高强度聚焦超声间歇式治疗中焦域温度分布的仿真研究

探究不同治疗深度、组织类型和治疗模式对高强度聚焦超声焦域温度场的影响.采用有限元法建立高强度聚焦超声辐照组织的二维轴对称仿真模型,通过Westervelt方程和Pennes生物热传导方程计算高强度聚焦超声焦域的声场和温度场分布.仿真结果表明:随着治疗深度的增加,焦域内温度逐渐降低,有效温升面积减小;不同组织类型在相同条...     

高强度聚焦超声用于肿瘤治疗的研究

高强度聚焦超声（ＨＩＦＵ）能在短时间内使病变组织的温度升至７０℃以上,导致病变组织凝固坏死,是一种具有巨大潜力的、非侵入的、有效的肿瘤治疗手段。本文对ＨＩＦＵ的动物试验、临床应用及治疗装置的研究情况进行了总结,分析了该技术尚存在的问题,最后展望了其应用前景。     

微泡对高强度聚焦超声焦域影响的研究

微泡对高强度聚焦超声(HIFU)治疗具有增效作用,而HIFU治疗中不同声学条件下微泡对HIFU治疗焦域的影响尚不清楚。本文基于声传播方程、Yang-Church气泡运动方程、生物热传导方程、时域有限差分法(FDTD)、龙格-库塔(RK)法数值仿真研究输入功率、激励频率和气泡初始半径对HIFU在含气泡体模中形成焦域的影响,并利用含Sono Vue造影剂的仿组织体模研究进行实验验证。结果表明,增大输入功率、气泡初始半径和升高激励频率均可增大焦域,随着输入功率的增大,焦域形状可能发生变化,而随着激励频率升高和气泡初始半径的增大,焦域会向远离换能器的方向移动。     

相控阵高强度聚焦超声的研究进展

相控阵高强度聚焦超声（high Intensity focused ultrasound,HIFU）技术可以通过电子调相自由控制聚焦区域中焦点的形状、位置、个数等,实现高精度、高效率的治疗。文章主要介绍了相控聚焦超声的原理、阵型设计、声场优化、控制算法、电路设计以及换能器材料等几个方面。     

微泡对高强度聚焦超声声压场影响的仿真研究*

微泡对高强度聚焦超声(HIFU)治疗焦域具有增效作用,而HIFU治疗中不同声学条件下微泡对HIFU形成声压场的影响尚不清楚。本文基于气液混合声波传播方程、Keller气泡运动方程、时域有限差分(FDTD)法和龙格-库塔(RK)法数值仿真研究输入声压、激励频率、气泡初始空隙率和气泡初始半径对HIFU形成声压场的影响。研究结果表明,随着输入声压的增大,焦点处声压升高但焦点处最大声压与输入声压的比值减小,焦点位置几乎不变;随着激励频率和气泡初始半径的增大,焦点处声压升高且焦点位置向远离换能器方向移动;随着气泡初始空隙率的增大,焦点处声压降低且焦点位置向换能器方向移动。     

基于被动波束成像的高强度聚焦超声焦点定位*

针对高强度聚焦超声治疗中实际焦点偏离引导治疗的几何焦点这一问题,本文基于被动波束成像原理,将治疗探头与影像探头联合,探讨一种新的焦点定位策略。首先,基于k-Wave声学软件创建了具有多层组织结构的超声传播模型,通过理论仿真探究了不同脂肪、肌肉厚度条件下被动波束成像方法定位焦点的准确性;除此之外,还通过仿体在实验环境下对该方法的有效性进行了初步验证。结果表明,在不同脂肪厚度的仿真模型中,被动波束合成所定位的焦点和几何焦点在轴向距离上分别与实际焦点平均相差（0.54±0.15）mm和（4.76±0.95）mm。在不同肌肉厚度的仿真模型中,由合成算法定位的焦点和几何焦点在轴向距离上分别与实际焦点平均相差（0.51±0.26） mm、（4.95±0.47） mm。仿体实验也验证了被动波束成像定位的焦点比几何焦点更接近实际损伤位置。本文从理论仿真和实验两个角度验证了被动波束成像方法在高强度聚焦超声焦点定位中的优越性,可为该方法进一步走向临床应用提供支撑,对提升高强度聚焦超声手术治疗的安全性有推动作用。     

高强度聚焦超声的临床应用

高强度聚焦超声是近几年发展起来的一种新的非介入性肿瘤治疗技术,临床应用越来越广,文章就其在不同肿瘤如前列腺癌、肝癌、胰腺癌、子宫肌瘤等治疗中的应用及进展进行评述。     

高强度聚焦超声的临床应用

高强度聚焦超声是近几年发展起来的一种新的非介入性肿瘤治疗技术,临床应用越来越广,文章就其在不同肿瘤如前列腺癌、肝癌、胰腺癌、子宫肌瘤等治疗中的应用及进展进行评述。     

基于换能器驱动信号特征的高强度聚焦超声焦域损伤实时监测

高强度聚焦超声(high intensity focused ultrasound,HIFU)焦域的实时监测是聚焦超声临床治疗面临的关键问题,目前临床常采用B超图像强回声的变化实现焦域组织损伤的监测,而B超图像出现的强回声大多与焦域处的空化及沸腾气泡相关,无法准确、实时地监测治疗状态.HIFU治疗中焦域组织会伴随温度升高、空化、沸腾和组织特性等变化,换能器表面的声学负载也在不断变化,针对该问题,本文构建了换能器电压电流实时检测平台,通过测量换能器电学参数来感知焦域组织的状态变化.以离体牛肝组织作为HIFU辐照对象,并将相位差变化的结果与离体牛肝组织损伤的结果进行了对照,实验结果表明,在HIFU辐照过程中,换能器电压与电流的相位会出现由相对平稳到大幅波动的过程,此时停止辐照可见焦域出现明显损伤,而此时B超图像灰度无明显变化;此外,当焦域出现空化时,其波动幅度与范围将较之更大.此方法可为HIFU焦域组织损伤监测提供一种新的研究方案和手段.     

高强度聚焦超声在医学超声领域中的发展与应用

高强度聚焦超声(high intensity focused ultrasound,简称HIFU)作为一种非侵入性、无毒副作用、具有巨大潜力的治疗肿瘤的手段,近年来已经越来越受到国内外学者的广泛关注。HIFU技术能将超声能量聚焦到人体组织的肿瘤内,产生高温,使肿瘤组织温度迅速上升至65℃以上,而发生不可逆转的凝固性坏死,从而达到消融肿瘤组织的目的。目前中国的HIFU肿瘤治疗技术和临床居国际领先。文章对HIFU在医学超声领域中的发展历史、现状和前景进行了探讨。     

Lysis of Chlamydomonas reinhardtii by high-intensity focused ultrasound as a function of exposure time

Efficient lysis of microalgae for lipid extraction is an important concern when processing biofuels. Historically, ultrasound frequencies in the range of 10–40 kHz have been utilized for this task. However, greater efficiencies might be achievable if higher frequencies could be used. In our study, we evaluated the potential of using 1.1 MHz ultrasound to lyse microalgae for biofuel production while using Chlamydomonas reinhardtii as a model organism. The ultrasound was generated using a spherically focused transducer with a focal length of 6.34 cm and an active diameter of 6.36 cm driven by 20 cycle sine-wave tone bursts at a pulse repetition frequency of 2 kHz (3.6% duty cycle). The time-average acoustic power output was 26.2 W while the spatial-peak-pulse-average intensity (I_SPPA) for each tone burst was 41 kW/cm². The peak compressional and rarefactional pressures at the focus were 102 and 17 MPa, respectively. The exposure time was varied for the different cases in the experiments from 5 s to 9 min and cell lysis was assessed by quantifying the percentage of protein and chlorophyll release into the supernate as well as the lipid extractability. Free radical generation and lipid oxidation for the different ultrasound exposures were also determined. We found that there was a statistically significant increase in lipid extractability for all of the exposures compared to the control. The longer exposures also completely fragmented the cells releasing almost all of the protein and chlorophyll into the supernate. The cavitation activity did not significantly increase lipid oxidation while there was a minor trend of increased free radical production with increased ultrasound exposure.     

Boosting the electrochemiluminescence of luminol by high-intensity focused ultrasound pretreatment combined with 1T/2H MoS2 catalysis to construct a sensitive sensing platform

In the luminol-O₂ ECL system, O₂ as an endogenous coreactant has the advantages of non-toxicity and stability. Improving the efficiency to generate radicals of O₂ is a challenge currently. In this work, a strategy combining physical method - ultrasound and nanomaterial with unique physicochemical properties was designed to enhance the ECL signal of luminol-O₂ system. Specifically, high-intensity focused ultrasound (HIFU) pretreatment as a non-invasive method could generate ROS (H₂O₂, O₂^•−, OH•, ¹O₂) in situ, triggering and boosting the ECL signal of luminol. In addition, 1T/2H MoS₂ with excellent catalytic activity could catalyze the H₂O₂ produced in situ, accelerate the oxidation of luminol and further enhance the ECL response. At the same time, combined with the catalytic hairpin assembly (CHA) reaction, the constructed ECL biosensing platform showed excellent performance for the detection of miRNA-155. The concentration range of 0.1 fM ∼ 1 nM with the detection limit as low as 0.057 fM were obtained. Furthermore, the ECL biosensor was also successfully applied to the determination of miRNA-155 in human serum samples. The established ECL sensing platform opens up a promising method for the detection of clinical biomarkers.     

Treatable focal region modulated by double excitation signal superimposition to realize platform temperature distribution during transcranial brain tumor therapy with high-intensity focused ultrasound

Recently, the phase compensation technique has allowed the ultrasound to propagate through the skull and focus into the brain. However, the temperature evolution during treatment is hard to control to achieve effective treatment and avoid over-high temperature. Proposed in this paper is a method to modulate the temperature distribution in the focal region.It superimposes two signals which focus on two preset different targets with a certain distance. Then the temperature distribution is modulated by changing triggering time delay and amplitudes of the two signals. The simulation model is established based on an 82-element transducer and computed tomography(CT) data of a volunteer's head. A finitedifference time-domain(FDTD) method is used to calculate the temperature distributions. The results show that when the distances between the two targets respectively are 7.5–12.5 mm on the acoustic axis and 2.0–3.0 mm in the direction perpendicular to the acoustic axis, a focal region with a uniform temperature distribution(64–65℃) can be created.Moreover, the volume of the focal region formed by one irradiation can be adjusted(26.8–266.7 mm~3) along with the uniform temperature distribution. This method may ensure the safety and efficacy of HIFU brain tumor therapy.     

Safety of ultrasound-guided high-intensity focused ultrasound ablation for diffuse adenomyosis: A retrospective cohort study

ObjectivesTo evaluate the safety of ultrasound-guided high-intensity focused ultrasound (HIFU) ablation for patients with diffuse adenomyosis.MethodsThis was a retrospective cohort study. The data was collected from 417 symptomatic adenomyosis patients who underwent ultrasound-guided HIFU between January 2012 and December 2015 at 1st Affiliated Hospital of Chongqing Medical University, Chongqing, China. Among them were 260 patients with diffuse adenomyosis (Group D) and 157 patients with focal adenomyosis (Group F). All patients underwent contrast-enhanced magnetic resonance imaging (MRI) one week before and the day after HIFU treatment. Successful treatment with HIFU was measured by the non-perfused volume ratio (NPVR). Intraprocedural and postprocedural adverse effects and complications were recorded to assess the safety of the procedure. Patients were followed-up for three months post-treatment. Complications were given a grade A through F according to the SIR Standards.ResultsAll patients successfully completed the procedure, non-perfused regions appeared in 415 (99.5%) patients. The non-perfused volume ratio (NPVR) of Group D was significantly lower than that of Group F (P < 0.05). During the procedure, the odds ratio of skin-burning pain was 1.7 (OR = 1.617, 95% CI: 1.103–2.532), when comparing Group D with Group F, while the odds ratio of inguinal pain was equal to 2.0 (OR = 2.038, 95% CI: 1.161–3.580), when Group F was compared to Group D. 97 patients (23.3%) received nominal therapy due to complications ([Society of interventional radiology, SIR]-B grade), among them, there were 62 cases (23.8%) in Group D and 35 cases (22.3%) in Group F. No significant difference was found between the two groups (P > 0.05) and neither of the reported complications of SIR-C-SIR-F occurred within the two groups.ConclusionsBased on our results, ultrasound-guided HIFU is safe for the treatment of diffuse adenomyosis, and controlling the ablation zone is crucial to ensure patients’ safety.     

Applications of high-intensity focused ultrasound in medicine: Spotlight on neurological applications

High-intensity focused ultrasound (HIFU) has the potential to become a modality of treatment for a wide range of clinical conditions. HIFU enables non-invasive, selective ablation of tissues including tumors and punctured vessels. Another promising area of research within the field of therapeutic ultrasound is the application of HIFU to treat neurological disorders by selectively targeting the brain, spinal cord, or nerves. This paper provides an overview of the current applications of focused ultrasound in medicine with an emphasis on its use in the fields of neurology and neurosurgery.     

剪切波对时间反转调相的经颅聚焦超声的影响*

为研究颅骨中的剪切波对经颅聚焦超声的影响,该文利用Kelvin-Voigt固体声波方程并结合时间反转法,分别模拟了考虑剪切波和不考虑剪切波时,256-单元平面相控阵为实现超声经颅聚焦所需的相位调控,并将这两种相位调控都分别作用于考虑剪切波和不考虑剪切波时的聚焦情形。对这两种相位调控以及基于它们的经颅聚焦超声场的对比分析结果表明:聚焦深度较大时,剪切波对基于时间反转进行的相位调控影响较小;不过,剪切波对经颅聚焦超声场的强度分布影响较大,忽略剪切波会导致对焦域处声场聚焦强度的高估以及对颅骨附近声能量沉积的低估。