<prompt> Investigation of choice for detection and characterization of interstitial lung disease is:MRIChest X-rayHigh resolution CT scanVentilation perfusion scan  <response>: Ans. is c ie high Resolution CT Scan Ref: CT and MR imaging of whole body, Haaga, 4e, p838; Sutton, 7e, p33HRCT is the investigation of choice for interstitial lung disease.HRCT can even delineate the lung parenchyma down to the level of the secondary pulmonary lobule.Also Remember Principles of HRCTThin sections collimation - 1 to 2 mm.High spatial resolution reconstruction algorithm eg the bone algorithm.Small field of view just large enough to encompass the region of interest. 