Shaveless focused-ultrasound-induced blood-brain barrier opening in mice

To demonstrate that focused ultrasound-induced blood-brain barrier opening (FUS-BBBO) in mice can be achieved without shaving hairs. We performed FUS-BBBO in mice by using oil as the coupling medium without shaving hairs. The hydrophobic nature of oil leads to a higher affinity to hair than water-based ultrasound gel. FUS-BBBO outcome was compared under three conditions: “oil + hairs,” “gel + hairs,” and “gel + no hairs.” T2-weighted, T1-weighted MRI, and fluorescence imaging of the ex vivo brain slices were performed to measure the quality of coupling and outcome of FUS-BBBO. Results showed that “oil + hairs” consistently achieved high-quality acoustic coupling without trapping air bubbles (Figures A & B). FUS-BBBO outcome was not significantly different between the “oil + hairs” group and the “gel + no hairs” group based on T1-weighted MRI (Figures C & D) and ex vivo fluorescence imaging (Figure E). The FUS-BBBO efficiencies for both the “oil + hairs” and “gel + no hairs” groups were significantly higher than the “gel + hairs” group. This study demonstrated that FUS-BBBO in mice could be achieved without shaving hairs. Oil provides a simple solution for achieving effective acoustic coupling for transcranial FUS procedures.