It is traditionally considered that someone with a positive tuberculin skin test (TST) (and/or positive result in Cell Interferon-Gamma Release Assay (TIGRA), depending on the different countries' guidelines) is infected but not ill when the absence of lesions is demonstrated in a thorax X-Ray assay. Even though, the experiences described in literature using cows and pigs as animal models for the study of LTBI demonstrate the presence of this kind of lesion in the animals, even too small to be detected by X-Ray assay, which would suggest they also could happen in human LTBI. Nowadays, the High Resolution Scanners (HR TC) offer the possibility of detecting any lesion approximately 1 mm in diameter, so the investigators plan to use this technique to screen people already infected by M. tuberculosis (but not ill, following the Diagnosis Standard Guidelines).