Abstract: Objective To analyze the chest CT features of two kinds of common slow growing nontuberculous mycobacterial pulmonary diseases and improve the understanding of their imaging signs. Methods 63 patients with pulmonary disease caused by Mycobacterium Kansas (group A) and 60 patients with pulmonary disease caused by Mycobacterium avium cytoplasmic complex (MAC) (group B) in Guangzhou chest hospital from January 2018 to December 2020 were collected. The two groups of patients met the diagnostic criteria for pulmonary disease caused by nontuberculous Mycobacterium. The CT signs of group A and group B were retrospectively analyzed. Results ①The proportion of women, age and the proportion of bronchiectasis in group B were significantly higher than those in group A (all P<0.05). ②Columnar bronchiectasis accounted for 21.74% (10/46) in group A and 48.15% (26/54) in group B; The percentage of cystic bronchiectasis was 43.48% (20/46) in group A and 22.22% (12/54) in group B (P<0.05). ③In group B, 40 cases (74.07%) showed right middle lobe bronchiectasis and 38 cases (70.37%) showed left lingual bronchiectasis; There was significant difference between the two groups (t = 5.881, P= 0.002). ④In group A, consolidation (30.16%), cavity (76.19%), wormhole (18.75%) and thick walled cavity (31.25%) were significantly higher than those in group B; The tree bud sign (65.00%), ground glass shadow (16.67%) and pleural thickening rate (23.33%) in group B were significantly higher than those in group A (P<0.05). Conclusion The CT signs of Kansas lung disease are characterized by columnar bronchiectasis, ground glass patch shadow of both lungs and lung consolidation, while MAC lung disease is characterized by cystic bronchiectasis and micronodule (tree bud sign), involving a wide range of lung lobes and scattered distribution. The CT signs of Kansas lung disease and MAC lung disease have their own characteristics.

Key words: Nontuberculous mycobacteria, Lung, Avian intracellular Mycobacterium complex, Computed tomography