Investigation of choice for detection & char-acterization of interstitial lung disease is

C i.e. HRCT High Resolution CT (HRCT) is investigation of choice for interstitial lung disease (parenchymal lung disease) and bronchiectasisQ as it can delineate the lung parenchyma upto the level of secondary pulmonary lobule. Principles of HRCT are: 1.Narrow beam collimation leading to thin section (r:: 1.5 mm) 2.Small field view 1/t increased resolution. 3. High spatial reconstruction algorythm (edge enhancing or sharp algorythm)Q eg. Bone algorythm, that makes structure visible sharper & reduce smoothing, but it makes image noise more obvious.