The influence of the lordotic projection on the interpretation of the chest radiograph

The advantages of the lordotic projection, particularly in elucidating suspected pathology at the lung apex, are well known. However, the distortion and artefact of the images of thoracic structures produced by this projection can lead to diagnostic errors. In order to determine the differences in the images produced we compared 14 pairs of lordotic and standard chest radiographs, taken within 24 h of each other, in the same patients. The main artefacts seen in the lordotic views were apparent elevation of the diaphragm, poor visualisation of the lung bases, loss of definition of the aortic knuckle, and apparent widening of the superior mediastinum. These artefacts were greatly exaggerated when lordosis coexisted with pathology, or technical factors such as patient rotation or inadequate respiration. Caution should be exercised to avoid misinterpretation of lordotic films.