title: Intravertebral vacuum phenomenon following fractures: CT study on frequency and etiology.
abstract: OBJECTIVE
  The purpose of this work was to determine the frequency and etiology of the intravertebral vacuum phenomenon (IVP).
  
  
  METHODS
  CT examinations of 96 vertebral fractures were evaluated for IVP. Bone mineral density (BMD) was determined in nonfractured vertebrae. For calibration purposes, densities of a standard phantom measured in 30 patients who underwent quantitative CT examinations in the same time period were used and precision was calculated.
  
  
  RESULTS
  Eleven of 96 fractures (11.5%) showed IVP. IVP was present in 4 of 20 fractures at T12 (20%), in 4 of 23 at L1 (17.4%), and 1 IVP was found at L2-4 each. Mean +/- SD age of patients with IVP was 68.3 +/- 10.5 years and without 47.8 +/- 19.4 years (p < 0.001). Mean +/- SD density of nonaffected vertebra was 45.9 +/- 17.0 mg of hydroxyapatite/ml for patients with IVP and 139.5 +/- 62.6 mg/ml for those without IVP (p < 0.0005). An average precision of 1.2% was calculated for the density measurements over the investigated time.
  
  
  CONCLUSIONS
  Following vertebral fractures, IVP on CT scans is more common than presumed and increases with age. There exists a significant inverse correlation between the BMD and the frequency of IVP.
authors.affiliation: Department of Diagnostic Radiology, Ludwig Maximilians University Munich, Grosshadern Clinic, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Stäbler
authors.forename: P
authors.initials: P
authors.lastname: Schneider
authors.forename: T M
authors.initials: TM
authors.lastname: Link
authors.forename: P
authors.initials: P
authors.lastname: Schöps
authors.forename: O S
authors.initials: OS
authors.lastname: Springer
authors.forename: H R
authors.initials: HR
authors.lastname: Dürr
authors.forename: M
authors.initials: M
authors.lastname: Reiser
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density; D002138:Calibration; D016022:Case-Control Studies; D017886:Durapatite; D005260:Female; D005740:Gases; D006801:Humans; D015994:Incidence; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement; D012189:Retrospective Studies; D016103:Spinal Fractures / Q000000981:diagnostic imaging* / Q000209:etiology; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries*
chemical_list: D005740:Gases; D017886:Durapatite