (B)-mode US plus Doppler mode-provide a rapid, cost-efficient way to visualize an established plaque and give a rapid risk stratification of the patient through the Gray-Weale standardization-echolucent plaques with ≥50% stenosis have a significantly greater risk of ipsilateral stroke. Although rather disputed, the measurement of carotid intima-media thickness (C-IMT) may prove useful in identifying subclinical atherosclerosis. In addition, contrast-enhanced ultrasonography (CEUS) allows for a better image resolution and the visualization and quantification of plaque neovascularization, which has been correlated with future cardiovascular events. Newly emerging elastography techniques such as strain elastography and shear-wave elastography add a new dimension to this evaluation-the biomechanics of the arterial wall, which is altered in atherosclerosis. The invasive counterpart, intravascular ultrasound (IVUS), enables an individualized assessment of the anti-atherosclerotic therapies, as well as a direct risk assessment of these lesions through virtual histology IVUS.

Medical and Revascularization Management of Stable Ischemic Heart Disease: An Overview

Stable ischemic heart disease (SIHD) affects approximately 10 million Americans with 500,000 new cases diagnosed each year. Patients with SIHD are primarily managed in the outpatient setting with aggressive cardiovascular risk factor modification via medical therapy and lifestyle changes. Currently, this approach is considered as the mainstay of treatment. The recently published ISCHEMIA trial has established the noninferiority of medical therapy in comparison to coronary revascularization in patients with moderate to severe ischemia. Percutaneous coronary intervention is currently recommended for patients with significant left main disease, large ischemic myocardial burden, and patients with severe refractory angina despite maximal medical therapy.

Construction of an intravascular ultrasound catheter with a micropiezoelectric motor internally installed

Intravascular ultrasound (IVUS) has become a useful tool in the detection of coronary artery disease. However, non-uniform rotation distortion (NURD) reduces the image quality. In order to suppress the influence of NURD, a piezoelectric motor that can meet the requirements of IVUS catheters has been proposed. The motor has a diameter of 1 mm and a length of 10 mm using the new polarization direction proposed in the paper. A 45° mirror is fixed on the top of the motor to reflect the ultrasound transmitted from the transducer. The manufacture and drive of the piezoelectric motor is simple, and the maximum speed of the piezoelectric motor can reach 6450 rpm under the voltage of 20Vp-p. The minimum power required by the rotating motor is only 0.038 W, which can be directly driven by the signal generator without a power amplifier. The motor can operate at a low voltage and still has a high and stable speed. Meanwhile, the speed of the motor is controllable and has a satisfactory stability with a maximum angular error of 8°. The images detected by the cooperation of the motor and the ultrasonic transducer are also shown, which indicates that the motor has the rotational stability that meets the imaging requirements and the potential for application in the IVUS catheter to help improve the image quality of the coronary arteries and prevent and help treat potential diseases.

Spontaneously Recanalised Coronary Thrombus in the Left Anterior Descending Artery Presenting as Ventricular Tachycardia

Spontaneously recanalized coronary thrombus (SRCT), also known as honeycomb, lotus root or Swiss-cheese lesion, is an increasingly recognised finding in patients undergoing coronary angiography. It is thought to arise from partial resorption of an initially occlusive thrombus. Most patients present with angina or exertional breathlessness. We describe a case of a 69-year-old patient who presented with ventricular tachycardia and was found to have SRCT in the left anterior descending artery on coronary angiography. Echocardiography and left ventricular (LV) angiography showed an akinetic, aneurysmal, thin-walled LV apex, diagnostic of an old anterior infarct. We highlight the role of optical coherence tomography in making the diagnosis and discuss the available management options of this condition.

A review of serial coronary computed tomography angiography (CTA) to assess plaque progression and therapeutic effect of anti-atherosclerotic drugs

Change in coronary artery plaque on serial catheter intravascular ultrasound (IVUS) is an established technique to monitor the therapeutic effect of drugs on coronary atherosclerosis. Recent advances in coronary computed tomography angiography (CTA) now allow for non-invasive assessment of change in coronary plaque. Because coronary CTA is noninvasive, it enables clinical trials with lower-risk populations, higher retention rates, and lower costs. This review presents an overview of serial coronary CTA as a noninvasive imaging technique to gauge the therapeutic effect of anti-atherosclerotic therapies. Furthermore, it reviews the increasing use of serial CTA as an imaging endpoint in completed and ongoing clinical trials.

High contrast power Doppler imaging in side-viewing intravascular ultrasound imaging via angular compounding

The ability to assess likelihood of plaque rupture can determine the course of treatment in coronary artery disease. One indicator of plaque vulnerability is the development of blood vessels within the plaque, or intraplaque neovascularization. In order to visualize these vessels with increased sensitivity in the cardiac catheterization lab, a new approach for imaging blood flow in small vessels using side-viewing intravascular ultrasound (IVUS) is proposed. This approach based on compounding adjacent angular acquisitions was evaluated in tissue mimicking phantoms and ex vivo vessels. In phantom studies, the Doppler CNR increased from 3.3 ± 1.0 to 13 ± 2.6 (conventional clutter filtering) and from 1.9 ± 0.15 to 7.5 ± 1.1 (SVD filtering) as a result of applying angular compounding. When imaging flow at a rate of 5.6 mm/s in 200 µm tubes adjacent to the lumen of ex vivo porcine arteries, the Doppler CNR increased from 5.3 ± 0.95 to 7.2 ± 1.3 (conventional filtering) and from 23 ± 3.3 to 32 ± 6.7 (SVD filtering). Applying these strategies could allow increased sensitivity to slow flow in side-viewing intravascular ultrasound imaging.

In vivo intravascular photoacoustic imaging at a high speed of 100 frames per second

Intravascular photoacoustic (IVPA) imaging technology enables the visualization of pathological characteristics (such as inflammation activities, lipid deposition) of the artery wall. Blood flushing is a necessary step in improving the imaging quality in in vivo IVPA imaging. But the limited imaging speed of the systems stretches their flushing time, which is an important obstacle of their clinical translations. In this paper, we report an improvement in IVPA/IVUS imaging speed to 100 frames per second. The high-speed imaging is demonstrated in rabbit in vivo, visualizing the nanoparticles accumulated on abdominal aorta wall at the wavelength of 1064 nm, in real time display. Blood flushing in vivo improves the IVPA signal-noise-ratio by around 3.5 dB. This study offers a stable, efficient and easy-to-use tool for instantaneous disease visualization and disease diagnosis in research and forwards IVPA/IVUS imaging technology towards clinical translations.

Influence of Ezetimibe on Plaque Morphology in Patients with ST Elevation Myocardial Infarction Assessed by Optical Coherence Tomography: An OCTIVUS Sub-Study

AIMS

The aim of the trial was to examine the influence of ezetimibe on plaque morphology in patients with ST-segment Elevation Myocardial Infarction (STEMI) with respect to fibrous cap thickness (FCT) and arcs of lipid plaque, calcific plaque, and macrophages using Optical Coherence Tomography (OCT).

METHODS AND RESULTS

In 87 statin naïve patients with STEMI treated with primary percutaneous intervention, a non-culprit study plaque in a non-infarct related coronary artery was assessed with OCT at baseline and after 12 months. Patients were treated with atorvastatin 80 mg and randomized (1:1) to ezetimibe 10 mg (n = 43) or placebo (n = 44). An increase in median FCT (ezetimibe 200 (140-260) μm to 240 (190-305) μm (p = 0.002) vs. placebo 205 (135-260) μm to 230 (180-270) μm (p < 0.001), between groups p = ns), a reduction in lipid arc (ezetimibe 1728.5 (1022.5-3904.7)° to 1164.5 (736.6-2580.1)° (p = 0.001) vs. placebo 1671.6 (978.3-2868.7)° to 1373.7 (791.2-2267.3)° (p = 0.019), between groups p = ns), and macrophage arc (ezetimibe 1730.3 (965.7-2984.4)° to 1324.8 (819.0-2819.7)° (p < 0.05) vs. placebo 1570.5 (794.7-3016.8)° to 1418.9 (584.1-2501.1)° (p < 0.01), between groups p = ns) were observed.

CONCLUSION

Aggressive LDL-lowering resulted in changes in OCT assessed plaque composition by increased FCT thickness and a reduction in lipid content and macrophage infiltration. Addition of ezetimibe 10 mg to atorvastatin 80 mg resulted in further LDL reduction, but no additional change in plaque composition was found.

Predict pneumonia with chest X-ray images based on convolutional deep neural learning networks

The chest X-ray examination is one of the most important methods for screening and diagnosing of many lung diseases. Diagnosis of pneumonia by chest X-ray is one of the common methods used by medical experts. However, the image quality of chest X-Ray has some defects, such as low contrast, overlapping organs and blurred boundary, which seriously affects detecting pneumonia in chest X-rays. Therefore, it has important medical value and application significance to construct a stable and accurate automatic detection model of pneumonia through a large number of chest X-ray images. In this paper, we propose a novel hybrid system for detecting pneumonia from chest X-Ray image: ACNN-RF, which is an adaptive median filter Convolutional Neural Network (CNN) recognition model based on Random forest (RF). Firstly, the improved adaptive median filtering is employed to remove noise in the chest X-ray image, which makes the image more easily recognized. Secondly, we establish the CNN architecture based on Dropout to extract deep activation features from each chest X-ray image. Finally, we employ the RF classifier based on GridSearchCV class as a classifier for deep activation features in CNN model. It not only avoids the phenomenon of over-fitting in data training, but also improves the accuracy of image classification. During our experiment, the public chest X-ray image dataset used in the experiment contains 5863 images, which comprises 4265 frontal-view X-ray images of 1574 unique patients. The average recognition rate of pneumonia is up to 97% by the proposed ACNN-RF. The experimental results show that the ACNN-RF identification system is more effective than the previous traditional image identification system.

Effect of the dipeptidyl peptidase-4 inhibitor linagliptin on atherosclerotic lesions in Watanabe heritable hyperlipidemic rabbits: iMap-IVUS and pathological analysis

Dipeptidyl peptidase-4 (DPP-4) inhibitors have potential as a treatment for atherosclerosis. However, it is unclear whether DPP-4 inhibitors stabilize atherosclerotic plaque or alter the composition of complex plaque. Sixteen Watanabe heritable hyperlipidemic rabbits aged 10-12 weeks with atherosclerotic plaque in the brachiocephalic artery detected by iMap^™ intravascular ultrasound (IVUS) were divided into a DPP-4 inhibitor group and a control group. Linagliptin was administered to the DPP-4 inhibitor group via nasogastric tube at a dose of 10 mg/kg/day for 16 weeks, and control rabbits received the same volume of 0.5% hydroxyethylcellulose. After evaluation by IVUS at 16 weeks, the brachiocephalic arteries were harvested for pathological examination. IVUS revealed that linagliptin significantly reduced the plaque volume and vessel volume (control group vs. DPP-4 inhibitor group: ∆plaque volume, 1.02 ± 0.96 mm³ vs.  - 3.59 ± 0.92 mm³, P = 0.004; ∆vessel volume,  - 1.22 ± 2.36 mm³ vs.  - 8.66 ± 2.33 mm³, P = 0.04; %change in plaque volume, 6.90 ± 5.62% vs.  - 15.06 ± 3.29%, P = 0.005). With regard to plaque composition, linagliptin significantly reduced the volume of fibrotic, lipidic, and necrotic plaque (control group vs. DPP-4 inhibitor group: ∆fibrotic volume, 0.56 ± 1.27 mm³ vs.  - 5.57 ± 1.46 mm³, P = 0.04; ∆lipidic volume, 0.24 ± 0.24 mm³ vs.  - 0.42 ± 0.16 mm³ P = 0.04; ∆necrotic volume, 0.76 ± 0.54 mm³ vs.  - 0.84 ± 0.25 mm³, P = 0.02). Pathological examination did not show any significant differences in the %smooth muscle cell area or %fibrotic area, but infiltration of macrophages into plaque was reduced by linagliptin treatment (%macrophage area: 12.03% ± 1.51% vs. 7.21 ± 1.65%, P < 0.05). These findings indicate that linagliptin inhibited plaque growth and stabilized plaque in Watanabe heritable hyperlipidemic rabbits.

Co-registration of Intravascular Ultrasound With Angiographic Imaging for Carotid Artery Disease

BACKGROUND

Intravascular ultrasound (IVUS) provides endoluminal views and cross-sectional images of carotid arteries but lacks overview of vascular territory provided by angiography. Co-registration of IVUS with angiographic images may provide the potential to navigate both imaging modalities in a synchronous manner. The objective of this study is to evaluate the feasibility and accuracy of co-registering both imaging modalities in the carotid vasculature of the neck.

METHODS

Fourteen patients with 15 cervical carotid artery lesions underwent angiography and subsequent treatment. In each case, an IVUS catheter was advanced to the target lesion and a reference angiography sequence was acquired. This was followed by an electrocardiography-triggered fluoroscopy sequence that was initiated upon IVUS catheter pullback. IVUS data collected during pullback were registered with fluoroscopy and evaluated for error and clinical usability.

RESULTS

A total of 32 landmarks were identified that demonstrated reasonable agreement during IVUS-angiography co-registration. There was a mean registration error distance of 3.36 mm (SD 2.82 mm) between targets. The longitudinal extent and severity of the disease through the target segment could be easily evaluated after co-registration.

CONCLUSION

Semiautomatic tracking and co-registration of angiography and IVUS is a new technology and has the potential to increase the use of IVUS in carotid disease and to proivde the opportunity to optimize procedural outcomes.

Lipid-rich large plaques in a non-culprit left main coronary artery and long-term clinical outcomes

BACKGROUND

An integrated backscatter (IB) intravascular ultrasound (IVUS) provides an information about tissue components and vulnerability of coronary plaques. The presence of vulnerable plaque in non-culprit lesion is associated with future clinical events. The purpose of this study was to assess the association between the characteristics of non-culprit left main coronary artery (LMCA) plaques evaluated by IB-IVUS and long-term clinical outcomes in patients undergoing percutaneous coronary intervention (PCI).

METHODS

Among the patients who underwent non-LMCA PCI, we studied 366 patients with adequate LMCA IVUS images. Conventional and IB-IVUS analyses of the LMCA segment were performed. Lipid-rich large plaque was defined as the presence of both a lager plaque volume and a higher percentage of the lipid component than the obtained median values. Major adverse cardiovascular events (MACE) included cardiac death, myocardial infarction, and unplanned revascularization.

RESULTS

The mean age of the patients was 68.5 ± 10.2 years, 79.8% were men. Median follow-up period was 6.0 years (IQR: 4.2-8.1 years). The incidence of MACE was significantly higher in patients with lipid-rich large plaques (P = .006). The incidence rates of cardiac death, myocardial infarction, and unplanned revascularization were significantly higher in patients with lipid-rich large plaques (P = .02, 0.004, and 0.02, respectively). Multivariate Cox regression analysis showed that the presence of a lipid-rich large plaque was significantly associated with MACE (HR: 1.74; 95%CI: 1.17-2.58; P = .006).

CONCLUSION

The presence of lipid-rich large plaques in a non-culprit LMCA can be associated with the long-term MACE in patients who have undergone PCI.

Stent edge vascular response and in-stent geometry after aerobic exercise

The purpose of the present study was to investigate the edge vascular response in patients treated with second-generation drug-eluting stents (DES) after 3 months of aerobic exercise intervention. Thirty-two patients with significant coronary artery disease underwent percutaneous coronary intervention with DES implantation prior to randomization to aerobic interval training (AIT, 14 patients) versus moderate continuous training (MCT, 18 patients). Plaque changes were assessed using grayscale and radiofrequency intravascular ultrasound at baseline and follow-up. The main endpoints were changes in plaque burden and necrotic core content in the 5-mm proximal and distal stent edges. Plaque burden in the distal stent edges decreased significantly in both groups (AIT: − 3.3%; MCT: − 0.4%, p = 0.01 for both), and more in the AIT group (p = 0.048). Necrotic core content decreased significantly in the distal stent edges in both groups (− 2.1 mm³ in AIT, − 0.3 mm³ in MCT, p = 0.01 for both), and more in the AIT group (p = 0.03). There were no significant changes in proximal stent edges or in in-stent geometry at follow-up. In this small study of patients treated with DES implantation, 3 months of aerobic exercise training demonstrated decreased plaque burden and necrotic core content in the distal stent edges, with larger reductions in the AIT group.

Contemporary practices using intravascular imaging guidance with IVUS or OCT to optimize percutaneous coronary intervention

Introduction: Angiography is routinely used to perform percutaneous coronary intervention (PCI). However, angiography has many limitations that prevent accurate assessment of coronary lesions. The development and evolution of intravascular imaging have offset the limitations of angiography. Overwhelming evidence supports intravascular imaging guidance to optimize PCI results and studies have shown that it is associated with better outcomes. Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) are the most commonly used modalities and both have far greater spatial resolution compared with angiography. There are advantages and disadvantages to both IVUS and OCT, and the optimal modality will depend on patient factors and indications.Areas covered: This review will summarize clinical evidence and current practices in the use of intravascular imaging in PCI. Literature review from year 2000-2019 was completed via PubMed search using keywords.Expert commentary: Intravascular imaging is an essential tool in PCI that has outcome implications, but it is still underutilized. Proper image acquisition, accurate interpretation, and correct decision-making are needed for patients to benefit from imaging-guided PCI. Training and education are essential in successful utilization of imaging technology. High-definition IVUS is likely to gain favor as there is improved image resolution without the use of contrast.

Intravascular Ultrasound for the Peripheral Vasculature-Current Applications and New Horizons

Intravascular ultrasound (IVUS) is a proven and rapidly developing imaging modality that can be used for a multitude of both diagnostic and interventional purposes. By allowing for superior intraluminal characterization, compared with angiography, IVUS has emerged as a technically valuable tool in interventional procedures such as transjugular intrahepatic portosystemic shunt/direct intrahepatic portosystemic shunt, venous interventions (May Thurner stenting, inferior vena cava filter placement, recanalization in the setting of chronic venous thrombosis/insufficiency), percutaneous fenestration in the setting of aortic dissection and angioplasty. Additional applications evaluating coronary arteries and plaque morphology have been described, but are outside the scope of this review. In addition to IVUS's merit as a pre- and intra-procedural guidance modality, there are also several advantages compared to the gold standard of angiography which include decreased need for iodinated contrast, decreased radiation exposure and decreased procedural times in certain cases. With current research, such as that aimed at supraharmonic imaging, further improvements in imaging depth, resolution and contrast to noise ratio are on the horizon.

Intracoronary Imaging for Assessment of Vascular Healing and Stent Follow-up in Bioresorbable Vascular Scaffolds

Bioresorbable Vascular Scaffolds (BVS) are polymer-based materials implanted in the coronary arteries in order to treat atherosclerotic lesions, based on the concept that once the lesion has been treated, the material of the implanted stent will undergo a process of gradual resorption that will leave, in several years, the vessel wall smooth, free of any foreign material and with its vasomotion restored. However, after the first enthusiastic reports on the efficacy of BVSs, the recently published trials demonstrated disappointing results regarding long-term patency following BVS implantation, which were mainly attributed to technical deficiencies during the stenting procedure. Intracoronary imaging could play a crucial role for helping the operator to correctly implant a BVS into the coronary artery, as well as providing relevant information in the follow-up period. This review aims to summarize the role of intracoronary imaging in the follow-up of coronary stents, with a particular emphasis on the role of intravascular ultrasound and optical coherence tomography for procedural guidance during stent implantation and also for follow-up of bioabsorbable scaffolds.

Intravascular Ultrasound in Carotid Web

Background

Carotid web (CaW) is a shelf-like linear filling defect in the posterior aspect of the internal carotid bulb, representing an intimal variant of fibromuscular dysplasia. The diagnosis of CaW is traditionally restricted to digital subtraction angiography (DSA), CT/MR angiography (CTA/MRA), and Duplex ultrasonography. In this series of patients with acute ischemic stroke, we evaluated the potential utility of intravascular ultrasound (IVUS) in further characterizing suspected CaWs.

Methods

This is a case series of three patients with suspected CaW who underwent DSA for treatment or investigation of large vessel occlusion strokes. In all cases the stroke investigation failed to identify an alternative cause, and the stroke etiology was attributed to a symptomatic CaW. The procedure consisted of positioning a guide catheter in the common carotid artery, navigating the IVUS probe distal to the carotid bulb, and then retracting the probe with a manual pullback. The acquired images were then reviewed in an independent workstation

Results

In two of the three cases, IVUS showed an isoechoic-to-hyperechoic focal eccentric area at the posterior carotid bulb, consistent with CaW. The endoluminal protrusion was inconspicuous on IVUS due to the low resolution of ultrasound not allowing a clear differentiation between fibrosis, thrombosis, and atherosclerosis. No abnormalities commonly associated with atherosclerotic disease or dissections were noted. The CaW could not be depicted in the third patient.

Conclusion

The use of IVUS in the diagnosis of CaW may have limited relevance. Continued investigation of other imaging modalities for accurate CaW diagnosis is recommended.

Markers for Inflammation and Oxidative Stress in Patients with Coronary Artery Disease and Microvascular Disease – Is there a Difference?

Introduction: The clinical significance of inflammation (and markers such as resistin, hsCRP) and oxidative stress (e.g. 8-isoprostanes) for microvascular disease (MVD) and coronary artery disease (CAD) is still elusive.

Aims: To determine the role of the markers for inflammation and oxidative stress as independent markers for MVD.

Methods: Ninety consecutive patients were recruited: twenty-five of them had CAD; thirty – MVD and thirty-five were controls. The latter included patients with atypical chest pain, risk factors, lack of coronary artery disease and negative adenosine test. Coronary angiography was performed in all participants. The adenosine test was performed in those without CAD, hs CRP, resistin in plasma and urine 8-isoprostanes were measured. The correlation of all these indicators with CAD and MVD was analyzed.

Results: The 8-isoprostanes showed significant differences between patients with MVD and CAD (0,055/0,52 pg/mmol Cre; p = 0,028). The same trend was found between CAD patients and the control group (0,055/0,003 pg/mmol Cre; p = 0,041); as well as between those with MVD and the control group (0,52/0,003 pg/mmol Cre; p = 0,001). The highest values of 8-isoprostanes were detected in patients with MVD – 0,52 pg/mmol Cre. Markers for inflammation were similar in patients with MVD and CAD (hsCRP- p = 0,091; resistin − p = 0,32).

Conclusions: hs CRP, resistin and 8-isoprostanes are involved in the pathogenesis of both CAD and MVD. However, oxidative stress is probably more important for MVD, therefore 8-isoprostanes can be a part of panel of markers for its detection and analysis.

A three-dimensional quantification of calcified and non-calcified plaques in coronary arteries based on computed tomography coronary angiography images: Comparison with expert's annotations and virtual histology intravascular ultrasound

The detection, quantification and characterization of coronary atherosclerotic plaques has a major effect on the diagnosis and treatment of coronary artery disease (CAD). Different studies have reported and evaluated the noninvasive ability of Computed Tomography Coronary Angiography (CTCA) to identify coronary plaque features. The identification of calcified plaques (CP) and non-calcified plaques (NCP) using CTCA has been extensively studied in cardiovascular research. However, NCP detection remains a challenging problem in CTCA imaging, due to the similar intensity values of NCP compared to the perivascular tissue, which surrounds the vasculature. In this work, we present a novel methodology for the identification of the plaque burden of the coronary artery and the volumetric quantification of CP and NCP utilizing CTCA images and we compare the findings with virtual histology intravascular ultrasound (VH-IVUS) and manual expert's annotations. Bland-Altman analyses were employed to assess the agreement between the presented methodology and VH-IVUS. The assessment of the plaque volume, the lesion length and the plaque area in 18 coronary lesions indicated excellent correlation with VH-IVUS. More specifically, for the CP lesions the correlation of plaque volume, lesion length and plaque area was 0.93, 0.84 and 0.85, respectively, whereas the correlation of plaque volume, lesion length and plaque area for the NCP lesions was 0.92, 0.95 and 0.81, respectively. In addition to this, the segmentation of the lumen, CP and NCP in 1350 CTCA slices indicated that the mean value of DICE coefficient is 0.72, 0.7 and 0.62, whereas the mean HD value is 1.95, 1.74 and 1.95, for the lumen, CP and NCP, respectively.

The role of precise imaging with intravascular ultrasound in coronary and peripheral interventions

Angiography remains a widely utilized imaging modality during vascular procedures. Angiography, however, has its limitations by underestimating the true vessel size, plaque morphology, presence of calcium and thrombus, plaque vulnerability, true lesion length, stent expansion and apposition, residual narrowing post intervention and the presence or absence of dissections. Intravascular ultrasound (IVUS) has emerged as an important adjunctive modality to angiography. IVUS offers precise imaging of the vessel size, plaque morphology and the presence of dissections and guides interventional procedures including stent sizing, assessing residual narrowing and stent apposition and expansion. IVUS-guided treatment has shown to yield superior outcomes when compared to angiography-only guided therapy. The cost-effectiveness of the routine use of IVUS during vascular procedures needs to be further studied.