OP4 – Clinical efficacy of acoustic radiation force impulse (ARFI) imaging in the diagnosis of thyroid nodules

      Takahiro, Fukuhara1; Eriko, Matsuda1; Satoshi Koyama1; Naritomo, Miyake1; Kazunori, Fujiwara1; Hiroya, Kitano1; Hiromi, Takeuchi1 1 Department of Otolaryngology-Head and Neck Surgery, Tottori University Faculty of Medicine   Background: ARFI imaging is a new technique; therefore, its efficacy is unknown. In this study, we compared ARFI imaging with strain elastography (SE) and shear wave velocities (SWVs) to evaluate the utility of ARFI imaging for diagnosing thyroid nodules. Subjects and Methods: The subjects for this study included 234 thyroid nodules (184 benign nodules and 50 malignant nodules). The nodules were evaluated with SE and ARFI imaging, and SWVs of the nodules were simultaneously measured. ARFI images were classified into four grades based on the gray-scale intensity and we elucidated further on the grades which were assumed to be as malignant. Finally, the sensitivity, specificity, and diagnostic accuracy were compared between SE and ARFI imaging. Results: The median value of the SWVs for the nodules in each ARFI imaging grade were as follows: 1.57 m/s in Grade 1, 1.68 m/s in Grade 2, 2.20 m/s in Grade 3, and 2.30 m/s in Grade 4. The SWVs in Grades 3 and 4 were significantly higher than those in Grades 1 and 2. The sensitivity, specificity, and diagnostic accuracy, respectively, were 32.2%, 85.0%, and 63.7% using SE, compared with 63.2%, 92.1%, and 85.0% using ARFI imaging. Conclusions: The SWVs of the Grades 3 and 4 nodules with ARFI images were higher than those of the Grades 1 and 2 nodules. The diagnostic accuracy of ARFI imaging for differentiating malignant thyroid nodules was higher than those of SE when the Grade 3 and 4 nodules were assumed as malignant.


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