Objective To investigate the value of amide proton transfer (APT) magnetic resonance imaging in the diagnosis of acute cerebral ischemia and hemorrhage. Methods 45 subjects were enrolled, including 15patients of acute cerebral ischemia (ischemia group),15 patients of acute cerebral hemorrhage (hemorrhage group) and 15 age-matched healthy volunteers (control group). All subjects underwent APT MRI and standard MRI (including T2WI, T1WI and DWI). The APT image was acquired on the transverse slice with the largest area of the lesions in ischemia group and hemorrhage group, and in control group the slice of basal ganglia was selected to acquire the APT image and detect the APT effect. The magnetic resonance ratio asymmetry(MTRaysm) values at 3.5 ppm, which were named APT weighted (APTw) values of the lesions were measured on APT images, and APTw values on the contralateral side of normal appearance white matter regions was also observed. APTw values of the largest lesions among the ischemia group, the hemorrhage group and the control group were compared with one-way analysis of variance(ANOVA). The differences of APTw values between the lesion side and contralateral normal regions in the ischemia group and hemorrhage group were compared with the paired t test. Results APTw values of the infarcted side and the contralateral side in the ischemia group were (-0.59±0.38) % and (0.52±0.25) %, respectively (P<0.001). APTw values of the hemorrhagic side and the contralateral side in the hemorrhage group were (2.05±1.14) % and (0.62±0.30) %, respectively (P=0.005). In the control group, there was not significantly difference between the two normal appearance sides. The ANOVA results showed the differences of APTw values among three groups of the lesion side were significant (F= 35.525, P<0.001). ConclusionsAPT MRI can non-invasively, nonradiatively and sensitively detect the existence and differences of acute cerebral ischemia and hemorrhage, which could be potentially served as a useful tool for the clinical diagnosis in the future.