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首页> 外文期刊>Ultrasonics, Ferroelectrics and Frequency Control, IEEE Transactions on >Controlled cavitation to augment SWL stone comminution: mechanistic insights in vitro
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Controlled cavitation to augment SWL stone comminution: mechanistic insights in vitro

机译：控制空化以增强SWL结石粉碎作用：体外机理的见解

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Stone comminution in shock wave lithotripsy (SWL) has been documented to result from mechanical stresses conferred directly to the stone, as well as the activity of cavitational microbubbles. Studies have demonstrated that the presence of this cavitation activity is crucial for stone subdivision; however, its exact role in the comminution process remains somewhat weakly defined, in part because it is difficult to isolate the cavitational component from the shock waves themselves. In this study, we further explored the importance of cavitation in SWL stone comminution through the use of histotripsy ultrasound therapy. Histotripsy was used to target model stones designed to mimic the mid-range tensile fracture strength of naturally occurring cystine calculi with controlled cavitation at strategic time points in the SWL comminution process. All SWL was applied at a peak positive pressure (p+) of 34 MPa and a peak negative pressure (p–) of 8 MPa; a shock rate of 1 Hz was used. Histotripsy pulses had a p– of 33 MPa and were applied at a pulse repetition frequency (PRF) of 100 Hz. Ten model stones were sonicated in vitro with each of five different treatment schemes: A) 10 min of SWL (600 shocks) with 0.7 s of histotripsy interleaved between successive shocks (totaling to 42 000 pulses); B) 10 min of SWL (600 shocks) followed by 10 min of histotripsy applied in 0.7-s bursts (1 burst per second, totaling to 42 000 pulses); C) 10 min of histotripsy applied in 0.7-s bursts (42 000 pulses) followed by 10 min of SWL (600 shocks); D) 10 min of SWL only (600 shocks); E) 10 min of histotripsy only, applied in 0.7-s bursts (42 000 pulses). Following sonication, debris was collected and sieved through 8-, 6-, 4-, and 2-mm filters. It was found that scheme D, SWL only, generated a broad range of fragment sizes, with an average of 14.9 u000b1; 24.1% of the original stone mass remaining > 8 mm. Scheme E, histotripsy only, eroded the surface of stones to tiny partic- late debris that was small enough to pass through the finest filter used in this study (<2 mm), leaving behind a single primary stone piece (>8 mm) with mass 85.1 u000b1; 1.6% of the original following truncated sonication. The combination of SWL and histotripsy (schemes A, B, and C) resulted in a shift in the size distribution toward smaller fragments and complete elimination of debris > 8 mm. When histotripsy-controlled cavitation was applied following SWL (B), the increase in exposed stone surface area afforded by shock wave stone subdivision led to enhanced cavitation erosion. When histotripsy-controlled cavitation was applied before SWL (C), it is likely that stone surface defects induced by cavitation erosion provided sites for crack nucleation and accelerated shock wave stone subdivision. Both of these effects are likely at play in the interleaved therapy (A), although shielding of shock waves by remnant histotripsy microbubble nuclei may have limited the efficacy of this scheme. Nevertheless, these results demonstrate the important role played by cavitation in the stone comminution process, and suggest that the application of controlled cavitation at strategic time points can provide an adjunct to traditional SWL therapy.
机译：冲击波碎石术（SWL）中的碎石是由直接施加于石头的机械应力以及空化微泡的活动引起的。研究表明，空化作用的存在对于石材的细分至关重要。但是，其在粉碎过程中的确切作用仍然定义不清，部分原因是很难将空化成分与冲击波本身隔离开。在这项研究中，我们通过组织切片超声疗法进一步探讨了空化在SWL碎石中的重要性。组织分裂症被用于靶向模型宝石，该模型旨在模拟自然存在的胱氨酸结石的中程拉伸断裂强度，并在SWL粉碎过程中的关键时刻控制空化。所有SWL均以34 MPa的峰值正压（p +）和8 MPa的峰值负压（p-）施加；使用的冲击率为1 Hz。组织碎裂脉冲的p–为33 MPa，以100 Hz的脉冲重复频率（PRF）施加。用五种不同的治疗方案中的每一种在体外对十个模型结石进行超声处理：A）10分钟的SWL（600次电击），两次连续电击之间间隔0.7 s的组织学曲张（总计42 000脉冲）； B）10分钟的SWL（600次电击），然后在0.7秒的脉冲（每秒1脉冲，总计42 000脉冲）中施加10分钟的组织曲张； C）在0.7 s的脉冲（42 000脉冲）中施加10分钟的组织曲张，然后进行10分钟的SWL（600次电击）； D）仅10分钟的SWL（600次电击）； E）仅在10分钟内进行组织学检查，以0.7秒的脉冲（42 000脉冲）施加。超声处理后，收集碎屑并通过8、6、4和2毫米过滤器进行筛分。发现仅方案D，SWL，产生了大范围的片段大小，平均为14.9 u000b1。剩余的原始石材质量的24.1％> 8毫米。方案E，仅是组织曲折性的，将石头表面腐蚀成细小的微粒，其碎片小到足以通过本研究中使用的最精细的过滤器（<2毫米），留下一块原石（> 8毫米）质量85.1 u000b1;截短的超声处理后原始数据的1.6％。 SWL和组织曲霉的组合（方案A，B和C）导致尺寸分布向较小的碎片移动，并完全消除了大于8毫米的碎片。当在SWL（B）之后应用组织学控制的空化时，冲击波碎石细分所提供的裸露石材表面积增加导致空化侵蚀增强。当在SWL（C）之前应用组织曲控制的空化时，由空化侵蚀引起的石材表面缺陷可能提供了裂纹成核和加速冲击波石材细分的场所。在交错疗法中，这两种作用都可能发挥作用（A），尽管通过残留的组织曲霉微泡核屏蔽冲击波可能限制了该方案的疗效。尽管如此，这些结果证明了空化作用在石块粉碎过程中起着重要作用，并且表明在战略时间点应用受控的空化作用可以为传统的SWL治疗提供辅助。

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