title: Chest imaging comparison between non-tuberculous and tuberculosis mycobacteria in sputum acid fast bacilli smear-positive patients.
abstract: OBJECTIVE
  The aim of this study was to distinguish and compare the chest imaging features of non-tuberculous mycobacteria lung disease (NTM-LD) and pulmonary tuberculosis (PTB) in patients with sputum acid fast bacillus (AFB)-smear positive since an earlier differential diagnosis between these two is very important in clinical practice.
  
  
  METHODS
  A total of 4167 previously untreated cases with AFB smear-positive sputum were collected from January 2011 to January 2014, in Shanghai Pulmonary Hospital, Tongji University, China. Among them, 124 cases were identified with NTM-LD after specimen culture and strain identification. A cohort of 210 patients with PTB was randomly selected from the remaining 4043 cases with PTB as comparator. The clinical and chest computed tomography (CT) imaging data were compared.
  
  
  RESULTS
  The most prevalent pathogens in patients with NTM-LD were Mycobacterium abscessus (42%, 52/124) and Mycobacterium intracellulare (34%, 42/124). Univariate analysis showed patients with NTM-LD more frequently had bronchiectasis (85.5% vs. 45.7%, p < 0.001), thin-walled cavity (D ≥ 3 cm) (16.9% vs. 7.6%, p = 0.011) compared to PTB patients. Additionally, the location of lesion also differed and the right middle lobe (23.9% vs. 16.3%, p < 0.001) and left lingual segment bronchiectasis (19.9% vs. 8.2%, p < 0.001) were more prominent in NTM-LD. Multivariate analysis showed, bronchiectasis (OR = 8.521, 95% CI: 4.209-17.250, p < 0.001) and thin-walled cavity (D ≥ 3 cm) (OR = 3.561, 95% CI: 1.394-9.097, p = 0.008) were also the independent predictors for the diagnosis of NTM-LD.
  
  
  CONCLUSIONS
  Bronchiectasis in the right middle lobe or left lingual segment and thin-walled cavity with a diameter of more than 3 cm are the frequently the chest CT features in patients with NTM-LD, which might be helpful for an early diagnosis in patients with AFB-smear positive.
authors.affiliation: Department of Respiratory Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China. xiwen_sun333@126.com.
authors.forename: H-Q
authors.initials: HQ
authors.lastname: Chu
authors.forename: B
authors.initials: B
authors.lastname: Li
authors.forename: L
authors.initials: L
authors.lastname: Zhao
authors.forename: D-D
authors.initials: DD
authors.lastname: Huang
authors.forename: Z-M
authors.initials: ZM
authors.lastname: Zhang
authors.forename: J-F
authors.initials: JF
authors.lastname: Xu
authors.forename: J-B
authors.initials: JB
authors.lastname: Zhang
authors.forename: T
authors.initials: T
authors.lastname: Gui
authors.forename: L-Y
authors.initials: LY
authors.lastname: Xu
authors.forename: X-W
authors.initials: XW
authors.lastname: Sun
mesh_terms: D001407:Bacillus; D002681:China / Q000453:epidemiology; D015331:Cohort Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000382:microbiology; D008297:Male; D008875:Middle Aged; D009165:Mycobacterium Infections, Nontuberculous / Q000000981:diagnostic imaging* / Q000453:epidemiology; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification; D013183:Sputum / Q000382:microbiology*; D014057:Tomography, X-Ray Computed / Q000379:methods; D014397:Tuberculosis, Pulmonary / Q000000981:diagnostic imaging* / Q000453:epidemiology