# DTI Histogram and Texture Features as Early Predictors of Post-Radiotherapy Cognitive Decline
## 3 Results
### Correlation Between Changes in DTI Features and Cognitive Performance 4 Months Post-Radiation  
Multiple linear regression analysis (Table 4) revealed that \(\Delta\)ADmean was significantly associated with list learning performance (\(\beta\) = \(-\)2.404 \(\times\) 10\({}^{4}\), r = \(-\)0.330, \(p\) = 0.027). This negative association is illustrated in Figure 2A, which shows that a greater increase in \(\Delta\)ADmean corresponds to poorer list learning scores. There was a trend toward significance for \(\Delta\)ADskewness (\(\beta\) = 3.188, r = 0.154, \(p\) = 0.072), whereas \(\Delta\)RD kurtosis showed no significant association (\(p\) = 0.683). The overall model explained approximately 31% of the variance in list learning scores (R\({}^{2}\) = 0.308, adjusted R\({}^{2}\) = 0.169, F(3,15) = 2.223, \(p\) = 0.128). \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Outcome Variable** & **Predictor** & **Estimate (\(p\))** & **Standard Error** & **t Value** & **r Value** & **p Value** & **R\({}^{2}\)** & **Adjusted** & **R\({}^{2}\)** & **FQ,153** & **\(p\) Value** & **R\({}^{2}\)** \\ \hline \multirow{2}{*}{List learning *} & \(\Delta\)ADmean & \(-\)2.404 \(\times\) 10\({}^{4}\) & 9.819 \(\times\) 10\({}^{4}\) & \(-\)2.448 & \(-\)0.330 & 0.027 & & & & & \\  & \(\Delta\)ADmean & 3.188 & 1.645 & 1.938 & 0.154 & 0.072 & 0.308 & 0.169 & 2.223 & 0.128 & 2.864 \\  & \(\Delta\)ADmean & \(-\)0.289 & 0.694 & \(-\)0.416 & 0.147 & 0.683 & & & & & \\ \hline \multirow{2}{*}{Semantic fluency *} & \(\Delta\)ADmean & \(-\)3.303 \(\times\) 10\({}^{4}\) & 0.869 \(\times\) 10\({}^{4}\) & \(-\)3.803 & \(-\)0.413 & 0.002 & & & & & \\  & \(\Delta\)ADmean & 4.642 & 1.455 & 3.191 & 0.073 & 0.006 & 0.521 & 0.425 & 5.428 & 0.010 & 2.533 \\  & \(\Delta\)ADmean & \(-\)1.505 & 0.614 & \(-\)2.453 & \(-\)0.172 & 0.027 & & & & & \\ \hline \multirow{2}{*}{MMSE} & \(\Delta\)ADmean & \(-\)1.536 \(\times\) 10\({}^{4}\) & 0.683 \(\times\) 10\({}^{4}\) & \(-\)2.251 & \(-\)0.402 & 0.040 & & & & & \\  & \(\Delta\)ADmean & 1.553 & 1.143 & 1.358 & \(-\)0.042 & 0.194 & 0.254 & 0.105 & 1.703 & 0.209 & 1.991 \\ \cline{1-1}  & \(\Delta\)ADmean & \(-\)0.384 & 0.482 & \(-\)0.797 & \(-\)0.033 & 0.438 & & & & & \\ \hline \hline \end{tabular} Abbreviations: DTI, diffusion tensor imaging; ADmean, change in mean of axial diffusivity; ADmean, change in skewness; or axial diffusivity; ARD kurtosis; change in kurtosis of radial diffusivity; RSE, residual standard error.  
\({}^{a}\): \(p\) value for individual predictor variables (\(t\)-test). \({}^{b}\): \(p\) value for overall model significance (F-test). \({}^{a}\): age-adjusted.  
\end{table} 
Table 4: Multiple linear regression analysis of \(\Delta\) DTI features predicting cognitive outcome. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Neurocognitive Function Test** & **Mean \(\pm\) Standard Deviation** \\ \hline RBANS * & List learning & 9 \(\pm\) 3.1 \\  & List recall & 7 \(\pm\) 3.3 \\  & List recognition & 9 \(\pm\) 2.6 \\  & Semantic fluency & 9 \(\pm\) 2.2 \\ Z-score TMT & Part A & \(-\)0.33 \(\pm\) 1.58 \\  & Part B & \(-\)0.70 \(\pm\) 1.19 \\ MMSE & & 27 \(\pm\) 2.0 \\ \hline \hline \end{tabular} Abbreviations: RBANS, Repeatable Battery for the Assessment of Neuropsychological Status; TMT, Trail Making Test; MMSE, Mini-Mental State Examination. *, age-adjusted.  
\end{table} 
Table 2: 4-month neurocognitive status of the patients. As shown in Table 4, all three \(\Delta\) DTI features significantly predicted semantic fluency performance. \(\Delta\)AD\({}_{\text{mean}}\) demonstrated the strongest effect (\(\beta=-3.303\times 10^{4}\), r = \(-0.413\), \(p\) = 0.002), whereas \(\Delta\)AD\({}_{\text{skewness}}\) (\(\beta=4.642\), r = 0.073, \(p\) = 0.006) and \(\Delta\)RD\({}_{\text{kurtosis}}\) (\(\beta=-1.505\), r = \(-0.172\), \(p\) = 0.027) showed more minor but significant associations with semantic fluency scores.