title: Relationship between surface area and volume of the mastoid air cell system in adult humans.
abstract: BACKGROUND
  The geometry of the adult human mastoid air cell system has not previously been described over a large range of mastoid air cell volumes.
  
  
  METHODS
  Twenty subjects with a wide range of mastoid air cell pneumatised areas, as determined by X-ray, underwent computed tomography scanning of the middle ear. Mastoid air cell surface areas and volumes were then reconstructed from serial imaging sections, using Image J software.
  
  
  RESULTS
  Mastoid air cell volumes varied from 0.7 to 21.4 ml, and were linearly related to the pneumatised area. Right and left mastoid air cell volumes and surface areas were highly correlated. The mastoid air cell surface area was a linear function of volume.
  
  
  CONCLUSIONS
  The relationship between mastoid air cell surface area and volume is similar over a wide range of volumes. Given that the rate of gas exchange across the mastoid air cell mucosa is related to the mastoid air cell surface area, that rate will thus also be a direct linear function of the mastoid air cell volume.
authors.affiliation: Department of Otolaryngology, Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pennsylvania, USA. dswarts@pitt.edu
authors.forename: J D
authors.initials: JD
authors.lastname: Swarts
authors.forename: B M Cullen
authors.initials: BM
authors.lastname: Doyle
authors.forename: W J
authors.initials: WJ
authors.lastname: Doyle
mesh_terms: D000328:Adult; D000388:Air; D002648:Child; D004432:Ear, Middle / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008416:Mastoid / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D008954:Models, Biological; D009092:Mucous Membrane / Q000378:metabolism; D009929:Organ Size; D010033:Otitis Media / Q000473:pathology; D013499:Surface Properties; D014057:Tomography, X-Ray Computed; D055815:Young Adult