  To address existing challenges with intravascular mechanical thrombectomy
devices, a novel ultrasound-enhanced aspiration approach is being developed to
mechanically degrade clots using cavitation. This method employs standing waves
within a mm-scale hollow cylindrical transducer to generate high pressures
sufficient to perform histotripsy on clots situated within the transducer lumen
and generate substantial lesions. The objective of this study is to assess the
feasibility of self-sensing cavitation detection by analyzing voltage signals
across the transducer during treatment pulses. External ultrasound imaging of
the transducer lumen validated cavitation detection. Impedance was also altered
by the presence of clot material within the lumen. Experiments varying the
driving voltage in water-filled lumens demonstrated changes in the relative
amplitudes of the envelopes of the pulse body and ringdown portions of the
voltage signals above the cavitation threshold, as well as changes in the
spectral domain. In particular both broadband and ultraharmonic signals showed
an increase in amplitude above the cavitation threshold. Similar temporal and
spectral voltage signal changes in the presence of cavitation were also
observed when treating clots within the lumen. This work demonstrates a highly
sensitive method for detecting cavitation within the lumen, enabling monitoring
with readily acquired signals without additional sensors in the catheter
configuration. These findings hold significant potential for improving the
efficacy of ultrasound-enhanced aspiration thrombectomy procedures.
