Chest Computed Tomography Features of Nontuberculous Mycobacterial Pulmonary Disease Versus Asymptomatic Colonization

Abstract

Background: Asymptomatic colonization by nontuberculous mycobacteria (NTM) found in sputum isolates are commonly encountered and clinicians lack a biomarker for prognosticating the risk of transition asymptomatic colonization to active clinical disease. Chest computed tomography (CT) imaging is commonly obtained in this patient population and may serve a role for this purpose. Methods: We conducted a single-center, cross-sectional study of patients followed in the NTM clinic at our center between August 2019 and August 2020. All patients had a history of NTM isolated from their airways and were cohorted as either nontuberculous mycobacteria-pulmonary disease (NTM-PD) if they met ATS/IDSA guidelines for treatment or as nontuberculous mycobacteria-colonized (NTM-C) if they did not meet ATS/IDSA criteria for NTM treatment. Patients with a chest CT were included in the analysis and CT scans were assessed for features including bronchiectasis, nodules, and cavities. Bronchiectasis severity was calculated using the modified Reiff scoring system. Univariate analyses were conducted to compare patients with NTM-C and NTM-PD. Results: Eighty-four patients were included in the analysis and 27 were classified as NTM-C and 57 as NTM-PD. NTM-PD patients had a greater median number of lung lobes affected by bronchiectatic airways (6 [1] NTM-PD vs. 5 [3] NTM-C P=0.005) and a greater frequency of cystic bronchiectasis (17.5% NTM-PD vs. 0% NTM-PD, P=0.016). Bronchiectasis severity was higher for NTM-PD patients (7 [9] NTM-PD vs. 5 [1.5] NTM-C, P<0.001). Conclusions: Patients with NTM-PD have greater bronchiectatic airway involvement and the forms of bronchiectasis present are more severe compared with NTM-C patients. In addition, cavitation of lung parenchyma was a radiographic feature solely associated with NTM-PD. Features identified on chest CT may be useful as a prognostic biomarker for the risk of transition from NTM-C to NTM-PD.

Differential radiological features of patients infected or colonised with slow-growing non-tuberculous mycobacteria

“…Different non-MAC species exhibited relatively similar CT scores. Overall, patients fulfilling the ATS criteria displayed higher CT scores, than those that did not, confirming previous studies: Garcia et al have shown higher extent of bronchiectasis in patients with NTM-PD compared to those that are solely colonised by NTM 23 .…”

Clinical characteristics of patients with non-tuberculous mycobacterial pulmonary disease: a seven-year follow-up study conducted in a certain tertiary hospital in Beijing

“…Patients with predominant lesion types of bronchiectasis and nodules were found to be more susceptible to NTM-PD, followed by the presence of predominant cavitary lesions, with thin-walled cavities accounting for 90.91% of cases. Symptoms and imaging features of NTM-PD were similar to those of PTB, as previous studies have shown ( Hu et al., 2019 ; Garcia et al., 2022 ). However, clinical differentiation between PTB and NTM-PD depends on bacteriology and molecular biology.…”

Imaging to Advance Bronchiectasis Phenotyping

“…Similarly, using the Reiff radiographic score, another study showed that higher scores could distinguish between patients with bronchiectasis who had NTM-associated pulmonary disease and patients with bronchiectasis who did not ( 7 ). These observations were supported by research on 84 patients with a history of NTM airway isolation, revealing a correlation between radiographic severity and NTM active disease but not colonization ( 8 ). The study by Pieters and colleagues echoes these observations, further highlighting that a comprehensive radiographic score could serve as a biomarker for phenotyping patients with bronchiectasis.…”