Fig. 5

Cerebrospinal fluid effusions and susceptibility effects are observed after blood–brain barrier opening. Frontal and parietal FUS target sites are shown on T2-weighted images in three patients A. Post-contrast T1 (T1 + C) and T2-FLAIR (FLAIR + C) MRI images in a 73 year-old woman with Alzheimer’s disease (same patient shown in Fig. 2B) show CSF space hyperintensity (arrowheads), indicating CSF effusions, over frontal and parietal brain regions treated with FUS. GRE images in a 67 year-old woman with Alzheimer’s disease C show development of punctate foci of signal dropout at targeted frontal brain region (arrowheads) compared to baseline, with resolution of these signal changes by 48 h post FUS. The GRE signal changes did not always completely resolve, however were not associated with any clinical adverse effects in any subject. GRE images in a 54 year-old woman with Alzheimer’s disease D show development of superficial siderosis (arrowhead) along the surface of the treated parietal precuneus. Perivenous siderosis (arrowhead) is also shown following FUS in a 57 year-old male trial participant