- Start outside, work in – soft tissues, then bones, then lungs/heart, finally neck/infradiaphragmatic.
- Safety check – position of lines/tunes, check apices for pneumothorax, any foreign bodies?
- Rotation – look at symmetry of clavicles and anterior rib ends.
- If clavicles high, then lordotic film. May obscure apices.
- Penetration – should just be able to make out intravertebral spaces, without lung fields being too dark.
- Inspiration – hila become artificially prominent if underinflated.
Pesky thing! Can look like pneumonia. Latter more likely if air bronchograms, volume loss (displaced fissure/trachea/mediastinum), effusion. Classically:
- indentations where ribs overlie.
- Pointy outside edge (“sail sign”).
- No mass effect
- Lowish density – should still be able to see vascular markings of lung behind
Spinnaker sign is where pneumomediastinum around thymus creates long curving line.
Other normal things
Azygos lobe – normal variant where RUL has near vertical line extending up and out, giving impression of mediastinal mass.
Mach effect – a line parallel to heart border, looks like pneumocardium but actually optical illusion where your eye “detects” border where there isn’t one…
One diaphragm usually higher than other – both ok, as long as no more than 2cm (one rib space).
Hilum – rings or tram lines suggest bronchitis. Round opacity adjacent to and larger than ring suggests vascular prominence due to left to right shunt.
Silhouette sign – where heart border and/or diaphragm obscured in lower zone due to consolidation in lower lobe (left or right).
Effusion – vertical line at costophrenic angle.
Round pneumonia – will have air bronchograms, compare mass.
Collapse vs consolidation – sharp lower border is the fissure so if deviated then collapse.
Pneumothorax – lucency without clear edge may suggest lung hyperinflation eg bronchial atresia.
If edge projects below diaphragm then likely to be skin fold!
Foreign body – get expiratory film, which will enhance air trapping.