Background: Grayscale intravascular ultrasound (IVUS) was developed to assess atherosclerotic plaque and improve on the shortcomings of angiography. However, neither IVUS nor angiography can detect plaques that are at high risk of causing myocardial infarction or stroke (vulnerable plaques). Grayscale IVUS uses the amplitude of the reflected ultrasound signal to generate an image, whereas virtual histology (VH)-IVUS uses the amplitude, power and frequency to characterizes plaque as fibrotic, fibrofatty, dense calcium, or necrotic core with a predictive accuracy of 87 - 97%.
Objective: This manuscript will review the current data on the use of VH-IVUS in evaluation of coronary atherosclerotic lesions and offer opinions on its future role in cardiovascular imaging.
Methods: Peer-reviewed articles and recent abstracts presented at national and international meetings focused on VH-IVUS development and clinical use were surveyed.
Conclusion: Published data have shown that VH-IVUS provides a reliable representation of plaque composition and morphometry. Thin-capped fibroatheromas can be identified using VH-IVUS and most often occur at known sites of acute vessel occlusion and plaque rupture and are associated with positive remodeling. Necrotic core seen on VH, most probably the most active component of plaque, usually does not coincide with the site of maximum lumen compromise. Necrotic core size may also help determine lesions most at risk for distal embolization during percutaneous coronary intervention. Ongoing large-scale clinical trials will help in the understanding of the temporal changes of coronary plaques and how VH-IVUS can be used as a decision-making tool in an individual patient.