Quantitative assessment of collateral time on perfusion computed tomography in acute ischemic stroke patients oleh Yao Xu, Jianhong Yang, Xiang Gao, Jie Sun, Qing Shang, Qing Han, Yuefei Wu, Jichuan Li, Tianqi Xu, Yi Huang, Yi Huang, Yuning Pan, Mark W. Parson, Mark W. Parson, Longting Lin, Longting Lin