Intravascular Ultrasound: Principles and Cerebrovascular Applications

Abstract

SUMMARY: Intravascular sonography is a valuable tool for the morphologic assessment of coronary atherosclerosis and the effect of pharmacologic and nonpharmacologic interventions on the progression or stabilization of atherosclerosis. An analysis of the different modes, applications, and limitations is provided on the basis of review of existing data from multiple clinical case studies, trials, and mechanistic studies. Intravascular sonography has been used to assess the outcomes of different percutaneous interventions, including angioplasty and stent implantation, and to provide detailed characterization of atherosclerotic lesions, aneurysms, and dissections within the cerebrovascular circulation. Evolution of intravascular sonographic technology has led to the development of more sophisticated diagnostic tools such as color-flow, virtual histology, and integrated backscatter intravascular sonography. The technologic advancement in intravascular sonography has the potential of providing more accurate information prior, during, and after a medical or endovascular intervention. Continued assessment of this diagnostic technique in both the intracranial and extracranial circulation will lead to increased use in clinical practice with the intent to improve outcomes.ABBREVIATIONS: CI ϭ confidence interval; EEL ϭ external elastic lamina; O.D. ϭ outer diameter C urrently there are 3 types of sonography used to assess the extracranial and the intracranial circulation: 1) transcranial Doppler, 2) B-mode sonography, and 3) intravascular sonography (Table). The morphologic appearance of the intra-arterial and intravenous circulation can now be visualized by using intravascular sonography, which has become a commonly used diagnostic technique for randomized clinical trials assessing coronary plaque progression and regression. With excellent resolution, intravascular sonography provides cross-sectional images of both the arterial wall and lumen and identifies intimal flaps and irregularities, and the composition and extent of the atherosclerotic plaque.2-6 Evolution of the intravascular sonography technology has led to the development of more sophisticated diagnostic tools such as colorflow, virtual histology, and integrated backscatter intravascular sonography. 7 The successful application of conventional (gray-scale) intravascular sonography in the coronary arteries has led to its application within the extracranial and intracranial arteries. Recently, intravascular sonography has also been used to identify and characterize carotid artery aneurysm, dissection, and thrombus. 8 Intravascular sonography has been used successfully to assist in making measurements before and after percutaneous transluminal balloon angioplasty and stent placement, with emphasis on the identification of stent underexpansion, poor apposition, subacute stent thrombosis, and plaque protrusion.9,10 Real-time dynamic intravascular sonography of the cervical common carotid artery and internal carotid artery can detect defects that are not readily appar...

Intracranial-Derived Atherosclerosis Assessment: An In Vitro Comparison between Virtual Histology by Intravascular Ultrasonography, 7T MRI, and Histopathologic Findings

“…3 Intravascular ultrasonography (IVUS) and high-resolution MR imaging are gaining prominence in the imaging of characteristics of atherosclerotic plaques. [4][5][6] Despite numerous studies regarding the use of these modalities in coronary and carotid arteries, such data are lacking in intracranial arteries and atherosclerotic plaques. Intra-cranial arteries have unique features including a smaller wall-tolumen ratio, thinner wall thickness, and thinner intima compared with coronary and carotid arteries.…”

Intracranial Aneurysms and Vascular Malformations: Diagnosis for Therapy

“…For the judgement of what to do with a incidentally found aneurysm we will need more information about the wall, flow, local coagulation situation, intima etc., so probably the intravascular view with ultrasound in addition to CT and MR could be another help to make a decision to treat or to control an intracranial aneurysm found incidentally and trying to answer the questions like, probability of rupturing "or rupturing not at all" 11,25 . For the patients is the utmost important question to answer: should we treat the patient (patient with multiple aneuryms?)…”

A Review on Carotid Ultrasound Atherosclerotic Tissue Characterization and Stroke Risk Stratification in Machine Learning Framework

“…Table 1 explains the plaque morphology and corresponding IVUS gray level features. The information regarding plaque morphology is directly obtainable from the IVUS images [55].…”