The protective role of intracranial primary collaterals on plaque vulnerability is not well established. We aimed to explore the association of intracranial collateral status with arterial wall features including arterial remodeling and culprit plaque features in severe symptomatic intracranial vertebrobasilar atherosclerosis (sIVBAS). Posterior circulation stroke or TIA patients owing to sIVBAS from a three-dimensional high-resolution MRI (3D HRMRI) prospective observational study was included for current analysis. Participants were dichotomized into poor and good collateral groups according to a modified semiquantitative grading system for primary collateral of posterior circulation. Differences of arterial remodeling, culprit plaque distribution, enhancement, intraplaque hemorrhage (IPH), and calcification on HRMRI were compared between the two groups. Seventy-four eligible patients were included, wherein 39 in poor collateral group and 35 in good collateral group. The average age was 57.0 ± 9.0 years, 65 (87.8%) were male, 62 (83.8%) were diagnosed with ischemic stroke and 12 (16.2%) with TIA. Patients with good collateral had lower occurrence of arterial positive remodeling and plaque diffuse distribution, enhancement (Adjusted OR = 0.17 [0.05–0.54], p < 0.01; adjusted OR = 0.26 [0.06–0.99], p = 0.05; adjusted OR = 0.17 [0.03–0.96], p = 0.04, respectively). No significant differences on IPH and calcification were found between poor and good collateral group (p > 0.05). Intracranial good collateral of posterior circulation may be associated with lower risk of arterial positive remodeling and culprit plaque diffuse distribution, plaque enhancement in patients with severe sIVBAS. clinicaltrials.gov Identifier: NCT02705599.

The protective role of intracranial primary collaterals on plaque vulnerability is not well established. We aimed to explore the association of intracranial collateral status with arterial wall features including arterial remodeling and culprit plaque features in severe symptomatic intracranial vertebrobasilar atherosclerosis (sIVBAS). Posterior circulation stroke or TIA patients owing to sIVBAS from a three-dimensional high-resolution MRI (3D HRMRI) prospective observational study was included for current analysis. Participants were dichotomized into poor and good collateral groups according to a modified semiquantitative grading system for primary collateral of posterior circulation. Differences of arterial remodeling, culprit plaque distribution, enhancement, intraplaque hemorrhage (IPH), and calcification on HRMRI were compared between the two groups. Seventy-four eligible patients were included, wherein 39 in poor collateral group and 35 in good collateral group. The average age was 57.0 ± 9.0 years, 65 (87.8%) were male, 62 (83.8%) were diagnosed with ischemic stroke and 12 (16.2%) with TIA. Patients with good collateral had lower occurrence of arterial positive remodeling and plaque diffuse distribution, enhancement (Adjusted OR = 0.17 [0.05–0.54], p < 0.01; adjusted OR = 0.26 [0.06–0.99], p = 0.05; adjusted OR = 0.17 [0.03–0.96], p = 0.04, respectively). No significant differences on IPH and calcification were found between poor and good collateral group (p > 0.05). Intracranial good collateral of posterior circulation may be associated with lower risk of arterial positive remodeling and culprit plaque diffuse distribution, plaque enhancement in patients with severe sIVBAS. clinicaltrials.gov Identifier: NCT02705599.