Assessment of Intracranial Collaterals on CT Angiography in Anterior Circulation Acute Ischemic Stroke. by Yeo, L, Paliwal, P, Teoh, H, Seet, R, Chan, B, Ting, E, Venketasubramanian, N, Leow, W, Wakerley, B, Kusama, Y, Rathakrishnan, R, Sharma, V