title: Grading of Regional Apposition after Flow-Diverter Treatment (GRAFT): a comparative evaluation of VasoCT and intravascular OCT.
abstract: BACKGROUND
  Poor vessel wall apposition of flow diverter (FD) stents poses risks for stroke-related complications when treating intracranial aneurysms, necessitating long-term surveillance imaging. To facilitate quantitative evaluation of deployed devices, a novel algorithm is presented that generates intuitive two-dimensional representations of wall apposition from either high-resolution contrast-enhanced cone-beam CT (VasoCT) or intravascular optical coherence tomography (OCT) images.
  
  
  METHODS
  VasoCT and OCT images were obtained after FD implant (n=8 aneurysms) in an experimental sidewall aneurysm model in canines. Surface models of the vessel wall and FD device were extracted, and the distance between them was presented on a two-dimensional flattened map. Maps and cross-sections at potential locations of malapposition detected on VasoCT-based maps were compared. The performance of OCT-based apposition detection was evaluated on manually labeled cross-sections using logistic regression against a thresholded (≥0.25 mm) apposition measure.
  
  
  RESULTS
  VasoCT and OCT acquisitions yielded similar Grading of Regional Apposition after Flow-Diverter Treatment (GRAFT) apposition maps. GRAFT maps from VasoCT highlighted 16 potential locations of malapposition, of which two were found to represent malapposed device struts. Logistic regression showed that OCT could detect malapposition with a sensitivity of 98% and a specificity of 81%.
  
  
  CONCLUSIONS
  GRAFT delivered quantitative and visually convenient representations of potential FD malapposition and occasional acute thrombus formation. A powerful combination for future neuroendovascular applications is foreseen with the superior resolution delivered by intravascular OCT.
authors.affiliation: Department of Radiology, New England Center for Stroke Research, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: Kajo
authors.identifier: http://orcid.org/0000-0003-1099-9498
authors.initials: K
authors.lastname: van der Marel
authors.affiliation: Department of Radiology, New England Center for Stroke Research, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Gounis
authors.affiliation: Department of Neurosurgery, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: John P
authors.initials: JP
authors.lastname: Weaver
authors.affiliation: Department of Radiology, New England Center for Stroke Research, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: Antonius M
authors.initials: AM
authors.lastname: de Korte
authors.affiliation: Department of Radiology, New England Center for Stroke Research, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: Robert M
authors.initials: RM
authors.lastname: King
authors.affiliation: Stryker Neurovascular, Fremont, California, USA.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Arends
authors.affiliation: Department of Radiology, New England Center for Stroke Research, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: Olivia W
authors.initials: OW
authors.lastname: Brooks
authors.affiliation: Department of Radiology, New England Center for Stroke Research, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: Ajay K
authors.initials: AK
authors.lastname: Wakhloo
authors.affiliation: Department of Radiology, New England Center for Stroke Research, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: Ajit S
authors.initials: AS
authors.lastname: Puri
mesh_terms: D000465:Algorithms; D000818:Animals; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000379:methods*; D001808:Blood Vessels / Q000000981:diagnostic imaging*; D001931:Brain Mapping; D054893:Cone-Beam Computed Tomography / Q000295:instrumentation / Q000379:methods*; D004285:Dogs; D057510:Endovascular Procedures / Q000295:instrumentation / Q000379:methods*; D005260:Female; D007091:Image Processing, Computer-Assisted; D002532:Intracranial Aneurysm / Q000601:surgery; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000379:methods; D041623:Tomography, Optical Coherence / Q000295:instrumentation / Q000379:methods*; D016896:Treatment Outcome
keywords: Aneurysm; Angiography; Endoscopy; Flow Diverter; Technology