This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Misc., Subject name: Medicine
HIDA scan is useful in: 
Select and explain. 
A. Acute cholecystitis, B. Meckel's diveiculum, C. Colonic angio-dysplasia, D. Diveiculitis
A: Acute cholecystitis
Answer: A: Acute cholecystitis 
Explanation: HIDA Scan: 99mTc hepatobiliary imaging (using iminodiacetic acid compounds), also known as the HIDA scan. is useful in demonstrating an obstructed cystic duct, which is the cause of acute cholecystitis in most patients.