Focal or diffuse tracheal narrowing, wall thickening that spares or involves the posterior membrane, and dynamic collapse on expiration: stenosis after intubation, tracheobronchomalacia, relapsing polychondritis, amyloid, granulomatosis with polyangiitis and tumours.
Orient first
- Posterior membrane sparing: relapsing polychondritis, tracheobronchopathia osteochondroplastica (cartilage diseases).
- Posterior membrane involved: amyloid, GPA, tumour.
- Tracheobronchomalacia: > 50–70% expiratory collapse (verify threshold) on dynamic CT.
Acquire the study
- CT chest with thin sections, inspiratory and dynamic expiratory acquisitions; multiplanar and minimum-intensity airway reformats and virtual bronchoscopy.
The manoeuvre
- Airway reformats: length and minimal diameter of any stenosis in mm; distance from the vocal cords and carina.
- Wall thickening: circumferential vs sparing the posterior membrane; calcification.
- Dynamic expiratory acquisition: % reduction of cross-sectional area.
- Endoluminal mass: its base and extent.
What confirms it
- A mapped stenosis or collapse with a named pattern.
What licenses you to exclude it
- Normal calibre on inspiratory and expiratory images excludes significant central airway disease.
The classic misread
- Calling the normal expiratory bowing of the posterior membrane malacia.