title: Blood flow imaging: an angle-independent ultrasound modality for intraoperative assessment of flow dynamics in neurovascular surgery.
abstract: OBJECTIVE
  The objective of this study was to investigate the clinical applicability of navigated blood flow imaging (BFI) in neurovascular applications. BFI is a new 2-dimensional ultrasound modality that offers angle-independent visualization of flow. When integrated with 3-dimensional (3D) navigation technology, BFI can be considered as a first step toward the ideal tool for surgical needs: a real-time, high-resolution, 3D visualization that properly portrays both vessel geometry and flow direction.
  
  
  METHODS
  A 3D model of the vascular tree was extracted from preoperative magnetic resonance angiographic data and used as a reference for intraoperative any-plane guided ultrasound acquisitions. A high-end ultrasound scanner was interconnected, and synchronized recordings of BFI and 3D navigation scenes were acquired. The potential of BFI as an intraoperative tool for flow visualization was evaluated in 3 cerebral aneurysms and 3 arteriovenous malformations.
  
  
  RESULTS
  The neurovascular flow direction was properly visualized in all cases using BFI. Navigation technology allowed for identification of the vessels of interest, despite the presence of brain shift. The surgeon found BFI to be very intuitive compared with conventional color Doppler methods. BFI allowed for quality control of sufficient flow in all distal arteries during aneurysm surgery and made it easier to discern between feeding arteries and draining veins during surgery for arteriovenous malformations.
  
  
  CONCLUSIONS
  BFI seems to be a promising modality for neurovascular flow visualization that may provide the neurosurgeon with a valuable tool for safer surgical interventions. However, further work is needed to establish the clinical usefulness of the proposed imaging setup.
authors.affiliation: SINTEF Health Research, Trondheim, Norway.
authors.forename: Frank
authors.initials: F
authors.lastname: Lindseth
authors.forename: Lasse
authors.initials: L
authors.lastname: Lovstakken
authors.forename: Ola M
authors.initials: OM
authors.lastname: Rygh
authors.forename: Geir A
authors.initials: GA
authors.lastname: Tangen
authors.forename: Hans
authors.initials: H
authors.lastname: Torp
authors.forename: Geirmund
authors.initials: G
authors.lastname: Unsgaard
mesh_terms: D002536:Cerebral Arteries / Q000000981:diagnostic imaging* / Q000502:physiology / Q000601:surgery*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D002538:Intracranial Arteriovenous Malformations / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D018810:Magnetic Resonance Angiography; D016343:Monitoring, Intraoperative / Q000379:methods*; D019635:Neurosurgical Procedures / Q000379:methods*; D014463:Ultrasonography / Q000379:methods*; D014656:Vascular Surgical Procedures / Q000379:methods