title: Posterior cranial fossa crowdedness is related to age and sex: an magnetic resonance volumetric study.
abstract: OBJECTIVE
  To measure 3-dimensional (3D) posterior cranial fossa (PCF) crowdedness and to evaluate the effect of age, sex, and body height on PCF.
  
  
  METHODS
  Fifty-two healthy volunteers (24 M and 28 F; mean age 55.4 +/- 17.2 years; range 24-82 years) were recruited. Using a semi-automated magnetic resonance technique, we calculated a PCF crowdedness index (CI) as the ratio of hindbrain (HB) volume to PCF volume x 100% and correlated this index with age, sex, body height, and other crowdedness parameters.
  
  
  RESULTS
  The mean PCF CI was 93.7 +/- 2.7%. Women had a more crowded PCF than men (95.0+1.7% versus 92.1 +/- 2.7%; P<0.001). PCF CI declined with age for both men (r = -0.61; P=0.002) and women (r = -0.68; P<0.001). The association with age--but not HB volume was maintained after we controlled for sex and body height. On multiple regression, both age and sex accounted for 57.5% of the PCF CI variance.
  
  
  CONCLUSIONS
  Our study shows that PCF CI is associated with age and sex, and can therefore be used as a surrogate to assess hindbrain atrophy in a cross-sectional sample. Moreover, sex- and age-specific normal ranges may be needed to evaluate the PCF CI in clinical practice.
authors.affiliation: Department of Radiology and Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: J F
authors.initials: JF
authors.lastname: Lirng
authors.forename: J L
authors.initials: JL
authors.lastname: Fuh
authors.forename: Y Y
authors.initials: YY
authors.lastname: Chen
authors.forename: S J
authors.initials: SJ
authors.lastname: Wang
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001827:Body Height; D003388:Cranial Fossa, Posterior / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D012737:Sex Factors