Vascular tissue characterisation with IVUS elastography

Knowledge about the mechanical properties of the vessel wall and plaque is important for guiding intravascular interventional procedures and detection of plaque vulnerability. Rupture of atherosclerotic plaques is associated with acute myocardial infarction and unstable angina pectoris. In a plaque with a lipid core, the stress due to the arterial pulsation will be concent rated in the cap and a thin cap may be unable to bear this stress. In this study, the potential of intravascular elastography to characterise fibrous, fibro-fatty and fatty tissue based on their mechanical properties was inve stigated. Using a custom-made set-up, intravascular echograms and elastograms of exci sed human femoral arteries were determined. High frequency r.f. data (30 MH z) were acquired using an intravascular catheter. The tissue was compressed using intravascular pressures of 80 and 100 mmHg. The cross-sections of in terest were marked with a needle for matching with histology. Using cross-c orrelation estimation of gated echosignals, elastograms (images of the loca l strain) were determined. After the intravascular experiments, the specimens were fixed in formaldehy de and processed for paraffin embedding. Sections were stained with picrosi rius red and alpha-actin to counterstain collagen and smooth muscle cells ( SMC), respectively. Results of vessel cross-sections with fibrous and fatty prague regions will be presented. The elastograms of these specimens show that the strain in f atty tissue is higher than the strain in fibrous material. In conclusion, these in vitro experiments on human femoral arteries indicat e the potential of intravascular elastography to characterise different pla que components. (C) 2000 Elsevier Science B.V. All rights reserved.