ULTRASONIC BUBBLE GENERATION FOR UROLOGIC DIAGNOSIS

在之前的赠款期间，进行了实验以开发 对尿液中气泡形成过程的认识 Track和我们对声场要求的了解 对比生产有了很大的改善。犬尿切除手术 膀胱和最初的体内试验表明，单一的声学 在一些体外和体外实验中，产生了6.6兆帕和250ms持续时间的脉冲串 在活体情况下，云中的气泡显然足够 反流诊断的回声和持续时间。然而，这样的 爆发，即使高达14兆帕，也不会可靠地产生明显的 在这些条件下的空化，其中颗粒和气体 含量很低。然而，阈值较低(8.9+/-1.7兆帕 125ms脉冲串)，并且气泡产生的可靠性 在兔子模型中(7或8只动物)显著更大 自然产生的颗粒物可能会将门槛降低到 所采用的脉冲系统可获得的水平。这允许一个 天然气含量变化对回声特性影响的研究 这表明大量的空化可能是 在体内产生的二氧化碳含量在阈值和 回声。在水中也进行了对照实验， 这再次表明，在阈值可能是 如果可靠地达到，生理上相关的气体含量可以产生 大量的气泡生产。言下之意是，如果有足够的 声幅达到空化阈值时，气泡可以 在气体含量与尿液相似的液体中产生的。 最近的犬类实验表明，可靠的目标是 现在已经使用具有UP的短脉冲系统实现了发电 到幅度的两倍，且脉冲序列仅为1/4000 与较早的250毫秒脉冲一样准时。空化现象反复出现 在犬的膀胱中产生，显然没有对 膀胱壁。而回声量较低。 发现对于兔模型来说，重复的脉搏可以 使用该系统执行，或者低幅度的生长脉冲应该 产生必要的回声和气泡持续时间，特别是 尿液中二氧化碳的生理性操作是否足够安全 适用于气体含量较低的情况。 鉴于这种程度的成功，这是研究的目标 建议开发一个系统来生成、收集和增长 微泡达到诊断尿反流所需的程度。 为此，拟议的研究重点是低颗粒含量 影响安全的脉冲参数影响的系统，以及 对比寿命和可检测性可以用来开发一种 在活体系统中工作。

In the previous grant period, experiments were performed to develop an understanding of the bubble generation process in the urinary tract and our knowledge of the acoustic field requirements for contrast production has greatly improved. Excise canine urinary bladders and initial in vivo trails demonstrated that single acoustic bursts of 6.6 Mpa and 250 ms duration produced, in a few in vitro and in vivo cases, clouds of bubbles with apparently quite sufficient echogenicity and duration for reflux diagnosis. However, such bursts, even up to 14 Mpa, would not reliably produce noticeable cavitation under these conditions where both the particulate and gas content is low. However, the threshold was lower (8.9 +/- 1.7 Mpa with 125 ms bursts) and reliability of bubble generation was significantly greater (7 or 8 animals) in a rabbit model where naturally occurring particulates may have reduced the threshold to an obtainable level with the employed pulsed system. This allowed a study of the effects of natural gas content variation on echogenicity yield which indicated that copious quantities of cavitation could be produced in vivo and that CO2 content was important in threshold and echogenicity. Controlled experiments in water were also performed, which again indicated that under conditions where threshold could be reached reliably, physiologically relevant gas contents could produce copious bubble production. The implication is that with sufficient acoustic amplitude to reach the cavitation threshold, bubbles can be produced in fluids with gas contents similar to that of urine. Recent canine experiments indicate that the goal of reliable generation has now been achieved using a short pulse system with up to twice the amplitude and with pulse sequences on only 1/4000 as much on-time as the earlier 250 ms pulses. Cavitation was repeatedly produced in the canine bladder with apparently no gross damage to the bladder wall. While the amount of echogenicity was lower than that found for the rabbit model, the repeated pulsing which can be performed with this system, or a low amplitude growth pulse should produce the requisite echogenicity and bubble duration, particularly if physiologic manipulation of CO2 in the urine is sufficiently safe for cases of low gas content. Given this level of success, it is the objective of the research proposed to develop a system to generate, collect and grow microbubbles to the degree necessary for diagnosis of urinary reflux. To this end, the proposed research focuses on low particle content systems where the effects of pulse parameters affecting safety, and contrast longevity and detectability can be addressed to develop a working in vivo system.