The Roentgen Appearance of Lobar and Segmental Collapse of the Lung

Abstract

The purpose of this paper is to present certain signs which are of value in the recognition of collapse of an entire lung, or the major part thereof. Because of the existing confusion in the use of the terms “collapse” and “atelectasis,” we have arbitrarily chosen “collapse” to mean a decrease in size and “atelectasis” to indicate airless alveoli which are smaller than normal. No attempt will be made to discuss the etiology of collapse. From a total of approximately 85,000 chest examinations conducted at the Massachusetts General Hospital during the past seven years, we reviewed in detail 1,200 in which a diagnosis of tumor, bronchiectasis, foreign body, or tuberculosis was made. After discarding the cases in which the roentgenograms were inadequate (films in two projections, the posteroanterior and lateral, being considered the minimal requirement for determining the size of a lobe or its segments), approximately 600 remained in which at least one lobe was less than two-thirds of its normal size. Only collapse produced by intrinsic disease of the lung was included; collapse attributable to extrinsic factors, as pneumothorax, pleural fluid, or a pleural tumor, was excluded. Analysis of this group of 600 cases revealed that collapse was limited to a single lobe, or segment, in 71 per cent, that it involved two or more lobes in 18 per cent, and was massive in 11 per cent. Collapse of the left lung was more frequently observed than collapse of the right lung. The various lobes were involved as follows: left lower lobe, 42 per cent; right lower lobe, 26 per cent; right middle lobe, 26 per cent; left upper lobe, 8 per cent; right upper lobe, 8 per cent. The percentage of cases with extensive collapse would have been greater had all the cases in which massive collapse followed operative procedures been included. In many of these patients, however, examination was limited to a single portable roentgenogram, which was insufficient to warrant their inclusion in this study. Since our present interest is to describe as accurately as possible the findings in collapse of an entire lung, or the greater portion of a lung, a group of 30 cases in which the requisite number of roentgenograms were available was selected as a basis for our conclusions. Detailed description of collapse of the various lobes will be presented in subsequent papers. Collapse of an entire lung, whether it be acute or chronic, usually shows the characteristic roentgenologic signs by which collapse has long been recognized (1b, 2, 3, 4): an abnormal shadow of increased density, elevation of the diaphragm, displacement or shift of the mediastinum, and narrowing of the rib spaces. In acute collapse of the lung, the shadow of increased density is as a rule homogeneous, indicating complete atelectasis, although certain segments of some lobes may not be atelectatic. The structure of the involved lung, including the hilar shadow and septa, is obscured.