Mycobacterium avium complex lung disease in immunocompetent patients: radiography-CT correlation

This study aimed to describe and correlate the chest radiography and CT findings of Mycobacterium avium complex (MAC) lung disease in immunocompetent patients. 26 patients fulfilled The American Thoracic Society criteria for MAC lung disease and underwent chest radiography and CT within 6 weeks of positive cultures. All abnormalities and predominant lobar involvement were recorded and abnormalities on chest radiography were correlated with those on CT. The images were evaluated by two chest radiologists and decisions were reached by consensus. 21 females and 5 males, with an overall mean age of 69 years, were included in the study. All chest radiographs and CT scans were abnormal. On chest radiography, overinflation was demonstrated in 18 patients. CT scan abnormalities included atelectasis (n=17), bronchiectasis (n=24), cavities (n=13), consolidation (n=3), emphysema (n=11), ground-glass opacity (n=8), linear opacities (n=26), mediastinal lymphadenopathy (n=3), nodules (n=25) and pleural disease (n=15). CT findings were at variance with chest radiography findings in 15 lobes. A new feature from this study is that the majority of patients with MAC lung disease demonstrate overinflation on chest radiography. 19% of cases had predominant upper lobe disease, indistinguishable from post-primary Mycobacterium tuberculosis infection. 77% of cases demonstrated the major imaging criteria of MAC lung disease. These are ill defined nodules, bronchiectasis, predominant middle lobe and/or lingular abnormalities, with or without overinflation. We believe that these characteristic radiological signs will assist the physician in the diagnostic work-up of patients with MAC lung disease.