Objective To investigate the application value of acoustic radiation force impulse imaging (ARFI) in differential diagnosis of small solid thyroid nodules coexisting with Hashimoto's thyroiditis (HT).Methods A total of 136 patients with 155 small solid nodules (≤1 cm in diameter) confirmed by pathology were included.The small solid nodules were divided into HT group and normal group.All patients underwent virtual tissue imaging (VTI) and virtual touch tissue quantification (VTQ).The stiffness of small solid thyroid nodules in two groups was respectively scored based on VTI images,and the area ratios of nodules in VTI images to gray scale images were calculated.Taking pathological diagnosis as the gold standard,the ROC curve were performed to explore the optimal points and efficacy of area ratio and shear wave velocity (SWV) in the diagnosis of malignant nodules in two groups respectively.Results Regarding VTI score≥4 as the diagnostic standard of malignant nodules,the sensitivity of HT group and normal group in diagnosis of malignant nodules had significant difference (64.29％[27/42] vs 81.69％[58/71],P＜0.05).In two groups,the area ratio and SWV of malignant nodules were significantly higher than those of benign nodules (all P＜0.05).The area ratio and SWV of thyroid benign nodules and malignant nodules had no significantly difference between two groups (all P＞0.05).Taking 1.41 as the cutoff point of area ratio,the sensitivity and specificity in diagnosis of malignant nodules in HT group were 85.7％ and 88.9％.Taking 2.87 m/s as the cutoff point of SWV,sensitivity and specificity in diagnosis of malignant nodules in HT group were 85.7％ and 94.4％.Taking 1.40 as the cutoff point of area ratio,the sensitivity and specificity in diagnosis of malignant nodules in normal group were 91.5％ and 95.8％.Taking 2.67 m/s as the cutoff point of SWV,the sensitivity and specificity in diagnosis of malignant nodules in normal group were 88.7％ and 95.8％.Conclusion ARFI technology can evalu-ate the hardness of the small solid thyroid nodules through the intuitive VTI images and objective SWV values in HT,which is helpful in diagnosis of malignant nodules in HT backgroud.

Objective To compare the diagnostic value of shear wave elastography (SWE) and acoustic radiation force impulse imaging (ARFI) in benign and malignant thyroid nodules (TNs).Methods A total of 43 patients with 51 thyroid nodules were included.According to the diameter,all nodules were divided into small nodules (diameter ≤1 cm) and large nodules (1 cm＜diameter≤3 cm).All patients underwent both SWE and ARFI examinations at the same time.SWE (Emax,Emean,Emin),virtual touch tissue quantification (VTQ) and virtual touch tissue imaging (VTI) area ratio were obtained.The optimal cut-off values of SWE,VTQ,VTI area ratio were calculated with ROC curve to identify malignant thyroid nodules from benign ones,and the sensitivity,specificity,accuracy of Emax,VTQ and VTI area ratio were calculated respectively.Results The cut-off value of Emax,VTQ,VTI area ratio in differential diagnosis of benign and malignant TNs was 37.74 kPa,2.19 m/s and 1.24,respectively.The sensitivity was 85.30％ (29/34),76.50％ (26/ 34),64.71％ (22/34),the specificity was 100％ (17/17),94.10％ (16/17),88.20％ (15/17),the accuracy was 90.20％ (46/51),90.20％ (46/51),72.55％ (37/51) of E VTQ and VTI area ratio in diagnosis of malignant thyroid nodules,respectively.The sensitivity of Emax and VTQ in the diagnosis of malignant large NTs was 92.31％ (12/13) and 100％ (13/13),respectively,while the sensitivity of VTI area ratio and Emax in the diagnosis of malignant small NTs were both 80.95％ (17/21).Conclusion Either SWE or ARFI has good diagnostic performance in distinguishing malignant thyroid nodules from benign ones.Emax is of equal value in diagnosing thyroid benign and malignant nodules.VTQ has advantage for diagnosing large NTs,while VTI area ratio shows better diagnostic performance for small NTs.