Malignancy Risk Assessment Of Category 4 Nodules By Applying Acoustic Radiation Force Impulse In Thyroid Imaging Reporting And Data System

This study aimed to determine whether acoustic radiation force impulse (ARFI) can help to regulate thyroid imaging reporting and data system (TI-RADS) category 4 lesions and reassess the malignancy risk for a better selection of nodules submitted to fine-needle aspiration (FNA). ARFI was performed on 265 patients with 271 TI-RADS category 4 thyroid nodules. We calculated virtual touch tissue imaging (VTI) image grade, area ratio (VTIAR) and shear wave velocity (SWV) of lesions with VTI and virtual touch tissue quantification (VTQ). The categories of nodules were upgraded with higher-stiffness and downgraded with lower-stiffness, and the risks of malignancy changed accordingly. Surgical histology findings confirmed that 109 nodules were malignant and 162 nodules were benign. The cut-off values were VTI grade >= IV, VTIAR >= 1.12 and SWV >= 2.81 m/s, respectively. The diagnostic performance of the modified TI-RADS was statistically higher than that of TI-RADS (AUC: 0.939 vs 0.857; P < 0.05). By limiting the sizes and malignancy risks of nodules using the modified TI-RADS, the number of benign nodules which should undergo FNA could be reduced by 62 cases. ARFI is helpful to adjust the TI-RADS classification and aid doctors in making appropriate decisions in terms of FNA recommendation.