This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: ULTRASOUND, Subject name: Radiology
[{'content': 'Filarial Dance sign is seen on \nSelect and explain. \nA. USG, B. CT, C. Scintigraphy, D. Radiography', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The Filarial dance sign refers to a twirling motion of microfilariae (e.g.W. bancrofti) noted in dilated lymphatic channels. It is identified as a characteristic sign and indicator of scrotal filariasis. The dilated channels are identified with absence of color flow on Color Doppler study (CDS) and the microfilariae as curvilinear echogenic undulating structures within it. Generally 5-6 microfilariae are seen per channel. GIF image: Filarial dance sign on USG', 'role': 'assistant'}]