Thoracic Imaging
The Thoracic Imaging domain tests pattern recognition on chest radiograph and CT, application of nodule guidelines and rapid triage of acute thoracic disease.
Pattern vocabulary
- Consolidation with air bronchograms indicates alveolar filling; ground-glass opacity spares vessels; reticulation and honeycombing indicate fibrosis.
- Distribution matters: upper-zone fibrosis suggests sarcoidosis, silicosis, ankylosing spondylitis or tuberculosis; basal subpleural honeycombing with traction bronchiectasis is the usual interstitial pneumonia (UIP) pattern.
- Perilymphatic nodules follow fissures, pleura and bronchovascular bundles (sarcoidosis); centrilobular nodules spare the pleura (aspiration, infection).
Nodules
Fleischner 2017 applies to incidental solid nodules in patients aged 35 years or older, not to screening or immunosuppressed patients. Measure the average of long and short axis. Solid nodules 6-8 mm: CT at 6-12 months; more than 8 mm: PET/CT, biopsy or CT at 3 months. Subsolid and ground-glass nodules need longer follow-up because they grow slowly.
Acute disease
CT pulmonary angiography is first line for pulmonary embolism; right ventricular enlargement (RV/LV ratio above 1) and septal bowing flag severity. Stanford type A dissection involves the ascending aorta and needs urgent surgery; type B spares it.
Worked example
A 62-year-old smoker has an incidental 7 mm solid nodule, no prior imaging. It measures 7 mm average, so it falls in the 6-8 mm band; Fleischner advises follow-up CT at 6-12 months rather than immediate PET, because PET has low sensitivity for small nodules and pre-test probability is modest. Document the recommendation and compare with any older study.
Traps
Applying Fleischner to lung cancer screening (use Lung-RADS) or to a 30-year-old; quoting the long axis alone; missing a prior CT that would show stability for two years.