The films often done for cerebral infarction are cranial CT and cranial MRI. When looking at the head CT, the main observation is whether there is any abnormal density in the patient’s brain. The infarct lesions in patients with cerebral infarction show up as low density on the head CT, and fresh lesions will have fuzzy edges around them, often accompanied by edema, but the degree of edema is not heavy. In old cerebral infarction, the lesions have sharper edges, have formed softened foci, and are much less dense. If it is a large cerebral infarction, the patient should also be observed for compression of the ventricular system, displacement of normal brain tissue, and the risk of severe cerebral edema leading to brain herniation. In the case of MRI films, when observing acute brain infarction, the main thing to look at is the diffusion phase, which can show fresh brain infarct lesions alone and old ones not. In the FLAIR phase, T1 phase and T2 phase, both fresh and old brain infarct lesions can be observed as long T1 and long T2 signals and high signal in the FLAIR phase, respectively.