ULTRASONIC BUBBLE GENERATION FOR UROLOGIC DIAGNOSIS

在上一个赠款期间，进行了实验，以开发 了解尿液中气泡的产生过程 道和我们的知识的声场要求， 对比度生产得到了极大的改善。 离体犬尿 膀胱和最初的体内试验表明， 6.6 Mpa和250 ms持续时间的爆发，在一些体外和 在体内情况下，气泡云与明显相当充分的 回声强度和持续时间用于反流诊断。 但这种 即使高达14 Mpa，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 含量低。 然而，阈值较低（8.9 +/- 1.7 Mpa 125 ms爆破）和气泡生成的可靠性， 在兔模型中显著更高（7或8只动物）， 天然存在的颗粒可能已经将阈值降低到 可获得的水平与所采用的脉冲系统。 这使得A 天然气含量变化对回声强度影响的研究 产量，这表明大量的空化可以是 CO_2含量对阈值有重要影响， 回声性 还进行了水中的对照实验， 这再次表明，在阈值可以 达到可靠，生理相关的气体含量可以产生 大量的气泡产生。 这意味着，如果有足够的 声振幅达到空化阈值时，气泡可以 产生于气体含量类似于尿液的液体中。 最近的犬类实验表明， 现在已经使用具有up的短脉冲系统实现了产生 到两倍的幅度和脉冲序列上只有1/4000作为 与较早的250 ms脉冲相比导通时间更长。 空洞反复出现， 在犬膀胱中产生， 膀胱壁 而回声强度低于 对于兔子模型，发现重复的脉冲， 使用该系统进行，或者低幅度生长脉冲应该 产生必要的回声和气泡持续时间，特别是 如果对尿液中CO2的生理控制足够安全 对于气体含量低的情况。 鉴于这种成功程度，研究的目标是 建议开发一个系统， 微泡达到诊断尿反流所需的程度。 为此，建议的研究重点是低颗粒含量 脉冲参数影响安全的系统，以及 可以解决对比度寿命和可检测性的问题， 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.