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
String sign of Kantor is seen in: March 2013 (b, c, d, g) 
Select and explain. 
A. Ulcerative colitis, B. TB, C. Carcinoma, D. Crohn's disease
D: Crohn's disease
Answer: D: Crohn's disease 
Explanation: Ans. D i.e. Crohn's disease Gastrointestinal tract: Radiological signs and conditions Single bubble sign: Pyloric stenosis IOC for acute cholecystitis: HIDA scan Features of cholecystitis: Thick gall bladder wall, Peri-gall bladder halo etc. Double bubble sign: - Annular pancreas, - Duodenal atresia etc. Chain of lake appearance: Chronic pancreatitis Fox sign: Acute pancreatitis Widening of duodenal C loop: Ca head of pancreas Bird of prey sign: Sigmoid volvulus Thumb printing sign: Ischemic colitis