Up to 40% of immune-sensitized TB contacts with normal chest radiographs (CXR) have abnormalities on conventional chest CT. FDG-PET/CT not only will allow characterization of the metabolic activity of these lesions but is also likely to reveal significantly increased metabolic activity within regional lymph nodes that may otherwise be anatomically normal. Based on previous studies, we predict that up to 65% of contacts will have combined chest PET/CT abnormalities and that up to 50% of contacts who are treated, will have increased FDG uptake that will resolve with treatment. By contrast, PET screening studies demonstrate abnormal pulmonary FDG uptake occurs in 0.9% of healthy individuals.