Ring sign with dilated bronchi on CXR is a feature of

(B) Bronchiectasis # RADIOGRAPHIC FEATURES of BRONCHIECTASIS> Plain film: Chest x-rays are usually abnormal, but are inadequate in the diagnosis or quantification of bronchiectasis. Tram-track opacities are seen in cylindrical bronchiectasis, and air-fluid levels may be seen in cystic bronchiectasis.> Overall there appears to be an increase in bronchovascular markings, and bronchi seen end on may appear as ring shadows 8.> Pulmonary vasculature appears ill-defined, thought to represent peribronchovascular fibrosis 8-9.> CT: CT and HRCT especially excels at demonstrating the airways, and is able to a greater or lesser degree to distinguish some of the various underlying causes.> A number of features are helpful in diagnosing bronchiectasis 8-9; Bronchus visualised within 1 cm of pleural surface Especially true of lung adjacent to costal pleura Most helpful sign for early cylindrical change Lack of tapering Increased bronchoarterial ratio Diameter of a bronchus should measure approximately 0.65 -1.0 times that of the adjacent pulmonary artery branch Between 1 and 1.5 may be seen in normal individuals, especially those living at high altitude Greater than 1.5 indicates bronchiectasis> A number of ancillary findings are also recognised: Bronchial wall thickening: normally wall of bronchus should be less than half the width of accompanying pulmonary artery branch Mucoid impaction Air-trapping and mosaic perfusion> Signs described on CT include: Tram-track sign Signet ring sign String of pearls sign Cluster of grapes sign