HRCT Patterns of Pulmonary Tuberculosis and Their Correlation with Sputum Smear Positivity

Abstract

Background: Pulmonary tuberculosis remains a major public health concern, particularly in high-burden settings where sputum smear microscopy is still widely used despite limited sensitivity in early and paucibacillary disease. High-resolution computed tomography may provide complementary information by identifying radiological patterns associated with disease activity and bacillary burden. Objective: To determine the frequency of HRCT patterns in clinically suspected pulmonary tuberculosis and assess their association with sputum smear positivity. Methods: This cross-sectional observational study included 150 patients with clinically suspected pulmonary tuberculosis who underwent HRCT chest and sputum smear microscopy using Ziehl-Neelsen staining. HRCT findings, including consolidation, cavitation, tree-in-bud pattern, centrilobular nodules, ground-glass opacity, fibrosis, lymphadenopathy, laterality, and lobar extent, were compared between smear-positive and smear-negative groups using Chi-square testing, with odds ratios and 95% confidence intervals calculated for key associations. Results: Of 150 patients, 88 (58.7%) were smear-positive and 62 (41.3%) were smear-negative. Consolidation was the most frequent HRCT finding (72.0%), followed by tree-in-bud pattern (66.7%), centrilobular nodules (60.0%), and cavitation (48.7%). Cavitation showed the strongest association with smear positivity (OR 8.08, 95% CI 3.78-17.24), followed by tree-in-bud pattern (OR 4.15, 95% CI 2.02-8.51). Bilateral and multilobar involvement were also significantly associated with smear positivity, whereas ground-glass opacity was more frequent in smear-negative patients. Conclusion: Cavitation, tree-in-bud pattern, and greater disease extent on HRCT were strongly associated with sputum smear positivity, supporting the complementary role of HRCT in evaluating suspected pulmonary tuberculosis