Removal of residual nuclei following a cavitation event: a parametric study

Duryea, Alexander P.; Tamaddoni, Hedieh Alavi; Cain, Charles A.; Roberts, William W.; Hall, Timothy L.

doi:10.1109/tuffc.2014.006601

Cited by 12 publications

(29 citation statements)

References 42 publications

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“…For example, increasing the treatment PRF has the potential to further shorten the treatment time under the same treatment dose if the cavitation memory effects can be reduced. Cavitation residual nuclei can be consolidated to reduce cavitation memory effects by interweaving low pressure ultrasound pulses with histotripsy pulses (Duryea et al 2015). Another possible investigation to further reduce cavitation memory effects would be to divide the treatment into more than two treatment passes.…”

Section: Discussionmentioning

confidence: 99%

Histotripsy Thrombolysis on Retracted Clots

Owens

Cain

et al. 2016

Ultrasound in Medicine & Biology

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Retracted blood clots have been previously recognized to be more resistant to drug-based thrombolysis methods, even with ultrasound and microbubble enhancements. Microtripsy, a new histotripsy approach, has been investigated as a non-invasive, drug-free, and image-guided method that uses ultrasound to break up clots with improved treatment accuracy and a lower risk of vessel damage when compared to the traditional histotripsy thrombolysis approach. Unlike drug-mediated thrombolysis, which is dependent on the permeation of the thrombolytic agents into the clot, microtripsy controls acoustic cavitation to fractionate clots. We hypothesize that microtripsy thrombolysis is effective on retracted clots and that the treatment efficacy can be enhanced using strategies incorporating electronic focal steering. To test our hypothesis, retracted clots were prepared in vitro and the mechanical properties were quantitatively characterized. Microtripsy thrombolysis was applied on the retracted clots in an in vitro flow model using three different strategies: single-focus, electronically-steered multi-focus, and a dual-pass multi-focus strategy. Results show that microtripsy was used to successfully generate a flow channel through the retracted clot and the flow was restored. The multi-focus and the dual-pass treatments incorporating the electronic focal steering significantly increased the recanalized flow channel size compared to the single-focus treatments. The dual-pass treatments achieved a restored flow rate up to 324 mL/min without cavitation contacting the vessel wall. The clot debris particles generated from microtripsy thrombolysis remained within the safe range. The results in this study show the potential of microtripsy thrombolysis for retracted clot recanalization with the enhancement of electronic focal steering.

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Section: Discussionmentioning

confidence: 99%

Histotripsy Thrombolysis on Retracted Clots

Owens

Cain

et al. 2016

Ultrasound in Medicine & Biology

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“…Wang et al (2012) showed that the number of pulses required to fractionate 25% of the target volume is reduced by more than an order of magnitude by increasing the time between pulses from 2 ms to >200 ms. Additionally, previous studies have employed an active acoustic technique termed bubble-removal to mitigate the cavitation memory effect. Duryea et al (2014, 2015a, 2015b) found that applying a low-amplitude ultrasound pulse with many cycles (~1000) following a cavitation event promoted the coalescence (by means of the secondary Bjerknes force) and aggregate translation (primary Bjerknes force) of residual nuclei from the focus.…”

Section: Introductionmentioning

confidence: 99%

Non-invasive, Rapid Ablation of Tissue Volume Using Histotripsy

Lundt

Allen

Shi

et al. 2017

Ultrasound in Medicine & Biology

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Histotripsy is a noninvasive, non-thermal ablation technique that uses high-amplitude, focused ultrasound pulses to fractionate tissue via acoustic cavitation. The goal of this study was to show the potential of histotripsy with electronic focal steering to achieve rapid ablation of a tissue volume at a rate matching or exceeding current clinical techniques (~1–2 mL/min). Treatment parameters were established in tissue-mimicking phantoms and applied to ex vivo tissue. 6-μs pulses were delivered by a 250 kHz array. The focus was electrically steered to 1000 locations at 200 Hz PRF (0.12 % duty cycle). MRI and histology of the treated tissue shows a distinct region of necrosis in all samples. Mean lesion volume was 35.6 ± 4.3 mL, generated at 0.9–3.3 mL/min, a speed faster than any current ablation method for a large volume. These results suggest that histotripsy has the potential to achieve noninvasive, rapid, homogenous ablation of a tissue volume.

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“…Our recent work has aimed to develop a strategy for the active removal of residual bubble nuclei following a cavitation event [27, 28]. We have demonstrated that the application of appropriately designed low-amplitude ultrasound pulses can stimulate the aggregation and subsequent coalescence of a population of residual bubbles, effectively removing them from the field.…”

Section: Introductionmentioning

confidence: 99%

“…We have demonstrated that the application of appropriately designed low-amplitude ultrasound pulses can stimulate the aggregation and subsequent coalescence of a population of residual bubbles, effectively removing them from the field. These pulses—which we term bubble removal pulses—are typically on the order of one millisecond in duration and have maximal nuclei consolidation effects near a mechanical index (MI) of 1 [27, 28]. Previous work has also demonstrated that higher frequency bubble removal pulses (2 MHz) are more effective in comparison to lower frequency (500 kHz) for consolidation of the remnant cavitation nuclei that persist following histotripsy bubble cloud collapse [28].…”

Section: Introductionmentioning

confidence: 99%

“…These pulses—which we term bubble removal pulses—are typically on the order of one millisecond in duration and have maximal nuclei consolidation effects near a mechanical index (MI) of 1 [27, 28]. Previous work has also demonstrated that higher frequency bubble removal pulses (2 MHz) are more effective in comparison to lower frequency (500 kHz) for consolidation of the remnant cavitation nuclei that persist following histotripsy bubble cloud collapse [28]. This is hypothesized to be a result of the secondary Bjerknes force being the major facilitator of the coalescence phenomenon, the attractive magnitude of which is maximized when neighboring bubbles oscillate in-phase with one another [29].…”

Section: Introductionmentioning

confidence: 99%

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Removal of residual cavitation nuclei to enhance histotripsy erosion of model urinary stones

Duryea

Roberts

Cain

et al. 2015

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Histotripsy has been shown to be an effective treatment for model kidney stones, eroding their surface to tiny particulate debris via a cavitational bubble cloud. However, similar to shock wave lithotripsy, histotripsy stone treatments display a rate-dependent efficacy with pulses applied at low rate generating more efficient stone erosion in comparison to those applied at high rate. This is hypothesized to be the result of residual cavitation bubble nuclei generated by bubble cloud collapse. While the histotripsy bubble cloud only lasts on the order of 100 µs, these microscopic remnant bubbles can persist on the order of 1 second—inducing direct attenuation of subsequent histotripsy pulses and influencing bubble cloud dynamics. In an effort to mitigate these effects, we have developed a novel strategy to actively remove residual cavitation nuclei from the field using low-amplitude ultrasound pulses. Previous work has demonstrated that with selection of the appropriate acoustic parameters these bubble removal pulses can stimulate the aggregation and subsequent coalescence of microscopic bubble nuclei—effectively deleting them from the target volume. Here, we incorporate bubble removal pulses in histotripsy treatment of model kidney stones. It was found that when histotripsy is applied at low rate (1 Hz), bubble removal does not produce a statistically significant change in erosion. At higher pulse rates of 10, 100, and 500 Hz, incorporating bubble removal results in 3.7-, 7.5-, and 2.7-fold increases in stone erosion, respectively. High speed imaging indicates that the introduction of bubble removal pulses allows bubble cloud dynamics resulting from high pulse rates to more closely approximate those generated at the low rate of 1 Hz. These results corroborate previous work in the field of shock wave lithotripsy regarding the ill-effects of residual bubble nuclei, and suggest that high treatment efficiency can be recovered at high pulse rates through appropriate manipulation of the cavitation environment surrounding the stone.

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Removal of residual nuclei following a cavitation event: a parametric study

Cited by 12 publications

References 42 publications

Histotripsy Thrombolysis on Retracted Clots

Histotripsy Thrombolysis on Retracted Clots

Non-invasive, Rapid Ablation of Tissue Volume Using Histotripsy

Removal of residual cavitation nuclei to enhance histotripsy erosion of model urinary stones

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