Optional (but useful) bits of equipment for FUS-BBBO include a transducer-integrated hydrophone to measure cavitational activity of microbubbles, and an imaging device to track the BBB opening. Cavitational activity can be recorded from a hydrophone and transferred into an oscilloscope. We use an inexpensive USB-connected oscilloscope from Picotech (~$150). Tracking the BBB opening is usually done using an MRI. When a BBB-impermeable contrast agent (such as Prohance) is injected intravenously, it can extravasate locally at the site of BBB opening producing a visible image contrast. Another recently developed possibility is to use an imaging ultrasound transducer to observe a location of cavitational activity during FUS insonation (see: power cavitation imaging). Power cavitation imaging could be helpful to groups that do not have an access to MRI equipment.