Diagnostic Accuracy of High-Resolution Computed Tomography in Assessing Activity of Pulmonary Tuberculosis

Purpose: To evaluate the diagnostic accuracy of high-resolution computed tomography (HRCT) of the chest in detecting pulmonary tuberculosis (PTB), using acid-fast bacillus (AFB) smear microscopy as the reference standard. Methods: This cross-sectional validation study enrolled 135 patients with clinically suspected PTB who underwent HRCT chest and AFB sputum smear examination at a tertiary care centre. Study was conducted from 15th February 2025 to 20th May, 2025. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall diagnostic accuracy were derived from a 2×2 contingency table. Chi-square tests were applied to assess associations between HRCT findings and AFB results across demographic subgroups. Results: The mean patient age was 34.73 ± 11.87 years; 59.3% were male. AFB smear was positive in 46 patients (34.1%) and HRCT was positive for PTB in 55 patients (40.7%). HRCT demonstrated a sensitivity of 89.1%, specificity of 84.3%, PPV of 74.5%, NPV of 93.8%, and an overall diagnostic accuracy of 85.9%. The association between HRCT findings and AFB smear results was statistically significant (χ² = 67.7, p<0.001). Subgroup accuracy ranged from 81.7% to 89.0%, with sensitivity highest in non-smokers (94.4%), rural patients (96.2%), and those with symptoms of 1–2 weeks duration (100%). Conclusion: HRCT chest is a reliable imaging modality for diagnosing PTB with high sensitivity and NPV, making it particularly useful for excluding disease in clinically suspected but smear-negative patients. It can meaningfully supplement, though not replace, microbiological confirmation.