title: Increased corticospinal tract fractional anisotropy can discriminate stroke onset within the first 4.5 hours.
abstract: OBJECTIVE
  The role of diffusion tensor imaging in determining stroke age remains unclear. We tested the ability of diffusion tensor imaging metrics to discriminate ischemic stroke <4.5 hours of onset.
  
  
  METHODS
  We enrolled 60 consecutive patients for multimodal 1.5 T MRI within 12 hours of middle cerebral artery ischemic stroke onset. We measured fractional anisotropy (FA), mean diffusivity (MD), apparent diffusion coefficient (ADC), and T2-weighted signal intensity in affected ipsilateral and unaffected contralateral deep gray matter, cortical gray matter, deep white matter in the corticospinal tract (CST), and subcortical white matter and calculated ipsilateral-to-contralateral ratios (r). Hyperintensity in infarcted tissue was considered fluid-attenuated inversion recovery-positive.
  
  
  RESULTS
  We analyzed the 48 patients (17 women; mean age, 68 ± 14 years) with known onset. In 25 (52.1%) patients, onset was ≤ 4.5 hours (mean, 182.3 ± 65.6 minutes). Variables differing significantly between infarcts <4.5 hours and >4.5 hours were rFA CST (P = 0.001), rMD cortical gray matter (P = 0.036), rADC cortical gray matter (P = 0.009), rT2 CST (P = 0.006), and fluid-attenuated inversion recovery (P<0.001). rFA at CST was the most reliable to discriminate infarcts <4.5 hours (Goodman-Kruskal = 0.76). The sensitivity, specificity, and positive and negative predictive values for infarct <4.5 hours of onset by rFA at CST >0.970 were 93.8%, 84.6%, 88.2%, and 91.7%, respectively.
  
  
  CONCLUSIONS
  These preliminary results suggest rFA at CST may be a surrogate marker of acute stroke age.
authors: Department of Radiology-IDI and IDIBGI, Hospital Universitari Dr Josep Trueta, Ctra França, 17007 Girona, Spain. jpuigalcantara@idibgi.org
authors: Josep
authors: J
authors: Puig
authors: Gerard
authors: G
authors: Blasco
authors: Josep
authors: J
authors: Daunis-I-Estadella
authors: Götz
authors: G
authors: Thomalla
authors: Mar
authors: M
authors: Castellanos
authors: Guadalupe
authors: G
authors: Soria
authors: Alberto
authors: A
authors: Prats-Galino
authors: Javier
authors: J
authors: Sánchez-González
authors: Imma
authors: I
authors: Boada
authors: Joaquín
authors: J
authors: Serena
authors: Salvador
authors: S
authors: Pedraza
mesh_terms: D000328:Adult; D000368:Aged; D016880:Anisotropy; D001921:Brain / Q000473:pathology; D002545:Brain Ischemia / Q000473:pathology; D001931:Brain Mapping / Q000379:methods; D004058:Diffusion; D005260:Female; D006801:Humans; D020244:Infarction, Middle Cerebral Artery / Q000503:physiopathology / Q000517:prevention & control* / Q000628:therapy*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D011712:Pyramidal Tracts / Q000473:pathology*; D013997:Time Factors