Chest CT Scan

CT is excellent for detecting both acute and chronic changes in the lung parenchyma. (parenchyma means internals, in this case, of the lungs. It is relevant here because normal two dimensional x-rays do not show up defects in the internals of the lungs). A variety of different techniques are used depending on the suspected abnormality. For evaluation of chronic interstitial processes (emphysema, fibrosis, and so forth), thin sections with high spatial frequency reconstructions are used - often scans are performed both in inspiration and expiration. This special technique is called High resolution CT (HRCT). HRCT is normally done with thin section with skipped areas between the thin sections. Therefore it produces a sampling of the lung and not continuous images. Continuous images are provided in a standard CT of the chest.