title: Validation of the Automated Electronic Microemboli Detection System in Patients Undergoing Carotid Endarterectomy.
abstract: OBJECTIVE
  To assess the diagnostic value of automatic embolus detection software (AEDS) in transcranial Doppler (TCD) monitoring for the detection of solid microemboli in patients at risk for perioperative stroke during carotid endarterectomy (CEA).
  
  
  METHODS
  In 50 patients undergoing CEA, perioperative TCD registration was recorded. All recorded events, identified and saved by the AEDS, were analyzed off-line doubly by two human experts (HEs) within a time frame of > 4 months. The inter- and intraobserver variability was assessed. The overall agreement with the HEs, the sensitivity, specificity, negative and positive predictive values (NPV and PPV) of the AEDS were computed for different cut-offs (patient displaying perioperative 5, 10, 20, 25, or 50 microemboli).
  
  
  RESULTS
  77 233 events were analyzed. The inter- and intraobserver variability was good (min κ = 0.72, max κ = 0.79). AEDS and the HEs identified 760 and 470 solid emboli, respectively. The agreement between AEDS and the HEs for solid emboli detection was poor (κ = 0.24, SE = 0.016). The specificity and NPV were high (99.2 % and 99.6 %) but the sensitivity and PPV were low (30.6 % and 19.8 %). Applying a threshold of > 20 microemboli resulted in the best sensitivity (100.0 %), specificity (84.4 %), PPV (42.7 %), NPV (100.0 %) and area under the curve (0.898). However, 58.3 % of the patients were false positive as classified by AEDS.
  
  
  CONCLUSIONS
  In this validation cohort, AEDS has insufficient agreement with HEs in the identification of solid emboli. AEDS and HEs disagree with respect to the identification of specific patients at risk. Therefore, AEDS cannot be used as a standalone system to identify patients at risk for perioperative stroke during CEA.
authors.affiliation: Vascular Surgery, University Medical Center Utrecht, Netherlands.
authors.forename: Tesse
authors.initials: T
authors.lastname: Leunissen
authors.affiliation: Clinical Neurophysiology, University Medical Center Utrecht, Netherlands.
authors.forename: Daniel
authors.initials: D
authors.lastname: van Vriesland
authors.affiliation: Experimental Cardiology, University Medical Center Utrecht, Netherlands.|Neurology/Clinical Neurophysiology, Academic Hospital Maastricht, Netherlands.
authors.forename: Hester
authors.initials: H
authors.lastname: den Ruijter
authors.affiliation: Vascular Surgery, University Medical Center Utrecht, Netherlands.
authors.forename: Frans
authors.initials: F
authors.lastname: Moll
authors.affiliation: Neurology/Clinical Neurophysiology, Academic Hospital Maastricht, Netherlands.
authors.forename: Werner
authors.initials: W
authors.lastname: Mess
authors.affiliation: Vascular Surgery, University Medical Center Utrecht, Netherlands.
authors.forename: Gert Jan
authors.initials: GJ
authors.lastname: de Borst
mesh_terms: D001331:Automation; D016893:Carotid Stenosis; D003936:Diagnosis, Computer-Assisted; D004617:Embolism / Q000175:diagnosis; D016894:Endarterectomy, Carotid; D006801:Humans; D020766:Intracranial Embolism; D012680:Sensitivity and Specificity; D012984:Software; D017585:Ultrasonography, Doppler, Transcranial