This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ocular trauma , Subject name: Ophthalmology
[{'content': 'Investigation of choice for intraocular foreign body is- \nSelect and explain. \nA. CT scan, B. MRI, C. USG, D. X-ray', 'role': 'user'}, {'content': "Answer: A \nExplanation: *Computed tomography provides much more reliable information regarding the size, shape, and localization of the foreign body. *MRI generally is not used in metallic IOFB. MRI may be more effective in localizing nonmetallic IOFB such as wood. *Ultrasound can be a useful adjunct in localizing IOFB and to determine if the object is metallic. Ultrasound could be performed carefully in case of an open globe injury'. Ref: Current trends in the management of intraocular foreign bodies. Cure Opin Ophthalmol, 2008 May;19(3):225-33.", 'role': 'assistant'}]