CT Angiography of Collateral Vessels and Outcomes in Endovascular-Treated Acute Ischemic Stroke Patients

Background and purpose: Measuring the extent of the collateral blood vessels using computed tomography (CT) angiography source images may promote tissue survival and functional gain in acute ischemic stroke patients who are candidates for endovascular recanalization treatment.

Methods: Of 5,558 acute stroke patients registered in a prospective clinical stroke registry, 104 met the selection criteria of endovascular recanalization treatment for internal cerebral artery or middle cerebral artery main-stem (M1) occlusions and presented for treatment ≤4 hours after the event. Using CT angiography source images, two independent and blinded reviewers measured the extent of collateral circulations at four regions, with good interrater reliability. The functional recovery at 3 months after stroke was used as an outcome variable.

Results: Cases with a sufficient collateral circulation at the Sylvian fissure showed significantly increased likelihood of having a modified Rankin Scale score of ≤2 at 3 months after stroke (adjusted odds ratio=3.03, 95% confidence interval=1.19-7.73, p=0.02), but the association became nonsignificant after adding the infarct volume to the model (p=0.65). The association between leptomeningeal convexity collaterals and functional recovery was no longer significant after adjusting for the infarct volume (p=0.28). The natural indirect effect of infarct volume on functional recovery was significant for both the Sylvian fissure (p=0.03) and leptomeningeal convexity (p=0.02) collaterals.

Conclusions: The extent of collateral circulation at the Sylvian fissure was significantly associated with functional recovery, which may be mediated via the volume of the final infarction.