title: Radioanatomical study of a true tracheal bronchus using multidetector computed tomography.
abstract: OBJECTIVE
  True tracheal bronchus (TTB) is a rare anomaly in which a lobar or segmental ectopic bronchus arises from the trachea. We examined the frequency and multidetector computed tomography (MDCT) appearances of TTB.
  
  
  METHODS
  We retrospectively analyzed 9781 chest MDCT examinations. In cases in which there was an abnormal bronchus suggesting TTB on axial CT images, the following imaging of the abnormal bronchi was undertaken: multiplanar reformation (MPR), multiprojection volume reconstruction (MPVR), volume rendering (VR), and virtual endoscopy (VE).
  
  
  RESULTS
  Of 9781 MDCT examinations, 30 TTBs were observed in 10 females and 20 males. The frequency of TTB was 0.21% among 4622 females, 0.39% among 5159 males (0.31 % in the overall patient population). TTBs arose from the right lateral wall of the trachea; 17 TTBs were of the displaced type and 13 of the supernumerary type. With the displaced type, all segments of the right upper lobe were supplied by the TTB in 8 patients, and the apical segment was supplied in 8 patients. With the supernumerary type, TTBs showed blind termination in 10 patients, and the TTB had a small lobule in 3 patients. All TTBs were clearly visualized on MPR, MPVR, VR, and VE.
  
  
  CONCLUSIONS
  TTB was identified by MDCT with an incidence of 0.31%.
authors.affiliation: Department of Quantum Medical Technology, Graduate School of Medical Science, Kanazawa University, Kodatsuno, Kanazawa, Japan. suzuki@mhs.mp.kanazawa-u.ac.jp
authors.forename: Masayuki
authors.initials: M
authors.lastname: Suzuki
authors.forename: Osamu
authors.initials: O
authors.lastname: Matsui
authors.forename: Hiroko
authors.initials: H
authors.lastname: Kawashima
authors.forename: Akihiro
authors.initials: A
authors.lastname: Takemura
authors.forename: Kosuke
authors.initials: K
authors.lastname: Matsubara
authors.forename: Norio
authors.initials: N
authors.lastname: Hayashi
authors.forename: Wataru
authors.initials: W
authors.lastname: Koda
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Shibata
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001980:Bronchi / Q000002:abnormalities*; D001995:Bronchography; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed; D014132:Trachea / Q000002:abnormalities*; D055815:Young Adult