title: Prognostic value of brain diffusion-weighted imaging after cardiac arrest.
abstract: OBJECTIVE
  Outcome prediction is challenging in comatose postcardiac arrest survivors. We assessed the feasibility and prognostic utility of brain diffusion-weighted magnetic resonance imaging (DWI) during the first week.
  
  
  METHODS
  Consecutive comatose postcardiac arrest patients were prospectively enrolled. AWI data of patients who met predefined specific prognostic criteria were used to determine distinguishing apparent diffusion coefficient (ADC) thresholds. Group 1 criteria were death at 6 months and absent motor response or absent pupillary reflexes or bilateral absent cortical responses at 72 hours or vegetative at 1 month. Group 2 criterion was survival at 6 months with a Glasgow Outcome Scale score of 4 or 5 (group 2A) or 3 (group 2B). The percentage of voxels below different ADC thresholds was calculated at 50 x 10(-6) mm(2)/sec intervals.
  
  
  RESULTS
  Overall, 86% of patients underwent DWI. Fifty-one patients with 62 brain DWIs were included. Forty patients met the specific prognostic criteria. The percentage of brain volume with an ADC value less than 650 to 700 x 10(-6)mm(2)/sec best differentiated between Group 1 and Groups 2A and 2B combined (p < 0.001), whereas the 400 to 450 x 10(-6)mm(2)/sec threshold best differentiated between Groups 2A and 2B (p = 0.003). The ideal time window for prognostication using DWI was between 49 and 108 hours after the arrest. When comparing DWI in this time window with the 72-hour neurological examination, DWI improved the sensitivity for predicting poor outcome by 38% while maintaining 100% specificity (p = 0.021).
  
  
  CONCLUSIONS
  Quantitative DWI in comatose postcardiac arrest survivors holds promise as a prognostic adjunct.
authors.affiliation: Stanford Stroke Center, Department of Neurology and Neurological Sciences, Stanford University, Palo Alto, CA 94304, USA. cwijman@stanford.edu
authors.forename: Christine A C
authors.initials: CA
authors.lastname: Wijman
authors.forename: Michael
authors.initials: M
authors.lastname: Mlynash
authors.forename: Anna Finley
authors.initials: AF
authors.lastname: Caulfield
authors.forename: Amie W
authors.initials: AW
authors.lastname: Hsia
authors.forename: Irina
authors.initials: I
authors.lastname: Eyngorn
authors.forename: Roland
authors.initials: R
authors.lastname: Bammer
authors.forename: Nancy
authors.initials: N
authors.lastname: Fischbein
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Albers
authors.forename: Michael
authors.initials: M
authors.lastname: Moseley
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000378:metabolism / Q000473:pathology*; D001931:Brain Mapping; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D018450:Disease Progression; D005240:Feasibility Studies; D005260:Female; D006323:Heart Arrest / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D009460:Neurologic Examination; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D018709:Statistics, Nonparametric; D013997:Time Factors; D055815:Young Adult