## 4 Discussion  
This analysis explores the impact of different segmentation methods and target lesion selection on the performance of radiomic models in a cohort of DLBCL patients, whereas the clinical considerations of the obtained results are the object of another publication. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Analysis**} & \multirow{2}{*}{**Segmentation**} & \multirow{2}{*}{**Representative Lesion**} & \multirow{2}{*}{**Model**} & \multicolumn{2}{c}{**C-Index (95\% CI)**} \\ \cline{5-6}  & & & & **PFS** & **OS** \\ \hline \multirow{2}{*}{Main} & \multirow{2}{*}{Method-2} & \multirow{2}{*}{\(\text{SUV}_{\text{max}}\) lesion} & \multicolumn{2}{c}{Radiomic} & 0.81 (0.75–0.88) & 0.84 (0.76–0.91) \\ \cline{3-6}  & & & Clinical–Radiomic & 0.83 (0.76–0.90) & 0.90 (0.82–0.98) \\ \hline \multirow{2}{*}{\begin{tabular}{c} Sensitivity \\ Case 1 \\ \end{tabular} } & \multirow{2}{*}{Method-1} & \multirow{2}{*}{\(\text{SUV}_{\text{max}}\) lesion} & \multicolumn{2}{c}{Radiomic} & 0.79 (0.72–0.86) & 0.82 (0.72–0.92) \\ \cline{3-6}  & & & Clinical–Radiomic & 0.80 (0.72–0.87) & 0.87 (0.78–0.96) \\ \hline \multirow{2}{*}{\
\begin{tabular}{c} Sensitivity \\ Case 2 \\ \end{tabular} } & \multirow{2}{*}{Method-2} & \multirow{2}{*}{\(\text{VOL}_{\text{max}}\) lesion} & \multicolumn{2}{c}{Radiomic} & 0.80 (0.72–0.87) & 0.87 (0.78–0.96) \\ \cline{3-6}  & & & Clinical–Radiomic & 0.82 (0.74–0.90) & 0.85 (0.76–0.94) \\ \hline \multirow{2}{*}{
\begin{tabular}{c} Sensitivity \\ Case 3 \\ \end{tabular} } & \multirow{2}{*}{Method-1} & \multirow{2}{*}{\(\text{VOL}_{\text{max}}\) lesion} & \multicolumn{2}{c}{Radiomic} & 0.79 (0.72–0.89) & 0.84 (0.73–0.94) \\ \cline{3-6}  & & & Clinical–Radiomic & 0.81 (0.73–0.89) & 0.83 (0.73–0.94) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: C-index (95% CI) values for the radiomic and clinical–radiomic models obtained with the different methodological choices implemented in the main analysis and in the sensitivity analysis. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Variable**} & \multicolumn{4}{c}{**PFS**} & \multicolumn{4}{c}{**OS**} \\ \cline{2-9}  & \multicolumn{2}{c}{**Radiomic**} & \multicolumn{2}{c}{**Clinical–Radiomic**} & \multicolumn{2}{c}{**Radiomic**} & \multicolumn{2}{c}{**Clinical–Radiomic**} \\ \cline{2-9}  & **HR (95\% CI)** & _p_**-Value** & **HR (95\% CI)** & _p_**-Value** & **HR (95\% CI)** & _p_**-Value** & **HR (95\% CI)** & _p_**-Value** \\ \hline \multirow{2}{*}{**SUV\({}_{\text{max}}\)**} & 0.98 & \multirow{2}{*}{0.15} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & 1.00 & \multirow{2}{*}{0.92} & \multirow{2}{*}{-} & \multirow{2}{*}{-} \\  & (0.94–1.01) & & & & & (0.96–1.04) & & & \\ \hline \multirow{2}{*}{**TMTV *} & 1.07 & \multirow{2}{*}{0.02} & 0.99 & 0.66 & 1.09 & 0.98 & 0.98 & 0.98 & 0.54 \\  & (1.01–1.13) & & & & & (1.0–1.16) & & & \\ \hline \multirow{2}{*}{**Vol(SUV\({}_{\text{max}}\) lesion)***} & 1.04 & \multirow{2}{*}{0.17} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & 1.06 & \multirow{2}{*}{0.10} & \multirow{2}{*}{-} & \multirow{2}{*}{-} \\  & (0.98–1.10) & & & & & (0.99–1.10) & & & \\ \hline \multirow{2}{*}{**WTLG ***} & 1.02 & \multirow{2}{*}{0.55} & \multirow{2}{*}{-} & 1.04 & \multirow{2}{*}{-} & 1.04 & \multirow{2}{*}{0.11} & \multirow{2}{*}{-} & \multirow{2}{*}{-} \\  & (0.96–1.07) & & & & & (0.99–1.10) & & & \\ \hline \multirow{2}{*}{**IPI score**} & **Low** & 1.00 (Ref) & - & 1.00 (Ref) & - & 1.00 (Ref) & - & 1.00 (Ref) & - \\ \cline{2-9}  & \multirow{2}{*}{High} & 2.60 & \multirow{2}{*}{0.01} & 2.68 & \multirow{2}{*}{0.01} & 10.20 & \multirow{2}{*}{0.0002} & 8.12 & \multirow{2}{*}{0.001} \\  & (1.25–5.48) & & & (1.22–5.86) & & & (2.97–35.01) & & \\ \hline \multirow{2}{*}{**Radiomic Score**} & 3.56 & \multirow{2}{*}{\(<\)0.0001} & 3.65 & \multirow{2}{*}{\(<\)0.0001} & 3.83 & \multirow{2}{*}{\(<\)0.0001} & 3.08 & \multirow{2}{*}{\(<\)0.0001} \\  & (2.29–5.54) & & & (2.26–5.89) & & & & \\ \hline \hline \end{tabular}
\end{table}