Characteristics of computed tomography images at admission Group Signs Total ≤ 3 hour > 3 hour p OR n=103% n=103% n=103% Normal 30 29.1 19 44.2 11 18.3 <0.01 3.5 Ischemic 73 65.9 24 55.8 49 81.7 Cerebral atrophy 15 14.6 9 20.9 6 10.0 >0.05 0.4 Pre-stroke 20 19.4 8 18.6 12 20.0 >0.05 1.1 With AIS due to LVO of anterior system, CT images normal was 29.1%.