Briefly describe the MRI manifestations of different types of cerebral infarction?

The MRI findings are different with the location and etiology of cerebral infarction: ① Cerebral hemisphere infarction is generally fan-shaped or irregular, and the distribution of lesions is consistent with the blood supply location of cerebral artery. ② Brain stem infarction is mostly oval or fissure-shaped, which is more common in pons. If infarction occurs in the dorsal part of a medulla oblongata and cerebellar hemisphere at the same time, it is often caused by infarction of inferior posterior cerebellar artery. ③ Hemorrhagic cerebral infarction, also known as hemorrhage after cerebral infarction, is the recanalization of blood vessels in the ischemic area, and there is blood oozing in the infarcted area, leading to hemorrhagic softening. It is characterized by hematoma formation, patchy hemorrhage or a small amount of hemorrhage around the infarction area. Magnetic * * * vibration is mainly manifested as the change of infarction signal, or the change of infarction signal first and then bleeding signal. However, this bleeding signal changes weakly, unlike the typical changes of cerebral hemorrhage. ④ Cerebral embolism refers to cerebral infarction caused by an embolus suddenly entering the blood circulation and suddenly blocking the cerebral arterial system. Although it is similar to the pathological changes and magnetic resonance manifestations of cerebral infarction mentioned above, the lesions usually occur in the trunk of middle cerebral artery and its branches, and there are more chances of hemorrhagic cerebral infarction, and the lesions can be multiple. ⑤ Watershed cerebral infarction refers to the infarction at the junction of two main cerebral arteries, and its morphological and signal changes are the same as those of general cerebral infarction.