## 4 Discussion  
Conventional ultrasound proved its usefulness in examining the thyroid over a period of time. Although it only suggests the diagnosis, as biological determinations are also  
Figure 5: Box-and-whisker distribution plots comparing SR mean values, in euthyroid patients compared to treated hypothyroidism patients. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameters** & **r Coefficient** & **Correlation** \\ \hline ATPO & 0.65 & Strong positive \\ \hline ATG & 0.29 & Weak positive \\ \hline Thyroid volume & 0.49 & Strong positive \\ \hline BSA & 0.32 & Moderate positive \\ \hline ATPO—Anti-thyroid peroxidase antibodies; ATG—Antithyroglobulin antibodies; SR—Strain Ratio; BSA—Body Surface Area; r—[PERSON]’s coefficient for correlation. & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Correlation between SR and different parameters. necessary, it is highly suggestive for CAT if the appearance ishypoechoic and heterogeneous. It can also have micronodules or a pseudolobulated appearance of the parenchyma [16]. Several studies have shown that elastography is an adjuvant method, adding value to the classic examination. SE was studied on various groups of patients. A study conducted in Baghdad that included 25 patients with diffuse thyroid disease (DTD) and 25 control subjects found significant differences between the two groups. The mean value of elasticity for the patient group was 1.36, much higher than the control group, 0.82. The cut-off value established for AITD was 0.89 (80% Sensitivity, 70% specificity) [49]. Another study compared the thyroid stiffness of patients with CAT and healthy controls with significant differences between the groups. The median SR value for CAT group was 1.39 \(\pm\) 0.72, while the control group had much lower values (0.76 \(\pm\) 0.55). The optimal cut-off value for the prediction of CAT was 0.677 (96% sensitivity, 67% specificity, AUROC 0.775). In addition, a positive correlation was found between SR and the values of ATPO (r = 0.682) [50]. [PERSON] et al. included in their study 94 patients with HT and 82 subjects with no thyroid pathology. Although they obtained differences between the study groups (8.4 \(\pm\) 9.6 vs. 1.37 \(\pm\) 0.8), the values were higher than those obtained in the two studies mentioned previously [51]. A study that included 180 CAT patients and 70 healthy subjects established the optimal cut-off value as 1.64 (69% sensitivity, 92% specificity, 95,4 PPV, 54% NPV, AUROC 0.87). The mean SR values for CAT group were 2.81 \(\pm\) 2.11, significantly higher than the control group (1.03 \(\pm\) 0.51) (\(p\) < 0.0001). No statistically significant correlation was found between thyroid stiffness and ATPO [52]. Although different mean values and cut-off values were obtained, all the previously mentioned studies concluded that there are significant stiffness differences between the healthy thyroid parenchyma and the one affected by CAT when using SE. Compared to studies on adult population, studies that include children are fewer. There are some studies that compare thyroid elasticity in children using the SWE method [53,54]. The cut-off values proposed for diagnosing CAT varies: 1.41 m/s [55], 2.39 m/s [53], 12.2 kPa [54], as well as the mean values: 3.7 \(\pm\) 1.2 (2.59-6.25) m/s [53], 14.9 kPa (12.9-17.8 kPa) [56]. However, significant differences between the thyroid elasticity of healthy children compared to children diagnosed with HT were observed in all papers mentioned above. To our knowledge, there are only two studies that include children with CAT evaluated using SE.Yurttan et al. conducted a study on 54 healthy children to determine the SR of normal thyroid parenchyma. The mean value found was 0.54 \(\pm\) 0.38, results that are consistent with our results (0.68 \(\pm\) 0.2). No correlations were found between SR and age (r = 0.22; \(p\) = 0.15) or gender (r = 0.007; \(p\) = 0.96) [57].