title: Comparing diffusion-weighted and T2-weighted MR imaging for the quantification of infarct size in a neonatal rat hypoxic-ischemic model at 24h post-injury.
abstract: OBJECTIVE
  In a neonatal rat model of hypoxic-ischemic (HI) brain injury, using T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI), we aim to determine the best MRI method of lesion quantification that reflects infarct size.
  
  
  METHODS
  Twenty 7-day-old rats underwent MRI 24h after HI brain injury was induced. Lesion size relative to whole brain was measured using T2WI and apparent diffusion coefficient (ADC) maps, applying thresholds of 60%, 70% and 80% contralateral control hemisphere mean ADC, and at day 10 post-HI on pathology with TTC staining. Multiple linear regression analysis was used to study the relationships between lesion size at MRI and pathology.
  
  
  RESULTS
  Lesion size measurement using all MRI methods significantly correlated with infarct size at pathology; using T2WI, r=0.808 (p<0.001), using 80% ADC, 70% ADC and 60% ADC thresholds, r=0.888 (p<0.001), 0.761, (p<0.001) and 0.569 (p=0.014), respectively. Eighty percent ADC threshold was found to be the only significant independent predictor of final infarct volume (adjusted R(2)=0.775).
  
  
  CONCLUSIONS
  At 24h post-HI, lesion size on DWI, using 80% ADC threshold is the best predictor of final infarct volume. Although T2WI performed less well, it has the advantage of superior spatial resolution and is technically less demanding. These are important considerations for experiments which utilize MRI as a surrogate method for lesion quantification in the neonatal rat HI model.
authors.affiliation: Diagnostic Radiology, University of Hong Kong, Hong Kong, China.
authors.forename: Yanxin
authors.initials: Y
authors.lastname: Wang
authors.forename: Pik-To
authors.initials: PT
authors.lastname: Cheung
authors.forename: Gary X
authors.initials: GX
authors.lastname: Shen
authors.forename: Inderjeet
authors.initials: I
authors.lastname: Bhatia
authors.forename: Ed Xue
authors.initials: EX
authors.lastname: Wu
authors.forename: Deqiang
authors.initials: D
authors.lastname: Qiu
authors.forename: Pek-Lan
authors.initials: PL
authors.lastname: Khong
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D020520:Brain Infarction / Q000209:etiology* / Q000473:pathology*; D004195:Disease Models, Animal; D020925:Hypoxia-Ischemia, Brain / Q000150:complications*; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley