This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Genito Urinary System, Subject name: Radiology
[{'content': 'Investigation of choice for torsion testis is \nSelect and explain. \nA. Colour Doppler, B. MRI, C. CT, D. Routine USG', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans: a) Colour Doppler [ Ref:- Sutton - 7th edition Page No:-Doppler ultrasound is the imaging of choice for torsion testis. It helps in the diagnosis of torsion by virtue of reduced vascularity ( absence or poor colour flow, reduced peak systolic velocities) compared with the unaffected side.', 'role': 'assistant'}]