Non-invasive embolus trap using histotripsy-an acoustic parameter study.

Free-flowing particles in a blood vessel were observed to be attracted, trapped and eroded by a histotripsy bubble cloud. This phenomenon may be used to develop a non-invasive embolus trap (NET) to prevent embolization. This study investigates the effect of acoustic parameters on the trapping ability of the NET generated by a focused 1.063 MHz transducer. The maximum trapping velocity, defined by the maximum mean fluid velocity at which a 3-4 mm particle trapped in a 6 mm diameter vessel phantom, increased linearly with peak negative pressure (P-) and increased as the square root of pulse length and pulse repetition frequency (PRF). At 19.9 MPa P-, 1000 Hz PRF and 10 cycle pulse length, a 3 mm clot-mimicking particle could remain trapped under a background velocity of 9.7 cm/s. Clot fragments treated by NET resulted in debris particles <75 μm. These results will guide the appropriate selection of NET parameters.