imaging findings associated with reactivation TB

What are the imaging findings associated with reactivation TB?

Postprimary or reactivation TB most often affects the apical or posterior segments of the upper lobes and less commonly the superior segments of the lower lobes. Imaging findings may include focal consolidation or nodular opacities, areas of cavitation, centrilobular, acinar, and/or tree-in-bud nodular opacities (due to endobronchial spread of infection), interstitial miliary nodules (due to hematogenous spread of infection), bronchiectasis, and thoracic lymphadenopathy (often with areas of central hypoattenuation due to necrosis on CT) (see Figure 18-13 ). When these findings are seen on imaging, one should alert the referring physician to the possibility of active TB.