title: A DSA-based method using contrast-motion estimation for the assessment of the intra-aneurysmal flow changes induced by flow-diverter stents.
abstract: OBJECTIVE
  Flow-diverter stents modify intra-aneurysmal blood flow and induce the progressive thrombosis of intracranial aneurysms followed by stable vascular reconstruction. The aim of this study was to report a new method for the appraisal of intracranial blood flow from DSA performed during endovascular treatment procedures.
  
  
  METHODS
  A cohort of 24 patients with unruptured IAs who underwent FDS implantation was prospectively recruited. Pre- and post-DSA sequences in combination with 3D rotational angiography were acquired. The quantification of arterial and intra-aneurysmal flow was accomplished by using an optical flow approach. Flow reduction was assessed by using a new metric termed the mean aneurysm flow amplitude ratio. The correlation between the MAFA ratio and the incidence of aneurysm thrombosis was assessed by using receiver operating characteristic analysis and the Fisher exact test when the optimum Youden index was found.
  
  
  RESULTS
  The quantification of flow was successfully achieved in 21 of 24 patients (87.5%). On the imaging follow-up, 18 aneurysms developed complete thrombosis (87.5%) and 3 displayed residual circulation (12.5%). The threshold analysis of the MAFA ratio significantly predicted thrombosis at 12 months below a threshold of 1.03 (P=.035). There was no significant correlation between the time for complete occlusion of the aneurysm and contrast stagnation inside the aneurysm after treatment (P>.05).
  
  
  CONCLUSIONS
  The MAFA ratio based on DSA flow quantification appears to be a reliable predictor for the assessment of stent treatment outcomes in this small study. These results open the door for perioperative flow quantification and provide indices that may help clinicians make appropriate intraprocedural decisions.
authors.affiliation: Interventional Neuroradiology Unit, Service of Neuroradiology, University Hospital of Geneva, Geneva, Switzerland. vitor.mendespereira@hcuge.ch
authors.forename: V M
authors.initials: VM
authors.lastname: Pereira
authors.forename: O
authors.initials: O
authors.lastname: Bonnefous
authors.forename: R
authors.initials: R
authors.lastname: Ouared
authors.forename: O
authors.initials: O
authors.lastname: Brina
authors.forename: J
authors.initials: J
authors.lastname: Stawiaski
authors.forename: H
authors.initials: H
authors.lastname: Aerts
authors.forename: D
authors.initials: D
authors.lastname: Ruijters
authors.forename: A P
authors.initials: AP
authors.lastname: Narata
authors.forename: P
authors.initials: P
authors.lastname: Bijlenga
authors.forename: K
authors.initials: K
authors.lastname: Schaller
authors.forename: K-O
authors.initials: KO
authors.lastname: Lovblad
mesh_terms: D000328:Adult; D000368:Aged; D015901:Angiography, Digital Subtraction / Q000379:methods*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D057510:Endovascular Procedures / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D010865:Pilot Projects; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D015607:Stents; D013927:Thrombosis / Q000000981:diagnostic imaging