## 3 Results
Intra- and interobserver analysis of the morphologic parameters demonstrated a very good reproducibility in the validation cohort for volume and centerline length (LoA \(\leq\)15.7 mL and \(\leq\)12.2 mm, respectively; COV = 8-22%, r = 0.89-0.98, ICC = 0.90-0.98), and an excellent reproducibility for diameter (LoA \(\leq\)5.0 mm, COV = 3-7%, r = 0.98-0.99, ICC = 0.96-0.99) and a good reproducibility for curvature radius (LoA \(\leq\)46.4 mm, COV = 21-35%, r = 0.72-0.87, ICC = 0.90-0.92). See Supplementary Materials Figures S1-S13 for the corresponding Bland-Altman plots. These plots demonstrated no dependency of the measured differences relative to the mean for most analyses and morphologic parameters, except for the maximal diameter, which had a slightly increasing difference relative to the mean for the interobserver analyses. The intra- and interobserver reproducibility results per anatomical segment are presented in Supplementary Materials Tables S3 and S4, respectively. The intra- and interobserver analysis showed for the validation cohort a similar reproducibility for most morphologic and hemodynamic parameters per segment. However, the reproducibility was slightly decreased within the aortic root for several parameters (i.e., flow displacement, WSS\({}_{\rm mag}\), WSS\({}_{\rm ax}\), absolute helicity, volumes with increased absolute LNH, aortic segment volume, centerline length, and curvature radius). Furthermore, the reproducibility of the maximal diameter was slightly decreased within the proximal part of the aorta (i.e., the aortic root, proximal and distal ascending aorta) compared to the other anatomical segments further distally to the ascending aorta (intraobserver LoA \(\leq\)2.7 and \(\leq\)1.8 mm; interobserver LoA \(\leq\)7.6 and \(\leq\)3.3 mm, respectively). Moreover, the reproducibility of WSS\({}_{\rm angle}\) was slightly decreased within the proximal and distal descending aorta. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Study**} & \multicolumn{2}{c}{**Bland–Altman**} & \multirow{2}{*}{**COV (\%)**} & \multirow{2}{*}{**Spearman RankCorrelation**} & \multirow{2}{*}{**Intraclass Correlation**} & \multirow{2}{*}{**LoA\({}_{\rm diff}\) (\%)**} \\ \cline{2-2} \cline{6-7}  & & & & & **Coefficient** & & **Coefficient** \\ \hline \multicolumn{7}{c}{**Curvature Radius (mm)**} \\ \hline IA-O & 2.3 & 37.2 & 29 & 0.87 & 0.92 & 30 \\ \hline IE-O1 & \(-\)2.7 & 46.4 & 35 & 0.77 & 0.90 & 14 \\ \hline IE-O2 & 3.6 & 42.4 & 34 & 0.77 & 0.90 & \(-\)72 \\ \hline IE-O3 & 6.3 & 43.5 & 34 & 0.72 & 0.92 & \(-\)70 \\ \hline \multicolumn{7}{c}{**Curracities are presented per cohort over all subjects, anatomical segments, and systolic phases (\(n=300\)). All probability values \(<\)0.01. Abbreviations: Mean Diff—mean difference; LoA—limits of agreement (1.96\(\times\) standard deviation); COV—coefficient of variation; IA-O—intracobserver analysis by the first observer with 4 years’ experience; IE-O1—intracobserver analysis by the first and second observer with 4 and 3 years’ experience, respectively; IE-O2—intracobserver analysis by the first and third observer with 4 and 1 years’ experience, respectively; IE-O3—intracobserver analysis by the second and third observer with 3 and 1 years’ experience, respectively; WSS—wall shear stress; and LoA\({}_{\rm diff}\) –relative difference in limits of agreement between the training and validation cohort.