Fig. 4 

Venous permeabilization is observed multifocally within the brain following FUS mediated blood–brain barrier opening and persists beyond the time of BBB closure, for up to one week post FUS intervention. Parietal, frontal, and hippocampal FUS target sites are shown on T2-weighted images in three patients A. Post-contrast T1-weighted images show venous permeabilization manifesting as linear and curvilinear contrast enhancement within the FUS-treated zones within parietal, frontal, and hippocampal regions (arrowheads in C, E–G, I, K, respectively). This enhancement revealed branching configurations, and discrete arborized patterns, as shown in I, J extending to the deep venous system (i.e. basal vein of Rosenthal via hippocampal veins shown in I, J, K) and the dural venous sinuses (i.e. inferior sagittal sinus via posterior pericallosal vein, shown in C, D; see Additional files 3, 4 for additional images). Venous permeabilization enhancement corresponded anatomically to intraparenchymal and extraparenchymal parietal, frontal, and hippocampal venous architecture, as shown on susceptibility-weighted imaging (arrowheads, D, H, K)