Abstract:

Objective This study aimed to explore the CT features of Mycobacterium avium-intracellulare complex (MAC) lung disease with cavities, which might be able to assist in clinical diagnosis.Methods A total of 21 patients who diagnosed as MAC lung disease and presented chest CT scan with cavities (served as the observation group) were retrospectively collected from the Taizhou Hospital affiliated to Wenzhou Medical University between June 2014 to December 2018. Meanwhile, based on 1∶1 case-control study, 21 patients with cavitary tuberculosis who met the inclusion criteria as well as matched by gender and age ±2 year were selected as the control group. Then several indicators, including types of cavities, wall thickness, diameter, bronchiectasis, consolidation, nodules or masses with a long diameter >1 cm, central nodules of the lobes (including tree buds), pleural effusion, mediastinal lymph node calcification, were compared between the two groups.Results A total of 74 cavities were detected in the observation group, among which, the median (quartile) diameter of the cavity (M(Q₁,Q₃)) was 27.9 (17.3, 39.8) mm, and the median wall thickness of the cavity was 2.7 (1.7, 4.1) mm; meanwhile, 55 cavities were detected in the control group with 20.6 (13.4, 32.0) mm of the median diameter of the cavity and 3.6 (2.5, 4.7) mm of the median wall thickness of the cavity. There were significantly statistical differences in terms of diameter and wall thickness between the two groups (Z values: -2.241, and -2.431, respectively, and all P values <0.05). The detection ratio of thin-walled cavities as well as the detection rates of bronchiectasis, and bronchiectasis accompanied with central nodules of the lobes in the observation group were 60.8% (45/74), 85.7% (18/21), and 57.1% (12/21), respectively, which were higher than those in the control group (36.4% (20/55), 38.1% (8/21), and 23.8% (5/21), respectively), with the statistically significant differences ( {\mathrm{\chi }}^2 values: 7.543, 10.096, and 4.842, respectively; all P values <0.05); the detection ratios of thick-walled cavities, surrounding satellite foci, and drainage bronchus, as well as the detection rate of lung nodules with long diameter >1 cm in the observation group were 39.2% (29/74), 58.1% (43/74), 28.4% (21/74), and 23.8% (5/21), respectively, which were lower than those in the control group(63.6% (35/55), 94.5% (52/55), 63.6% (35/55), and 76.2% (16/21), respectively), with the statistically significant differences (χ ² values: 7.543, 21.582, 15.966, and 11.524, respectively; all P values <0.05). Conclusion Patients with MAC lung disease more likely present CT scans with thin-walled cavities accompanied with bronchiectasis and small pulmonary nodules; while CT scans of tuberculosis patients more likely show thick-walled cavities accompanied with drainage bronchus, surrounding satellite foci, and pulmonary nodules with a long diameter >1 cm. The CT findings of different patients display their own characteristics, which can contribute to the early clinical diagnosis and treatment.

Key words: Lung diseases, Mycobacterium avium-intracellulare infection, Tuberculosis,pulmonary, Disease attributes, Comparative study