Segmental localization of pulmonary disease on the postero-anterior chest roentgenogram.

Abstract

With the advent of bronchoscopy and bronchography and especially under the influence of modern thoracic surgery, the sublobar divisions of the lung have come to be recognized as important units. The term “bronchopulmonary segment,” although applicable to any area of lung supplied by a bronchus, has through common usage come to designate that portion supplied by a tertiary bronchus. The importance of these pulmonary segments in pathogenesis, diagnosis, and treatment of many lung diseases is now widely recognized. To the specialist in pulmonary diseases, the distribution of certain segments and the direction of their draining bronchi explain the effects of gravity on the localization of lung abscess (4) and suggest more effective methods of postural drainage for lungs and bronchi (12). To the thoracic surgeon, segmental resection for bronchiectasis (7), tuberculosis (5, 6), and other diseases, presents an opportunity for conservation of pulmonary tissue and pulmonary function. The bronchopulmonary segments are consequently of interest to all clinicians having occasion to study chest roentgenograms. Attention has been called to the radiographic appearance of segmental pulmonary disease (16) and to the influence of retrocardiac processes on the contour of the cardiac silhouette (9, 15). The extent, however, to which segmental localization of pulmonary disease can be recognized from the conventional posteroanterior chest roentgenogram, is not fully appreciated. By applying the principles of x-ray projection to the three-dimensional anatomy of the bronchopulmonary segments, the writer has found it possible, in most instances, to determine from the routine chest film the anterior or posterior location of lung processes, as well as the segment involved. The following schematic presentation is offered as a guide to segmental localization on the postero-anterior chest roentgenogram. It is not intended to exclude the use of oblique or lateral films, or to minimize either the importance of lateral chest planigraphy for accurate preoperative localization of tuberculosis or the need for bronchography in mapping out the extent of surgery for bronchiectasis. Lobes For orientation, it may be well to review the five lobes into which the two lungs divide, as well as the commonly recognized accessory lobes. Although the lobe formations are not always separated by fully developed fissures, the appearance of their total involvement as seen on the posteroanterior chest film must be distinguished from that of their component segments. The distribution of the three lobes of the right lung and the two lobes of the left lung, as well as the extent to which they overlap the contours of heart, diaphragm, and adjacent lobes, is shown in the three-dimensional drawing in Figure 1.