<prompt> Investigation of choice for bronchiectasis is-X-rayEndoscopyM.R.I.HRCT  <response>: Ans. is d i.e., HRCT HRCT is the investigation of choice for bronchiectesis The CT criteria for diagnosis include signet -ring sign bronchus being larger than accompanying vessel, bronchial wall thickening, and bronchi visible within 1 cm of the pleura. Three types are described according to Their appearance :-A. Cylindrical:- Mild diffuse dilatation of the bronchi. Radiologically there is Tram - Trank appearance, i.e. lack of peripheral tapering.B. Varicose:- Cystic bronchial dilatation interrupted by focal areas of narrowing, giving radiological appearance ofString of pearl string of beads.C. Saccular cystic:- Clusters of bronchi with marked saccular dilatation. Cystic bronchiectasis in any region is easily recognized as clusters of rounded lucencies, often containing air - fluid levels; this appearance has been linked to a cluster of grapes.Investigations of choice in respiratory systemDiseaseInvestigation Interstitial lung disease HRCT Bronchiectasis HRCT 1st choice Bronchography 2nd choice Pulmonary embolism CT with i.v. Contrast 1st choice VQ scan 2nd choice Solitary pulmonary nodule CT scan Calcification CT scan Pulmonary malignancy CT scan except in superior sulcus or pancoast tumor Superior sulcus or pancoast tumor MRI 