Focused Ultrasound Blood-Brain Barrier Disruption for the Treatment of High-Grade Glioma in Patients Undergoing Standard Chemotherapy

The goal of this clinical trial is to evaluate the safety and feasibility of focused ultrasound (FUS)-mediated blood-brain barrier (BBB) disruption using the Next Generation Dome Helmet (NGDH) in adults with glioblastoma (GBM) undergoing the maintenance phase of the standard "Stupp protocol". Participants will: * Undergo repeated FUS BBB disruption treatments during the maintenance phase of temozolomide (TMZ) chemotherapy. * Receive intravenous ultrasound contrast (DEFINITY®) prior to each FUS session to facilitate targeted BBB disruption. * Undergo serial MRI scans and clinical assessments to evaluate safety and the extent of BBB opening. * Provide blood samples (and tumor tissue if available) for biomarker analysis related to BBB permeability, tumor presence, and treatment response. * Be followed for progression-free survival (PFS) and overall survival (OS) during routine neuro-oncology visits until end of life.