Diagnosis of Thyroid Nodule with New Ultrasound Imaging Modalities.

Introduction: B-mode ultrasound (US) technology is an integral part of diagnosing and assessing risk stratification of thyroid nodules (TNs). The addition of shear wave elastography and three-dimensional (3D) US imaging may improve risk stratification for thyroid cancer (TC). Materials and Methods: The patient was evaluated in our clinic with US imaging including B-mode, shear wave elastography, 3D-US, and fine needle aspiration biopsy (FNAB). Laboratory measurements were performed at LabCorp. The patient gave informed consent. Case: A 20-year-old female referred for hypothyroidism who was on levothyroxine 25µg daily. Her thyroid-stimulating hormone (TSH) was 3.870 (0.45-4.5 µIU/mL). Thyroid peroxidase antibody and thyroglobulin antibody were elevated, suggestive of Hashimoto's thyroiditis. Her thyroid ultrasongraph showed a heterogeneous thyroid gland with a hypoechoic TN in the right lobe measuring 9.2 × 8.9 × 9 mm. Shear wave elastography examination was suggestive of a hard TN. The shear wave velocity (SWV) measurements for the target TN was 3.9 m/s. 3D-US examination demonstrated a hypoechoic TN with irregular margins and a volume of 0.322 cm³. FNAB of right TN was performed. The cytopathology was read as malignant (Bethesa Category VI), diagnostic for papillary thyroid cancer (PTC). She underwent total thyroidectomy. Surgical pathology report showed an 8 mm PTC in the right lobe and 2 mm PTC in the left lobe with a background of Hashimoto's thyroiditis. There were 3/10 positive lymph nodes (LNs) for metastases. The largest metastatic LN measured 5 mm at level 6. Discussion: This case illustrates recent advances in US technology. For decades, clinicians relied on B-mode US to assess the risk for TC. This case illustrates important challenges and advances in US technology. Current ACR-TIRADS guideline for TN management is based on B-mode US features and TN size.¹ In our experience, including additional factors such as elastography, 3D-US, and laboratory evaluation helps to improve our diagnostic accuracy. In this case, her laboratory was suggestive of autoimmune thyroid disease. This information was helpful to put this patient in a higher risk category. Recent large studies reported an association between differentiated TC and autoimmune thyroid disease and/or TSH when all Bethesda classifications were included.^2-4 Shear wave elastography examination showed that this TN had a high SWV, suggestive of a hard TN, which is suspicious for malignancy. Several recent publications have reported that elastography can assess the malignant potential of TN.^5-10 In our prospective study, we reported that in a single cutoff analysis for predicting malignancy in TNs, a maximum SWV of 3.54 m/s had the best sensitivity. With greater SWV values, specificity increased but sensitivity decreased.⁶ 3D-US technology enhances our ability to visualize the target lesion because of adding a new dimension, coronal view, to the existing B-mode that consists of transverse and longitudinal views. In this case, irregular margins of the TN are seen much better with 3D-US. This is a preliminary report, and more studies need to be done. Conclusion: Adding SWE and 3D-US technology to B-mode US may enhance our ability for risk stratification for TN before FNAB. 3D-US may improve our ability to visualize the margins of TN. No competing financial interests exist. Runtime of video: 2 mins 5 secs.