Inclusion Criteria:  Adult patients operated between January 2018 and January 2020 with a pathological diagnosis of WHO grade IV astrocytoma (Glioblastoma). Intraoperative ultrasound study that includes B-mode images  Exclusion Criteria:  Other histopathological diagnoses. Even though the international database will be established in such a way that other tumor types can be included prospectively. Artifacts in ultrasound images that make their analysis impossible Stereotactic biopsies.