Imaging of the Vulnerable Plaque: New Modalities

Abstract

Atherosclerosis is currently considered to be an inflammatory and thus a systemic disease affecting multiple arterial beds. Recent advances in intravascular imaging have shown multiple sites of atherosclerotic changes in coronary arterial wall. Traditionally, angiography has been used to detect and characterize atherosclerotic plaque in coronary arteries, but recently it has been found that plaques that are not significantly stenotic on angiography cause acute myocardial infarction. As a result, newer imaging and diagnostic modalities are required to predict which of the atherosclerotic plaque are prone to rupture and hence distinguish "stable" and "vulnerable" plaques. Intravascular ultrasound can identify multiple plaques that are not seen on coronary angiography. Thermography has shown much promise and is based on the concept that the inflammatory plaques are associated with increased temperature and can also identify "vulnerable patients." Of all these newer modalities, magnetic resonance imaging has shown the most promise in identification and characterization of vulnerable plaques. In this article, we review the newer coronary artery imaging modalities and discuss the limitations of traditional coronary angiography.

Intracranial Atherosclerotic Plaque Enhancement in Patients with Ischemic Stroke

“…2 In addition to serum markers, the use of noninvasive imaging modalities including CT, MR imaging, and nuclear medicine for the characterization of plaque inflammation has been gaining interest over the past several years. 3,[10][11][12][13][14][15][16][17] Investigations with FDG-PET imaging have shown that it may be used as a surrogate marker for inflammation of plaques, as patients with the highest levels of FDG uptake had the greatest concentrations of inflammatory biomarkers. 10,11 MR imaging characterization of extracranial atherosclerotic plaque has been well studied and well established.…”

Localization to atherosclerotic plaque and biodistribution of biochemically derivatized superparamagnetic iron oxide nanoparticles (SPIONs) contrast particles for magnetic resonance imaging (MRI)

“…Coupled with the insidious nature of developing atherosclerosis, the excellent outcomes of pre-event therapy (Kolodgie et al 2003a,b;Bhatia et al 2003;Strauss et al 2004) suggest that non-invasive detection of patients at high risk for imminent cardiovascular events would be beneficial. Identification of patients at risk for imminent vascular events requires screening of largely disease-free or asymptomatic populations, so low morbidity imaging methods, like CT (computerized tomography) or MRI (magnetic resonance imaging), would seem ideal (Kolodgie et al 2003b).…”

“…Differentiating features of vulnerable plaque include plaque morphology and structure (thin fibrous caps over large lipid-containing cores, sometimes plaques with non-occlusive morphology), as well as cellular and biochemical composition (heavy infiltration of macrophages that are often apoptotic, high concentrations of molecules associated tissue remodeling and inflammation, plaques with large necrotic cores etc. (Cui et al 2005;Bhatia et al 2003;Hegyi et al 2001;Libby et al 1995)). In principal, location of plaque in vasculature, the gross morphology of plaque and the chemical composition of plaque might be addressed minimally invasively by MR imaging, providing there are available contrast agents that can access and specifically direct contrast to plaque biochemical constituents indicative of vulnerability.…”

“…Parameters will include location of atherosclerotic lesions in the vascular tree, reading on the likely consequences of thrombotic occlusion at those sites. Furthermore, atherosclerotic lesions are differentiated by the stage of disease they represent (Kolodgie et al 2003b;Bhatia et al 2003;Strauss et al 2004), with so-called vulnerable plaque presenting the highest risk for catastrophic thrombosis. Differentiating features of vulnerable plaque include plaque morphology and structure (thin fibrous caps over large lipid-containing cores, sometimes plaques with non-occlusive morphology), as well as cellular and biochemical composition (heavy infiltration of macrophages that are often apoptotic, high concentrations of molecules associated tissue remodeling and inflammation, plaques with large necrotic cores etc.…”

Advances in Atheroma Imaging in the Carotid

“…There have been encouraging data from small studies looking at the effects of statins using MRI characteristics of plaque and residual lumen, in animals [64] and in humans, both retrospectively [65] and prospectively [66, 67]. Alternative strategies for assessing changes in plaque burden or activity include PET [42], USPIO-enhanced MRI [48], novel ultrasound agents [68], molecular imaging of apoptosis [69], infrared imaging [70] and multi-slice computer tomography [71]. …”