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ObjectiveTo analyze the ultrasonic characteristics of false-negative and false-positive results of shear wave elastography (SWE) in the diagnosis of thyroid nodules to clarify the influence of nodular characteristics on SWE and to guide the clinical application of SWE.MethodsA total of 435 thyroid nodules from 343 patients with the diagnosis confirmed by surgical pathology were analyzed. Preoperative ultrasonography and SWE were conducted. The conventional ultrasound characteristics of thyroid nodules and the maximum Young’s modulus were recorded. The false negativity and false positivity of SWE for the diagnosis of thyroid nodules were calculated. The ultrasonic characteristics of thyroid nodules with SWE false results were analyzed, and logistic regression analysis was adopted to determine the ultrasonic characteristics associated with SWE false results of thyroid nodules.ResultsAmong 323 malignant nodules, the SWE false negativity was 27.2% (88/323). The false positivity of SWE in 112 benign nodules was 19.6% (22/112). Regression analysis showed that an increase in the nodule volume increased the risk of SWE false-positive results (odds ratio [OR] 3.286; 95% confidence interval [CI]: 1.572–6.871; P = 0.002) and decreased the risk of false-negative results (OR 0.238; 95% CI: 0.115–0.493; P < 0.001). Nodules with coarse calcification had an increased risk of SWE false-positive results compared with those without calcification (OR 5.303; 95% CI: 1.098–25.619; P = 0.038). However, nodules with scattered hyperechoic foci had a reduced risk of SWE false-negative results (OR 0.515; 95% CI: 0.280–0.951; P = 0.034).ConclusionNodular size and calcification were correlated with SWE false results, and the clinical application of SWE should be combined with conventional ultrasound features. Fine needle aspiration or a puncture biopsy should be conducted if necessary.

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In shear wave elastography (SWE) studies, the optimal cutoff value of Young’s modulus for the diagnosis of benign and malignant thyroid nodules varies greatly, which affects the clinical application of the method. The objective of this study was to evaluate the influence of thyroid nodule size on the clinical diagnostic efficacy of SWE. A total of 356 thyroid nodules of 280 patients were divided into three groups according to size (Group A: ≤ 1 cm; Group B: 1–2 cm; Group C: ≥ 2 cm). SWE was used to measure the maximum Young's modulus (Emax) values of all thyroid nodules. Receiver operating characteristic (ROC) curves were drawn with pathological results as the gold standard. For all nodules, the optimal cutoff value of Emax in SWE for diagnosing malignant thyroid nodules was 36.2 kPa. The sensitivity and specificity were 76.5% and 78.4%, respectively. Groups A, B, and C had different optimal Emax cutoff values of 33.7 kPa, 37.7 kPa, and 55.1 kPa, respectively. The area under the ROC curve (AUC) values of Groups A, B, and C (0.844, 0.886, and 0.935, respectively) were all greater than the values for all lesions (0.830). The specificity values of Groups A, B, and C (86.4%, 82.6%, and 88.2%, respectively) were all increased, and the sensitivity values of Groups B and C (89.7% and 96.4%, respectively) were also increased compared with the values for all lesions. Thyroid nodule size affects the optimal Emax cutoff value of SWE. We suggest that different cutoff values be used to diagnose benign and malignant thyroid nodules according to lesion size.