Figure 2.

Mechanical focused ultrasound energy regimens for cancer immunotherapy. Left Column: Mechanical disruption using pulsed, high-pressure, focused ultrasound after intravenous injection of contrast agent microbubbles (top row: yellow dots evident in red blood vessels). Driving microbubbles into inertial cavitation by sweeping the ultrasound focus through the tumor volume disrupts cell membranes and mechanically injures tumor tissue. Due to the use of very low duty-cycles, this energy regimen is not typically associated with tumor heating. Right Column: Blood-brain and/or blood-tumor barrier opening for delivering systemically administered immunotherapeutic drugs (top row: green dots evident in red blood vessels) to the CNS using pulsed, low-pressure, focused ultrasound. Here, contrast agent microbubbles (top row: yellow dots evident in red blood vessels), which are i.v. injected with the immunotherapeutic drug, stably oscillate in the FUS field. Stable oscillations open the BBB/BTB, permitting targeted immunotherapeutic drug deliver to treated CNS tissue (bottom row; green dots).