Magnetic Resonance Imaging-Detected Carotid Intraplaque Hemorrhage and the Ability To Identify a High Cardiovascular Risk Phenotype

Magnetic resonance images of the carotid arteries showing intraplaque hemorrhage (bright regions)

Our understanding of the biology of vascular disease is quickly moving away from a simplistic model based on luminal stenosis. We have learned that vessels are not simple conduits. They are complex dynamic organs that have downstream effects on end-organ pathobiology. A commonly used model for the study of disease has been based on endarterectomy specimens. This approach has significantly added to our knowledge of atherosclerosis. However, histological specimens can only give a snapshot at one moment in time. Usually, a patient undergoes a surgical procedure once the extent of disease is severe; therefore, only one part of the spectrum of disease is available for analysis.

Identifying patients most at risk for atherosclerosis-related cardiovascular events (e.g., heart attacks, strokes, related death) is a challenge in research and clinical practice. Intraplaque hemorrhage (IPH), a component of unstable atherosclerotic plaque, is emerging as a marker that can identify such high-risk cardiovascular patients.

Magnetic resonance imaging can image the vessel wall with high resolution. It can also extract multiple tissue characteristics. One characteristic that is of great interest and is easily detectable by MRI is IPH. Early studies, including ours (Radiology. 2009 Aug;252(2):502–8) promisingly suggest the ability of MRI-detected IPH to identify patients at risk of heart attacks and strokes. Magnetic resonance imaging is able to reliably, rapidly and noninvasively detect IPH in routine clinical practice.

We continue to investigate MRI-detected IPH in retrospective and prospective trials to establish whether the marker improves patient outcomes.