# Texture Analysis is a Useful Tool to Assess the Complexity Profile of Microcirculatory Blood Flow
## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Texture Entropy**} & \multirow{2}{*}{**
\begin{tabular}{c} **Sine Wave** \\ **Signal** \\ \end{tabular}} & \multicolumn{2}{c}{**Test Foot**} & \multicolumn{2}{c}{**Control Foot**} & \multirow{2}{*}{\(p\)**-Value (T vs. C)**} \\ \cline{3-3} \cline{5-7}  & & & **Mean \(\pm\) SD** & & **\(p\)-Value** & & **Mean \(\pm\) SD** & & **\(p\)-Value** \\ \hline \multirow{3}{*}{card} & Phase I & \multirow{3}{*}{6.1} & 6.6 \(\pm\) 0.5 & - & 6.8 \(\pm\) 0.3 & - & 0.198 \\  & Phase II & & 6.2 \(\pm\) 0.7 & 0.004 \({}^{\star}\) & 6.9 \(\pm\) 0.3 & 0.011 \({}^{\star}\) & 0.001 \({}^{\star}\) \\  & Phase III & & 7.0 \(\pm\) 0.2 & 0.563 & 7.0 \(\pm\) 0.2 & 0.022 \({}^{\star}\) & 0.713 \\ \hline \multirow{3}{*}{resp} & Phase I & \multirow{3}{*}{5.4} & 6.5 \(\pm\) 0.2 & - & 6.5 \(\pm\) 0.2 & - & 0.551 \\  & Phase II & & 5.5 \(\pm\) 1.3 & 0.013 \({}^{\star}\) & 6.3 \(\pm\) 0.2 & 0.286 & 0.045 \({}^{\star}\) \\  & Phase III & & 6.5 \(\pm\) 0.2 & 0.638 & 6.4 \(\pm\) 0.2 & 0.530 & 0.478 \\ \hline \multirow{3}{*}{myo} & Phase I & \multirow{3}{*}{5.2} & 6.6 \(\pm\) 0.3 & - & 6.7 \(\pm\) 0.1 & - & 0.089 \\  & Phase II & & 6.3 \(\pm\) 0.4 & 0.008 \({}^{\star}\) & 6.6 \(\pm\) 0.1 & 0.433 & 0.028 \({}^{\star}\) \\  & Phase III & & 6.5 \(\pm\) 0.2 & 0.289 & 6.7 \(\pm\) 0.2 & 0.754 & 0.266 \\ \hline \multirow{3}{*}{sym} & Phase I & \multirow{3}{*}{5.3} & 6.2 \(\pm\) 0.3 & - & 6.2 \(\pm\) 0.4 & - & 0.671 \\  & Phase II & & 6.2 \(\pm\) 0.2 & 0.147 & 6.2 \(\pm\) 0.2 & 0.814 & 0.887 \\  & Phase III & & 6.0 \(\pm\) 0.2 & 0.594 & 6.1 \(\pm\) 0.3 & 0.239 & 0.630 \\ \hline \multirow{3}{*}{NOd} & Phase I & \multirow{3}{*}{5.3} & 5.8 \(\pm\) 0.5 & - & 5.9 \(\pm\) 0.4 & - & 0.630 \\  & Phase II & & 6.4 \(\pm\) 0.2 & 0.012 \({}^{\star}\) & 5.7 \(\pm\) 0.5 & 0.272 & 0.001 \({}^{\star}\) \\ \cline{1-1}  & Phase III & & 6.1 \(\pm\) 0.3 & 0.007 \({}^{\star}\) & 5.9 \(\pm\) 0.3 & 0.307 & 0.060 \\ \hline \multirow{3}{*}{NOi} & Phase I & \multirow{3}{*}{6.2} & 6.0 \(\pm\) 0.4 & - & 5.9 \(\pm\) 0.4 & - & 0.551 \\  & Phase II & & 6.2 \(\pm\) 0.3 & 0.010 \({}^{\star}\) & 5.5 \(\pm\) 0.7 & 0.753 & 0.001 \({}^{\star}\) \\ \cline{1-1}  & Phase III & & 6.2 \(\pm\) 0.3 & 0.594 & 5.8 \(\pm\) 0.8 & 0.126 & 0.060 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Mean and standard deviation (SD) of the texture entropy for each foot on each phase of the protocol (card—cardiac, resp—respiratory, myo—myogenic, sym—sympathetic, NOd—endothelial NO-dependent, NOi—endothelial NO-independent). Statistical comparison to Phase I and between the test and control limbs are shown (\({}^{\star}\)—\(p\) \(<\) 0.05). respiratory, and myogenic components, an increase in both endothelial components and no change in the sympathetic. Regarding the control foot, an overall entropy decrease was observed with both tools. MSE recorded a decrease in the complexity of all components, although not so pronounced as in the test foot, which again is likely attributable to the magnitude of the perfusion decrease. Again, TE showed more subtle changes, only significant for the respiratory and NOi components. Overall, MSE and TE showed similar responses in the high frequency components (cardiac, respiratory, myogenic), and dissimilar responses in the low frequency components (sympathetic, NOd, NOi), suggesting that TE loses analytical sensitivity in the latter regions. This loss of sensitivity may be attributed to an incomplete visual resolution of the scalogram bands of the low frequency components, leading to a less precise identification of the respective ROIs. Nevertheless, TE was able to differentiate the entropies of most components during VAR between the test and control limbs. Overall, although both TE and MSE were able to detect differences in entropy, MSE was consistently more sensitive. One should keep in mind that MSE and TE ensure different scale evaluations--frequency for TE and time for MSE, which are two aspects of the same reality (i.e., perfusion signal).