This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Radiology
[{'content': 'There is a lesion in the orbit. Can you diagnose? \nSelect and explain. \nA. Choroidal melanoma, B. Ocular retinoblastoma, C. Foreign body in the orbit, D. Optic nerve drusen', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A. Choroidal melanomaThe hyperintensity on T1 weighted MRI very specific for presence of melanin containing tumor in the orbit.The other causes of T1 hyperintensities are1. Blood products2. Proteinaceous substances3. Fat4. Gadolinium', 'role': 'assistant'}]