Figure 3 (A–C) Schematic diagram illustrating early ring enhancement of At-PI in thyroid nodules. A thyroid nodule was identified in the right lobe of a 48-year-old woman. The left image displays the US in double condition, the middle image presents the At-PI image and the right image illustrates the pathological image. The white arrow indicates the target nodule. The US revealed hypoechoic nodules with an irregular shape, unclear edges, uniform echogenicity, and an aspect ratio greater than 1. These nodules were classified as C-TIRADS category 4b. The At-PI image demonstrates a centripetal perfusion pattern, characterized by early enhancement of the tissue surrounding the nodule, which is color-coded in orange. Notably, there is clear early ring enhancement observed on the At-PI image at 10 seconds. Figure was produced using PowerPoint version 2016 (Microsoft Corporation, Washington, USA).