Intravascular ultrasound: principles and cerebrovascular applications

Abstract

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.

Fig 1.

Intravascular sonography catheters, components, and signal-intensity characteristics. A, Eagle Eye Gold imaging catheter (20 MHz, Volcano Corporation). B and C, Atlantis SR Pro imaging catheter (40 MHz, Boston Scientific).

Fig 2.

A, Conventional intravascular sonography image demonstrates severe stenosis with plaque outside the struts of the carotid stent (arrows). No plaque inside the stent is identified. B, There is improvement in vessel lumen diameter after poststent angioplasty.

Fig 3.

Virtual histology intravascular sonography mapping of carotid atherosclerotic plaque. The image demonstrates various components as follows: dark green, fibrous material; yellow/green, fibrofatty component; white, calcification; and red, necrotic lipid core.

Fig 4.

Angiographic images demonstrate a retraction of the intravascular sonographic probe (arrows) by using a motorized device (not shown) after carotid stent placement to visualize any residual stenosis and apposition of the stent to the surrounding vessel wall.