Intravascular Ultrasound Technology Research Articles

Intravascular Ultrasound Guidance for TIPS Procedures: A Review.

The most challenging and time-consuming step of TIPS procedures is obtaining appropriate portal vein (PV) access. Given the lack of real-time direct target visualization, conventional fluoroscopic guidance requires multiple passes, contributing to complications. In comparison, intravascular ultrasound (IVUS) guidance during TIPS procedures provides direct visualization of hepatic structures and real-time guidance for PV puncture. IVUS guidance during TIPS creation improves procedural metrics such as radiation dose, contrast agent volume, procedure time, and technical success rate and is particularly beneficial in technically challenging cases (e.g., in patients portal vein thrombosis, small or variant portal vein anatomy, Budd-Chiari syndrome, or liver masses). The purpose of this review is to summarize current IVUS technology, describe the technical aspects of IVUS-guided TIPS creation, and discuss the clinical indications for and benefits of using IVUS for TIPS creation, while presenting available evidence supporting the technique's use. Given the improved safety profile and overall success rate in comparison with conventional guidance methods, IVUS guidance has the future potential to become the standard practice for TIPS placement.

Key Technologies of New Type of Intravascular Ultrasound Image Processing.

Since entering the 21st century, the application of ultrasound technology has developed rapidly. Intravascular ultrasound technology has been widely used in the diagnosis and treatment of cardiovascular diseases. With the help of computer image processing technology, it can provide clinicians with more accurate diagnosis. Based on the information to improve the success rate of clinical treatment. Based on this, this article combines the development history of intravascular ultrasound technology, explores the principles of new intravascular ultrasound technology, and analyzes the application of new intravascular ultrasound technology. On this basis, the preprocessing of intravascular ultrasound image data is discussed, involving the acquisition of intravascular ultrasound image data and image analysis. On this basis, explore the combined application of new intravascular ultrasound technology and other imaging examination methods, such as X-rays to use three-dimensional image technology to reconstruct new intravascular ultrasound image sequences, and provide doctors with clearer morphology and properties of tube wall lesions. In order to make a more accurate diagnosis of the lesion, a more detailed and accurate treatment plan can be given, which has extremely high clinical application value.

Intravascular Ultrasound in the Endovascular Treatment of Patients With Peripheral Arterial Disease: Current Role and Future Perspectives.

Over the last decade, intravascular ultrasound (IVUS) has emerged as a useful adjunctive tool to angiography in an increasing number of catheter-based procedures for peripheral arterial disease (PAD). IVUS catheters offer accurate cross-sectional imaging of arterial vessels with high dimensional accuracy and provide accurate information about lesion morphology. IVUS enables assessment of the plaque morphology, vessel diameter, and the presence of arterial dissections. Furthermore, IVUS is able to properly guide the best choice of appropriate percutaneous transluminal angioplasty (PTA) technique, guide the delivery of different devices, and assess the immediate result of any endovascular intervention. In the present review, the role of IVUS for PAD will be discussed, specifically the applications of IVUS technology during interventional procedures including PTA, stent sizing, crossing total occlusion, assessing residual narrowing and stent apposition and expansion, and atherectomy. Future perspectives of IVUS-guided treatments and cost-effectiveness of the systematic use of IVUS during endovascular interventions will be also discussed.

Optically Generated Ultrasound for Intracoronary Imaging.

Conventional intravascular ultrasound (IVUS) devices use piezoelectric transducers to electrically generate and receive US. With this paradigm, there are numerous challenges that restrict improvements in image quality. First, with miniaturization of the transducers to reduce device size, it can be challenging to achieve the sensitivities and bandwidths required for large tissue penetration depths and high spatial resolution. Second, complexities associated with manufacturing miniaturized electronic transducers can have significant cost implications. Third, with increasing interest in molecular characterization of tissue in-vivo, it has been challenging to incorporate optical elements for multimodality imaging with photoacoustics (PA) or near-infrared spectroscopy (NIRS) whilst maintaining the lateral dimensions suitable for intracoronary imaging. Optical Ultrasound (OpUS) is a new paradigm for intracoronary imaging. US is generated at the surface of a fiber optic transducer via the photoacoustic effect. Pulsed or modulated light is absorbed in an engineered coating on the fiber surface and converted to thermal energy. The subsequent temperature rise leads to a pressure rise within the coating, which results in a propagating ultrasound wave. US reflections from imaged structures are received with optical interferometry. With OpUS, high bandwidths (31.5 MHz) and pressures (21.5 MPa) have enabled imaging with axial resolutions better than 50 μm and at depths >20 mm. These values challenge those of conventional 40 MHz IVUS technology and show great potential for future clinical application. Recently developed nanocomposite coating materials, that are highly transmissive at light wavelengths used for PA and NIRS light, can facilitate multimodality imaging, thereby enabling molecular characterization.

Intravascular ultrasound-guided laparoscopic division of the median arcuate ligament.

Median arcuate ligament syndrome is a rare and poorly understood condition that can have a significant impact on the quality of life of patients. Diagnosis is often difficult and delayed because of the need to exclude other pathologic processes. Treatment strategies traditionally involve open or laparoscopic division of the median arcuate ligament, with or without vascular reconstruction. This report portrays a case of median arcuate ligament syndrome with compression of two visceral arteries and distal embolic complications. A novel hybrid technique is described using intravascular ultrasound technology to aid in laparoscopic median arcuate ligament division. This allowed real-time intravascular visualization of the compressive segment, guided release of the ligament fibers, and demonstrated confirmation of decompression.

Application of Intravascular Imaging in Forensic Autopsy.

With the emergence of new technologies and devices including minimally invasive catheters and rotary couplers, the application of imaging technology such as traditional ultrasound and optical coherence tomography （OCT） is gradually expanded. In recent years, intravascular ultrasound （IVUS） and OCT have become increasingly mature as coronary intravascular imaging techniques, and therefore become an important complementary means of coronary angiography. Although studies on feasibility of clinical applications of IVUS and OCT have been confirmed in the evaluation of previous cadaver studies, these techniques have been neglected in forensic autopsy. This paper reviews the application value of IVUS and OCT in forensic autopsy, especially in the adjuvant evaluation of coronary artery disease. Including the characteristics of IVUS and OCT imaging technology, the problems of coronary examination in traditional autopsy and the specific application of new intravascular imaging technology in forensic autopsy.

Semiquantitative analysis of virtual histology derived from intravascular ultrasound images at vascular access stenosis.

Vascular access failure, such as recurrent stenosis and thrombosis, is a major concern in patients with end-stage kidney disease. Neointimal hyperplasia development at the anastomosis site of outflow vessels is a primal cause for recurrent vascular access failure. We previously shed some lights into a role of vitamin D, which exerts a protective effect against neointimal hyperplasia formation. Virtual histology, derived from intravascular ultrasound technology, provides novel insights into plaque composition analysis in atherosclerotic diseases. However, there is so far a lack of evidence on the relation between virtual histology and pathophysiological findings. To elucidate this missing link, we comprehensively reviewed 10 chronic hemodialysis patients who underwent repeated intravascular ultrasound-guided balloon angioplasty. Their age, dialysis vintage, and follow-up period were 75.0 ± 4.24, 20.5 ± 2.12, and 11.5 ± 0.71 (mean ± standard deviation) years, respectively. Pathological cross-sectional analyses were performed using specimens from vascular access surgeries during the follow-up period. Interestingly, positive relation is found between virtual histology-constructed fibrous tissue and pathological neointimal hyperplasia. Strikingly, immunohistological analysis revealed that vitamin D receptor-positive myofibroblasts were abundantly distributed in the equivalent area to virtual histology fibrous tissue. Our 10-year follow-up data of resistant vascular access stenosis indicates strong correlation between vitamin D receptor-rich neointimal vessel hypertrophy and intravascular ultrasound-assisted virtual histological analysis. Intravascular ultrasound technology is one of the minimally invasive diagnostic tools to provide histologically relevant tissue structure information and help determine target vessel stenosis on vascular access.

The Role of Virtual Histology Intravascular Ultrasound in the Identification of Coronary Artery Plaque Vulnerability in Acute Coronary Syndromes.

Markers of coronary plaque vulnerability, such as a high lipid burden, increased inflammatory activity, and a thin fibrous cap, have been identified in histological studies. In vivo, grayscale intravascular ultrasound (IVUS) provides more in-depth information on coronary artery plaque burden than conventional angiography but is unable to accurately distinguish between noncalcific tissue types within the plaque. An analysis of IVUS radiofrequency backscatter based on spectral pattern recognition, such as virtual histology IVUS, allows detailed scrutiny of plaque composition and classification of coronary lesions. This review discusses the virtual histology IVUS technology and its accuracy in identifying vulnerable plaque features, focusing on its use in predicting patient outcomes after acute coronary syndrome, and its limitations in clinical practice.

Using sound advice-intravascular ultrasound as a diagnostic tool.

Intravascular ultrasound (IVUS) uses varying-frequency catheter-based transducers for assessment of blood vessel dimensions and morphology. Along with advances in the field of interventional cardiology, IVUS technology has progressed in the last two decades. Dedicated training centers in combination with enthusiasm from a new generation of cardiologists complemented by well-established evidence for simplicity, safety and efficacy of IVUS systems have led to increased routine use of this imaging modality. Currently available catheters use sound frequencies in the range of 20–70 MHz, moving from older grayscale IVUS to radiofrequency IVUS (RF-IVUS) and more recently high-definition IVUS (HD-IVUS) devices, some with the ability to differentiate plaque composition.

Next Generation Fractional Flow Reserve and Intravascular Ultrasound Technology: Catheter-based and High Definition Intravascular Ultrasound

Next Generation Fractional Flow Reserve and Intravascular Ultrasound Technology: Catheter-based and High Definition Intravascular Ultrasound

Microbubble-mediated intravascular ultrasound imaging and drug delivery

Intravascular ultrasound (IVUS) provides radiation-free, real-time imaging and assessment of atherosclerotic disease in terms of anatomical, functional, and molecular composition. The primary clinical applications of IVUS imaging include assessment of luminal plaque volume and real-time image guidance for stent placement. When paired with microbubble contrast agents, IVUS technology may be extended to provide nonlinear imaging, molecular imaging, and therapeutic delivery modes. In this review, we discuss the development of emerging imaging and therapeutic applications that are enabled by the combination of IVUS imaging technology and microbubble contrast agents.

Multi-frequency intravascular ultrasound (IVUS) imaging.

Acute coronary syndrome (ACS) is frequently associated with the sudden rupture of a vulnerable atherosclerotic plaque within the coronary artery. Several unique physiological features, including a thin fibrous cap accompanied by a necrotic lipid core, are the targeted indicators for identifying the vulnerable plaques. Intravascular ultrasound (IVUS), a catheter-based imaging technology, has been routinely performed in clinics for more than 20 years to describe the morphology of the coronary artery and guide percutaneous coronary interventions. However, conventional IVUS cannot facilitate the risk assessment of ACS because of its intrinsic limitations, such as insufficient resolution. Renovation of the IVUS technology is essentially needed to overcome the limitations and enhance the coronary artery characterization. In this paper, a multi-frequency intravascular ultrasound (IVUS) imaging system was developed by incorporating a higher frequency IVUS transducer (80 to 150 MHz) with the conventional IVUS (30-50 MHz) system. The newly developed system maintains the advantage of deeply penetrating imaging with the conventional IVUS, while offering an improved higher resolution image with IVUS at a higher frequency. The prototyped multifrequency catheter has a clinically compatible size of 0.95 mm and a favorable capability of automated image co-registration. In vitro human coronary artery imaging has demonstrated the feasibility and superiority of the multi-frequency IVUS imaging system to deliver a more comprehensive visualization of the coronary artery. This ultrasonic-only intravascular imaging technique, based on a moderate refinement of the conventional IVUS system, is not only cost-effective from the perspective of manufacturing and clinical practice, but also holds the promise of future translation into clinical benefits.

Reconstruction of nonuniform residual stress for soft hyperelastic tissue via inverse spectral techniques

Residual stress is a stress that can exist in a body in the absence of externally applied loads. It is a challenge to model and predict it in soft tissues both theoretically and experimentally. Mathematical inverse spectral techniques are developed in this article to reconstruct the residual stress in the arterial wall. The techniques are theoretically based on a novel use of the intravascular ultrasound technology (IVUS) by obtaining several natural frequencies of the vessel wall material. As the IVUS is interrogating inside the artery, it produces small amplitude, high frequency time harmonic vibration superimposed on the quasi-static deformation of the pre-stressed artery resulting from pulsatile blood flow. Accordingly, two categories of boundary value problems are formulated to form Sturm–Liouville problems (SLP) with the natural eigenfrequencies from IVUS implementation as eigenvalues of the SLP. Via an optimization approach instead of the traditional equation-solving method, the algorithms for an inverse spectral technique are established to recover the residual stress as functions. Robustness of the algorithms is increased by overestimation of the problem. Comprehensive tests are performed to assess the accuracy of the solution. Numerical examples are displayed to illustrate the application of the technique.

Coronary Intravascular Ultrasound (IVUS): Contemporary Applications and Bases for the Future

Despite the great innovations of non-invasive coronary imaging, coronary angiography still remains the gold standard for the assessment of coronary artery disease (CAD), even if with several limitations. In fact visual assessment of coronary stenosis is convenient and rapid, but often associated with large inter and intra-observer variability, above all in the setting of unstable CAD with complex lesions. Coronary intravascular ultrasound (IVUS) allows accurate tomographic assessment of the coronary lumen and wall. IVUS has several diagnostic applications and is useful for choosing the most appropriate interventional strategy as well as for optimizing percutaneous coronary interventions (PCI) results. The present review focuses on: (1) the role of IVUS to guide therapeutic strategies in complex lesions requiring PCI, (2) IVUS capacity to interrogate borderline coronary stenoses, (3) new perspectives and recent patents for the future of IVUS technology. Keywords: Coronary artery disease, intravascular ultrasound, IVUS, percutaneous coronary intervention, virtual histology IVUS.

Mapping Intravascular Ultrasound Controversies in Interventional Cardiology Practice

Intravascular ultrasound is a catheter-based imaging modality that was developed to investigate the condition of coronary arteries and assess the vulnerability of coronary atherosclerotic plaques in particular. Since its introduction in the clinic 20 years ago, use of intravascular ultrasound innovation has been relatively limited. Intravascular ultrasound remains a niche technology; its clinical practice did not vastly expand, except in Japan, where intravascular ultrasound is an appraised tool for guiding percutaneous coronary interventions. In this qualitative research study, we follow scholarship on the sociology of innovation in exploring both the current adoption practices and perspectives on the future of intravascular ultrasound. We conducted a survey of biomedical experts with experience in the technology, the practice, and the commercialization of intravascular ultrasound. The collected information enabled us to map intravascular ultrasound controversies as well as to outline the dynamics of the international network of experts that generates intravascular ultrasound innovations and uses intravascular ultrasound technologies. While the technology is praised for its capacity to measure coronary atherosclerotic plaque morphology and is steadily used in clinical research, the lack of demonstrated benefits of intravascular ultrasound guided coronary interventions emerges as the strongest factor that prevents its expansion. Furthermore, most of the controversies identified were external to intravascular ultrasound technology itself, meaning that decision making at the industrial, financial and regulatory levels are likely to determine the future of intravascular ultrasound. In light of opinions from the responding experts', a wider adoption of intravascular ultrasound as a stand-alone imaging modality seems rather uncertain, but the appeal for this technology may be renewed by improving image quality and through combination with complementary imaging modalities.

Estudo iWONDER (Imaging WhOle vessel coroNary tree with intravascular ultrasounD and iMap® in patiEnts with acute myocaRdial infarction): racional e desenho do estudo

BACKGROUND: Intravascular ultrasound (IVUS) provides a sensitive and reproducible measurement of coronary artery dimensions, atherosclerotic plaque, and arterial lumen. Advances in IVUS technology now allow the characterization of the composition and morphology of atherosclerotic plaques. Although previous studies have reported data using IVUS radiofrequency analysis, the use of a new modality (iMap®, Boston Scientific, Santa Clara, USA) of atherosclerotic plaque characterization is very little known. Our objective is to analyze the morphological, phenotypic and tissue characteristics of culprit and non-culprit atherosclerotic plaques determined by angiography in patients undergoing coronary angiography due to acute myocardial infarction (AMI). METHODS: Prospective, cross-sectional, single center study (Hospital Sao Paulo - Escola Paulista de Medicina - Universidade Federal de Sao Paulo/UNIFESP, Sao Paulo, SP, Brazil). Fifty patients will be selected for ultrasound analysis according to the following inclusion criteria: age < 75 years, non-ST-segment elevation AMI or recent ST-segment elevation AMI, with or without previous fribrinolytic agents. CONCLUSIONS: The present study is aimed at obtaining morphological, phenotypic and tissue characteristics of the atherosclerotic plate using an imaging modality not extensively evaluated in patients with AMI.

IWONDER (Imaging WhOle vessel coronary tree with intravascular ultrasounD and iMap® in patiEnts with acute myocaRdial infarction) Study: Rationale and Study Design

ABSTRACT Background Intravascular ultrasound (IVUS) provides a sensitive and reproducible measurement of the coronary artery dimensions, atherosclerotic plaque, and arterial lumen. Advances in IVUS technology now allow for the characterisation of the composition and morphology of atherosclerotic plaques. Although previous studies have reported data using IVUS with radiofrequency analysis, little is known regarding the use of a new modality (iMap®, Boston Scientific – Santa Clara, CA, USA) of atherosclerotic plaque characterisation. This study aims to analyse the morphological, phenotypic, and tissue characteristics of ‘culprit’ and ‘non-culprit’ atherosclerotic plaques determined by angiography in patients undergoing coronary angiography due to acute myocardial infarction (AMI). Methods This will be a prospective, cross-sectional, single centre study (Hospital Sao Paulo – Escola Paulista de Medicina – Universidade Federal de Sao Paulo/UNIFESP, Sao Paulo, SP, Brazil). Fifty patients will be selected for the ultrasound analysis according to the following inclusion criteria: age Conclusions This study aims to obtain the morphological, phenotypical, and tissue characteristics of the atherosclerotic plaque using an imaging modality that has not been extensively evaluated in patients with AMI.

IVUS detects more coronary calcifications than MSCT; matter of both resolution and cross-sectional assessment?

IVUS detects more coronary calcifications than MSCT; matter of both resolution and cross-sectional assessment?

International Society for Heart and Lung Transplantation working formulation of a standardized nomenclature for cardiac allograft vasculopathy—2010

The development of cardiac allograft vasculopathy remains the Achilles heel of cardiac transplantation. Unfortunately, the definitions of cardiac allograft vasculopathy are diverse, and there are no uniform international standards for the nomenclature of this entity. This consensus document, commissioned by the International Society of Heart and Lung Transplantation Board, is based on best evidence and clinical consensus derived from critical analysis of available information pertaining to angiography, intravascular ultrasound imaging, microvascular function, cardiac allograft histology, circulating immune markers, non-invasive imaging tests, and gene-based and protein-based biomarkers. This document represents a working formulation for an international nomenclature of cardiac allograft vasculopathy, similar to the development of the system for adjudication of cardiac allograft rejection by histology.

Intravascular ultrasound: Virtual histology IVUS, integrated backscatter IVUS, and palpography

The concept of the vulnerable plaque is the focus of much research, although our knowledge of the histology, pathobiology, natural history, and therapy of vulnerable plaque remains incomplete. The evolving intravascular ultrasound technologies of virtual histology, integrated backscatter, and palpography have yielded complementary information to traditional grayscale intravascular ultrasound, and advanced our understanding of vulnerable plaque. Although each of these techniques has enjoyed success in the academic arena, none of these techniques has been sufficiently validated to the extent that would allow it to play a part in clinical decision-making. Their future role, both in regard to risk stratification and identification of vulnerable plaque, will depend upon additional rigorous studies of the natural history and treatment of vulnerable plaque.