title: Paratracheal air cysts using low-dose screening chest computed tomography: clinical significance and imaging findings.
abstract: OBJECTIVE
  The aim of this study was to evaluate the prevalence and clinical relevance of paratracheal air cysts in a general population who underwent low-dose computed tomography (LDCT).
  
  
  METHODS
  From July 2005 to March 2008, a total of 2002 persons underwent LDCT and were included in the study. We retrospectively reviewed the chest CT images and analyzed the location, level, and size of the air cysts. We checked whether the cysts had communication with the trachea. Other abnormalities of the lung were noted. We evaluated whether the presence of paratracheal air cysts is associated with abnormal pulmonary function.
  
  
  RESULTS
  In all, 75 persons (3.7%) had 77 paratracheal air cysts: 76 (98.7%) at the right side and 36 (46.7%) at the level of the T2 vertebral body. The mean anteroposterior diameter of the paratracheal air cysts was 7.5 mm, and mean transverse diameter was 4.2 mm. Altogether, 26 paratracheal air cysts (33.8%) showed communication with the trachea. Only two persons had respiratory symptoms. Pulmonary function tests showed that five patients (6.7%) had an obstructive pattern.
  
  
  CONCLUSIONS
  The paratracheal air cysts were mostly located at the right side of the trachea and at the thoracic inlet level. One-third had communication with the trachea. Paratracheal air cysts are not associated with respiratory symptoms or obstructive lung disease clinically or radiologically.
authors.affiliation: Department of Radiology, Dongguk University Ilsan Hospital, Dongguk University, 814 Siksa-dong, Ilsandong-gu, Goyang-si 410-773, South Korea. jeungkim@dumc.or.kr
authors.forename: Jeung Sook
authors.initials: JS
authors.lastname: Kim
authors.forename: Ah-Young
authors.initials: AY
authors.lastname: Kim
authors.forename: Yup
authors.initials: Y
authors.lastname: Yoon
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000388:Air; D005260:Female; D006801:Humans; D008297:Male; D008476:Mediastinal Cyst / Q000000981:diagnostic imaging* / Q000453:epidemiology; D008875:Middle Aged; D015995:Prevalence; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D013902:Radiography, Thoracic; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014132:Trachea / Q000000981:diagnostic imaging*