title: Microemboli during carotid angiography. Association with stroke risk factors or subsequent magnetic resonance imaging changes?
abstract: OBJECTIVE
  Carotid angiography is associated with a 1% risk of major stroke. Recently, transcranial Doppler ultrasonography (TCD) has shown cerebral microemboli during carotid angiography. To determine their significance, we correlated the number of microemboli during angiography with clinical characteristics, angiography findings, and preangiography and postangiography cerebral magnetic resonance imaging (MRI).
  
  
  METHODS
  One middle cerebral artery was monitored with TCD in 24 patients during angiography for carotid territory ischemia. The number of microemboli was correlated with angiographic and clinical characteristics. T2-weighted cerebral MRI was performed before and < or = 48 hours after angiography, and the number of new ischemic lesions was determined in a blinded review.
  
  
  RESULTS
  Microemboli were seen in all patients, with an average of 51 per procedure (range, 12 to 154). The majority of microemboli had signal characteristics typical of air. Sixteen of the 24 patients had both preangiography and postangiography MRI. One of 24 patients had an angiographic stroke, with a single new thalamic lesion on MRI. No other patient had a new lesion. The microembolus count correlated with the angiographic contrast volume (P < .001) but not with any other radiological or clinical characteristic.
  
  
  CONCLUSIONS
  This study confirmed the presence of numerous cerebral microemboli during carotid angiography. The microembolic signal characteristics and the correlation with contrast volume indicate that introduced air is the cause. These microemboli are usually clinically silent and do not lead to new changes on cerebral MRI.
authors.affiliation: Neurosciences Department, Royal Melbourne Hospital, Parkville, Australia.
authors.forename: R P
authors.initials: RP
authors.lastname: Gerraty
authors.forename: D N
authors.initials: DN
authors.lastname: Bowser
authors.forename: B
authors.initials: B
authors.lastname: Infeld
authors.forename: P J
authors.initials: PJ
authors.lastname: Mitchell
authors.forename: S M
authors.initials: SM
authors.lastname: Davis
mesh_terms: D000328:Adult; D000368:Aged; D002339:Carotid Arteries / Q000000981:diagnostic imaging* / Q000473:pathology*; D002533:Cerebral Angiography / Q000009:adverse effects*; D002561:Cerebrovascular Disorders / Q000209:etiology*; D005260:Female; D006801:Humans; D002542:Intracranial Embolism and Thrombosis / Q000175:diagnosis / Q000209:etiology*; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D012307:Risk Factors