Characterisation of plaque components with IVUS elastography

The availability to characterise different plaque components could be used to guide intravascular interventional procedures. Additionally, the vulnerability of a plaque to rupture is related to the different plaque components. In this study, the potential of intravascular ultrasound elastography to characterise different components is investigated. Intravascular ultrasound (30 MHz) echograms and elastograms of excised human femoral arteries (n=10) were determined. Elastograms were determined using crosscorrelation from IVUS frames acquired at 80 and 100 mmHg. Next, the specimens were processed for histology and stained for collagen and smooth muscle cells to characterise fibrous and fatty plaque components. Additionally, each section was stained for the presence of macrophages. The cross-sections were segmented in regions based on the strain values. Observers, blinded to the elastographic results determined the dominant tissue type. Significant different (Kruskall-Wallis, p<0.001) strain values were found in fibrous, fibro-fatty and fatty plaque components (0.27%, 0.44% and 0.66%). No difference in echogenicity was found in these plaque components (Kruskall-Wallis, p=0.996). Furthermore, high strain values were found in regions with an increased macrophage activity. These in vitro experiments on human femoral arteries indicate the potentials of intravascular elastography to characterise fibrous, fibro-fatty and fatty plaque components