title: Inflammatory response after ischemic stroke: a USPIO-enhanced MRI study in patients.
abstract: OBJECTIVE
  The intensity of the inflammatory response may be related to the volume of acute infarction. Ultra-small superparamagnetic particles of iron oxide (USPIO) may enable assessment of neuroinflammation. We aimed to assess whether the intensity of the inflammatory response might be related to the subacute ischemic lesion volume.
  
  
  METHODS
  We enrolled patients who presented with acute anterior circulation stroke. MRI was performed at day 0, day 6, and day 9. The MRI protocol included T1-weighted imaging, gradient-echo T2*-weighted imaging, diffusion-weighted imaging, perfusion-weighted imaging and MR angiography. Blood-brain barrier disruption was defined as post-gadolinium enhancement on T1-weighted images. USPIO was administered after day 6 MRI. USPIO enhancement ratios were defined as the ratio between USPIO-related signal volume on day 9 T1-weighted imaging (respectively T2*-weighted imaging) and day 6 diffusion-weighted imaging infarct volume. The relationship between day 6 infarct volume and the enhancement ratio was assessed using Pearson and Spearman correlation tests.
  
  
  RESULTS
  The protocol was completed in 10 patients. Signal alterations after USPIO injection was observed in 9/10 patients on day 9 T1-weighted imaging and in 5/10 patients on day 9 T2*-weighted imaging. USPIO-related MRI enhancement was heterogeneous. Lesion volume on day 6 diffusion-weighted imaging had no impact on USPIO enhancement at day 9 according to the Pearson correlation test (P=0.39) or Spearman test (P=0.25). There was no relationship between blood-brain barrier disruption and USPIO enhancement.
  
  
  CONCLUSIONS
  USPIO MRI enhancement is heterogeneous and not clearly related to subacute lesion volume.
authors.affiliation: Hospices Civils de Lyon, Cerebrovascular Unit, Hôpital Neurologique, Lyon, France. norbert.nighoghossian@chu-lyon.fr
authors.forename: Norbert
authors.initials: N
authors.lastname: Nighoghossian
authors.forename: Marlène
authors.initials: M
authors.lastname: Wiart
authors.forename: Serkan
authors.initials: S
authors.lastname: Cakmak
authors.forename: Yves
authors.initials: Y
authors.lastname: Berthezène
authors.forename: Laurent
authors.initials: L
authors.lastname: Derex
authors.forename: Tae-Hee
authors.initials: TH
authors.lastname: Cho
authors.forename: Chantal
authors.initials: C
authors.lastname: Nemoz
authors.forename: François
authors.initials: F
authors.lastname: Chapuis
authors.forename: Guy-Louis
authors.initials: GL
authors.lastname: Tisserand
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Pialat
authors.forename: Paul
authors.initials: P
authors.lastname: Trouillas
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Froment
authors.forename: Marc
authors.initials: M
authors.lastname: Hermier
mesh_terms: D000368:Aged; D001921:Brain / Q000000981:diagnostic imaging / Q000473:pathology; D002545:Brain Ischemia / Q000150:complications / Q000000981:diagnostic imaging* / Q000473:pathology; D003911:Dextrans; D005260:Female; D052203:Ferrosoferric Oxide; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007249:Inflammation / Q000000981:diagnostic imaging; D007501:Iron; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D008297:Male; D008875:Middle Aged; D010087:Oxides; D011859:Radiography; D020521:Stroke / Q000150:complications / Q000000981:diagnostic imaging* / Q000473:pathology; D013997:Time Factors
chemical_list: D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; C097921:ferumoxtran-10; D007501:Iron; D052203:Ferrosoferric Oxide