Astrocytoma is the most common neuroepithelial tumor, accounting for 13%-26% of intracranial tumors and 21.2%-51.6% of glial forms according to the literature. Astrocytomas can occur in any part of the central nervous system, generally in the brain in adults and in the subscripts in children. It has been reported that supratentorial astrocytomas account for 3/4 of the tumors and infratentorial astrocytomas account for l/4. Supratentorial astrocytomas are more common in the frontal and decubitus lobes, followed by the parietal lobe and less common in the occipital lobe. The tumors can also be found in the optic nerve, the thalamus and the third paraventricular ventricle, while the subscripts are mostly located in the cerebellar hemispheres and the fourth ventricle, and also in the cerebellar earth and brainstem. Pathological tumors are mainly located in the white matter and show infiltrative growth. Solid tumors do not have obvious borders and are mostly not limited to one lobe. About half of the tumors are partially cystic. The cystic fluid is yellowish and transparent, with high protein content and easy to self-clot at rest, which is called positive Froin’s sign. We call tumors with cystic changes “cysts within the tumor”. The astrocytic skull located in the cerebellum is often a large capsule with a tumor nodule on the wall of the capsule, which is composed of fibrous connective tissue and glial fibers, so only the atoma nodule can be removed for the purpose of curing the tumor. A small number of cerebellar astrocytomas are substantial, with infiltrative growth and no obvious border, and the prognosis is worse than that of cystic ones. According to the histological characteristics of the tumor, astrocytomas can be divided into three subtypes: fibrous, protoplasmic, and obese cell type. The clinical manifestations of astrocytoma are the continuous growth of tumor occupying the space in the cranial cavity and the obstruction of cerebrospinal fluid circulation pathway by the tumor, resulting in fluid accumulation and/or cerebral edema in the brain. The obstruction of cerebrospinal fluid reabsorption can cause the increase of intracranial pressure. The normal cranial cavity volume is about 10% larger than the brain tissue, and when the brain volume increases by 8%-10%, there may be no symptoms of cranial hypertension, but when the intracranial occupying lesion occupies more than 150 ml of volume, it may produce corresponding symptoms of cranial hypertension. Most astrocytomas of the cerebral hemispheres are slow to develop and have a long course, with localized signs and symptoms due to direct tumor destruction followed by symptoms of increased intracranial pressure. Most astrocytomas of the cerebellum present first with symptoms of increased intracranial pressure because of the early impact on cerebrospinal fluid circulation. The symptoms of increased intracranial pressure mainly include headache, vomiting, optic nerve papillary edema, visual field changes, epilepsy, diplopia, cranial enlargement (in children) and changes in vital signs. CT examination: Fibrous and protoplasmic astrocytomas, because of the water content of 81% to 82%, have low density CT, with CT value between 14-25Hu, and most of the lesions are not surrounded by edema. The tumor location and its size vary, showing the corresponding occupancy effect. The third ventricular astrocytic dried up can be seen after obstruction of the third ventricle and Monro’s foramen, causing enlargement of both ventricles and obstructive hydrocephalus. Optic nerve tumors can be seen as shuttle-shaped enlargement of the optic nerve segment, located intraorbital or intracranially, sometimes in a dumbbell shape. Cerebellar astrocytomas show hypo- and/or mixed-density lesions in the parenchymal portion of the tumor on cT, which may be mildly enhanced by contrast enhancement, while the cystic portion remains consistently hypointense. The cystic portion of the wall may show circumferential or arcuate enhancement. Astrocytoma of the brainstem is seen on CT with brainstem thickening, left-right asymmetry and hypointense or mixed density tumor foci. However, cT shows that brainstem gliosis is not as ideal as MRI. 2. MRI examination: benign astrocytoma has increased water inside and outside the cells due to tumor growth, resulting in prolonged T1 and T2, which shows low signal conduction in Tl-weighted image and high signal in T2-weighted image, with uniform signal intensity and slight peritumor edema. As the tumor grows, cystic degeneration occurs within the tumor, making MRI inhomogeneous. The tumor and the surrounding edema are not as easily distinguished in T1-weighted images as in T2-weighted images, and the tumor may be mildly enhanced. Malignant astrocytomas have mixed signal in T1-weighted images, with predominantly low signal, interspersed with lower or higher signal, reflecting intra-tumor necrosis or hemorrhage; T2-weighted images show high signal with heterogeneous signal intensity, and curved or dotted low signal areas caused by tumor vessels can be seen. On the proton density enumeration (long-DR short TE) images, the tumor signal is lower than the surrounding edema signal, while the signal of the necrotic area inside the tumor is higher than the surrounding edema signal; on the long TR long TE images, the signal intensity of the necrotic area inside the tumor approximates the signal intensity of the surrounding edema, and the tumor signal intensity is relatively reduced. As a result of gliosis in the surrounding tissue, a low signal halo is sometimes seen around the tumor, between the tumor and edema, which is more common in tumors with high malignancy. The latter often has significant abnormal contrast enhancement, with long duration of enhancement and patchy, linear, wreath-like or nodular enhancement, but no contrast enhancement occurs in areas of tumor necrosis or hemorrhage Treatment and Prognosis Treatment of astrocytoma is based on surgical resection. If the tumor is located in a non-functional area, it can be resected together with the lobes of the brain, and if the tumor is located deep, it can be partially resected with external decompression. For optic nerve glioma and third ventricle tumor, care should be taken to protect the lower thalamus. If the tumor is “within the capsule”, radical treatment can be achieved by removing the nodule. Brain stem tumors can be resected by microscopic techniques, and lateral ventriculoperitoneal shunts can be performed if obstructive hydrocephalus is not resolved. In general, it is difficult to make radical resection for substantial astrocytoma, but postoperative radiotherapy and chemotherapy should be given to prolong the survival time. It has a positive effect on prolonging survival. The 5-year survival rate for astrocytoma located in the cerebral hemisphere is 20% with surgery alone, but up to 31.7% with radiotherapy after surgery. If the astrocytoma is located in the subscale and the tumor is in the capsule, no radiation therapy is allowed after removal of the tumor nodule, and the 5-year survival is up to 50% and 88%. Most of the survivors can resume normal study or work. However, if the cerebellar tumor is solid and invades the brainstem, the survival period is significantly shortened. The average time to recurrence is about 2.5 years, the average survival period is about 3 years, and the 5-year survival period is 14%-31% after surgery.