HIFU在牛肝组织中的传播衰减研究

运用辐射压力法研究高强度聚焦超声在牛肝组织中的传播衰减。在室温 2 0℃下 ,利用 4种治疗超声换能器 ,在不同的换能器表面输出声功率下 ,分别测量 2 0、4 0、6 0、80 m m不同厚度新鲜离体牛肝在放入脱气水前后的声辐射力 F、F′,然后计算出声衰减。使用治疗超声换能器 4 ,对于不同辐照深度 ,以声强 ISATA=2 2 .0× 10 3W/cm2、辐照时间 5 s的超声剂量定点辐照新鲜离体牛肝 ,以断层方式剖开后测量凝固性坏死组织体积。研究结果表明 ,对于一个具体的治疗超声换能器 ,在牛肝厚度一定时 ,辐射力穿透率 F′/F法与换能器表面声强及样品近治疗超声换能器表面声窗面积无关。采用最小 F′/F法拟合得出辐射力穿透率随牛肝厚度增加呈指数规律递减 ,且与凝固性坏死组织体积随牛肝厚度 (辐照深度 )增加呈指数规律递减趋势一致。采用最小二乘法拟合得出高度聚集超声在牛肝组织中传播的声衰随频率近似线性增加且呈幂函数关系。这为进一步研究高强度聚焦超声治疗剂量学提供了实验依据     

高强度聚焦超声热疗技术的发展和应用

高强度聚焦超声热疗技术以其微创、精确度高、副作用小且并发症少而被应用于临床治疗。目前,该技术主要用于前列腺癌、肝癌、原发性恶性骨肉瘤及乳腺癌等疾病的治疗。主要论述高强度聚焦超声热疗的现状、临床应用及进展。     

高强度聚焦超声治疗剂量对组织温升影响的研究

测量了高强度聚焦超声(HIFU)定点辐照新鲜离体牛肝脏时，不同声强和辐照时间下的组织焦点温升。根据Pennes传热方程，从理论上分析了高强度聚焦超声定点辐照生物组织前后组织温度变化的规律，研究结果表明；一定的声强下，总有一个辐照闻值时间存在，当辐照时间超过辐照阐值时间后，温升缓慢，声强越大，辐照阐值时同出现得更早l组织焦点温升、相对累积热剂量随声强、辐照时间的增加而增大，当治疗剂量一定时，声强对组织焦点温升的影响大于辐照时间对组织焦点温升的影响。因此，HIFU最适治疗剂量应满足：适度的声强、辐照时间为该声强下的辐照阈值时间。     

双频HIFU及其对组织焦斑的影响

引入具有双频工作模式和单频工作模式的新型HIFU，并用两种模式对不同状态的离体猪肝组织进行照射。实验结果表明：在相同的照射条件下，双频模式HIFU产生的焦斑明显大于单频模式时的焦斑；组织中的气体有扩大焦斑作用；双频模式下选择适当的差频对焦斑有明显影响。说明双频HIFU可以有效地提高大体积肿瘤的治疗效率和效果。同时对实验现象的机理进行了初步分析。     

HIFU技术的应用研究

高强度聚焦超声（ＨＩＦＵ）技术起源于四十年代，当时由于缺乏高精度的成像和定位技术，没有能迅速发展起来。现代成像技术和定位技术的发展为该技术提供了支持，其应用范围也深入到神经科、秘尿科、眼科、肿瘤学等领域。     

新型HIFU治疗头的研究

目的:肿瘤治疗中,焦区温度的实时监控和焦区体积的预测非常重要。本文旨在解决在超声治疗过程中对焦区的精确定位和对系统的声输出实现精确的实时控制的问题。方法:设计一种新型治疗头,通过在聚焦透镜上固定检测探头并整合计算机控制系统及超声图文信息管理系统。结果:不仅能实现对病灶的精确定位,并能对病灶进行实时的判断和治疗,从而实现治疗可控化。结论:新型治疗头设计的提出,可以实现对肿瘤的精确治疗的和在治疗过程中的实时检控。对HIFU治疗头的设计和研制有借鉴意义。     

比较影像学在评价HIFU治疗肝癌疗效中的应用

高强度聚焦超声是治疗肝癌的有效物理手段之一。影像学技术是评价高强度聚焦超声治疗肝癌疗效的重要手段。比较影像学是近年来一门新兴的医学学科,主要探讨比较影像学在高强度聚焦超声治疗肝癌评价中的应用。     

高强度聚焦超声制备兔股骨头坏死模型的可行性研究

目的:探讨高强度聚焦超声新方法制备兔股骨头坏死模型的可行性。方法:采用JC200型聚焦超声治疗系统,以80 w/cm~2强度超声照射家兔双侧股骨头,分别于照射后1、7、14、21 d取材,结合股骨头大体形态和组织石蜡切片H-E染色观察股骨头坏死情况。结果:股骨头外观7 d时可见界限明显的白色坏死区,表面光泽度稍下降;14 d时坏死区表面软骨变黄、皱缩;21 d时囊化、易剥脱。镜下见1 d时坏死区表面软骨可见少量软骨细胞核溶解,髓质可见小静脉扩张充血、血窦充血;7 d时坏死区表面软骨轻微挤压皱缩,软骨下区见骨小粱断裂和空骨陷窝,髓质造血组织明显减少,骨小梁表面成骨细胞消失,坏死骨小梁附近增生纤维组织,出现脂肪小囊,骺板稍变形;14 d时兔股骨头表面软骨变薄,偶可见破损,坏死软骨细胞增多,表面破损程度、骺板变形程度较7 d时加重,修复区可见增生肉芽组织和新生血管,有纤维组织附着于坏死骨小梁;21 d时,股骨头表面软骨破损严重,骺板进一步扭曲变形,坏死区骨小梁破碎、消失,修复区可见纤维组织包绕坏死骨小梁和新生骨小梁。结论:高强度聚焦超声制备的兔股骨头坏死模型效果稳定,具有清晰的病理演变特征,可作为一种制备股骨头坏死模型的新方法。     

基于磁共振温度图的高强度聚焦超声治疗热剂量研究

本实验研究基于磁共振T-Map的HIFU损伤组织的热剂量与实际凝固性坏死的关系。运用磁共振导航高强度聚焦超声治疗系统,使用1 MHz、焦距为150 mm、直径150 mm的聚焦超声换能器,定点辐照深度为20 mm的新鲜离体牛肝脏,辐照过程中用磁共振的测温序列采集各体素随时间变化的温度值并计算各体素的Eq43值,比较计算结果与发生凝固性坏死的Eq43参考阈值,判断该体素是否发生坏死。最后比较通过等效热剂量积分法得到的凝固性坏死面积和组织实际发生坏死的情况。结果表明基于磁共振T-Map的等效热剂量积分法得到的凝固性坏死的面积值能很好的反应实际发生凝固性坏死的情况,为HIFU治疗提供了一种新的判断凝固性坏死发生的方法,这种方法可以实时地反馈控制超声辐照剂量,提高了治疗的安全性。     

血管位置对HIFU焦域温度场的影响

目的 数值仿真研究不同位置的血管对高强度聚焦超声(HIFU)可治疗焦域的影响,为HIFU治疗安全性和可靠性提供理论依据.方法 应用超声非线性传播方程、Pennes生物热传导方程以及FDTD法数值仿真温度场分布.结果 考虑血流灌注与否,HIFU焦域温度场分布相一致.血管中心位于声轴时,焦域中心温升非常低;当血管偏离声轴小...     

高强度聚焦超声"切除"组织的剂量学研究

运用高强度聚焦超声（High intensity focused ultrasound．HIFU）技术完整切除组织块并确立相应的能效关系，从而进行HIFU剂量学研究。按照由生物学焦域（Biological focal region，BFR）→束损伤→片损伤→块损伤的治疗原则，使用ISATA为0～27700W／cm^2，扫描速度1～4mm／s，束损伤的空间间距5～10mm，片损伤的空间间距10～20mm，在离体牛肝组织中形成不同治疗深度的束损伤、片损伤和块损伤，从而实现完整切除组织块。并把形成单位体积凝固性坏死所需的HIFU超声能量叫做HIFU治疗的能效因子（Energy—efficiency factor．EEF），用EEF量化HIFU在组织内的能量存积。研究结果表明，在不同治疗深度处形成的束损伤的EEF随治疗深度的增加而增大。形成片损伤、块损伤的EEF远远小于在不同治疗深度处形成束损伤的EEF，且形成块损伤的EEF小于形成片损伤的EEF。形成片损伤、块损伤的EEF并不是不同治疗深度的束损伤的EEF、不同治疗层面的片损伤的EEF的简单叠加，它与一个已存在的损伤改变了组织声环境有关，提示可通过改变组织声环境来改变EEF。因此，用EEF来进行HIFU的剂量学研究是一个新思路。对一个固定的聚焦超声换能器，EEF除了与声功率、辐照时间、治疗深度、组织结构和功能状态有关外，另一个重要的影响因素是H1FU治疗过程中组织声环境的改变。     

一类高强度聚焦超声手术平台的定位过程规划

在高强度聚焦超声(High intensity focused ultrasound,HIFU)肿瘤手术平台的工作空间分析和定位过程分析的基础上提出利用定位区域球方法在工作空间中简化表示肿瘤的位置和姿态,并且利用定位区域球确定了定位过程中治疗焦点必须经过的终点位姿和中间路径点;根据确定的路径点在李群空间SE(3)中构造出一条C2连续的三次均匀B样条插值定位路径;最后给出了一个病例分析结果。     

一种用于高强度聚焦超声手术的八自由度机器人手术平台

机器人手术是未来外科手术的发展方向,高强度聚焦超声(Highintensityfocusedultrasound,HIFU)手术是一种崭新的无副作用癌症治疗方法。本文介绍了机器人集成超声手术系统、流程,并详细介绍了可以解决术中定位这一关键问题的八自由度机器人手术平台的设计、结构特征、运动机理。分别给出了C形臂和治疗床、C形臂和治疗头两个五维合成运动的可达工作空间分析。相对于已有的手术平台,该平台定位准确、便捷,可治疗的人体区域也更大,从而使治疗方案的设计更具灵活性。     

Higher Dosage of HIFU Treatment May Lead to Higher and Longer Efficacy for Moderate to Severe Perennial Allergic Rhinitis

Objectives: This study was to compare the efficacies and side effects of high intensity focused ultrasound (HIFU) treatment for perennial allergic rhinitis (PAR) with regular and increased dosage.Study design: A prospectively assembled cohort was retrospectively analyzed through visual analogue scale (VAS).Methods: Regular dosage of HIFU treatment was applied to 56 PAR patients in group A. An increased dosage as twice as the regular one was applied to 48 patients in group B. Nasal obstruction, sneezing, rhinorrhea and rhinocnesmus, which were recognized as the four main symptoms of allergic rhinitis (AR), were evaluated before treatment, 3 months after treatment, and 1 year after treatment. The satisfaction of patients was also evaluated at 1 year postoperatively. Biopsy of the inferior turbinate and morphometric analysis were applied to 11 patients in group A and 10 in group B before HIFU treatment and 3 months after treatment.Results: Comparing the AR symptoms before treatment, There is no statistical difference observed between group A and B (p>0.05). The four main symptoms at 3 months and 1 year after treatment were all significantly improved (p<0.01) in both group A and B. The VAS scores of AR symptoms in Group B were lower than those in Group A at the same stage after treatment, especially at 1 year after treatment (p<0.05). Comparing the results at 3 months and 1 year after treatment, a tendency of recurrence of these symptoms was observed statistically in group A (p<0.05), but not in group B (p>0.05). More cases of nasal dryness and perirhinal swelling were found in group B than those in group A (p<0.05), while all side effects were mild and temporary. Patients in group B were more satisfied than those in group A (p=0.0866 >0.05), though not statistically significant. More reduction of the eosinophils, other inflammatory cells, and the submucosal glands was observed after HIFU treatment in group B than that in group A (p<0.05).Conclusions: A proper increment of HIFU dosage may be recommended to meet the needs of more improvement of AR symptoms and less recurrence.     

High intensity focused ultrasound lithotripsy with cavitating microbubbles

In the medical ultrasound field, microbubbles have recently been the subject of much interest. Controlling actively the effect of the microbubbles, a novel therapeutic method has been investigated. In this paper, our works on high intensity focused ultrasound (HIFU) lithotripsy with cavitating microbubbles are reviewed and the cavitation detection method to optimize the HIFU intensity is investigated. In the HIFU lithotripsy, collapse of the cloud cavitation is used to fragment kidney stones. Cloud cavitation is potentially the most destructive form of cavitation. When the cloud cavitation is acoustically forced into a collapse, it has the potential to concentrate a very high pressure. For the control of the cloud cavitation collapse, a novel two-frequency wave (cavitation control [C-C] waveform) is designed; a high-frequency ultrasound pulse (1–4 MHz) to create the cloud cavitation and a low-frequency trailing pulse (500 kHz) following the high-frequency pulse to force the cloud into collapse. High-speed photography showed the cavitation collapse on the stone and the shock-wave emission from the cloud. In vitro erosion tests of model and natural stones were also conducted. In the case of model stones, the erosion rate of the C-C waveform showed a distinct advantage with the combined high- and low-frequency waves over either wave alone. For the optimization of the high-frequency ultrasound intensity, the subharmonic acoustic pressure was examined. The results showed relationship between the subharmonic pressure from cavitating bubbles induced by the high-frequency ultrasound and eroded volume of the model stones. Natural stones were eroded and most of the resulting fragments were less than 1 mm in diameter. The method has the potential to provide a novel lithotripsy system with small fragments and localized cavitating bubbles on a stone.     

邻近山羊门静脉行高强度聚焦超声消融的病理观察

观察使用磁共振(MRI)导航的高强度聚焦超声(MRgHIFU)消融靠近山羊门静脉的肝组织的病理变化;在MRI监控下,对50只山羊靠近门静脉0、5和10 mm处的肝组织进行热消融。其中40只山羊术后立即处死,另外10只在消融7 d后处死。病理观察显示靶区肝组织完全坏死,治疗后即刻0 mm组门静脉出现胶原纤维肿胀(CS)27/40(67.5%)例,血管壁断裂(VWF)为7/40(17.5%)例;5 mm组门静脉CS为8/40(20%)例,VWF(0/40,0%),两组间CS和VWF发生率差异有显著性(P<0.05);10 mm组未见CS(0/40,0%)和VWF(0/40,0%)。消融后7d,各组门静脉标本在光镜下均未见CS和VWF。以上结果表明,MRgHIFU在距山羊门静脉0~5 mm处消融肝组织可能会造成门静脉的急性损伤,但这种损伤是可逆的。     

Experimental ablation of the pancreas with high intensity focused ultrasound (HIFU) in a porcine model

The aim of this study was to determine the feasibility and safety of high intensity focused ultrasound''s (HIFU) in pancreatic diseases. Twelve pigs were divided into three groups. The pancreases of pigs in Group A were ablated directly with HIFU, but those in Group B and C ablated by extracorporeal HIFU. The pigs in Group C were sacrificed at day 7 after HIFU. Serological parameters were determined pre-operation and post-operation. The entire pancreas was removed for histological examination. Each animal tolerate the HIFU ablation well. The complete necrosis was observed in targeted regions. The margins of the necrotic regions were clearly delineated from the surrounding normal tissues. Infiltration of inflammatory cells and phorocytosis on the boundary were found in group C. Blood and urine amylase levels were relatively steady after HIFU. No acute pancreatitis or severe complications occurred. In conclusion, HIFU ablation on the pancreas was safe and effective in experimental pigs.