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
[{'content': 'Active pulmonary TB can be diagnosed on CT-scan by following finding ? \nSelect and explain. \nA. Tree in bud appearance, B. Honey comb appearance, C. Ground glass appearance, D. Signet ring sign', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Tree in bud appearance(Ref Chapman 4n/e p.142,143; Fundamentals of radiology) Tree-in-bud sign or pattern describes the CT appearance of multiple areas of centrilobular nodules with a linear branching pattern.This is a characteristic sign of active pulmonary TB.Other impoant sign of pulmonary TB on CT is lymph nodes showing peripheral rim enhancement because of necrosis.", 'role': 'assistant'}]