Abstract: Objective To evaluate the diagnostic value of chest CT for interferon-gamma release assay negative pulmonary tuberculosis. Methods A total of 126 patients were collected from the Department of Respiratory and Tuberculosis of Tianjin Haihe Hospital from January to June 2018, including 28 cases of confirmed tuberculosis and 98 cases of non-tuberculosis. All patients were tested negative by T-Spot.TB test. Using chest CT plain scan, 126 patients were graded into 0-3 grades, and the diagnostic value of each grade for tuberculosis was evaluated. Results Compared with the non-diagnosed patients, chest CT showed that the lesions were mainly located in the posterior apical segment of the upper lobe and the dorsal segment of the lower lobe in patients with confirmed diagnosis. The main manifestations were tree bud sign, core nodules of lobules, large nodules and consolidation of lobules. The three class score was used as the standard diagnosis of pulmonary tuberculosis. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were 60.7%, 89.8%, 83.3%, 63% and 88.9%. The two class score was used as the standard diagnosis, they were 100%, 78.6%, 83.3%, 57.1% and 100%. The one class score was used as the standard diagnosis, they were 100%, 60.2%, 69.0%, 41.8% and 100%. Conclusion Chest CT scoring system can screen false negative subjects in T-Spot. TB test and can effectively improve the detection rate of tuberculosis.

Key words: tuberculosis, pulmonary, tomography, X-ray computed, interferon-gamma release tests, diagnosis, differential, chest CT score