Figure 1.

Assessment of leptomeningeal collaterals according to collateral assessment method 1 (Tan et al.’s method). Four computed tomography angiography maximum intensity projection axial images from different patients showing leptomeningeal collaterals. (A) Absent collateral supply to the occluded middle cerebral artery territory (circle), compared to the contralateral normal side. (B) Collateral supply of greater than 0% but less than or equal to 50%. (C) Collateral supply of greater than 50% but less than 100%. (D) Complete collateral supply of 100%.