Thoracic Radiology
Thoracic Radiology
This domain tests pattern recognition on chest radiography and HRCT: consolidation, ground-glass, reticulation, nodules, cavitation, pleural disease, mediastinal compartments, and lung cancer staging.
Core rules
- Air bronchograms favor consolidation from alveolar filling; volume loss with fissure displacement favors atelectasis. The silhouette sign localizes opacity to an adjacent structure.
- Nodule distribution: centrilobular reflects bronchiolar disease (tree-in-bud in infection or aspiration; respiratory bronchiolitis in smokers), perilymphatic suggests sarcoidosis or lymphangitic spread, and random suggests hematogenous metastases or miliary TB.
- UIP pattern: basal, subpleural reticulation, honeycombing, traction bronchiectasis, and minimal ground-glass. NSIP shows basal ground-glass with reticulation but less honeycombing. Organizing pneumonia causes patchy peripheral consolidation.
- Mediastinal compartments: prevascular (thymoma, lymphoma, teratoma), visceral (lymphadenopathy, foregut cysts), and paravertebral (neurogenic tumors).
Worked example
A 68-year-old man has 2 years of exertional dyspnea. HRCT shows subpleural basal honeycombing and traction bronchiectasis without extensive ground-glass. This is a UIP pattern; in the correct clinical context it supports idiopathic pulmonary fibrosis without surgical biopsy. If instead there were profuse ground-glass and no honeycombing, NSIP or hypersensitivity pneumonitis would enter the differential.
Traps
Calling every upper-lobe nodule sarcoidosis; missing a subtle apical pneumothorax; misreading ground-glass as consolidation; using PET to characterize small subsolid nodules; forgetting that cavitation occurs in TB, malignancy, and vasculitis.