This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous System, Subject name: Radiology
[{'content': 'Investigation of choice in DCIS: \nSelect and explain. \nA. Mammography, B. CT, C. MRI, D. PET', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. C. MRIDuctal carcinoma-in-situ (DCIS) and lobular carcinoma-in-situ (LCIS) are confined to the ducts and acini, respectively. There are four subtypes of DCIS: comedocarcinoma, micropapillary carcinoma, cribriform carcinoma and solid carcinoma. Among these subtypes, comedocarcinoma is the most aggressive. DCIS now accounts for 20-40% of all cancers detected by screening mammography.MRI must be able to demonstrate and characterize mammographically detected lesions (including DCIS) and, ideally, reveal mammographically occult lesions. This requires MRI to have high-resolution capabilities.', 'role': 'assistant'}]