Lymphatic Contrast-enhanced US to Improve the Diagnosis of Cervical Lymph Node Metastasis from Thyroid Cancer

Background The presence of cervical lymph node (LN) metastases (LNMs) affects clinical staging and prognosis of thyroid cancer, but the role of conventional B-mode US is limited for preoperative diagnosis of LNMs. The diagnostic value of lymphatic contrast-enhanced US (LCEUS) in thyroid cancer is still being explored. Purpose To explore the diagnostic performance of LCEUS by means of thyroidal injection of contrast agent in comparison with US in detecting LNMs of suspected thyroid cancer. Materials and Methods In this single-center prospective study conducted from November 2020 to January 2021, consecutive participants with suspected thyroid cancer underwent B-mode US and LCEUS of cervical LNs before biopsy. LNMs were confirmed with fine-needle aspiration cytologic examination, thyroglobulin washout assessment, or histopathologic examination after surgery. The diagnostic performance of LCEUS for cervical LNs was compared with that of conventional B-mode US, and its association with LN size and location was evaluated. Results The final data set included 64 participants (mean age, 45 years ± 12 [SD]; 52 women) with 76 LNs. The sensitivity, specificity, and accuracy of LCEUS for LNM were 97%, 90%, and 93%, respectively, whereas they were 81%, 80%, and 80%, respectively, for LNM at conventional B-mode US. Compared with US, LCEUS had better diagnostic accuracy for the LNs smaller than 1 cm (82% vs 95%; P = .03) and for central neck LNs (level VI) (83% vs 96%; P = .04). Conclusion Lymphatic contrast-enhanced US had better diagnostic performance than conventional B-mode US for detecting cervical LN metastases in suspected thyroid cancer before surgery, especially for LNs smaller than 1 cm and central neck LNs. © RSNA, 2023 See also the editorial by Grant and Kwon in this issue.