Spectrum of imaging findings in pulmonary infections. Part 1: Bacterial and viral

Abstract

Chest radiography is generally the first imaging modality used for the evaluation of pneumonia. It can establish the presence of pneumonia, determine its extent and location, and assess the response to treatment. Computed tomography is not used for the initial evaluation of pneumonia, but it may be used when the response to treatment is unusually slow. It helps to identify complications, detect any underlying chronic pulmonary disease, and also to characterise complex pneumonias. Although not diagnostic, certain imaging findings may suggest a particular microbial cause over others. Knowledge of whether pneumonia is community-acquired or nosocomial, as well as the age and immune status of the patient, can help us in narrowing the differential diagnoses. The purpose of this article is to briefly review the various pulmonary imaging manifestations of pathogenic organisms. This knowledge along with clinical history and laboratory investigations of the patient may help in guiding the treatment of pneumonia.

Keywords: bacterial; fungal; mycobacterial; parasitic; pneumonia; viral.

Figure 1

Streptococcal pneumonia in a 35-year-old patient. A) Chest radiograph showing right middle and lower zone consolidation (asterisk) and associated pleural effusion. B) Chest computed tomography shows the presence of consolidation in the right lower lobe (asterisk) with ground glass opacities in the periphery (arrow)

Figure 2

Staphylococcal pneumonia. A) Chest radiograph shows hydropneumothorax (white arrow) on the right side and consolidation with cavitation in the left mid and lower zones (asterisk). B) Chest computed tomography (CT) image shows presence of thick-walled cavity with rupture into right pleural cavity (asterisk) and thick-walled cavity, with adjacent centrilobular nodules, in left upper lobe (black arrow). C) Chest CT in a different patient shows cavitating nodules (white arrow). D) Chest CT in another patient showing pneumatoceles in right upper lobe, following staphylococcal pneumonia (white arrow)

Figure 3

Mycoplasma pneumonia in an adult patient. Chest computed tomography demonstrates peribronchial areas of consolidation with centrilobular nodules and adjacent ground glass opacities (long arrow)

Figure 4

Legionella pneumonia in an adult male patient. A, B) Sequential chest radiographs show the presence of rapidly progressing bilateral lobar consolidation. C) Chest computed tomography shows lobar consolidation (asterisk) with bilateral pleural effusion (block arrows)

Figure 5

Klebsiella pneumonia in two different patients. A) Chest radiograph in a paediatric patient typically shows lobar consolidation with bulging fissure (long arrow). B) Chest computed tomography in another patient with Klebsiella pneumonia demonstrates lobar consolidation with bulging fissure and air bronchogram (short block arrow)

Figure 6

Escherichia coli lung abscess in an adult patient. A) Chest radiograph shows presence of cavity with air fluid level (white asterisk) in right upper lung zone. B) Chest computed tomography of the same patient shows presence of thick walled cavitary lesion with air-fluid level in right upper lobe (white asterisk)

Figure 7

Aspiration pneumonia in two different patients. A) Chest radiograph shows presence of consolidation with breakdown and air fluid level in right lower lung zone and consolidation in left lower lung zone (long black arrows). B) Chest computed tomography image shows presence of thick-walled cavity with air-fluid level in bilateral lower lobes (short block arrows) posteriorly, consistent with aspiration

Figure 8

Post renal transplant patient with persistent fever and cough. Fine needle aspiration from the cavity showed Nocardia asteroids. A) Chest radiograph shows presence of multiple patches of consolidations with areas of cavitation in bilateral lungs. B, C) Chest computed tomography shows presence of patchy areas of consolidation with breakdown in left lower lobe (long white arrow) and right middle lobe (short white arrow). Diffuse areas of ground glass opacities are also seen in both lungs (block white arrow)

Figure 9

Patient with H1N1 viral pneumonia. A) Chest radiograph shows presence of bilateral consolidation with perihilar predominance. B) Chest computed tomography shows presence of bilateral perihilar consolidation (asterisk) with air bronchograms

Figure 10

A) Young infant with upper respiratory infection and cough. Chest radiograph shows presence of perihilar reticulonodular opacities with peribronchial thickening (long white arrow). B) Chest computed tomography in an adult patient shows presence of patchy ground glass opacities and centrilobular nodules in right middle lobe (short white arrow), right lower lobe, left lower lobe, and lingula with associated peribronchial thickening (black arrow)

Figure 11

MacLeod’s syndrome. Chest computed tomography images show presence of small-calibre left pulmonary artery (white arrow in A), associated bronchiectatic changes in left lower lobe (asterisk in B and D), and left lung hypoplasia with hyperinflated right lung

Figure 12

Cytomegalovirus pneumonia in a patient with febrile neutropenia. A) Chest radiograph shows presence of ground glass opacities in bilateral lungs. B) Chest computed tomography shows presence of diffuse ground glass opacities and ill-defined centrilobular and random nodules in bilateral lungs

Figure 13

Patient with Varicella pneumonia. A) Chest radiograph shows presence of diffuse nodular opacities in bilateral lung fields. B) Chest computed tomography image shows presence of multiple tiny centrilobular nodules and random nodules in bilateral lungs