TACE．PVE．HIFU序贯治疗原发性肝癌的疗效评价

目的 研究TACE.PVE．HIFU序贯治疗原发性肝癌临床疗效及方法。方法将我院60例原发性肝癌患者随机分为两组：治疗组30例：TACE．PVE．HIFU序贯治疗;对照组30例：给予经导管化疗栓塞术（TACE）。两组患者治疗后对其临床疗效进行评价分析,所有患者随访3年观察生存情况,并分析相关因素。结果60例原发性肝癌患者,治疗组总有效率为16例占53．3％,而对照组7例占23．3％,治疗组治疗后临床疗效明显要好于对照组。两组原发性肝癌患者治疗后,其治疗组3年生存率为14例占46．7％,而对照组8例占26．7％,治疗组生存率明显高与对照组。60例原发性肝癌不同肝功能Child分级患者治疗后：6个月生存率51例占85．O％、1年生存率43例占71．7％、2年生存率32例占53．3％、3年生存率22例占36．7％。肝功能ChildA生存率较高。结论TACE．PVE．HIFU序贯治疗在原发性肝癌应用互为补充,最终达到彻底杀灭癌细胞的目的。     

基于文献计量的HIFU研究现状分析

目的 通过分析SCIE中海扶领域相关论文,了解目前海扶研究的现状与发展趋势.方法 利用Web of Science,从载文量、作者、地区与机构、关键词等角度统计分析.结果 共检索出479篇相关文献,涉及1 412位作者, 36个国家(地区)与382个科研机构.结论 海扶学科发展尚未成熟,拥有一支实力雄厚、造诣较深的核心作者群.中、美、法成为海扶研究的中心国家.手术消融治疗、肿瘤活体组织等依然是HIFU研究的主要内容,该学科需要在临床实践中进一步发展成熟.     

Optimization of encoding gradients for MR‐ARFI

MR acoustic radiation force imaging provides a promising method to monitor therapeutic ultrasound treatments. By measuring the displacement induced by the acoustic radiation force, MR acoustic radiation force imaging can locate the focal spot, without a significant temperature rise. In this work, the encoding gradient for MR acoustic radiation force imaging is optimized to achieve an enhanced accuracy and precision of the displacement measurement. By analyzing the sources of artifacts, bulk motion and eddy currents are shown to introduce errors to the measurement, and heavy diffusion‐weighting is shown to result in noisy displacement maps. To eliminate these problems, a new encoding scheme is proposed, which utilizes a pair of bipolar gradients. Improved precision is achieved with robustness against bulk motion and background phase distortion, and improved accuracy is achieved with reduced diffusion‐weighting and optimized encoding pulse width. The experiment result shows that the signal‐to‐noise ratio can be enhanced by more than 2‐fold. These significant improvements are obtained at no cost of scan time or encoding sensitivity, enabling the detection of a displacement less than 0.l μm in a gel phantom with MR acoustic radiation force imaging. Magn Reson Med 63:1050–1058, 2010. © 2010 Wiley‐Liss, Inc.     

Temperature‐induced tissue susceptibility changes lead to significant temperature errors in PRFS‐based MR thermometry during thermal interventions

Proton resonance frequency shift‐based MR thermometry (MRT) is hampered by temporal magnetic field changes. Temporal changes in the magnetic susceptibility distribution lead to nonlocal field changes and are, therefore, a possible source of errors. The magnetic volume susceptibility of tissue is temperature dependent. For water‐like tissues, this dependency is in the order of 0.002 ppm/°C. For fat, it is in the same order of magnitude as the temperature dependence of the proton electron screening constant of water (0.01 ppm/°C). For this reason, proton resonance frequency shift‐based MR thermometry in fatty tissues, like the human breast, is expected to be prone to errors. We aimed to quantify the influence of the temperature dependence of the susceptibility on proton resonance frequency shift‐based MR thermometry. Heating experiments were performed in a controlled phantom set‐up to show the impact of temperature‐induced susceptibility changes on actual proton resonance frequency shift‐based temperature maps. To study the implications for a clinical case, simulations were performed in a 3D breast model. Temperature errors were quantified by computation of magnetic field changes in the glandular tissue, resulting from susceptibility changes in a thermally heated region. The results of the experiments and simulations showed that the temperature‐induced susceptibility changes of water and fat lead to significant errors in proton resonance frequency shift‐based MR thermometry. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

Real‐time 3D target tracking in MRI guided focused ultrasound ablations in moving tissues

Magnetic resonance imaging‐guided high intensity focused ultrasound is a promising method for the noninvasive ablation of pathological tissue in abdominal organs such as liver and kidney. Due to the high perfusion rates of these organs, sustained sonications are required to achieve a sufficiently high temperature elevation to induce necrosis. However, the constant displacement of the target due to the respiratory cycle render continuous ablations challenging, since dynamic repositioning of the focal point is required. This study demonstrates subsecond 3D high intensity focused ultrasound‐beam steering under magnetic resonance‐guidance for the real‐time compensation of respiratory motion. The target is observed in 3D space by coupling rapid 2D magnetic resonance‐imaging with prospective slice tracking based on pencil‐beam navigator echoes. The magnetic resonance‐data is processed in real‐time by a computationally efficient reconstruction pipeline, which provides the position, the temperature and the thermal dose on‐the‐fly, and which feeds corrections into the high intensity focused ultrasound‐ablator. The effect of the residual update latency is reduced by using a 3D Kalman‐predictor for trajectory anticipation. The suggested method is characterized with phantom experiments and verified in vivo on porcine kidney. The results show that for update frequencies of more than 10 Hz and latencies of less then 114 msec, temperature elevations can be achieved, which are comparable to static experiments. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

Shock-Induced Heating and Millisecond Boiling in Gels and Tissue Due to High Intensity Focused Ultrasound

Nonlinear propagation causes high-intensity ultrasound waves to distort and generate higher harmonics, which are more readily absorbed and converted to heat than the fundamental frequency. Although such nonlinear effects have been investigated previously and found to not significantly alter high-intensity focused ultrasound (HIFU) treatments, two results reported here change this paradigm. One is that at clinically relevant intensity levels, HIFU waves not only become distorted but form shock waves in tissue. The other is that the generated shock waves heat the tissue to boiling in much less time than predicted for undistorted or weakly distorted waves. In this study, a 2-MHz HIFU source operating at peak intensities up to 25,000 W/cm² was used to heat transparent tissue-mimicking phantoms and ex vivo bovine liver samples. Initiation of boiling was detected using high-speed photography, a 20-MHz passive cavitation detector and fluctuation of the drive voltage at the HIFU source. The time to boil obtained experimentally was used to quantify heating rates and was compared with calculations using weak shock theory and the shock amplitudes obtained from nonlinear modeling and measurements with a fiber optic hydrophone. As observed experimentally and predicted by calculations, shocked focal waveforms produced boiling in as little as 3 ms and the time to initiate boiling was sensitive to small changes in HIFU output. Nonlinear heating as a result of shock waves is therefore important to HIFU, and clinicians should be aware of the potential for very rapid boiling because it alters treatments. (E-mail: mcanney@u.washington.edu).     

Pathological Changes on Human Breast Cancer Specimens Ablated in vitro with High-Intensity Focused Ultrasound

The purpose of this study was to evaluate the pathologic changes of human breast cancer specimens ablated with high-intensity focused ultrasound (HIFU) in vitro. Twenty specimens of pathologically confirmed breast cancer tissue were ablated with ultrasound-guided HIFU. The evaluation methods include histopathologic observation using hematoxylin-eosin staining, electron microscopic imaging, enzyme histochemical and immunohistochemical examination on tumor antigens. Vacuole-like structures in cytoplasm were observed by histopathologic observation but there were no significant changes in cell morphology and nucleus karyotype. Typical phenomena related to coagulation necrosis were observed in electron microscopic studies; the contour of cell structure was still preserved but the structures of cell (all kinds of organelles and nucleus) were damaged or disappeared. Acid phosphatase and succinate dehydrogenase staining showed that tumor cells were inactivated. In immunohistochemical evaluations, estrogen receptor, progesterone receptor, cerbB-2 and P53 expression changed from 85%, 82%, 75% and 80% in nonablation tissue to no expression in ablated tumor tissue, respectively. We, therefore, conclude that breast cancer cells appear normal contour immediately after ablation with HIFU under light microscopic but they were evaluated to be dead by electron microscopic imaging, enzyme histochemical and immunohistochemical examinations. (E-mail:wangzbpaper@haifu.com.cn)     

聚焦超声治疗外阴硬化性苔藓的疗效观察

目的探讨聚焦超声治疗外阴硬化性苔藓的疗效。方法2005年7月～2005年12月用聚焦超声治疗外阴硬化性苔藓病人30例(超声组),同期采用皮质激素、雄激素等药物治疗外阴硬化性苔藓病人33例(对照组),对两组病人的疗效进行比较分析。结果超声组与对照组在治疗后瘙痒评分有显著性差异(P<0.05),病灶面积缩小比较亦有显著性差异(P<0.01)。超声组和对照组的复发率分别为6.25%和50%。结论聚焦超声是一种安全、无创、疗效好、操作简便的治疗外阴硬化性苔藓的方法。