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 (EMax) and nodule depth/width (D/W) ratio: Category 1 (EMax ≥ 42.6 kPa; D/W < 0.9); Category 2 (EMax < 42.6 kPa; D/W < 0.9); Category 3 (EMax ≥ 42.6 kPa; D/W ≥ 0.9); and Category 4 (EMax < 42.6 kPa; D/W ≥ 0.9). The EMax 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 EMax and nodule D/W ratio was useful to predict the pathology of thyroid nodules.