title: Is white matter more prone to diffusion lesion reversal after thrombolysis?
abstract: OBJECTIVE
  In acute ischemic stroke, white matter (WM) is considered more resistant to infarction than gray matter (GM). To test this hypothesis, we compared the fate of WM and GM voxels belonging to the acute diffusion-weighted imaging (DWI) lesion, expecting WM voxels to be more prone to reversal after thrombolysis.
  
  
  METHODS
  Reversible acute DWI (RAD) lesion was defined voxel-wise as an acute lesion on initial DWI (DWI1) with no visible lesion on 24-hour DWI (DWI2). Only patients with RAD lesions >10 mL and >10% of DWI1 from our previously reported cohort were eligible. The core was defined as voxels hyperintense on DWI1 and DWI2. Semiautomated segmentation of DWI1, core, and RAD lesions, normalization into standard space, and WM/GM segmentation allowed calculations of WM/GM proportions in each region of interest using a voxel-counting algorithm.
  
  
  RESULTS
  Thirty patients were eligible (RAD lesion median volume [interquartile range], 23.3 mL [19.1-35.0 mL]; onset-to-treatment time, 134 minutes [105-185 minutes]). WM voxels fraction was greater in RAD lesions than in the core (59.4% [52.8%-68.9%] versus 49.6% [43.0%-57.5%]; P=0.011). The proportion of reversibility was greater for WM than for GM voxels (60.8% [25.5%-88.7%] versus 53.5% [21.1%-77.3%]; P=0.02). The percentage of RAD lesions increased with the proportion of WM present in the acute DWI lesion (P<0.0001; R=0.67).
  
  
  CONCLUSIONS
  Acute DWI lesions predominantly involving WM may be more prone to reversal and, hence, to respond to therapy than their GM counterparts.
authors: From the Departments of Radiology (M.T., C.M., L.L., M.E., M.-A.L., J.-F.M., C.O.) and Neurology (G.T., P.S., J.-L.M., J.-C.B.), Université Paris Descartes Sorbonne Paris Cité, Centre de Psychiatrie et Neurosciences, INSERM S894, Centre Hospitalier Sainte-Anne, Paris, France.
authors: Marie
authors: M
authors: Tisserand
authors: Caroline
authors: C
authors: Malherbe
authors: Guillaume
authors: G
authors: Turc
authors: Laurence
authors: L
authors: Legrand
authors: Myriam
authors: M
authors: Edjlali
authors: Marc-Antoine
authors: MA
authors: Labeyrie
authors: Pierre
authors: P
authors: Seners
authors: Jean-Louis
authors: JL
authors: Mas
authors: Jean-François
authors: JF
authors: Méder
authors: Jean-Claude
authors: JC
authors: Baron
authors: Catherine
authors: C
authors: Oppenheim
mesh_terms: D000208:Acute Disease; D000368:Aged; D002545:Brain Ischemia / Q000150:complications / Q000473:pathology* / Q000628:therapy; D038524:Diffusion Magnetic Resonance Imaging; D005500:Follow-Up Studies; D006801:Humans; D056784:Leukoencephalopathies / Q000209:etiology / Q000473:pathology* / Q000628:therapy; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D012189:Retrospective Studies; D020521:Stroke / Q000150:complications / Q000473:pathology* / Q000628:therapy; D015912:Thrombolytic Therapy; D061665:Time-to-Treatment
keywords: diffusion magnetic resonance imaging; ischemia; magnetic resonance imaging; stroke; thrombolytic therapy