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': 'In 7 year old posterior fossa mass with cyst formation, hypodense on CT, hyper intense on T2WI and showing post gadolinium nodule enhancement is \nSelect and explain. \nA. Medulloblastoma, B. Ependymoma, C. Astrocytoma, D. Cysticercous', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C i.e. Astrocytoma Posterior Fossa tumors in children Features Astrocytoma Ependymoma Medulloblastoma Cyst Formation Very cominonQ Common Rare CT scan IlypodenseQ Rare Isodense No Hyperdense Yes (15-40%) CSF seeding Transforaminal spread No Yes No Calcification -10% 40-50% 10-15% T2WI Hyper (intense) Hyper/Iso Iso T1 WI Iso/Hypo Iso/Hypo Iso/Hypo Postgadolinium (contrast) Nodule enhanceQ Mild Moderate', 'role': 'assistant'}]