title: Relationship between the concentration of supplemental oxygen and signal intensity of CSF depicted by fluid-attenuated inversion recovery imaging.
abstract: OBJECTIVE
  Prior reports have described increased signal intensity (SI) of CSF on fluid-attenuated inversion recovery (FLAIR) images of anesthetized patients receiving 100% O(2). This appearance can simulate that of diseases. We evaluated the relationship between the concentration of inhaled O(2) and the development of increased SI of CSF on FLAIR images.
  
  
  METHODS
  FLAIR was performed in 25 healthy volunteers breathing room air and 100% O(2) through a face mask for 5, 10, and 15 minutes. MR imaging, including FLAIR imaging, was performed in 52 patients with no potential meningeal abnormalities under general anesthesia: 21 received an equal mixture of N(2)O and O(2), and 31 received 100% O(2). The SI of CSF in volunteers and patients was graded in several locations by using a three-point scale.
  
  
  RESULTS
  SI of CSF significantly increased (P <.05) in various locations, in both volunteers and patients breathing 100% O(2), when compared with SI in the same volunteers breathing room air. Hyperintensity of CSF was not significantly different in volunteers receiving 100% O(2) through a face mask compared with anesthetized patients receiving 100% O(2) through a laryngeal airway or an endotracheal tube. No significant increase in SI occurred in patients receiving 50% O(2), when compared with the SI of volunteers breathing room air.
  
  
  CONCLUSIONS
  Supplemental oxygen at 100% is a main cause of artifactual CSF hyperintensity on FLAIR images, regardless of the anesthetic drug used. This artifact does not develop when 50% O(2) is administered.
authors.affiliation: Section of Radiology, Santa Casa de Misericórdia de São Paulo, Brazil.
authors.forename: Flávio T
authors.initials: FT
authors.lastname: Braga
authors.forename: Antônio J
authors.initials: AJ
authors.lastname: da Rocha
authors.forename: Guinel
authors.initials: G
authors.lastname: Hernandez Filho
authors.forename: Renê K
authors.initials: RK
authors.lastname: Arikawa
authors.forename: Ivone M
authors.initials: IM
authors.lastname: Ribeiro
authors.forename: Ricardo B
authors.initials: RB
authors.lastname: Fonseca
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000768:Anesthesia, General; D000777:Anesthetics; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology*; D002530:Cerebellopontine Angle / Q000033:anatomy & histology; D002555:Cerebrospinal Fluid; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010102:Oxygen Inhalation Therapy; D011446:Prospective Studies; D013346:Subarachnoid Space / Q000033:anatomy & histology
chemical_list: D000777:Anesthetics