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The value of conventional sonography and ultrasound elastography in decision-making for thyroid nodules in different categories of the Bethesda system for reporting thyroid cytopathology.

PURPOSE
The aim of this study was to evaluate the diagnostic value of conventional sonography and ultrasound elastography for thyroid nodules of each Bethesda category and to analyze their potential role in the corresponding management decision.


METHODS
This retrospective study included 557 thyroid nodules diagnosed by conventional ultrasound (US) and real-time ultrasound elastography (RTE) before fine-needle aspiration (FNA) from 458 patients. The US, RTE, and cytological results were collected and analyzed according to different Bethesda categories. Differences in the distribution of sonographic features between groups were evaluated by the Chi-square test or Fisher exact test. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of conventional US and RTE for the diagnosis of malignant nodules in each category were then calculated and analyzed.


RESULTS
The diagnostic accuracy of the comprehensive US diagnosis in all categories stayed at a relatively high level from 78.4% to 88.6%, and good specificities ranging from 77.3% to 100% were revealed in all Bethesda categories. As to RTE, the diagnostic accuracies in categories I-IV stayed at a relatively low level ranging from 44.6% to 65.6% except for better performance in categories V and VI (85.2%, 89.1%). Besides, the accuracies of comprehensive US (85.2%, 88.6%) and RTE (85.2%, 89.1%) is relatively low compared to the corresponding cytological diagnoses in categories V and VI.


CONCLUSIONS
Conventional US is complementary to FNA for providing additional hints especially in categories I-IV for further clinical managements, while RTE failed to provide useful diagnostic information in general.