Radiological Examination of the Chest

Radiological Examination of the Chest

• Learning objectives:
  • Evaluate the quality of a chest X-ray (CXR)
  • Learn basic radiographic anatomy on a CXR
  • Be aware of the "hidden areas"
  • Learn CXR imaging findings in common and emergency conditions

Methods Used

• Chest X-ray (CXR)
• Computerised Tomography (CT)
• Magnetic Resonance (MR) or Ultrasound (US) (rarely)
• Angiography (very rarely)

Chest X-ray (CXR)

• Two projections:
  • Posterior-Anterior (PA)
  • Lateral
• Lateral projection:
  • Taken with the left side on the film side
  • Magnification effect is reduced
  • Heart appears smaller
• Lateral decubitus position:
  • Detects pleural effusion
  • Not frequently used anymore

Quality of a Good Image

• Full inspiration
• Penetration:
  • Dorsal vertebra barely seen through the heart
  • Vessels are visible
• Rotation:
  • Clavicles are not rotated
• Superposition:
  • Scapulae are not superimposed on the lungs

Anatomy

Trachea and Bronchi

• Trachea:
  • Located to the right of the aortic arch
  • Radiolucent (black)
• Bronchi:
  • Large airways are radiolucent (black)
  • Trachea at the midline

The Hilum

• Main pulmonary bronchi
• Main pulmonary arteries

Lung Zones

• CXR is interpreted in zones, not lobes

Pleura

• Only visible in pathologic conditions

Lung Lobes and Fissures

• Both lungs have oblique fissures
• Right lung has a horizontal fissure
• Accessory fissures:
  • Azygos fissure and lobe (most common, 1-2%)

Costophrenic Angle and Recess

• Between the lateral chest wall and diaphragm
• Should be sharp and clearly visible
• Diaphragm:
  • Right side is higher than left
  • Stomach air is below the left diaphragm

Heart

• Cardiothoracic Ratio:
  • Lower than CT

Pneumonia

• Air Bronchogram

Tuberculosis

Primary Tuberculosis

• Initial infection
• Mostly in children, but rate increases in adults (25-35% of all adult cases)
• CXR is normal in 15%
• Features may overlap with reactivation
• Differentiation not always possible
• Parenchymal focus:
  • Dense consolidation in any lobe
  • Similar appearance to bacterial pneumonia
  • Lack of response to antibiotics
• Lymphadenopathy:
  • Seen in 96% of children and 43% of adult cases
  • Can be the only finding, especially in children
  • Calcified LAP + Ghon focus = Ranke complex
• Miliary Disease:
  • 1-7% of all forms of TBC
  • Elderly, infants, immunocompromised patients
  • Evenly distributed 2-3 mm sized nodules

Postprimary Tuberculosis

• Primarily a disease of adolescence and adulthood
• Re-infection or reactivation
• Progressive
• Cavitation
• Causes hematogenous spread
• Endobronchial:
  • Tree-in-bud pattern

Chronic Obstructive Pulmonary Disease (COPD)

• Resistance to expiratory airflow
• CXR is highly specific
• Hyper-expanded lungs with flattening of both hemi-diaphragms
• Barrel-shaped chest

Foreign Body Aspiration

• Symptoms: Asymptomatic > Choking
• CXR:
  • Foreign body may or may not be seen