Anterior Borderzone Angle for Hemodynamic Collateral Metric in Patients with Symptomatic Middle Cerebral Artery Stenosis

BACKGROUND AND AIMS: We aimed to introduce a parameter of anterior borderzone angle (ABZA) to quantitatively evaluate the ACA-MCA leptomeningeal collaterals for middle cerebral artery stenosis (MCAS). METHODS: Two hundred seventy-five patients with 50-100% MCAS and 100 controls were included. The 95% reference range of ABZA was obtained from the controls. ABZAtrans was defined as "ABZA/the 95% upper limit." Relationships between ABZA and MCAS, -ABZAtrans and the TICI grade, the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) collateral grade were analyzed. An ABZA grade model for the ACA leptomeningeal collaterals was tentatively developed. RESULTS: The 95% reference range of ABZA was 0.0o-23.0o. ABZA was significantly associated with MCAS by a function of the fourth power (R2 = 0.723, p < 0.001), and could predict hemodynamic MCAS (≥70%) with an AUC of 0.928 (95% CI 0.903-0.953). ABZAtrans was negatively correlated with the TICI grade (rho = -0.752, p < 0.001) and positively with the ASITN/SIR grade (rho = 0.921, p < 0.001). The ABZA grade was created by rounding -ABZAtrans to a nearest integer, and was closely associated with the ASITN/SIR grade (rho = 0.894, p < 0.001). CONCLUSIONS: ABZA can be used as a hemodynamic parameter to quantitatively evaluate ACA leptomeningeal collaterals.