Question 1

What is the ABCDE approach to chest X-ray interpretation?

Accepted Answer

The ABCDE approach ensures systematic CXR reading: A — Airway (trachea midline, carina angle <70°, main bronchi); B — Breathing (lung fields, pleural spaces, pneumothorax, effusion, consolidation); C — Cardiac (heart size <50% of thoracic width, borders, aortic knuckle); D — Diaphragm (right higher than left, costophrenic angles sharp, free air under diaphragm); E — Everything else (bones, soft tissues, lines, tubes, foreign bodies). Always check the technical quality first (RIPE: Rotation, Inspiration, Projection, Exposure) before interpreting.

Question 2

When should a GP request a CT scan versus an MRI?

Accepted Answer

CT is preferred for: acute emergencies (stroke, PE, aortic dissection, trauma), bony detail, lung parenchyma, abdominal organs, and when speed is critical. CT is fast (seconds) but uses ionising radiation (~10 mSv for CT abdomen/pelvis). MRI is preferred for: soft tissue detail (brain, spinal cord, joints, liver lesions), posterior fossa pathology, suspected spinal cord compression, and when radiation must be avoided (pregnancy, children). MRI takes 30–60 minutes and is contraindicated with certain metallic implants. For GP referrals, use iRefer (RCR) guidelines and always state the clinical question clearly.

Question 3

What are the key radiological signs of tension pneumothorax on CXR?

Accepted Answer

Tension pneumothorax on CXR: complete absence of lung markings on the affected side; tracheal deviation AWAY from the affected side (pushed by pressure); mediastinal shift away from the affected side; flattening or inversion of the ipsilateral hemidiaphragm; widened intercostal spaces on the affected side. CRITICAL: Tension pneumothorax is a clinical emergency — do NOT wait for CXR if the patient is haemodynamically compromised. Immediate needle decompression (2nd intercostal space, mid-clavicular line) followed by chest drain insertion is life-saving.

Lobe	Key Signs
Right Upper Lobe	Elevated right hilum; trachea deviated right; opacity in right upper zone
Right Middle Lobe	Loss of right heart border (silhouette sign); triangular opacity at right heart border
Right Lower Lobe	Loss of right hemidiaphragm; triangular opacity behind heart; right hilum pulled down
Left Upper Lobe	Veil-like opacity over left lung; loss of left heart border; Luftsichel sign (crescent of air)
Left Lower Lobe	Loss of left hemidiaphragm; triangular opacity behind heart; left hilum pulled down

Radiology for GPs

Systematic ABCDE Approach

Common CXR Findings

Lobar Collapse — Silhouette Signs