## 3 Results
\begin{table}
\begin{tabular}{l l l l l l l l} \hline \hline  & \multicolumn{3}{c}{**Strain (\%) at Max. Systolic Pressure \(t=0.30\) s**} & \multicolumn{3}{c}{**Residual Strain (\%) \(t=0.96\) s**} \\ \hline  & **Probe** & **Reference** & **Compounding** & **Zero-Degree** & **Reference** & **Compounding** & **Zero-Degree** \\ \hline \multirow{2}{*}{Vertical} & A & \(-\)42.9-7 & \(-\)43.9-8 & \(-\)4.9-7.7 & \(-\)1.1-2.3 & \(-\)1.1-2.3 & \(-\)1.2-2.3 \\  & B & \(\mathbf{-5.3}\)**-11.8** & \(\mathbf{-7.6}\)**-14.6** & \(\mathbf{-16.0}\)**-23.0** & \(\mathbf{-0.7}\)**-3.2** & \(\mathbf{-2.2}\)**-5.1** & \(\mathbf{-10.5}\)**-9.1** \\ \hline \multirow{2}{*}{Horizontal} & A & \(-\)**39.7-5** & \(-\)**7.0-13.0** & \(-\)**19.7-23.6** & \(\mathbf{-0.5}\)**-2.8** & \(\mathbf{-3.1}\)**-3.5** & \(\mathbf{-13.1}\)**-0.4** \\  & B & \(-\)32.6-8 & \(-\)32.6-7 & \(-\)32.6-7 & \(-\)0.6-1.8 & \(-\)0.6-1.9 & \(-\)0.6-1.8 \\ \hline \multirow{2}{*}{Longitudinal} & A & \(-\)38.4-7 & \(-\)43.5-0 & \(-\)39.4-7 & \(-\)5.6-10.7 & \(-\)6.0-11.0 & \(-\)5.6-10.7 \\  & B & \(-\)34.5-5 & \(-\)29.6-0 & \(-\)34.5-5 & \(-\)6.1-9.9 & \(-\)5.2-9.8 & \(-\)6.1-9.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Vertical, horizontal, and longitudinal 5 th–95 th percentile strain values for both probes and all methods. Figure 9: The vertical, horizontal, and longitudinal strain range (median and 5 th–95 th percentile) for the complete cardiac cycle for the reference, compounding, and zero-degree method for probe A and B. For the vertical strain of probe B and horizontal strain of probe A (i.e., lateral direction for each probe, percentile strain values are formatted in bold in Table 3), an increased strain range was found for the compounding technique. However, this range was much more increased for the zero-degree technique. Both strain graphs (Figure 9) show a divergence at \(t>0.8\) s of the strain range. This divergence is observed also for the longitudinal strain range for the complete pressure cycle leading to almost equal residual strain ranges in between \(\sim\)\(-6\%\) and \(\sim\)\(11\%\) for all methods and both probes. Eigenvector decomposition of a 3 \(\times\) 3 strain tensor provides 3 independent eigenvalues and eigenvectors that are perpendicular to each other. Figure 10 shows the minimum (bottom row) and maximum (top row) principal components, representing the most dominant compressive and tensile deformations as estimated by probe A at peak systolic pressure. For a dynamic development of these components for the complete cardiac cycle, please see video S2 (3D_Principal_MinMax_Strains.mp4). For visualization purposes, principal strains (color) and the corresponding eigenvectors (white arrows) are plotted for three distinct longitudinal positions. The top slice is situated in the common carotid artery. The middle slice is at the bifurcation, and the bottom slice shows the internal and external carotid arteries. In general, the tensile strain distribution is clearly oriented in the circumferential direction of the vessel wall with exception of a region in the bifurcation slice and one in the internal carotid artery slice, in which the orientation of the eigenvectors indicates a strong longitudinal preference. Figure 10: Maximum (tensile) and minimum (compressive) principal strain distributions for probe A for the reference, compounding, and zero-degree method in the bifurcation carotid artery region. Principal strains are visualized at the level of the COmmon carotid artery (CO), bifurcation, and distal from the bifurcation, in which the Internal Carotid Artery (ICA) and the External Carotid Artery (ECA) are present. Please note that the lengths of the eigenvectors were scaled to their corresponding eigenvalue. The compressive strain distribution is mostly oriented in the radial direction and is less dominant than the tensile strain distribution. High tensile strains are observed consistently for all methods at the flow divider of the bifurcation and at ten and two o'clock of the common carotid artery.