Figure 1

Examples of interrogated ROIs and corresponding waveforms, illustrating the different steps of the methodology. A – Plaque and wall ROIs in frame 1. Vertical yellow dotted lines indicate the boundaries of the investigated area. The top and bottom edges of the vertical yellow solid line correspond to the ROI pair for which waveforms are illustrated. B – Plaque and wall ROI pixel positions at three different frames representing different phases of the cardiac cycle, and corresponding time points, obtained after motion analysis. Pixel positions at diastole are superimposed on intermediate and systolic frames as dashed lines. C – Radial displacements of selected pixels of PTS, PBS and their difference (left column), and radial displacements of selected pixels of AWL, PWL and their difference, which represents the arterial wall diameter (right column). D – Displacement pairs for estimation of cross-correlation (top row), the corresponding cross-correlation waveforms (middle row) and the selected cross-correlation segment for calculation of features (bottom row). RDis: radial displacement, PRDef: plaque radial deformation, WD: wall diameter, LDis: longitudinal displacement.