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
In case of subarachnoid haemorrhage, investigation of choice is: March 2011 
Select and explain. 
A. Non contrast CT scan, B. MRI, C. MRI angio with imaging, D. Ultrasound
A: Non contrast CT scan
Answer: A: Non contrast CT scan 
Explanation: Ans. A: Non contrast CT scan The diagnosis of SAH can be made on CT, but a negative result does not exclude the diagnosis since small amounts of blood in the subarachnoid space cannot be detected by CT