Endocrine Abstracts

Introduction: Angiogenesis plays an important role in the growth and processes of tumors, often indicating neovascularity. However the role of vascularization in thyroid nodules observed with power or color doppler has always been debated. Therefore, most of thyroid nodules sonographic risk classification do not consider vascularization as an important features in predicting the risk of malignancy. In the last years a new vascular imaging technique, Superb Microvascular Imaging (SMI) has been developed and some studies suggested a diagnostic value in thyroid nodules.

Purpose: The aim of our study is to evaluate the role of SMI as an additional feature to ultrasound (US) risk stratifications proposed by the American Thyroid Association (ATA) in predicting the risk of malignancy.

Materials and methods: We evaluated 198 thyroid nodules selected for fine needle aspiration cytology (FNAC) and classified them according to ATA risk classification. Superb Microvascular Imaging was classified into four types and then grouped in Type 1-2 SMI and Type 3-4 SMI and Thy1 and Thy3 cytologies were excluded for the statistical analyses.

Results: According to the British Thyroid Association, FNAC was benign (Thy2) in 83.5% (111/133), and suspicious or malignant (Thy4/Thy5) in 16.5% (22/133) of the nodules. Based on ATA US risk assessment, thyroid nodules were classified into ‘very low/low suspicion’ (n =75, 56.3%), ‘intermediate suspicion’(n =38, 28.6%) and ‘high suspicion’(n =20, 15.1%). The rate of Thy4/5 cytologies was 1.3%, 15.8% and 75% in ‘very low/low suspicion’, ‘intermediate suspicion’ and ‘high suspicion’ thyroid nodules, respectively (P < 0.001). The rate of Thy4/5 cytologies was 10.3% in Type 1-2 SMI and 30.2% in Type 3-4 SMI nodules (P = 0.006). At multivariate analysis, both ATA risk class (P = 0.02 for intermediate risk and P < 0.001 for high risk categories) and SMI (P = 0.04) were independently associated with risk of malignancy. Stratifying SMI categories and ATA US risk classes, SMI was not associated with an increased rate of malignancy in ‘very low/low suspicion’ and ‘intermediate suspicion’ US risk nodules, whereas, in ‘high suspicion’ thyroid nodules, the presence of Type 3-4 SMI was significantly associated with a higher rate of Thy4/5 cytologies (50% Type 1-2 SMI and 100% for Type 3-4 SMI, P = 0.03).

Conclusions: In these preliminary data, Type 3-4 SMI is associated with a significant higher rate of Thy4/5 cytologies. However, SMI seems able to improve the positive predictive value of ATA US risk stratification only in ‘high suspicion’ category.