Ans. a. HRCTPersistence of a productive cough, clubbing, wheeze, and crackles is suggestive of bronchiectasis. HRCT is the diagnostic procedure of choice (most specific).HRCT findings in bronchiectasis:Airway dilation (detected as parallel "tram tracks" or as the "signet-ring sign").Lack of bronchial taperingBronchial wall thickening in dilated airwaysInspissated secretions (e.g., the "tree-in-bud" pattern)Cysts emanating from the bronchial wall (especially pronounced in cystic bronchiectasis)