# Morphological Foot Model for Temperature Pattern Analysis Proposed for Diabetic Foot Disorders
## 3 Results and Discussion
### Statistical Analysis  
Once the female and male models were established for each foot, the IR images were transformed following the workflow described in Figure 2. Figure 6a,c display the registered IR images for all the corresponding female and male subjects, for each foot, respectively. As can be seen, all feet are in the same coordinate system, although some mismatches can be observed near the toes as well as on the arch area. The variability observed may be due to small mismatches associated with the spatial registration as well as to the inherent heterogeneity of the group of subjects, since people vary in shape, gender, age, etc. Subsequently, for further processing, the IR images corresponding to the right foot were flipped and registered to the left foot model. Figure 6b,d show all the overlapped images for the female and male subjects, respectively. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Figure 5** & **DICE** & **IoU** & **Specificity** & **Sensitivity** & **False Positives** & **False Negatives** \\ \hline (b) & 96.83 & 93.86 & 99.66 & 98.40 & 3.53 & 2.80 \\ (e) & 93.23 & 87.32 & 99.23 & 96.56 & 9.61 & 3.74 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Overlap measures between the model, associated with the left and right feet, for a male subject presenting deformation in both feet. Average values are expressed as percentages. Figure 5: Male subject with variable degree of deformation in both feet. The upper row illustrates the workflow described in Figure 2 for the left foot whereas the lower one corresponds to the right foot. The first column, (**a,d**), displays the original IR images and the corresponding segmentation (pink mask). The second column, (**b,e**), shows the segmentation registered to and overlapped with the left and right models, respectively. The third column, (**c,f**), illustrates the final result in which the segmentation is applied to the original IR image for further processing. A pixel-wise comparison was carried out to identify the foot areas more prone to variability within a group of healthy subjects. Since the feet of all the subjects were in the same spatial coordinates, all the left feet were compared to all the right feet, at each time point, using [PERSON]'s matched-pairs test. A correction for multiple comparisons was conducted using the false discovery rate. It must be noted that an analogous analysis was performed for each gender. Figure 7 shows the pixels in which changes are statistically significant (\(p<0.05\)) at each time point and for each gender. As can be observed, for the female subjects the largest pixels' variability is found at the boundaries. This may be caused by small mismatches in the several spatial registrations performed, previous to this step, within the workflow. In the male model, the pixels' variability is more heterogeneous and not so subtle. A part of the same variation observed for the female model within the boundaries, that could be reduced by the application of a morphological dilation, the extension of the areas prone to change is considerably larger. A source of controversy in the assessment of diabetic foot disorders is the time required to achieve temperature normalization in a clinical setting prior to thermography acquisition. In some studies, normalization is expected after 10 min [15], whereas in others it is at 15 min [8]. As demonstrated, the difference between the plantar aspects of both feet at T0 does not suffice to pinpoint the areas in which an anomaly is found. By looking at Figure 7, for the female case, no substantial differences are subsequently found. However, for the male case, it can be seen that, just after 5 min, at T5, an entire new perspective can be appreciated. Furthermore, this trend is roughly maintained to T15. Therefore, at least a few minutes are required to achieve temperature normalization. This is an important issue to be considered by medical practitioners in a clinical setting but also when aiming at self-monitoring programs to be carried out at home by the patients [47].