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
Best method to diagnose hydrocephalus in 6 month old FETUS is: 
Select and explain. 
A. X-ray, B. Ultrasound, C. CT scan, D. MRI
B: Ultrasound
Answer: B: Ultrasound 
Explanation: 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