This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Radiology
[{'content': 'Contrast used for MRI: September 2012, March 2013 (f, g) \nSelect and explain. \nA. Iodine, B. Gadolinium, C. Metrazamide, D. Omnipaque', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B i.e. Gadolinium MRI MC contrast agent used in MRI: Gadolinium DTPA C/I to MRI: - Cardiac pacemakers, - Aneurysmal clips etc. Faradays cage: MRI rooms are shielded by continuous sheets of copper or aluminium from interference by external electromagnetic radiation.', 'role': 'assistant'}]