The Effect of Pulse Length on Theranostic Ultrasound-Mediated Blood-Brain Barrier Opening Volume, Closing Timeline, and Cavitation Mapping in Vivo

Theranostic Ultrasound (TUS) is a novel modality for combined blood-brain barrier (BBB) opening and cavitation mapping within a single multielement imaging transducer. While previous work developing TUS has focused on understanding qualitative spatial agreement of a cavitation mapping strategy called power cavitation imaging with regions of BBB opening indicated on contrast-enhanced magnetic resonance images (MRI), the impact of short pulse lengths on signal intensity of power cavitation images has yet to be resolved. In this study we evaluated the impact of short pulse lengths on BBB opening volume, power cavitation imaging signal intensity, and BBB closure with a novel rapid beam steering protocol, enabling comparison of TUS parameters within the same animal. Significant increases in BBB opening volume, power cavitation image signal intensity and BBB closing duration were observed with pulse length. Given the faster BBB closing rate facilitated by short pulse transmits, along with the highly tunable nature of TUS sonication protocols, TUS could prove promising as an alternative to conventional focused ultrasound (FUS) configurations in the clinic.