Which imaging modalities are commonly used to assess TB disease extent and involvement?

• A. Chest X-ray and CT
• B. Ultrasound alone
• C. MRI alone
• D. PET scan alone

Answer: (A)

Imaging to determine TB extent relies on chest radiography and CT. A chest X-ray is the first-line tool to detect pulmonary TB and to gauge the overall burden, showing upper-lobe infiltrates, cavitation, effusions, and general distribution of disease. CT adds detailed cross-sectional information that reveals smaller nodules, precise cavitation, bronchiectasis, and involvement of mediastinal or hilar lymph nodes, pleura, or extrapulmonary sites. This makes CT particularly helpful when the disease is complex or when confirming the full extent of disease is crucial for treatment planning. Other modalities have more limited roles in routine TB assessment: ultrasound can help identify pleural effusion or certain abdominal findings but doesn’t comprehensively evaluate the lungs; MRI provides excellent soft-tissue detail but is not standard for lung TB (more commonly used for CNS or spinal involvement); PET scans show metabolic activity but aren’t routinely used due to cost and lack of specificity in granulomatous infections, though they may be considered in specific, challenging cases. So the combination of chest X-ray and CT is the most commonly used approach to evaluate TB disease extent and involvement.