Localization of Intrathoracic Lesions by Means of the Postero-Anterior Roentgenogram

Abstract

With the rapid advances in thoracic surgery, segmental localization of pulmonary disease has assumed greater importance. This has required that the roentgenologist use any method which may serve to localize disease processes within the thorax. The earliest method of localization was by means of stereoscopic films. Later, combined postero-anterior and lateral roentgenograms were employed. More recent refinements in this direction have included oblique views, laminagraphy, bronchography, etc. It is often helpful, if possible, to determine the exact location of a pulmonary density from the postero-anterior film alone. The following criteria, currently utilized, are of distinct value in such localization. An area of radiopacity involving the extreme apex of a lung is almost invariably situated in an upper lobe. One which involves a pulmonary costophrenic angle usually lies in a lower lobe. An abnormality in the right upper lung field, the lower border of which is delineated by the minor fissure, lies in the right upper lobe, and in like fashion, a density in the right mid-lung field with a sharp horizontal upper border lies in the right middle lobe.2 At times a lesion may erode a rib, the sternum, or a portion of the spine, thereby indicating its location. Similarly, displacement of the trachea or barium-filled esophagus may indicate the position of a mass. Rigler (4) has shown that disease processes in the lower lobes or posterior mediastinum, although covered by the heart shadow in the frontal view, may be recognized by the use of slightly overexposed films. However, even with the use of all of these measures, the majority of pulmonary lesions cannot be localized from the postero-anterior view alone. It is the purpose of this communication to stress a method of localization which has received scant attention in the literature. This method is based on the premise that an intrathoracic radiopacity, if in anatomic contact with a border of the heart or aorta, will obscure that border. To our knowledge, the first reference to this phenomenon was made by the late Dr. H. Kennon Dunham (2), who stated, more than fifteen years ago, that obliteration of the left border of the heart by a contiguous pulmonary density indicated disease of the lingula. Subsequently, Robbins and Hale (5), in their classical series of articles on the roentgen appearance of lobar and segmental collapse, made numerous references to obliteration of portions of the silhouette of the heart, aorta, and diaphragm by disease in the lung in contact with these structures. They pointed out that the lung in immediate proximity to the right border of the heart consists almost exclusively of middle lobe, and showed that disease in this location produces loss in definition of the right heart border. They also showed that disease of the lingula obscures the left cardiac border3. These findings have been re-emphasized recently by Walker (7), Townsend (6), and Temple and Evans (9).