title: Solid or gaseous circulating brain emboli: are they separable by transcranial ultrasound?
abstract: High-intensity transient signals (HITS) detected by transcranial Doppler (TCD) ultrasound may correspond to artifacts or to microembolic signals, the latter being either solid or gaseous emboli. The goal of this study was to assess what can be achieved with an automatic signal processing system for artifact/microembolic signals and solid/gas differentiation in different clinical situations. The authors studied 3,428 HITS in vivo in a multicenter study, i.e., 1,608 artifacts in healthy subjects, 649 solid emboli in stroke patients with a carotid stenosis, and 1,171 gaseous emboli in stroke patients with patent foramen ovale. They worked with the dual-gate TCD combined to three types of statistical classifiers: binary decision trees (BDT), artificial neural networks (ANN), and support vector machines (SVM). The sensitivity and specificity to separate artifacts from microembolic signals by BDT reached was 94% and 97%, respectively. For the discrimination between solid and gaseous emboli, the classifier achieved a sensitivity and specificity of 81% and 81% for BDT, 84% and 84% for ANN, and 86% and 86% for SVM, respectively. The current results for artifact elimination and solid/gas differentiation are already useful to extract data for future prospective clinical studies.
authors.affiliation: Signal Processing Institute, Swiss Federal Institute of Technology, Lausanne, Switzerland.
authors.forename: Georges A
authors.initials: GA
authors.lastname: Darbellay
authors.forename: Rebecca
authors.initials: R
authors.lastname: Duff
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Vesin
authors.forename: Paul-André
authors.initials: PA
authors.lastname: Despland
authors.forename: Dirk W
authors.initials: DW
authors.lastname: Droste
authors.forename: Carlos
authors.initials: C
authors.lastname: Molina
authors.forename: Joachim
authors.initials: J
authors.lastname: Serena
authors.forename: Roman
authors.initials: R
authors.lastname: Sztajzel
authors.forename: Patrick
authors.initials: P
authors.lastname: Ruchat
authors.forename: Theodoros
authors.initials: T
authors.lastname: Karapanayiotides
authors.forename: Afksendyios
authors.initials: A
authors.lastname: Kalangos
authors.forename: Julien
authors.initials: J
authors.lastname: Bogousslavsky
authors.forename: Erich B
authors.initials: EB
authors.lastname: Ringelstein
authors.forename: Gérald
authors.initials: G
authors.lastname: Devuyst
mesh_terms: D000465:Algorithms; D016477:Artifacts; D016893:Carotid Stenosis / Q000150:complications; D002560:Cerebrovascular Circulation / Q000502:physiology; D003663:Decision Trees; D004618:Embolism, Air / Q000000981:diagnostic imaging*; D006344:Heart Septal Defects, Atrial / Q000150:complications; D006801:Humans; D020766:Intracranial Embolism / Q000000981:diagnostic imaging* / Q000209:etiology; D016571:Neural Networks, Computer; D012680:Sensitivity and Specificity; D020521:Stroke / Q000000981:diagnostic imaging / Q000209:etiology; D017585:Ultrasonography, Doppler, Transcranial