title: Early detection of global cerebral anoxia: improved accuracy by high-b-value diffusion-weighted imaging with long echo time.
abstract: OBJECTIVE
  Early and accurate detection of global cerebral anoxia is important for determination of prognosis and further management. We evaluated whether accuracy in early detection of global cerebral anoxia was improved by high-b-value diffusion-weighted imaging (DWI) with long echo time (TE).
  
  
  METHODS
  Routine DWI (b = 1000 s/mm(2); TE = 139 ms), high-b-value DWI (b = 3000 s/mm(2); TE = 190 ms), T2-weighted imaging (T2WI), and fluid-attenuated inversion recovery (FLAIR) imaging were acquired in six patients who experienced cardiopulmonary arrest within 24 hours and six volunteers. Region of interest-based analysis was performed. Regions of interest of patients showing significant decrease in apparent diffusion coefficient (ADC) values than volunteers were considered abnormal. Three neuroradiologists independently assessed images of the patients for conspicuity of hyperintensity within regions of interest. Receiver operating characteristic (ROC) analysis was performed, and the area under the curve (Az) was compared among sequences and observers. Average contrast and contrast-to-noise ratios between abnormal regions of interest and regions of interest of normal surrounding parenchyma were calculated.
  
  
  RESULTS
  For all observers, high-b-value DWIs achieved the largest Az, and FLAIR imaging the lowest Az. Az of routine DWI and T2WI were between these values. High-b-value DWI and FLAIR imaging showed no significant interobserver variation in Az, whereas routine DWI and T2WI did. High-b-value DWI also achieved the largest contrast and contrast-to-noise ratios.
  
  
  CONCLUSIONS
  High-b-value DWI with long TE improved accuracy in early detection of global cerebral anoxia. Application of the sequence would facilitate early diagnosis.
authors.affiliation: Department of Radiology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Khin K
authors.initials: KK
authors.lastname: Tha
authors.forename: Satoshi
authors.initials: S
authors.lastname: Terae
authors.forename: Toru
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Kudo
authors.forename: Chihiro
authors.initials: C
authors.lastname: Takahashi
authors.forename: Masaki
authors.initials: M
authors.lastname: Oka
authors.forename: Shinji
authors.initials: S
authors.lastname: Uegaki
authors.forename: Kazuo
authors.initials: K
authors.lastname: Miyasaka
mesh_terms: D000328:Adult; D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D002534:Hypoxia, Brain / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results