The degree of perineural edema of brain tumor is related to the malignancy, growth rate and growth site of the tumor, and the perineural edema of rapidly growing malignant tumors such as metastases and grade III-IV gliomas is obvious, while the perineural edema of slow growing benign tumors such as meningiomas is light. Metastatic tumor is small but obvious edema, meningioma is large but light edema, if compression of drainage vein can cause obvious edema. In pathology, perineural edema of brain tumor is mainly due to increased capillary permeability and disruption of blood-brain barrier, resulting in interstitial edema of perineural brain tissue. The main causes of perineural edema in meningiomas and metastases are increased capillary permeability and compression of local microcirculation by edema fluid. Vascular compression of edema fluid leads to decreased blood flow and blood volume in cerebral tissue , without significant changes in local neural and vascular structures. The rCBF and rCBV of peritumoral edema in meningiomas and metastases are significantly lower than those in the contralateral cerebral white matter, and the rCBV in the near-tumor edema area is found to be lower than that in the far-tumor edema area, which also suggests vascular compression edema. High-grade gliomas showed infiltrative growth, and the peritumoral edema area was partially or completely infiltrated with tumor tissue, which infiltrated to Table 1 rCBF, rCBV values of brain tumor peritumoral edema ( . x ± s) rCBF rCBV brain tumor peritumoral edema contralateral t value P value peritumoral edema contralateral t value P value meningioma 13112 ± 5181 28174 ± 16102 2192 0105), but both were Both were significantly lower than those of glioma (0191 ± 0126, 1156 ± 1141; t = 3105, 3137; P 110, metastatic tumor perineural edema to contralateral brain white matter ratio.