Longitudinal changes in radiographic features of pulmonary complex diseases.

Background: The radiographic features of complex pulmonary disease (MAC-PD), a major component of nontuberculous mycobacteria, consist of a variety of lesions; however, the responsiveness of each type of radiographic factor to treatment is unclear. Thus, we evaluated the longitudinal changes of each factor in serial computed tomography (CT) images using a mixed-effects model, and investigated the radiographic transition in patients with MAC-PD whose progress could be followed.

Methods: In this retrospective study, eighty-four patients diagnosed with MAC-PD and with yearly CT records were recruited after a review of 328 medical records with culture-positive MAC in respiratory specimens. The study participants were divided into two groups: treatment (n = 43) and no-treatment (n = 41) groups. Radiographic images were scored using the nodule (N), infiltration (I), cavity (C), ectasis (E) scoring system. Longitudinal changes in each radiographic lesion factor were analyzed using a mixed-effects model in treated and untreated patients.

Results: All factors tended to progress without treatment, and significant longitudinal changes were observed in the N, I, and E factors (N:  = 0.010, I:  = 0.004, E:  < 0.001). Although treatment tended to improve N and I in radiographic images (N:  = 0.006, I:  = 0.203), cavities and ectasis progressed, regardless of treatment (C:  = 0.057 and E:  = 0.033).

Conclusion: Radiographic changes of MAC-PD can be categorized into reversible (nodules and infiltrations) and irreversible (cavities and ectasis) lesions. Early treatment may prevent the accumulation of irreversible factors.