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Understanding Chest X-Rays for Lung Disease

Sep 2, 2024

Interpreting Chest X-Rays: Focal Lung Disease

Learning Objectives

  • Identify, localize, and describe focal opacities, particularly pneumonia.
  • Understand varied appearances of pulmonary nodules and cavitations with their differential diagnosis.

Lobar Anatomy and Radiographic Zones

Right Lung

  • Horizontal Fissure: Often visible on PA view, level of hilum, not usually on lateral view.
  • Right Upper Lobe: Superior region.
  • Right Middle Lobe: Makes a wedge shape from the side.
  • Right Lower Lobe: Inferior portion, extends up to the aortic arch.

Left Lung

  • Left Upper Lobe (Anterior Lobe): Front section.
  • Left Lower Lobe (Posterior Lobe): Rear section.

Lung Zones

  • Apical Zone: Above clavicle.
  • Upper Zone: Clavicle to superior hilum.
  • Mid Zone: Level of hilum.
  • Lower Zone: Below hilum.
  • Note: These zones differ from pulmonary physiology zones.

Focal Opacities

Terminology

  • Opacity, Infiltrate, Consolidation: Often used interchangeably; consolidation is a dense opacification.
  • Silhouette Sign: Loss of normal visibility of a border due to an adjacent density.
    • Examples of obscured borders: Right Upper Lobe with ascending aorta, Right Middle Lobe with heart border, etc.
  • Spine Sign: Increased opacification overlying spine, suggests lower lobe opacities.

Etiologies

  • Infections: Pneumonia (bacterial, viral, fungal, mycobacterial).
  • Malignancies: Primary lung cancer, metastatic disease, lymphoma.
  • Others: Pulmonary infarction, hemorrhage, vasculitis, eosinophilic pneumonia.

Pneumonia Types

  • Lobar Pneumonia: Homogenous consolidation, air bronchograms, sharp borders.
  • Segmental Pneumonia (Bronchopneumonia): Patchy opacification, bilateral, no air bronchograms.
  • Interstitial Pneumonia: Reticular pattern, develops into airspace disease.
  • Round Pneumonia: Spherical shape, common in children, can mimic tumors.
  • Cavity Pneumonia: May have air-fluid levels, seen in TB and staph infections.

Pulmonary Nodules

  • Solitary Pulmonary Nodule: Well-circumscribed, <3 cm. Larger is a lung mass.
  • Evaluation: Compare prior x-rays, adjust contrast for visibility.
  • Differential Diagnosis: Includes cancer, granulomas, round pneumonia, congenital issues.
  • Multiple Nodules: Broader differential includes infectious causes, rheumatoid arthritis, vasculitis, amyloidosis.

Pulmonary Embolism and Cavitation

  • Pulmonary Embolism: Rarely visible; findings include Hampton's hump, Westermarck sign, Fleischner sign.
  • Cavitating Lung Lesions: Include pneumonia, lung abscess, TB, metastatic diseases, pulmonary infarcts, Wegener's granulomatosis, rheumatoid nodules, pneumatocele, aspergilloma.

Conclusion

The video covers identification, localization, and description of focal lung diseases, particularly emphasizing pneumonia types and pulmonary nodules. Next video will discuss atelectasis, lines, tubes, devices, and prior surgeries.

Full transcript