<prompt> Investigation of choice in bronchiectasis isBronchoscopyMRI thoraxHRCT lungChest X-ray  <response>: HRCT chest is more specific for bronchiectasis and is the imaging modality of choice for confirming the diagnosis.CT findings include airway dilationdetected as parallel tram tracks or as the signet-ring sign-a cross sectional area of the airway with a diameter at least 1.5 times that of the adjacent vessel,lack of bronchial taperingincluding the presence of tubular structures within 1 cm from the pleural surface.,bronchial wall thickening in dilated airways,inspissated secretions eg.,the tree-in-bud pattern ,or cysts emanating from the bronchial wallespecially pronounced in cystic bronchiectasis. Reference:Harrisons medicine-18th edition,page no:2143. 