title: Microembolism versus hemodynamic impairment in rosary-like deep watershed infarcts: a combined positron emission tomography and transcranial Doppler study.
abstract: OBJECTIVE
  Deep watershed infarcts are frequent in high-grade carotid disease and are thought to result from hemodynamic impairment, particularly when adopting a rosary-like pattern. However, a role for microembolism has also been suggested, though never directly tested. Here, we studied the relationships among microembolic signals (MES) on transcranial Doppler, rosary-like deep watershed infarcts on brain imaging, and cerebral hemodynamic compromise on positron emission tomography (PET), all in severe symptomatic carotid disease. We hypothesized that rosary-like infarcts would be significantly associated with worse hemodynamic status, independent of the presence of MES.
  
  
  METHODS
  Sixteen patients with ≥70% carotid disease ipsilateral to recent transient ischemic attack/minor stroke underwent magnetic resonance imaging including diffusion-weighted imaging, (15)O-PET, and transcranial Doppler. Mean transit time, a specific marker for hemodynamic impairment, was obtained in the symptomatic and unaffected hemispheres.
  
  
  RESULTS
  Eleven of 16 patients had rosary-like infarcts (Rosary+) and 8 patients had MES. Mean transit time was significantly higher (P=0.008) in Rosary+ patients than in healthy controls (n=10), and prevalence of MES was not different between Rosary+ and Rosary- patients. Contrary to our hypothesis, however, the presence of MES within the Rosary+ subset was associated (P=0.03) with a better hemodynamic status than in their absence, with a significant (P=0.02) negative correlation between mean transit time and rate of MES/h.
  
  
  CONCLUSIONS
  Contrary to mainstream understanding, rosary-like infarcts were not independent of presence and rate of MES, suggesting that microembolism plays a role in their pathogenesis, probably in association with hemodynamic impairment. Pending confirmation in a larger sample, these findings have management implications for patients with carotid disease and rosary-like infarcts.
authors.affiliation: Stroke Research Group, Department of Clinical Neurosciences, University of Cambridge, UK.
authors.forename: Ramez Reda
authors.initials: RR
authors.lastname: Moustafa
authors.forename: Isabelle
authors.initials: I
authors.lastname: Momjian-Mayor
authors.forename: P Simon
authors.initials: PS
authors.lastname: Jones
authors.forename: Silvia
authors.initials: S
authors.lastname: Morbelli
authors.forename: Diana J
authors.initials: DJ
authors.lastname: Day
authors.forename: Franklin I
authors.initials: FI
authors.lastname: Aigbirhio
authors.forename: Tim D
authors.initials: TD
authors.lastname: Fryer
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Warburton
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Baron
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002544:Cerebral Infarction / Q000175:diagnosis* / Q000503:physiopathology; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D020766:Intracranial Embolism / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods; D011446:Prospective Studies; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods