Mechanisms, Imaging Phenotypes, and Therapeutic Advances of Neovascularization in Brain Metastases

Brain metastases have a distinctive vascular ecosystem—shaped by sprouting angiogenesis, vessel co-option, vasculogenic mimicry, and tumor cell transdifferentiation—that governs tumor perfusion, drug exposure, and therapeutic responsiveness. These heterogeneous vascularization patterns exhibit characteristic differences in enhancement morphology, perfusion levels, and metabolic uptake on contrast-enhanced MRI, perfusion imaging, and amino acid PET, providing crucial imaging cues for identifying routes of blood supply, inferring the state of the blood–tumor barrier, and guiding individualized therapeutic strategies. Anti-VEGF therapy is primarily used to alleviate cerebral edema and radiation necrosis, yet it confers limited survival benefit, underscoring the spatiotemporal heterogeneity of the blood–tumor barrier and the persistence of non-classical vascularization pathways. Building on the concept of “vascular normalization,” combinations of anti-angiogenic therapy with immunotherapy, radiotherapy, or targeted agents have shown encouraging intracranial activity in selected settings—most robustly in melanoma brain metastases—but remain insufficiently validated in randomized, brain-metastasis-focused trials. By integrating mechanistic, imaging, and therapeutic perspectives, this review outlines how vascular-ecosystem-based stratification and physics-informed drug-delivery strategies may help transition anti-vascular therapy from symptomatic control toward mechanism-driven precision intervention.