Tuberculosis

Tuberculosis (TB) is an airborne infection caused by Mycobacterium tuberculosis, an obligate aerobe, nonmotile, non-spore-forming bacillus. TB is a major cause of morbidity and mortality especially in developing countries. Patients with impaired cellular immunity including HIV (+), elderly, prisoners, and indigents and homeless patients have an increased susceptibility for active TB disease. Primary infection usually resolves without complications in immunocompetent patients. The most common radiologic manifestations of primary TB in children are consolidation and lymphadenopathy. Progressive primary TB with widespread hamatogenous dissemination may rarely occur. Patchy or nodular opacities in the upper lobes with associated cavitation are characteristic radiologic findings of active infection. While this pattern often correlates with relatively spared immunity, it denotes highly infectious individuals who require isolation.CT is very sensitive for the detection of bronchogenic spread of infection manifesting with discrete nodules, tree-in-bud opacities and cavitation.Miliary TB refers to hematogenous spread of infection.