Active pulmonary TB can be diagnosed on CT-scan by following finding ?

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.