[Radiological exploration of the thorax. Strategy and indications].

The widespread use of computed tomography and the advent of magnetic resonance imagery have considerably modified the methods and strategies of thoracic exploration over the last 10 years. Standard radiography remains the first-line examination for all thoracic diseases, and often is the only imagery required; further explorations are indicated on the basis of the information seen on standard films. Computed tomography has become an essential element in the work-up of all diseases involving a tumoural process in the lung. It is also indicated in bronchiestasis and for the exploration of chronic lung diseases. Further information may be obtained with magnetic resonance imagery. Although this method cannot be used to explore the pulmonary parenchyma, it is particularly adapted in cases involving the pleura, mediastinum (tumours and vessels) and the thoracic wall. Scintigraphy is mainly used to detect pulmonary migrations and to investigate lung function before thoracic surgery. Pulmonary angiography remains the reference imagery for the diagnosis of pulmonary embolism but has lost its other indications. Tomobronchography is exceptionally required. Current strategy in infectious diseases is to always begin with standard radiography, then to complete the work-up with further examinations only when necessary. Correct evaluation of tumoural processes relies heavily on tomography even for very small masses since it provides essential information on localization and extension. Management of primary bronchogenic cancers also requires repeated tomographic studies. Magnetic resonance images are indicated on the basis of the tomography results and are particularly useful in tumours of the apex and extension to the spinal column or mediastinum. For chronic bronchopathy, pulmonary scintigraphy is performed after standard films in the preoperative work-up then is sometimes completed with other techniques. In cases of suspected pulmonary emboli, a normal scintigraphy can eliminate the diagnosis. Inversely, certain teams propose coupling perfusion scintigraphy with ventilation scintigraphy to detect mismatches, particularly distinctive signs of pulmonary emboli. When the diagnosis remains uncertain, pulmonary angiography is the reference imagery technique.