Efficacy of Differential Diagnosis of Thyroid Nodules by Shear Wave Elastography—the Stiffness Map

BACKGROUND: Fine needle aspiration is the gold standard for differential diagnosis of thyroid nodules; however, the malignancy rate for indeterminate cytology is 20% to 50%. OBJECTIVE: We evaluated the efficacy of shear wave elastography added to ultrasonography for differential diagnosis of thyroid nodules. METHODS: We retrospectively reviewed the medical records of 258 consecutive patients. Thyroid nodules were divided into 4 categories according to maximum elasticity (E(Max)) and nodule depth/width (D/W) ratio: Category 1 (E(Max) ≥ 42.6 kPa; D/W < 0.9); Category 2 (E(Max) < 42.6 kPa; D/W < 0.9); Category 3 (E(Max) ≥ 42.6 kPa; D/W ≥ 0.9); and Category 4 (E(Max) < 42.6 kPa; D/W ≥ 0.9). The E(Max) cutoff value was set using receiver operating characteristic (ROC) curve analysis to predict nodular hyperplasia (NH) vs follicular neoplasm (FN). Cutoff value for nodule D/W ratio was set using ROC curve analysis for malignancy. RESULTS: NH was the most prevalent pathology group in Category 1, FN in Category 2, and papillary thyroid carcinoma in Category 3. Category 3 demonstrated the highest rate of malignancy (81.8%) and had 55.4% sensitivity and 90% specificity for predicting malignancy. When assessing the benign pathology of NH in follicular patterned lesion, Category 1 demonstrated the highest NH prevalence of 88.9% (34/37) and had 73.9% sensitivity and 85.0% specificity. CONCLUSION: The performance for malignancy was highest in Category 3 and predictive ability for benign pathology of NH in follicular lesion was highest in Category 1. The information of E(Max) and nodule D/W ratio was useful to predict the pathology of thyroid nodules.