# Micro-Computed Tomography Soft Tissue Biological Specimens Image Data Visualization
## 3 Results  
A total of 53 transfer functions (LUTs) were designed, 42 of which were validated and optimized to emphasize the soft tissues of selected biological samples from \(\upmu\)CT (mouse, rat, rabbit) using selected contrast agents (Aurovist, Omnipaque, KI in the ethanol solution, Mercox). The remaining 11 transfer functions could not be verified due to the absence of contrast in soft tissue samples from chickens. In total, 18 images and transfer functions are included within this text. Out of the 53 transfer functions, one transfer function was able to be suggested that would likely highlight the tongue of a 19-day-old chick scanned with the Bruker SkyScan 1275 [19] at an anode voltage of 40 kV. A total of 24 mice samples were statistically processed via correlation. Normality test was performed for all these samples in Matlab (Campus Wide Matlab, R2021a, The MathWorks, Inc., Natick, MA, USA) via Lilliefors test. These values were obtained for liver and kidneys of 24 mice in solutions of ethanol as a centroid value of the opacity LUT area under this graph (see example on Figure 10). Except for one dataset, all the others do not have a normal distribution according to this test. Results are available within Tables 1-4 below. From this follows that there is required to use Spearman's correlation coefficient. In Figure 10, we can see example of the opacity LUT with marked points, i.e., [X1,Y1], [X2,Y2], and [X3,Y3] whereby coordinate Y1 = 0 and Y3 = 0. These points form a homogeneous triangle that enables simplified computation of the centroid. Figure 9: Transfer functions design—**(a)** mouse (Aurovist, 42 kV), (**b**) histogram, and (**c**) transfer functions (opacity, RGB). \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Solution and Soft Tissue**} & **Value** & **Value** & **Value** & **Value** & **Value** \\  & **X1 1** & **X2 2** & **Y2 3** & **X3 4** & **X’ 5** & **c 6** & **d 7** \\  & **[-]** & **[-]** & **[-]** & **[-]** & **[-]** & **[-]** \\ \hline Ethanol, liver & 0.2461 & 0.4303 & 0.1898 & 0.4320 & 0.3695 & 50 & 8 \\ Ethanol, liver & 0.1200 & 0.1994 & 0.1551 & 0.2004 & 0.1733 & 50 & 17 \\ Ethanol, liver & 0.1476 & 0.223 & 0.1343 & 0.2241 & 0.1982 & 50 & 17 \\ Ethanol, liver & 0.1329 & 0.1827 & 0.1828 & 0.1838 & 0.1665 & 50 & 17 \\ Ethanol, liver & 0.2410 & 0.3718 & 0.2465 & 0.3735 & 0.3288 & 100 & 8 \\ Ethanol, liver & 0.1610 & 0.2374 & 0.1801 & 0.2385 & 0.2123 & 100 & 16 \\ Ethanol, liver & 0.2771 & 0.4010 & 0.4626 & 0.4028 & 0.3603 & 100 & 8 \\ Ethanol, liver & 0.1103 & 0.1467 & 0.2147 & 0.1906 & 0.1492 & 100 & 16 \\ Ethanol, liver & 0.2031 & 0.2048 & 0.3019 & 0.2995 & 0.2358 & 100 & 8 \\ Ethanol, liver & 0.1153 & 0.1687 & 0.2756 & 0.1704 & 0.1515 & 100 & 16 \\ Ethanol, liver & 0.0978 & 0.0989 & 0.1842 & 0.1378 & 0.1115 & 100 & 37 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Ethanol liver raw data for centroid and Spearman ’s correlation coefficient computation. Figure 10: Example of the opacity (pink color) LUT with marked points that are used for computation of the centroid. Such figure exists for every included image (mouse_1_liver_ethanol_100_%_day_16). The hypotheses mentioned within the Introduction were evaluated based on these data. This was a test of the alternative hypothesis that the Spearman correlation coefficient is not equal to 0. We used a relationship (see link within the [21]) where, given H0: r = 0, the t Student's statistic has a distribution with d.f. (degree of freedom): N--2 (see also link within the [22]). Ethanol liver: D.f. : 11, \(p\)-value: 0.3774 (for ethanol concentration) and D.f. : 11, \(p\)-value: 0.0001 (for days stored of the sample in ethanol solution). Ethanol kidneys: D.f. : 9, \(p\)-value: 0.8504 (for ethanol concentration) and D.f. : 9, \(p\)-value: 0.00001 (for days stored of the sample in ethanol solution). Overall, 18 LUTs from 53 LUTs were also validated on selected biological samples, selection of which is illustrated within this section and reported in Figures 9 and 11-13.