超声造影剂在高强度聚焦超声治疗肝癌中的应用

高强度聚焦超声(high-intensityfocusedultrasound,HIFU)技术是将体外低能量的超声波汇聚于体内肿瘤靶区,通过高温效应、空化效应和机械效应,使肿瘤组织产生凝固性坏死,从而达到治疗肿瘤的目的。超声造影剂(ultrasoundcontrastagents)在HIFU治疗肝癌(hepatocellularcarcinoma,HCC)中也有很大的应用价值。探讨了超声造影剂在HIFU治疗肝癌前定性、定位及治疗后疗效评定等方面的作用,尤其是造影剂在HIFU治疗过程中通过增强空化效应,改变声学环境从而提高HIFU治疗肝癌的生物学效应,使超声造影剂成为一种备受重视的HIFU增效剂。     

用于磁声耦合刺激的64阵元相控阵超声换能器的设计

本研究基于磁声耦合刺激技术(transcranial magneto-acoustic stimulation,TMAS)的需求,设计了用于线性64阵元相控阵的超声换能器,探究相控阵超声换能器压电晶体宽度及间距,优化超声换能器聚焦声场分布.采用MATLAB软件建立相控阵换能器模型,仿真聚焦声场分布.搭建三维声场分布测试...     

高强度聚焦超声治疗肿瘤

高强度聚焦超声已经由实验进入临床应用阶段.本文对高强度聚焦超声治疗肿瘤的基本原理与方法进行了探讨,对大量的实验和临床研究进行了总结,认为高强度聚焦超声是治疗实体肿瘤的一种有效方法.     

高强度聚焦超声治疗肿瘤

高强度聚焦超声已经由实验进入临床应用阶段，本文对高强度聚焦超声治疗肿瘤的基本原理与方法进行了探讨，对大量的实验和临床研究进行了总结，认为高强度聚焦超声是治疗实体肿瘤的一种有效方法。     

高强度聚焦超声治疗中空化效应的研究进展

高强度聚焦超声(high intensity focused ultrasound,HIFU)作为一种新技术已经成功的应用于临床治疗,其治疗机制一直是研究热点。本文就HIFU治疗中空化效应进行综述。     

高强度聚焦超声技术的发展与应用

高强度聚焦超声(HIFU)技术是起源于二十世纪40年代,利用高强度超声波束在体内聚焦,并对目标区域内的病变组织作选择性损坏的一种高强度聚焦超声外科治疗技术.虽然该技术在许多方面优越于传统的外科手术,并且具有极大的潜在临床应用价值,但是由于当时缺乏高精度的成像和定位技术,该技术在临床应用方面的潜能并没有得到广泛的研究和开发利用.近二十几年来,随着计算机、成像及材料等科学技术的迅速发展,众多研究人员对高强度聚焦超声技术再次产生了浓厚的兴趣,并从声源设计、组织损坏机理、消融区域的影像学特征、应用范围的推广等方面进行了广泛而细致的研究.     

高强度聚焦超声在肿瘤治疗中的焦域模型

高强度聚焦超声 (High intensity focused ultrasound,HIFU)技术作为一种新兴的肿瘤微创外科治疗技术 ,正日益引起人们的高度重视。尤其是相对于某些浅表肿瘤 ,如乳腺癌 ,HIFU技术可以在保证治疗效果的同时 ,最大限度的减低治疗过程对患者的伤害。本文根据细胞热致死理论 ,利用 Ω值表达式法对 HIFU治疗过程中的焦域形成进行了仿真数学模型的建立 ,并通过非相干多元阵自聚焦系统建立实验模型进行试验 ,结果表明本文提出的焦域模型对实际加热过程的模拟是可靠的 ,可以对其形成大小和时间进行准确的预测     

高强度聚焦超声治疗中晚期肝癌疗效分析

目的了解我国高强度聚焦超声(HIFU)治疗中晚期肝癌的基本情况,分析其疗效和不良反应.方法检索PubMed、中国生物医学文献数据库、中国期刊全文数据库,收录国内发表的HIFU治疗中晚期肝癌疗效评价的研究,提取研究所需数据进行统计分析.结果 35篇文献人选,治疗肝癌1599例,单纯HIFU治疗组和HIFU联合其他治疗组的显著缓解率分别为16.68%比16.73%,有效率73.20%比78.01%.血清AFP下降率61.94%比70.83%,肝区疼痛缓解率84.62%比89.45%.6个月、1年、2年生存率分别为78.0%比89.86%,54.55%比64.84%和26.34%比27.30%.平均生存期(9.3±2.86)个月比(10.0±0.57)个月.HIFU不良反应主要为术后一过性肝区疼痛(75/1103,6.8%),低热(68/1103,6.2%)和皮肤烧伤(278/1103,25.2%),严重并发症少.结论作为一种非侵入性治疗手段,HIFU对中晚期肝癌有较好的姑息治疗效果和临床安全性.     

空化增效高强度聚焦超声治疗研究进展

高强度聚焦超声（HIFU）已被证实是一种安全、有效的无创实体肿瘤消融方法,但目前面临的主要问题是治疗时间相对较长、治疗效率低。在HIFU治疗中可以通过空化实现增效,通过何种方式产生空化效应,如何提高空化对热效应的增效作用一直是研究者关注的问题。本文分别从体外引入空化核、声学驱动产生空化核两个角度,综述在HIFU治疗中通过微泡造影剂、相变纳米液滴、双频HIFU、脉冲波增强热效应、调强峰值声压增强HIFU的治疗效果。 【关键词】高强度聚焦超声;空化效应;热效应;增效;综述     

靶控输注镇痛镇静在高强度超声聚焦刀治疗子宫肌瘤中的应用

目的探讨丙泊酚和瑞芬太尼靶控输注镇痛镇静用于高强度超声聚焦刀治疗子宫肌瘤的可行性。方法取子宫肌瘤患者60例随机分成靶控组和对照组，于手术开始前10min靶控组静脉注射咪唑安定O．03ms／kg，同时开始靶控输注丙泊酚和瑞芬太尼，分别设定丙泊酚血浆靶浓度为0．6—1．5μg/ml、瑞芬太尼血浆靶浓度为0．5—1．5ns／ml，根据病人反应调整；对照组静脉注射咪唑安定0．03ms／kg、芬太尼1μg／kg。首次给药40rain后给咪唑安定0．02ms／kg、芬太尼1μg／kg，90rain后给咪唑安定0．02ms／kg、芬太尼0．8μg／kg，自此以后每延续1h给咪唑安定0.02ms／kg和芬太尼0．08μg／kg。采集两组患者于手术开始时、30min、60min、90min、120min和手术结束时病人的血压（MAP）、心率（HR）、呼吸（RR）及术中患者呼吸抑制次数。采用Ramsay镇静评分法和视觉模拟评分法（VAS）评价镇静镇痛情况。结果两组患者各时点MAP、HR及RR变化无统计学意义；以对照组术中呼吸抑制显著且手术时间较长；患者的镇静镇痛评分靶控组优于对照组，差异有统计学意义。结论靶控输注丙泊酚和瑞芬太尼镇痛镇静用于高强度超声聚焦刀治疗子宫肌瘤安全有效。     

聚焦超声手术目标定位中的呼吸幅度测量

聚焦超声手术是一种非常有前途的微损伤手术技术.目标定位是决定手术成功与否的重要方面.在平静状态时,呼吸运动是影响手术目标定位的主要因素.为了分析呼吸幅度与目标运动之间的关系,研制了一套呼吸幅度测量系统.该系统主要包括呼吸幅度传感器、信号调理与放大电路、数据采集卡以及计算机等组成.该系统通过测量人体胸廓周径随呼吸运动的变化来获得呼吸幅度.同时,为了检验所研制系统的可行性,另外设计了一套系统,该系统通过医学超声图像计算膈随呼吸运动的位置变化来获得呼吸幅度.两套系统对处于平静呼吸状态的受试者进行了同步数据采集,经过对两套数据预处理并做互相关运算,得到互相关系数为0.9765;同时计算得到膈的最大运动范围为13.88mm,在正常范围内.上述结果表明了所研制的呼吸幅度测量系统是可行的.     

高强度聚焦超声在医学领域中应用的新进展

本文综述了国内外在高强度聚焦超声（high intensity focused ultrasound，HIFU）技术方面研究与应用的新进展。介绍了HIFU的治疗功能原理，特别给出了焦斑半径的具体计算公式和对相关组织的热效应、空化效应、机械效应，辐照效应等损伤机理，重点研究了热效应随声波频率及声强变化的规律。给出了HIFU的一般试验模型即分层组织模型以及HIFU应用与临床的情况。重点研究了HIFU源，主要讨论了换能器的聚焦方式（1）球面自聚焦换能器，（2）声透镜聚焦换能器，（3）大功率多元超声换能器，（4）电子扫描或相控阵列聚焦换能器，以及频率选择与目标深度和辐照强度的关系，并指出与其匹配的几类聚焦换能器的优缺点，列举了HIFU技术在泌尿科、肿瘤学、神经外科、眼科、妇科、止血以及其他医学领域中的最新应用。最后评价了目前HIFU在治疗方面的优势与某些不足以及可能改进的有效措施．展望了HIFU技术广阔的应用前景．     

Image-Guided High-Intensity Focused Ultrasound for Conduction Block of Peripheral Nerves

The objective of our work has been to investigate the use of ultrasound image-guided high-intensity focused ultrasound (HIFU) to non-invasively produce conduction block in rabbit sciatic nerves in vivo, a technique that could become a treatment of spasticity and pain. The work reported here involved the investigation of the duration of such conduction blocks after HIFU treatment and whether they resulted in axon degeneration. The right sciatic nerves of 12 rabbits were treated, under guidance of ultrasound imaging, with repeated 5-s applications of 3.2 MHz HIFU with in situ intensity of 1930 W/cm² (spatial-average, temporal-average) until conduction block was achieved. Survival endpoints were 0, 7, or 14 days after HIFU treatment, at which point the nerve conduction was assessed. Qualitative and quantitative histological analysis of nerve sections proximal and distal to the HIFU site was performed. Conduction block of all 12 nerves was achieved with average HIFU treatment time of 10.5±4.9 s (mean±SD). The volume of necrosis of adjacent muscle was measured to be 1.59±1.1 cm³ (mean±SD). For all nerves, conduction block remained at the survival endpoint and the block resulted in degeneration of axons distal to the HIFU site, as confirmed by electrophysiological and histological methods. Potential clinical applications include treatment of spasticity in patients with spinal cord injury or pain in cancer patients.     

Fluorescence Imaging for Real-Time Monitoring of High-Intensity Focused Ultrasound Cardiac Ablation

Side effects and limitations of radio-frequency ablation of cardiac arrhythmias prompted search for alternative energy sources and means of their application. High-intensity focused ultrasound (HIFU) is becoming an increasingly attractive modality for ablation because of its unique ability for non-invasive or minimally invasive, non-contact focal ablation in 3D volume without affecting intervening and surrounding cells. The purpose of this study is to develop a real-time monitoring technique to elucidate HIFU-induced modifications of electrical conduction in cardiac tissues and to investigate the HIFU cardiac ablation process to help to achieve optimal HIFU ablation outcome. We conducted experimental studies applying HIFU at 4.23 MHz to ablate the atrio-ventricular (AV) node and ventricular tissue of Langendorff-perfused rabbit hearts. We employed fluorescent voltage-sensitive dye imaging and surface electrodes to monitor the electrical conduction activity induced by HIFU application in real time. In ventricular epicardium HIFU ablation, fluorescent imaging revealed gradual reduction of the plateau phase and amplitude of the action potential. Subsequently, conduction block and cell death were observed at the site of ablation. When HIFU was applied to the AV node, fluorescent imaging and electrograms revealed the development of the AV block. The study establishes that real-time fluorescent imaging provides novel monitoring and assessment to study HIFU cardiac ablation, which may be able to provide improved understanding of HIFU cardiac ablation process and mechanism useful for development of successful clinical applications.     

Flooded Lung Generates a Suitable Acoustic Pathway for Transthoracic Application of High Intensity Focused Ultrasound in Liver

Background: In recent years, high intensity focused ultrasound (HIFU) has gained increasing clinical interest as a non-invasive method for local therapy of liver malignancies. HIFU treatment of tumours and metastases in the liver dome is limited due to the adjacent ultrasound blocking lung. One-lung flooding (OLF) enables complete sonography of lung and adjoining organs including liver. HIFU liver ablation passing through the flooded lung could enable a direct intercostal beam path and thus improve dose deposition in liver. In this study, we evaluate the feasibility of an ultrasound guided transthoracic, transpulmonary HIFU ablation of liver using OLF.Methods: After right-side lung flooding, ultrasound guided HIFU was applied transthoracic- transpulmonary into liver to create thermal lesions in three pigs. The HIFU beam was targeted five times into liver, two times at the liver surface and three times deeper into the tissue. During autopsy examinations of lung, diaphragm and liver located in the HIFU path were performed. The focal liver lesions and lung tissue out of the beam path were examined histologically.Results: Fifteen thermal liver lesions were generated by transpulmonary HIFU sonication in all targeted regions. The lesions appeared well-demarcated in grey color with a cigar-shaped configuration. The mean length and width of the superficial and deeper lesions were 15.8 mm (range: 13-18 mm) and 5.8 mm (range: 5-7 mm), and 10.9 mm (range: 9-13 mm) and 3.3 mm (range: 2-5 mm), respectively. Histopathological, all liver lesions revealed a homogeneous thermal necrosis lacking vitality. There were no signs of damage of the overlying diaphragm and lung tissue.Conclusions: Flooded lung is a suitable pathway for applying HIFU to the liver, thus enabling a transthoracic, transpulmonary approach. The enlarged acoustic window could enhance the ablation speed for targets in the hepatic dome.     

遗传算法在医用非线性曲线拟合中的应用

本文提出医用非线性曲线拟合的遗传算法，并以指数曲线为例，选择了一组标样进行了具体研究，结果表明，该方法性能良好，可望成为各类医用非线性曲线拟合的有效工具。