Shear Wave Elastography Adds to the Sensitivity of Cancer Diagnosis in AUS-Nuclear and AUS-Other Nodules > 1 cm, but It Cannot Replace TIRADS Assessment and Repeat FNA.

Background/Objectives: The aim of the study was to compare the effectiveness of SWE in AUS-nuclear and AUS-other nodules, including nodules with an unequivocal cytology (UC), taking into account the size of the nodules. Methods: We evaluated 100 AUS-nuclear and 131 AUS-other nodules with known results of EU-TIRADS, repeat FNA (rFNA), and histopathological examination, and 92 nodules with UC: 47 malignant and 45 benign. Two SWE measures were used: Ewhole-capturing the largest possible area of the nodule; and Estiffest-limited to its hardest part. Results: In the UC group, values of both SWE measures above the thresholds were a significant malignancy risk feature regardless of the nodule size, but only Estiffest in nodules > 1 cm was an independent malignancy risk feature. In both AUS subcategories, similar results were obtained only for nodules > 1 cm; but, even in this group, rFNA and EU-TIRADS had a higher accuracy than SWE in the differentiation of benign and malignant nodules, and no SWE measures were an independent malignancy risk feature. However, in the AUS-nuclear subcategory, where PTC predominates among cancers, adding Estiffest to the EU-TIRADS and rFNA assessment led to some increase in sensitivity with an acceptable decrease in specificity. In the AUS-other subcategory, where the profile of cancers is more diverse, a similar effect was obtained by the addition of Ewhole. Conclusions: SWE may complement rFNA and TIRADS in category III nodules > 1 cm, but the decision whether to apply SWE and which measures should be used depends on the pre-test probability of cancer and the expected frequency of PTC among cancers.