Volume 137, Issue 2, Pages 467-479 (February 2010) Diagnostic Utility and Clinical Application of Imaging for Pleural Space Infections  John E. Heffner, MD, FCCP, Jeffrey S. Klein, MD, FCCP, Christopher Hampson, MD  CHEST  Volume 137, Issue 2, Pages 467-479 (February 2010) DOI: 10.1378/chest.08-3002 Copyright © 2010 The American College of Chest Physicians Terms and Conditions

Figure 1 The frontal radiograph (A) shows right-sided subpulmonic and loculated lateral pleural effusion and a pseudotumor in the medial, mid-lung field. The lateral projection (B) localizes the pseudotumor to the upper major fissure. The pseudotumor appears more rounded than the usual lenticular appearance. A contrast-enhanced chest CT slice (C) confirms the pseudotumor to be a loculated pleural effusion within the major fissure (arrow), with additional lateral and posterior locules. The CT scan does not visualize costal pleural membranes in the left hemithorax; what appear to be pleural membranes (arrowheads) actually represent a combination of visceral and parietal pleurae, physiologic pleural fluid, fascia, and the innermost intercostal muscles. CHEST 2010 137, 467-479DOI: (10.1378/chest.08-3002) Copyright © 2010 The American College of Chest Physicians Terms and Conditions

Figure 2 Frontal chest radiograph that demonstrates an air-fluid level within rounded density (arrow) that suggested a lung abscess in a patient with multiloculated empyema involving the right apex and paramediastinal pleurae. Contrast-enhanced CT scan (B) through the lower thorax showed fluid collections in the major fissure (F) and posteriorly with a cavitary abscess in the right lower lobe (arrow). The hilum is poorly defined on the frontal radiograph because of a paramediastinal fluid collection confirmed by CT scan (CT image not shown). CHEST 2010 137, 467-479DOI: (10.1378/chest.08-3002) Copyright © 2010 The American College of Chest Physicians Terms and Conditions

Figure 3 Frontal (A) and lateral (B) radiographs demonstrate a subpulmonic effusion with apparent elevation of the right diaphragm with a laterally displaced apex (arrow in A). In B, note the sloping interface (white arrows) between the effusion (*) and the middle lobe anterior to the major fissure (solid arrow). This appearance results from the oblique interface between the subpulmonic effusion and the middle lobe anterior to the major fissure, as the lung-fluid interface fails to create a sharp tangent to the lateral x-ray beam and therefore is not evident radiographically. CHEST 2010 137, 467-479DOI: (10.1378/chest.08-3002) Copyright © 2010 The American College of Chest Physicians Terms and Conditions

Figure 4 Frontal radiograph (A) of a patient with multilocular empyema demonstrating obscuration of the left hemidiaphragm by lung consolidation and pleural fluid and an ill-defined density in the medial, midlung field (arrow). The lateral view (B) demonstrates a nondependent loculated empyema (arrows) with the “d-sign.” CHEST 2010 137, 467-479DOI: (10.1378/chest.08-3002) Copyright © 2010 The American College of Chest Physicians Terms and Conditions

Figure 5 Supine portable radiograph (A) in a patient with large posterior bilateral pleural effusions that demonstrates increased density over both lung fields. The CT scan (B) shows the large effusions layering posteriorly. Passive atelectasis of the left and right lung (arrows) is demonstrated in this contrast-enhanced study. The homogeneity of the atelectatic lung on all sections excludes lung necrosis or abscess There is no evidence of parietal pleural thickening or enhancement on this CT level. CHEST 2010 137, 467-479DOI: (10.1378/chest.08-3002) Copyright © 2010 The American College of Chest Physicians Terms and Conditions

Figure 6 Portable radiograph (A) of a large left pleural effusion in a patient with mediastinal lymphoma (note mediastinal widening and obscuration of aortic arch) that demonstrates crescentic fluid density (arrow) over the lung apex. A contrast-enhanced CT scan (B) shows the left pleural effusion with the enhancing atelectatic left lung sharply delineated from the effusion. CHEST 2010 137, 467-479DOI: (10.1378/chest.08-3002) Copyright © 2010 The American College of Chest Physicians Terms and Conditions

Figure 7 Frontal radiograph of a patient with a pleural effusion that collects within an incomplete right major fissure, which creates a perihilar lucency outlined peripherally by a circumscribed concave opacity. CHEST 2010 137, 467-479DOI: (10.1378/chest.08-3002) Copyright © 2010 The American College of Chest Physicians Terms and Conditions

Figure 8 Sonogram of a normal patient shows a thin echogenic interface between the normal visceral pleura and underlying lung deep to the ribs that produces the normal pleural stripe (arrows). CHEST 2010 137, 467-479DOI: (10.1378/chest.08-3002) Copyright © 2010 The American College of Chest Physicians Terms and Conditions

Figure 9 The frontal radiograph (A) suggests a right parapneumonic effusion, which is confirmed by sonographic evidence (B) of a characteristic triangular anechoic fluid collection immediately above the diaphragm. Eff = effusion; L = lung; Li = liver. CHEST 2010 137, 467-479DOI: (10.1378/chest.08-3002) Copyright © 2010 The American College of Chest Physicians Terms and Conditions

Figure 10 Sonographic appearance of parapneumonic effusions with the patterns of homogeneously anechoic (asterisk denotes fluid) (A), complex nonseptated with internal echogenic foci (B), complex septated (C), and homogeneously echogenic (D). Most complicated parapneumonic effusions and empyemas have internal echoes or appear entirely echogenic. “L” denotes lung and curved arrow identifies the diaphragm. CHEST 2010 137, 467-479DOI: (10.1378/chest.08-3002) Copyright © 2010 The American College of Chest Physicians Terms and Conditions

Figure 11 Pyopneumothorax due to bronchopleural fistula complicating lung abscess. (A) Upright chest radiograph shows a large right hydropneumothorax with small air-fluid level in consolidated right mid lung (arrow). (B) Contrast-enhanced CT shows a cavity with air-fluid level (white arrow) reflecting an abscess within the consolidated middle lobe. There is a large right hydropneumothorax with thickening and enhancement of the parietal pleura (black arrow). (C) Sagittal reformatted image through the middle lobe abscess shows a large bronchopleural fistula (white arrows) extending posterosuperiorly from the abscess cavity to the posterior hydropneumothorax. Purulent material was recovered at surgery. CHEST 2010 137, 467-479DOI: (10.1378/chest.08-3002) Copyright © 2010 The American College of Chest Physicians Terms and Conditions

Figure 12 A patient with two chest tubes in the right hemithorax that drain a parapneumonic effusion. There is asymmetric thickening of the right posterolateral chest wall and expansion of the extrapleural fat (black straight arrow) due to edema, findings commonly observed with empyemas. A small amount of pleural fluid remains posteriorly (curved arrow). The left hemithorax demonstrates the normal appearance of the inner cortices of the ribs wherein no tissue can be visualized adjacent to the lung (arrowhead). In contrast, the finding of even a thin layer of tissue along the inner rib cortices establishes pleural thickening or effusion (white arrow). CHEST 2010 137, 467-479DOI: (10.1378/chest.08-3002) Copyright © 2010 The American College of Chest Physicians Terms and Conditions

Figure 13 CT image of a patient with a subpleural lung abscess (upper short arrow) and an adjacent region (lower short arrow) of either loculated pleural fluid of high attenuation or pleural thickening. Additional high-attenuation pleural fluid or thickening is seen posteriorly (long arrow). CHEST 2010 137, 467-479DOI: (10.1378/chest.08-3002) Copyright © 2010 The American College of Chest Physicians Terms and Conditions

Figure 14 A CT image of a patient with empyema demonstrating enhancing rims of parietal and visceral pleurae (short arrows) surrounding a loculated pleural fluid collection (split pleura sign). Note the hypertrophied extrapleural fat (long arrows) due to the chronic thickening and retraction of the pleural layers, which are commonly associated with empyemas. CHEST 2010 137, 467-479DOI: (10.1378/chest.08-3002) Copyright © 2010 The American College of Chest Physicians Terms and Conditions