Collateral Status on Baseline Computed Tomographic Angiography and Intra-Arterial Treatment Effect in Patients With Proximal Anterior Circulation Stroke. - Berkhemer OA; Jansen IG; Beumer D; Fransen PS; van den Berg LA; Yoo AJ; Lingsma HF; Sprengers ME; Jenniskens SF; Lycklama À Nijeholt GJ; van Walderveen MA; van den Berg R; et al. (Stroke, 2016)