Résumé
Background: distinguishing between latent TB infection (LTBI) and active TB disease remains a significant challenge in diagnostics. The positive predictive value (PPV) of existing diagnostic tools, such as the Interferon-Gamma Release Assay (IGRA) and chest radiography, is notably low. Despite the World Health Organization (WHO) not recommending Chest Computed Tomography (CT) for TB diagnosis, it may hold substantial value in high-income, low TB burden countries. This study evaluates the efficacy of combining Chest CT and IGRA for diagnosing active pulmonary TB and highlights specific CT features indicative of active disease. Methods: we conducted a retrospective analysis of 580 patients suspected of TB or exposed to bacteriologically confirmed cases. The participants underwent IGRA tests, Chest CT scans, and mycobacterial cultures. We analyzed Chest CT findings blindly and developed a composite score by integrating significant radiological signs with IGRA outcomes. We assessed diagnostic metrics, including sensitivity, specificity, PPV, and negative predictive value (NPV). Results: out of the cohort, 45 patients were diagnosed with active TB. IGRA tests alone showed low PPVs. However, CT findings, especially centrilobular nodules (OR, 7.18; 95% CI: 3.80-13.58), "tree in bud" patterns (OR, 9.56; 95% CI: 4.86-18.81), and necrotic lymph nodes (OR, 7.36; 95% CI: 2.07-26.18), were significantly associated with active TB (p<0.20). The composite score of these CT features and IGRA results yielded an area under the curve (AUC) of 0.8784, demonstrating high sensitivity (86.67%) and specificity (77.69%). Conclusion: integrating IGRA with Chest CT substantially enhances the diagnostic accuracy for active pulmonary TB, surpassing the performance of either method used independently.