Imaging Of Pulmonary Tuberculosis



Tuberculosis (TB) in one of the most important infections worldwide, especially in the context of concomitant HIV infection and it still remains a global emergency. The radiographic appearance of pulmonary TB does not depend on the time since infection .Indeed, the findings of active TB result from a balance between the host immune response and mycobacterial virulence primary infection and infection in HIV+ patient with CD4200 commonly causes patchy consolidations, cavitation, miliary disease and pleural effusion. Endobronchial spread is a feature of post primary tuberculosis.
Active TB can sometimes mimic sarcoidosis by interlobular septal thickening and galaxy of nodules. In these cases, absence of mediastinal lymphadenopathy and presence of tree in bud can suggest TB. After treatment of TB, cavities may remain. These cavities can be secondarily infected with aspergillosis. An important clue to mycetoma formation is pleural thickening of the remaining cavity wall.
No change in radiologic findings in 4-6 months means radiologic stability but this does not exclude activity of infection clinically. Computed tomography (CT) is more sensitive than plain films for detection of signs of activity (like small cavities and tree in bud)
Before starting anti TNF-α (tumor necrotic factor α) drugs (infliximab, adalimumab,…) it is mandatory to obtain chest x-ray and look for signs of active infection or residual lesions.
In some cases CT scan may also be indicated, because TNF-α antagonist therapy may result in granuloma break down and dissemination of mycobacteria. These patients may have unusual TB presentations like pleural and pericardial effusion which make precise diagnosis difficult.