Abstract: Objective To investigate the application value of perfusion weighted imaging(PWI) combined with diffusion weighted imaging (DWI) in the diagnosis of acute cerebral infarction. Methods The clinical and imaging data of 56 elderly patients with cerebral infarction within 1 h to 72 h after the onset of symptoms were collected by the retrospective study. Twenty patients were in hyperacute phase with time since stroke onset<6 h, and 36 patients were in acute phase with time since stroke onset 7-72 h. All the patients were examined by PWI and DWI. The main items for observation included abnormal regions and parameters of DWI and PWI, such as cerebral blood flow (CBF), cerebral blood volume (CBV), mean transient time (MTT) and time to peak (TTP) in affected brain tissue of cerebral infarction. Results PWI showed that MTT and TTP were prolongated. In hyperacute phase, the level of CBF decreased in 18 cases (90.00%) and remained normal in 2 cases (10.00%); the level of CBV decreased in 10 cases (50.00%), remained normal in 5 cases (25.00%), and increased in 5 cases (25.00%). In acute phase, the level of CBF decreased in 36 cases (100.00%); the level of CBV decreased in 26 cases (72.22%), remained normal in 5 cases (13.89%), and increased in 5 cases (13.89%). DWI in hyperacute phase showed less abnormal signal region than PWI in all cases. In acute phase, there were 21 cases with DWI <PWI, 10 cases with DWI=PWI, and 5 cases with DWI > PWI. Conclusions DWI can show the necrotic area of cerebral infarction, while PWI can show both the necrotic area of cerebral infarction and its surrounding ischemic penumbra. Combined use of DWI and PWI can define the range of cerebral infarction and ischemic penumbra.

Key words: magnetic resonance imaging, perfusion weighted imaging, diffusion weighted imaging, cerebral infarction