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
Computed Tomography (CT scan) is least accurate for diagnosi of – 
Select and explain. 
A. Aneurysm in the Hepatic Artery, B. Lymph node in the para- aortic region, C. Mass in the tail of pancreas, D. Gall stones
D: Gall stones
Answer: D: Gall stones 
Explanation: Computed Tomography (CT) scan has limited value in the diagnosis of gallstones since gallstones may exhibit the same radiographic density as bile and hence may not be seen on CT.