The Significance of Transcapsular Blood Flow for Assessing Moderate to Severe Extrathyroidal Extension: Results of a Two-Center Study

BACKGROUND: Extrathyroidal extension (ETE) is a crucial factor affecting the prognosis of thyroid cancer. Two-dimensional ultrasound is highly sensitive to ETE, but the sensitivity and specificity for severe ETE are unideal, so it does not improve the prognosis. MATERIALS AND METHODS: This retrospective study evaluated patients within three years of subcapsular thyroid cancer diagnosis with fine-needle aspiration (FNA). Routine ultrasound was performed and examined before surgery. In addition to the traditional two-dimensional assessment method, particular attention was paid to transcapsular blood vessels, and the diagnostic efficacy of the two methods for mild, severe, and anterior and posterior ETE was compared. RESULTS: A total of 208 thyroid cancer nodules were included. Tumor size and gender were correlated with whether ETE occurred. The general method is more accurate for the overall identification of ETE but is not specific enough for severe ETE, while the transvascular method is the opposite. The two are similar in identifying the ETE of the anterior capsule, but the transvascular method has higher specificity in identifying the ETE of the posterior capsule. CONCLUSION: The traditional two-dimensional method is highly sensitive to ETE detection in the anterior capsule, while transcapsular blood flow can more effectively detect extensive ETE and ETE in the posterior capsule.