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': 'Best method to diagnose hydrocephalus in 6 month old FETUS is: \nSelect and explain. \nA. X-ray, B. Ultrasound, C. CT scan, D. MRI', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B. UltrasoundHydrocephalusObstetric ultrasound study is one of the best methods for antenatal diagnosis of hydrocephalus as it is non-invasive and hazard-free not only to fetus but also to mother.However, assessment prior to GA of 20 weeks may be difficult, as ventricles constitute a large portion of cranial vault.Signs suggestive of fetal hydrocephalus on obstetric USG study are:a. Atrial size >10mmb. Dangling "choroid plexus" signc. Banana signd. Lemon signe. BPD > 95th percentilef. +- Polyhydramnios', 'role': 'assistant'}]