Fig. 2

FUS procedure for targeted transient blood–brain barrier opening. The study was conducted using the Insightec Type II FUS transducer in combination with Definity® microbubbles A. Imaging was acquired using a 3-Tesla Siemens MRI scanner and gadobutrol contrast tracer in 8 volunteer subjects with early Alzheimer’s disease. The treatment and MRI timeline is shown B. FUS target sites within the frontal and parietal lobes are shown in green C. MRI scans show blood–brain barrier (BBB) opening and closure within these targeted brain volumes in a 73-year-old woman with Alzheimer’s disease D–F. Post-contrast T1 weighted images, at baseline D, immediately after FUS treatment E, and 24 h after treatment F show contrast tracer extravasation into parenchyma (arrowheads, E) due to focal BBB opening at the prescribed treatment sites. The BBB is closed at 24 h post FUS intervention F, with no contrast enhancement seen at target sites following repeat gadobutrol contrast tracer administration. BBB blood–brain barrier, Hr hour, IV intravenous, Mo month, Tx treatment, Wk week, Yr year