Diagnostic Value of Unenhanced Chest CT Scan forActive Pulmonary Tuberculosis

Background: Pulmonary tuberculosis (PTB) is a common infectious disease, CT scan as a supplementary diagnostic method to faster treatment could be use. Purpose: To assess diagnostic value of Unenhanced Chest CT Scan for Active Pulmonary Tuberculosis. Method: prospective cross-sectional study performed in suspected tuberculosis patients admitted to Bu-Ali-Sina hospital in Zahedan city during 6 years from March 2014 to November 2020. Chest CT-Scan findings compared with culture of tuberculous or bacilli Bacillus Koch Polymerase Chain Reaction (BK-PCR) then accuracy of chest CT-Scan manifestations in positive and negative smear of Acid Fast Bacilli (AFB) patients was analysis. Result: Data of 130 PTB patients with mean age 53 entered in the study. 50.8 % were man and 49.20 % were woman. 85.4% were smear positive (35.5% +, 32.3% ++, 17.7% +++) and 14.6 % were smear negative. The certain CT-Scan manifestations had taken Centrilobular nodule (61.5%), cavitation (45.4%) and tree in bud (49.2%). Specificity, sensitivity, positive and negative pre value, youden index and likelihood ratio of certain CT scan findings (23.1%) for diagnosis PTB in patients with +1 AFB smear, (P=.20) was 58.7%, 62%, 56.7%, 71%, 0.12 and 2.5. In patients with +2 AFB smear, (P=.02) were 81.3%, 47.4%, 52.9%, 77.3%, 0.28 and 2.49. In patients with +3 AFB smear, (P=.23) was 46.2%, 72.4%, 49.2 %, 75%, 1.64 and 0.18. and in patients with negative AFB smear, (P=.57) was 25%, 86.7%, 33.3%, 81.3%, 0.11 and 1.87. Conclusion: There was a significant relationship between certain manifestations of PTB on chest CT scan and positive culture or BK-PCR test (P =.01, likelihood ratio>1) in suspicious PTB patients. Chest CT scan is a combination diagnostic method in patient with unreliable laboratory findings.