Thyroid Multimodal Ultrasound Evaluation—Impact on Presurgical Diagnosis of Intermediate Cytology Cases

Abstract

Fine needle aspiration (FNA) is recommended as the final evaluation in diagnosing thyroid nodules. Intermediate cytology is observed in about 15%–25% of the FNA results and has divergent recommendations: follow-up or surgery, either hemi- or total thyroidectomy. The present study aimed to assess the benefit of multimodal ultrasound (US) evaluation in clarifying the attitude in cases with intermediate cytology on FNA. Sixty-four successive cases with Bethesda III or IV cytology results were evaluated using two-dimensional B-mode US (2B), qualitative strain elastography, as well as planar and volumetric (3D) color Doppler using both a linear multifrequency probe and a linear volumetric probe (Hitachi Preirus Machine, Hitachi Inc. Japan). The analyzed nodules were all categorized as low, intermediate, or high risk, based on the following US criteria: taller-than-wide shape, marked hypoechogenicity, irregular borders, inhomogeneity, microcalcifications, or the presence of suspicious adenopathy. Elastographic criteria included stiff lesions, while volumetric Doppler criteria included moderate and marked perinodular vascularization, as suspicious for malignancy. The gold standard for the analysis was the result of the pathology report after thyroidectomy. Our results showed that the prevalence of cancer was 25% (16 cases). In five cases, borderline follicular neoplasia was identified, group which requires watchful waiting. These lesions were also considered as malignant in the final analysis, with a total number of 21 neoplasm cases. Sixteen of the 21 malignant nodules presented with high stiffness, while 15/21 had increased perinodular vascularization. Eight of the 21 cases displayed both important stiffness and perinodular vascularization. Cancer prevalence increased both with severity of stiffness (9.0%–15.0%–66.6%–80.0%) and intensity of vascularization in the adjacent perinodular parenchyma (18.2%–27.7%–35.29%–50.0%). Combining the use of grayscale US, elastography, and 3D Doppler in the evaluation of intermediate cytology cases showed a sensitivity of 85.7%, a specificity of 88.3%, and an accuracy of 90.3% in detecting thyroid cancer cases. We can conclude that the identification of highly suspicious US characteristics observed in 2B, qualitative elastography, and volumetric Doppler increases the risk of malignancy.

Keywords

• Bethesda III cytology
• cancer risk
• volumetric Doppler
• strain elastography
• multimodal ultrasound