Chest x-rays are often the first examination carried out at the bed side on patients in intensive care and their interpretation is often difficult. When CT scans are carried out they enable the mediastinum to be examined as well as the bronchi and pulmonary parenchyma. Using this technique to confirm a diagnosis or to explain those aspects on a standard x-ray which were difficult to analyse increasingly justifies the transportation of a patient the scanner. Spiral CT scans are particularly useful in the diagnosis of pulmonary emboli.