高强度聚焦超声生物学焦域温场研究

采用热电偶探针测温系统 ,研究了运用JC A型HIFU聚焦超声肿瘤治疗系统定点辐照新鲜离体牛肝脏的生物学焦域温场分布。研究结果表明 :焦域中心温度最高 ,温升可达 74 .4± 1.5℃。在空间上 ,远离焦点温升快速下降 ,Z轴有效温升宽度 12 .4mm ,X、Y轴有效温升宽度均为 5 .4mm。X、Y、Z轴有效温升宽度与生物学焦域大小一致。光镜下 ,生物学焦域与周围正常组织分界清楚。所以 ,在空间上 ,由生物学焦域中心向外缘 ,能量递减十分陡峭 ,具有“刀”的特征。高强度聚焦超声对深部组织定位损伤在空间上是精确的、有效的、安全的。     

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     

球面自聚焦换能器声场的焦域温度分布估计

利用声场叠加原理,对大口径球面自聚焦换能器的声场分布进行了模拟,以声强下降一半为界,确定了球面自聚焦换能器辐照组织的主要加热区域。从热量传递概念出发,对焦域内的分布和温度随时间的变化做了合理估计。结果表明：焦域内组织温度分布与声场分布类似;在一定时间和区域,组织温度可以迅速上升23℃以上,基本满足治疗要求。     

高强度聚焦超声作用下的组织焦域能量分析及实验验证

为研究发生空化前高强度聚焦超声(HIFU)作用的最佳治疗模式,从声场和热场的仿真计算和新鲜离体牛肝实验验证出发,根据声能转化成热能的原理,分析了组织焦域温度上升造成组织损伤的变化过程;建立了与温度相关的组织损伤预测模型;计算了形成1 mm宽度的生物学焦域所吸收的能量;并在75、100、125、150 W这4种声功率下,按照350 J能量,共进行了24组新鲜离体牛肝组织的实验,验证该能量强度形成的生物学焦域尺寸。结果表明,经组织衰减后生物学焦域吸收的超声能量为350 J时,在新鲜离体牛肝组织中形成的生物学焦域宽度为(1.1±0.1)mm;当换能器物理学焦域的长短轴之比在4～10之间变动时,吸收350 J形成的生物学焦域宽度保持在(1.0±0.2) mm。在充分除气的均匀介质牛肝中,当换能器的物理学焦域长短轴比在4～10之间时,吸收350 J能量,声功率100～150 W是形成(1.0±0.2) mm宽度的生物学焦域的最佳治疗模式。     

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胰腺癌致超声通道损伤的机制研究

目的探讨高强度聚焦超声治疗胰腺癌的效果及导致超声通道损伤的机制。方法选择11例诊断明确并接受高强度聚焦超声治疗的晚期胰腺癌患者,行开放手术评价超声通道区组织、器官损伤情况,分析可能机制。结果 8例出现皮肤Ⅰ、Ⅱ度烧伤,超声通道区腹壁呈局限性浅、深筋膜纤维化样改变,肝脏呈充血样改变,胃、十二指肠、空肠、胆囊、胆总管均未发现肉眼可见的损伤。结论高强度聚焦超声治疗晚期胰腺癌有效,其损伤超声通道区组织、器官的可能机制为靶区与皮肤距离较近及消融时间相对较长。     

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。     

高强度聚焦超声换能器声场的数值仿真与实验测量

目的 高强度聚焦超声(HIFU)肿瘤治疗过程中,HIFU换能器形成的声场分布是决定其治疗效果的关键因素之一,为了提高HIFU肿瘤治疗的安全性和可靠性,需要对HIFU换能器形成的声场进行预测.方法 采用时域有限差分(FDTD)法数值仿真水体内形成的声压分布与实验测量结果对比的研究方法,分析讨论了HIFU换能器在不同激励功...     

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"切除"肿瘤过程中的空化效应

随着高强度聚焦超声(HIFU)在多种肿瘤治疗中的广泛应用,对其生物学效应的研究也不断深入.空化效应是超声的主要生物学效应之一.本文对近年来众学者在HIFU治疗肿瘤过程中关于空化效应是否存在、产生空化效应的条件以及对空化效应的评价等问题进行了较为全面的阐述.     

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。     

In vivo characterization of tissue thermal properties of the kidney during local hyperthermia induced by MR-guided high-intensity focused ultrasound

The purpose of this study was to evaluate quantitatively in vivo the tissue thermal properties during high-intensity focused ultrasound (HIFU) heating. For this purpose, a total of 52 localized sonications were performed in the kidneys of six pigs with HIFU monitored in real time by volumetric MR thermometry. The kidney perfusion was modified by modulation of the flow in the aorta by insertion of an inflatable angioplasty balloon. The resulting temperature data were analyzed using the bio-heat transfer model in order to validate the model under in vivo conditions and to estimate quantitatively the absorption (α), thermal diffusivity (D) and perfusion (w(b)) of renal tissue. An excellent correspondence was observed between the bio-heat transfer model and the experimental data. The absorption and thermal diffusivity were independent of the flow, with mean values (± standard deviation) of 20.7 ± 5.1 mm(3) K J(-1) and 0.23 ± 0.11 mm(2) s(-1), respectively, whereas the perfusion decreased significantly by 84% (p < 0.01) with arterial flow (mean values of w(b) of 0.06 ± 0.02 and 0.008 ± 0.007 mL(-1) mL s(-1)), as predicted by the model. The quantitative analysis of the volumetric temperature distribution during nondestructive HIFU sonication allows the determination of the thermal parameters, and may therefore improve the quality of the planning of noninvasive therapy with MR-guided HIFU.     

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。     

Multiparametric MRI analysis for the evaluation of MR‐guided high intensity focused ultrasound tumor treatment

For the clinical application of high intensity focused ultrasound (HIFU) for thermal ablation of malignant tumors, accurate treatment evaluation is of key importance. In this study, we have employed a multiparametric MRI protocol, consisting of quantitative T₁, T₂, ADC, amide proton transfer (APT), T_1ρ and DCE‐MRI measurements, to evaluate MR‐guided HIFU treatment of subcutaneous tumors in rats. K‐means clustering using all different combinations of the endogenous contrast MRI parameters (feature vectors) was performed to segment the multiparametric data into tissue populations with similar MR parameter values. The optimal feature vector for identification of the extent of non‐viable tumor tissue after HIFU treatment was determined by quantitative comparison between clustering‐derived and histology‐derived non‐viable tumor fractions. The highest one‐to‐one correspondence between these clustering‐based and histology‐based non‐viable tumor fractions was observed for the feature vector {ADC, APT‐weighted signal} (R² to line of identity (R²_y=x) = 0.92) and the strongest agreement was seen 3 days after HIFU (R²_y=x = 0.97). To compare the multiparametric MRI analysis results with conventional HIFU monitoring and evaluation methods, the histology‐derived non‐viable tumor fractions were also quantitatively compared with non‐perfused tumor fractions (derived from the level of contrast enhancement in the DCE‐MRI measurements) and 240 CEM tumor fractions (i.e. thermal dose > 240 cumulative equivalent minutes at 43 °C). The correlation between histology‐derived non‐viable tumor fractions directly after HIFU and the 240 CEM fractions was high, but not significant. The non‐perfused fractions overestimated the extent of non‐viable tumor tissue directly after HIFU, whereas an underestimation was observed 3 days after HIFU. In conclusion, we have shown that a multiparametric MR analysis, especially based on the ADC and the APT‐weighted signal, can potentially be used to determine the extent of non‐viable tumor tissue 3 days after HIFU treatment. We expect that this method can be incorporated in the current clinical workflow of MR–HIFU ablation therapies. Copyright © 2015 John Wiley & Sons, Ltd.     

Injury to the infrapatellar branch of the saphenous nerve during tendon graft harvesting for knee ligament reconstruction: An ultrasound simulation study

The clinical anatomy of the infrapatellar branch of the saphenous nerve (IPBSN) is of particular importance during operations in the area of the knee, especially when material for anterior cruciate ligament reconstruction is harvested. The nerve can easily be injured during the harvesting procedure, leading to postoperative complications that reduce quality of life. Three different skin incisions are commonly used during hamstring tendon harvesting: horizontal, vertical, and oblique. The aim of this ultrasound simulation study was to assess the risk of IPBSN injury associated with the type of skin incision and the point‐of‐emergence of the IPBSN relative to the sartorius muscle. Thirty healthy volunteers (60 lower limbs) were recruited for identification of the IPBSN. When it was found, using a high‐frequency ultrasound probe, three different 3 cm skin incisions over the pes anserinus were simulated. Vertical, horizontal, or oblique lines simulating incisions were marked over the pes anserinus and ultrasound was used to visualize the structures that could be injured during the marked incisions. The IPBSN was visualized in 58 lower limbs (96.7%). The results of the simulation study indicated that the vertical incision should be avoided during hamstring tendon harvesting, as it is associated with a significantly higher risk of injury (25.9%) to the IPBSN than the horizontal (3.5%) or oblique (8.6%) incisions. We recommend that a preoperative ultrasound assessment of IPBSN anatomy be performed to minimize the risk of iatrogenic injury to the nerve and associated complications. Clin. Anat. 30:868–872, 2017. © 2017 Wiley Periodicals, Inc.