Computed tomography in the assessment of diffuse lung disease

Computed tomography (CT) has a significant impact on the evaluation of pati ents suspected of having diffuse lung disease. The technique is based on th in-section scans and high-resolution reconstruction. CT interpretation is b ased on a recognition of the main pattern, associated findings, and distrib ution of the lesions assessed at the regional level as well as the level of the secondary pulmonary lobule. CT may demonstrate clinically suspected ab normalities undetected on the radiographs. It may have characteristic pictu res in patients with non specific findings on the radiograph. It can be use d to limit the differential diagnosis to a few possibilities. In selected c ases, in the presence of the appropriate clinical setting, CT appearances c an be diagnostic or so strongly suggestive that lung biopsy can be avoided. When a lung biopsy is indicated, CT has a considerable value in determinin g the most appropriate site for the biopsy. To a certain extent, CT may als o provide information on disease activity and prognosis, particularly in th e differentiation between inflammatory changes, potentially treatable or re versible, and irreversible lung fibrosis.