Diagnosing Tuberculosis with Chest X-ray

Primary Radiographic Findings

Chest radiography is the first-line imaging modality for diagnosing tuberculosis, with typical findings including upper lobe infiltrates, cavitation, and fibro-cavitary disease in the apical and posterior segments of the upper lobes or superior segments of the lower lobes, as recommended by the American College of Radiology 1, 2
Infiltrates can be patchy or nodular in appearance, according to the MMWR Recommendations and Reports 3, 4

Lobar pneumonia with hilar and/or mediastinal adenopathy is a characteristic finding in primary TB, more common in children and severely immunocompromised individuals, as noted by the American College of Radiology 1, 5, 6
Apical posterior upper lobe or superior segment lower lobe fibro-cavitary disease is a typical finding in postprimary/Reactivation TB, with endobronchial spread through airways, as described by the American College of Radiology 1, 6

Atypical radiographic presentation is common in HIV-infected patients, with apical cavitary disease being less common than in HIV-negative patients, and more common findings including infiltrates in any lung zone, mediastinal or hilar adenopathy, as reported by the MMWR Recommendations and Reports 3, 4
CT should be considered for immunocompromised hosts, particularly those with low CD4 counts, as recommended by the American College of Radiology 5, 7

CT is recommended when chest x-ray is equivocal, as it increases specificity of diagnosis by better showing cavitation or endobronchial spread with tree-in-bud nodules, according to the American College of Radiology 1, 2, 5, 8
CT findings can help predict acid-fast bacilli smear positivity, as noted by the American College of Radiology 8

Perform frontal chest radiograph as initial imaging, and consider CT if chest radiography is equivocal, patient is immunocompromised, or classic findings are not present on chest x-ray, as recommended by the American College of Radiology and MMWR Recommendations and Reports 1, 2, 3, 5, 8
If radiographic findings are consistent with TB, proceed with sputum examination, as recommended by the MMWR Recommendations and Reports 3, 4