title: CT of the normal esophagus to define the normal air column and its extent and distribution.
abstract: OBJECTIVE
  This study was designed to quantify and characterize the air-containing thoracic esophagus on CT to help diagnose diseases and facilitate correlation with lung diseases that may be associated with aspiration.
  
  
  METHODS
  The maximal air-containing esophageal lumina on each section of standard CT scans of 110 subjects were measured. These subjects came from a cohort of 10,132 self-reported healthy individuals who underwent CT for measurement of coronary artery calcium. Measurements were interpolated to account for variation in the length of the thoraces.
  
  
  RESULTS
  Greater than 60% of the esophageal segments contained no air. On average the maximum air column was 10.5 (SD, 5.0) mm. Only 7.9% of the lumina were > 10 mm. Only 2% were > 15 mm, and only 0.2% were > 20 mm. The average number of lumina > 10 mm as a proportion of the entire esophageal length was 8% (14%). The average size at the carina was 2.6 (4.1) mm. In the upper 30% and from 61% to 75% down the length of the esophagus, < 5% of the lumina were > 10 mm. Less than 3% of subjects had air in the lowest two sections, indicating that the normal lower esophageal sphincter was closed.
  
  
  CONCLUSIONS
  Esophageal air of > 10 mm should be considered abnormal in all segments except between the cardiac ventricles and lower esophageal sphincter. In this area, > 15 mm should be considered abnormal. An air-fluid level is abnormal.
authors: Section of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, M/C 719, University of Illinois at Chicago, 840 S Wood St., Chicago, IL 60612-7323, USA. schrauf@uic.edu
authors: Dean E
authors: DE
authors: Schraufnagel
authors: Jon C
authors: JC
authors: Michel
authors: Todd J
authors: TJ
authors: Sheppard
authors: Patricia Cole
authors: PC
authors: Saffold
authors: George T
authors: GT
authors: Kondos
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D004947:Esophagus / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*