Intravascular ultrasound-based imaging of vasa vasorum for the detection of vulnerable atherosclerotic plaque.

Vulnerable plaques are dangerous atherosclerotic lesions that bear a high risk of complications that can lead to heart attacks and strokes. These plaques are known to be chronically inflamed. The vasa vasorum (VV) are microvessels that nourish vessel walls. Proliferation of VV is part of the "response to injury" phenomenon in the process of plaque formation. Recent evidence has shown strong correlations between neovessel formation and macrophage infiltration in atherosclerotic plaque, suggesting VV density as a surrogate marker of plaque inflammation and vulnerability. We have developed a novel method for imaging and analyzing the density and perfusion of VV in human coronary atherosclerotic plaques using intravascular ultrasound (IVUS). Images are taken during the injection of a microbubble contrast agent and the spatiotemporal changes of the IVUS signal are monitored using enhancement-detection techniques. We present analyses of in vivo human coronary cases that, for the first time, demonstrate the feasibility of IVUS imaging of VV.