## 4 Discussion  
Thyroid nodules present an increasing prevalence, hence, in order to avoid unnecessary surgeries, the target of clinicians when investigating thyroid nodules is to accurately identify the ones that are at risk. In this regard, FNA is still considered the most appropriate instrument for the characterization of thyroid lesions [4; 6], in spite of its notable diagnostic limitation, consisting of indeterminate results. Different anamnestic and clinical conditions were investigated as possible independent predictors of malignancy in intermediate cytology cases--male gender was found to increase the odds for thyroid \begin{table}
\begin{tabular}{c c c c c c} \hline  & **Se** & **Sp** & **PPV** & **NPV** & **Acc** \\ \hline
2B & 57.14 & 67.44 & 46.15 & 82.88 & 64.06 \\
2B + SE & 80.95 & 88.37 & 77.27 & 92.68 & 85.93 \\
2B + 3D & 71.42 & 67.44 & 51.72 & 82.85 & 68.75 \\
2B + SE + 3D & 85.71 & 88.37 & 78.26 & 92.68 & 90.32 \\ \hline \end{tabular}  
* 2B—conventional ultrasound; SE—strain elastography; 3D—volumetric Doppler evaluation; Se—sensitivity; Sp—specificity; PPV—positive predictive value; NPV—negative predictive value; Acc—accuracy of the method.  
\end{table} 
Table 4: Diagnostic qualities of different models of risk assessment in the studied cases (%). Figure 4: The area under the receiver operating characteristic (AUROC) curve for 3D Doppler as the only parameter in the evaluation of cases with Bethesda III and IV cytology compared to the pathology report. cancer by 1.5 times [35], as well as the growth and dimensions of the nodule. The predictive value of the size of the nodule is controversial [36]. Some data report that nodules larger than 4 cm increase the odds of thyroid cancer by two [35], others suggest that the lowest risk is suggested by nodules measuring 2.5 cm, and any increase or decrease in size by 1 cm will raise the risk by 40% to 50% [37]. Because of the conflicting data regarding gender, age, number of nodules, and size, we did not take these parameters into consideration. In intermediate cytology cases, several studies have described that high-risk ultrasound features, regardless of the model of risk assessment [14; 38; 39; 40], associate with high risk for thyroid cancer. From the 64 nodules with intermediate cytology on FNA that were analyzed in the present study, 32.8% were identified as malignancies, concordant with the different prevalences described in the literature [41; 42; 43; 44; 45; 46]. Conventional ultrasound evaluation remains the first approach in the examination of thyroid nodular pathology. Solid consistency, irregular margins, the presence of intramodular point/scattered calcifications, intense hypoechogenicity, and/or a taller-than-wide shape are the generally accepted parameters that define high-risk nodules [4; 5; 20]. Even if some particular ultrasound characteristics such as calcifications and metastatic lymph nodes [4] are highly suggestive of malignancy, their prevalence in nodular thyroid disease is rare. On the other hand, solid pattern or hypoechogenicity are present in both benign and malignant cases, thus US assessment does not offer good diagnostic quality for detecting malignancy when only one parameter is considered [20]. Diagnostic performance of conventional US-only evaluation has been studied before, with excellent results for nodules classified in Bethesda categories I, II, V, and VI, but poorer outcomes for intermediate categories III and IV, underlining the importance of additional evaluation for these cases [47]. We observed an enhancement of risk predictions by using combined conventional ultrasound characteristics and volumetric Doppler: 68.75% versus 64.06%; classical grayscale characteristics and degree of stiffness: 85.93% versus 64.06%; and all conventional, volumetric Doppler and elastography score: 90.32% versus 64.06%. Similar data were proposed by previous research with integrated elastographic information [14; 42; 44].