Tree-in-bud pattern of chest CT images for diagnosis of Mycobacterium abscesses

Objectives: Changes of chest CT images in Mycobacterium and non-Mycobacterium abscesses in patients with lung disease were with a view to making an early diagnosis.

Methods: 124 primary patients diagnosed with non-tuberculosis Mycobacterium infections with a positive sputum acid-fast smear were enrolled in this retrospective study. CT images and clinical data of these patients were analyzed.

Results: The 52 Mycobacterium abscess lung disease cases included bronchiectasis 82.7% (43/52), which was more easily detected bilaterally than unilaterally (29/52 vs. 14/52), lung consolidation 44.2% (23/52), nodules 44.2% (22/52), cavities 32.7% (17/52), tree-in-bud pattern 42.3% (22/52) and patchy shadow 63.5% (33/52) in CT images. Tree-in-bud pattern was more common in Mycobacterium abscess compared with non-Mycobacterium abscess lung disease (42.3% vs. 18.1%, P = 0.004). A significant difference of the lung area involved by tree-in-bud in CT was found between non-Mycobacteria abscess and Mycobacterium abscess lung disease (17.0% vs. 7.2%, P < 0.001), and tree-in-bud occurred more readily unilaterally (21.2% vs. 6.9%, P = 0.029), and in the inferior lobe of the right lung (3.2% vs. 0.2%, P = 0.029) in Mycobacterium abscess lung disease. Patchy shadow was more common in non-Mycobacterium abscess lung disease (63.5% vs. 80.1%, P = 0.041). Further multi-factor analysis confirmed that tree-in-bud was an independent predictor of Mycobacterium abscess lung disease.

Conclusions: Different CT results existed between non-Mycobacterium abscess and Mycobacterium abscess lung diseases. The tree-in-bud pattern might be helpful to choose a suitable therapy in patients, with an acid-fast bacilli smear-positive diagnosis of lung disease.