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Original research
Impact of the global outflow angle on recanalization after endovascular treatment of middle cerebral artery bifurcation aneurysms
  1. Yannick de La Torre1,
  2. Stéphane Velasco1,
  3. Jean-Pierre Tasu1,
  4. Cassandre Wanpouille1,
  5. Paul Chan1,
  6. Raphael Velasco2,
  7. Guillaume Sztark3,
  8. Pierre Ingrand4,
  9. Samy Boucebci1
  1. 1Department of Radiology, CHU of Poitiers, Poitiers, Vienne, France
  2. 2Laboratoire Des Technologies Innovantes, University of Picardie Jules Vernes, Amiens, France
  3. 3Department of Radiology, Hospital Center of Angoulême, Angoulême, France
  4. 4Department of Biostatics, Faculty of Medecine, University of Poitiers, Poitiers, France
  1. Correspondence to Dr Yannick de La Torre, Department of Radiology, CHU of Poitiers, 86 000 Poitiers, France; yannick.delatorre{at}


Background and purpose Intracranial aneurysm recanalization after endovascular treatment (EVT) remains a major problem. The goal of this study was to find new predictive factors of recanalization after EVT of middle cerebral artery (MCA) bifurcation aneurysms.

Methods 96 MCA bifurcationaneurysms, ruptured or unruptured, treated by EVT between Septembre 2009 and December 2014, were retrospectively included. Clinical parameters and aneurysm characteristics were recorded. From the initial three-dimensional DSA, spatial coordinates found on parent and daughter arteries of MCA bifurcations gave four different flow angle values; inflow, outflows 1 and 2, and the global outflow angle (the sum of the two outflow angles). Inter- and intra-observer reproducibilities of three-dimensional angle value measurements were performed.

Results Recanalization occurred in 25 cases (26%) and retreatment was performed in 11 cases (11%). Only 1 patient (1%) had rebleeding. Univariate analysis established the following as predictive factors of recanalization: high blood pressure (P=0.014), aneurysm height (P<0.001), aneurysm width (P<0.001), neck size (P<0.001), postoperative occlusion class (P=0.040), percentage of packing volume (P<0.001), as well as the two outflow angles (P=0.006 and 0.045), and the global outflow angle (P<0.001). Multivariate analysis revealed two independent risk factors for recanalization: the global outflow angle (OR=1.05; 95% CI 1.02 to 1.08; P<0.002) and aneurysm width (OR=0.67; 95% CI 0.46 to 0.96; P=0.031). A global outflow angle threshold <192° was found to be a risk factor for recanalization (OR=13.75; 95% CI 4.46 to 42.44), with a sensitivity of 80% and specificity of 77%.

Conclusions This study emphasizes that a new parameter, the global outflow angle, can be predictive of recanalization for MCA bifurcation aneurysms treated by EVT.

  • aneurysm
  • blood flow
  • hemorrhage
  • magnetic resonance angiography
  • subarachnoid

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  • Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.