Computed Tomography of the lungs Imaging of the lungs, traditionally with chest radiography, is an integral part of the examination of a patient with suspected lung disease. Computed Tomography (CT) has revolutionised the way in which lung disease is characterised. While pulmonary function tests provide an index of the extent of lung disease, CT gives structural, and sometimes histospecific, information about the cause of the functional deficit. In particular, high-resolution CT provides exquisite detail of the lungs that, in many cases, obviates the need for more invasive diagnostic procedures such as lung biopsy. In those cases in which bronchoalveolar lavage or lung biopsy is contemplated, CT provides a valuable road map that maximises the chances of yielding a successful biopsy. Additional indications for CT of the lung include: Detection and characterisation of airways disease, either of the large airways (e.g bronchiectasis) or small airways disease. The accurate staging of patients with lung cancer, which requires an optimal CT examination with intravenous contrast. Identifying reversibility in patients with diffuse interstitial lung disease, and likelihood of response to treatment. Elucidation of the cause of haemoptysis, for example, endobronchial lesions or bronchiectasis. In patients with mixed lung disease, HRCT can be used to tease out which is the dominant pathological process (for example, in patients with mixed emphysema and fibrosing lung disease). Case Study Case 1 A 64 year old smoker with a lesion in the right upper lobe on chest radiography. CT sections show the abnormality in the right upper lobe to be patchy consolidation that subsequently resolved. There is a background of severe centilobular emphysema and a section through the lung bases shows clinically unsuspected fibrosing alveolitis. Case 2 A 46 year old female patient thought to have cryptogenic fibrosing alveolitis. There are features of established fibrosis, particularly in the lower zones where there is distortion of the lung parenchyma. However, in the mid zones features of patchy air-trapping and poorly defined nodular opacities suggest extrinsic allergic alveolitis. The diagnosis was subsequently confirmed on transbronchial biopsy, but the antigen responsible was not identified in this case. print these case studies