High Intensity Focused Ultrasound Surgery Research Articles

Metal-Organic Framework-Mediated Synergistic Hypoxia-Activated Chemo-Immunotherapy Induced by High Intensity Focused Ultrasound for Enhanced Cancer Theranostics.

High intensity focused ultrasound (HIFU) has attracted considerable attention as a noninvasive, efficient, and economic therapeutic modality for solid tumors. However, HIFU surgery has its intrinsic limitation in completely ablating tumors, leading to residual tumor tissue. Furthermore, the severely hypoxic environment ensuring after surgery can exacerbate the unrestricted proliferation and metabolism of residual tumor cells, leading to tumor recurrence and metastasis. To address these limitations, a versatile HIFU-specific metal-organic framework nanosystem (called ADMOFs) is developed by coordinating hypoxia-activated prodrug AQ4N, Mn2+, and DOX based on the postoperative response to changes in the tumor microenvironment. ADMOFs loaded with AQ4N/Mn2+ exhibited remarkable tumor-targeting behavior in vivo and enhanced photoacoustic/magnetic resonance imaging effects, enabling more accurate guidance for HIFU surgery. After surgery, the ADMOFs exploited the severely hypoxic tumor environment induced by HIFU, overcoming hypoxia-associated drug resistance, and inducing immunogenic cell death. Finally, it effectively inhibited tumor growth and eliminated lung metastasis. Transcriptome studies revealed that this strategy significantly up-regulated genes involved in apoptosis, cell cycle, and HIF-1 signaling pathway while downregulating genes related to tumor proliferation and metastasis. These findings suggest that combining hypoxia-activated chemo-immunotherapy with HIFU is a promising strategy for enhancing cancer theranostics.

High-intensity Focused Ultrasound is a Better Choice for Women with Fertility Desire: A Systematic Review and Meta-analysis of the Comparison between High-intensity Focused Ultrasound and Laparoscopic Treatment of Uterine Fibroids

High-intensity focused ultrasound (HIFU) is commonly used to treat uterine fibroids and adenomyosis, but there is no evidence using metadata to compare fertility outcomes between conventional laparoscopic procedures and HIFU. The purpose of this study analysis is that evidence-based fertility outcomes may provide better treatment options for clinicians and patients considering fertility. The literature on fertility data for HIFU surgery versus laparoscopic myomectomy was searched in seven English language databases from January 1, 2010, to November 23, 2022. A total of 1375 articles were received in the literature, 14 of which were selected. We found that women who underwent HIFU surgery had higher rates of spontaneous pregnancy, higher rates of spontaneous delivery, and higher rates of full-term delivery but may have higher rates of miscarriage or postpartum complications than women who underwent laparoscopic myomectomy. Looking forward to future studies, it is hoped that the literature will examine endometrial differences in women who undergo HIFU and laparoscopic myomectomy to demonstrate the ability of endometrial repair. The location of fibroids in the sample should also be counted to allow for attribution statistics on the cause of miscarriage.

Real-time cavitation monitoring based on the entropic analysis of ultrasound RF signals

The violent inertial cavitation activity generated in high intensity focused ultrasound (HIFU) treatment has a risk of damaging healthy tissues around the target area, so that it is necessary to monitor the degree of cavitation during the treatment. Entropy, as a non-model-based statistical parameter, can effectively characterize the effect of cavitation on the structure of scatters within tissues. Thus, a real-time cavitation monitoring system was established based on the entropy analysis of ultrasound radio frequency (RF) signals, and the degree of cavitation was evaluated through entropy images. Based on the two-dimensional average filtering method, we achieved real-time monitoring of cavitation through the reconstruction of entropy image and the binarization of cavitation regions, breaking the inherent limitation of current systems that can only perform cavitation monitoring between HIFU pulses. The results showed that the entropy image retained more frequency components, which could determine the time and location of cavitation earlier and display cavitation areas. Moreover, as the acoustic pressure increased, the advance of cavitation indication in the entropy images became earlier. This method might provide a feasible evaluation scheme for improving real-time cavitation monitoring during HIFU treatment and was expected to become an effective reference index for imaging in HIFU surgery.

A radiomics nomogram model for predicting prognosis of pancreatic ductal adenocarcinoma after high-intensity focused ultrasound surgery

Objective To develop and validate a radiomics nomogram for predicting the survival of patients with pancreatic ductal adenocarcinoma (PDAC) after receiving high-intensity focused ultrasound (HIFU) treatment. Methods A total of 52 patients with PDAC were enrolled. To select features, the least absolute shrinkage and selection operator algorithm were applied, and the radiomics score (Rad-Score) was obtained. Radiomics model, clinics model, and radiomics nomogram model were constructed by multivariate regression analysis. The identification, calibration, and clinical application of nomogram were evaluated. Survival analysis was performed using Kaplan–Meier (K–M) method. Results According to conclusions made from the multivariate Cox model, Rad-Score, and tumor size were independent risk factors for OS. Compared with the clinical model and radiomics model, the combination of Rad-Score and clinicopathological factors could better predict the survival of patients. Patients were divided into high-risk and low-risk groups according to Rad-Score. K–M analysis showed that the difference between the two groups was statistically significant (p < 0.05). In addition, the radiomics nomogram model indicated better discrimination, calibration, and clinical practicability in training and validation cohorts. Conclusion The radiomics nomogram effectively evaluates the prognosis of patients with advanced pancreatic cancer after HIFU surgery, which could potentially improve treatment strategies and promote individualized treatment of advanced pancreatic cancer.

Comparison of the Clinical Outcomes and Efficiencies of HIFU (High-Intensity Focused Ultrasound), Da Vinci Robotic Surgery and Laparoscopic Surgery for Uterine Fibroids: A Systematic Review and Meta-Analysis

Background: To compare the clinical outcomes and treatment efficiencies of advanced surgical treatments including High-Intensity Focused Ultrasound (HIFU), robotic surgery and laparoscopic surgery in the uterine fibroid patients. Methods: A total of 512 studies from 1995 to 2021 were identified by screening from Science Direct, Cochrane library, Medscape, Willey Online Library, PubMed, and Taylor Francis. From these studies 29 articles were qualitatively included in our systematic review and 24 of them considered quantitively eligible were included in the meta-analysis. Study analyzed by pooling the weighed mean difference (WMD) with the 95% confidence interval (CI) were study provided as a mean + (SD) and pooled risk ratio (RR) was expressed for dichotomous variables. Pooled results were assessed with either a random-effect or fixed-effect model. Heterogeneity was evaluated using the I2 statistic. Results: Comparison of HIFU and robotic surgeries with operation times of 86.13 ± 36.37 minutes to 120.2 ± 63 minutes and 166 ± 48.5 minutes to 278 ± 67 minutes were higher significant differences (I2 = 97%, p &lt; 0.00001), (WMD –111.88 [–189.68, –34.08]) with statistically significant (p = 0.005). Comparison of HIFU and laparoscopic surgery in operation time of 86.13 ± 36.37 minutes to 120.2 ± 63 minutes and 79 ± 30 minutes to 106.4 ± 38.5 minutes were not statistically significant (p = 0.75) with higher significant differences heterogeneity (I2 = 96%, p &lt; 0.00001), (5.51 [–27.82, 38.83]). Comparison of between blood losses and fibroid sizes at 154 ± 75 mL to 278 ± 164.6 mL and 6.5±2.9 cm to 13.6 ± 3.1 cm respectively in laparoscopic surgery was higher significant differences (I2 = 91%, p &lt; 0.0007), (WMD 202.29 [87.77, 316.80]) with statistically significant (p = 0.0005). Between hospital stay and blood loss in laparoscopic surgery at 1.2 ± 0.9 days to 5.4 ± 0.2 days and 200 ± 107 mL to 278 ± 164.6 mL showed significant differences (I2 = 90%, p &lt; 0.0001), (WMD –269.71 [–361.33, –178.09]) with statistically significant (p &lt; 0.00001) while in robotic surgery was not significant. The follow up uterine fibroid symptom &amp; health-related quality of life questionnaire (UF-QOL) at 3 months 45.3 + 26.9 to 70.6 + 26.9 in fibroids group and 61.6 + 41.4 to 79.64 + 17.91 in adenomyosis group and both shows significantly different (I2 = 83%, p = 0.02), (WMD 14.08 [4.42, 23.75]) with statistically significant (p = 0.0004) and (I2 = 97%, p &lt; 0.00001), (WMD –15.95 [–28.06, –3.84]) with (p = 0.010). SSS follow up 3 months 27.2 + 15.7 to 36.6 + 7.9 in fibroids of HIFU, the heterogeneity test showed significant differences (I2 = 95%, p &lt; 0.00001), (WMD 16.22 [8.33, 24.11]) with statistically significant (p &lt; 0.0001). In terms of pregnancy outcome, delivery outcome in live birth between HIFU and laparoscopic surgery 4 (8) within 165 (219) and (7) 23 within 158 (224), the heterogeneity was not significant (I2 = 0%, p = 0.44), (RR 1.06 [0.97, 1.17]) neither with for risk of delivering was not significant (p = 0.20). Conclusions: HIFU treatment reveals more efficient clinical and treatment outcomes than robotic or laparoscopic surgery, including improved symptoms, absence of bleeding, shorter operative time, shorter recovery time, and good benefits in both short-term and long-term quality-of-life.

Banoxantrone Coordinated Metal-Organic Framework for Photoacoustic Imaging-Guided High Intensity Focused Ultrasound Therapy.

Photoacoustic (PA) imaging with high spatial resolution has great potential as desired monitoring means in the high-intensity focused ultrasound (HIFU) surgery of tumor. However, its penetration depth in the tissue is insufficient for achieving accurate intraoperative navigation, leading to residual tumor tissue. Nanomedicine provides a new opportunity for PA imaging to guide HIFU surgery. Studies have found that the hypoxic heterogeneity of tumor is effectively reversed by HIFU. Herein, a specific metal-organic framework nanosystem, constructed by coordination of banoxantrone (AQ4N) and Mn2+ , is designed based on HIFU to reverse the hypoxic heterogeneity of tumors. It can provide exogenous light-absorbing substances, thus improving the penetrability of PA imaging signal through the deep tissue and achieving clearer PA imaging for guiding HIFU surgery. In turn, AQ4N, in the hypoxic homogenous environment of the tumor provided by HIFU, is activated sequentially to specifically treat the residual hypoxic tumor cells. This combination treatment manifests higher tumor suppressors activation and lower expression of genes related to tumor progression. This strategy addresses the dissatisfaction with PA imaging-guided HIFU therapy and is promising for translation into a clinical combination regimen.

Three birds with one stone: co-encapsulation of diclofenac and DL-menthol for realizing enhanced energy deposition, glycolysis inhibition and anti-inflammation in HIFU surgery.

Despite attracting increasing attention in clinic, non-invasive high-intensity focused ultrasound (HIFU) surgery still commonly suffers from tumor recurrence and even matastasis due to the generation of thermo-resistance in non-apoptotic tumor cells and adverse therapy-induced inflammation with enhanced secretion of growth factors in irradiated region. In this work, inspired by the intrinsic property that the expression of thermo-resistant heat shock proteins (HSPs) is highly dependent with adenosine triphosphate (ATP), dual-functionalized diclofenac (DC) with anti-inflammation and glycolysis-inhibition abilities was successfully co-encapsulated with phase-change dl-menthol (DLM) in poly(lactic-co-glycolic acid) nanoparticles (DC/DLM@PLGA NPs) to realize improved HIFU surgery without causing adverse inflammation. Both in vitro and in vivo studies demonstrated the great potential of DC/DLM@PLGA NPs for serving as an efficient synergistic agent for HIFU surgery, which can not only amplify HIFU ablation efficacy through DLM vaporization-induced energy deposition but also simultaneously sensitize tumor cells to hyperthermia by glycolysis inhibition as well as diminished inflammation. Thus, our study provides an efficient strategy for simultaneously improving the curative efficiency and diminishing the harmful inflammatory responses of clinical HIFU surgery.Graphical Supplementary InformationThe online version contains supplementary material available at 10.1186/s12951-022-01437-2.

Temperature Dependence of Tissue Thermal Parameters Should Be Considered in the Thermal Lesion Prediction in High-Intensity Focused Ultrasound Surgery

This study considers the temperature-dependent thermal parameters (specific heat capacity, thermal diffusivity and thermal conductivity) used when predicting the temperature rise of tissue exposed to high-intensity focused ultrasound (HIFU). Numerical analysis was performed using the Khokhlov–Zabolotskaya–Kuznetsov equation coupled with a bioheat transfer function. The thermal parameters were set as the functions of temperature using experimental data. The results revealed that, for liver tissue exposed to HIFU with a focal intensity of 3000 W/cm2 for 10 s, the predicted focal temperature rise was 23% lower and the thermal lesion area 41% smaller than those predicted without considering the temperature dependence. The prediction was validated by experimental observations on thermal lesions visualized in a tissue-mimicking phantom. The present results suggest that temperature-dependent thermal parameters should be considered in the prediction of HIFU-induced temperature rise to avoid lowering ultrasonic output settings for HIFU surgery. The aim of the present study was to investigate how significantly the temperature dependence of the thermal parameters affects the thermal dose imposed on the tissue by a typical clinical HIFU device. A numerical simulation was performed using a thermo-acoustic algorithm coupling the non-linear Khokhlov–Zabolotskaya–Kuznetsov (KZK) equation (Meaney et al. 1998; Filonenko and Khokhlova 2001) and a bio-heat transfer (BHT) equation (Pennes 1948). Thermal parameters of liver tissue were modeled in the present study as functions of temperature and were incorporated into the BHT equation to compensate for the variations in thermal parameters with temperature. Experimental validation was achieved by comparing the predictions with the thermal lesions formed in the tissue-mimicking phantoms.

A high-intensity focused ultrasound surgery theater design in a private clinic

Noninvasive high-intensity focused ultrasound (HIFU) surgery has become a popular surgical treatment for fibroids, adenomyosis, and various gynecological diseases in China and many countries. While traditional theater designs in hospitals are standardized and easily available for reference, an outpatient HIFU theater design is not yet available in the literature or is nonexistent. The authors presented the design and setup of an ultrasound-guided HIFU center in Hong Kong and listed the space and safety requirements and special features of their HIFU theater. Despite its limited space, the HIFU surgery center has made available a nursing station, a changing room, and an observation/recovery room. A room for learning HIFU treatment and viewing is also available without any intrusion of patient's privacy during treatment. The article concluded that because the space requirements for a HIFU theater were much reduced, the cost of the HIFU theater setup would be much cost-effective. Finally, its relaxing lighting environment was totally different and impossible to be installed in a traditional operating theater in a hospital.

Real-Time HIFU Treatment Monitoring Using Pulse Inversion Ultrasonic Imaging

Real-time monitoring of high-intensity focused ultrasound (HIFU) surgery is essential for safe and accurate treatment. However, ultrasound imaging is difficult to use for treatment monitoring during HIFU surgery because of the high intensity of the HIFU echoes that are received by an imaging transducer. Here, we propose a real-time HIFU treatment monitoring method based on pulse inversion of imaging ultrasound; an imaging transducer fires ultrasound twice in 0° and 180° phases for one scanline while HIFUs of the same phase are transmitted in synchronization with the ultrasound transmission for imaging. By doing so, HIFU interferences can be eliminated after subtracting the two sets of the signals received by the imaging transducer. This function was implemented in a commercial research ultrasound scanner, and its performance was evaluated using the excised bovine liver. The experimental results demonstrated that the proposed method allowed ultrasound images to clearly show the echogenicity change induced by HIFU in the excised bovine liver. Additionally, it was confirmed that the moving velocity of the organs in the abdomen due to respiration does not affect the performance of the proposed method. Based on the experimental results, we believe that the proposed method can be used for real-time HIFU surgery monitoring that is a pivotal function for maximized treatment efficacy.

Phase-Inverted Multifrequency HIFU Transducer for Lesion Expansion: A Simulation Study.

It has been well known that the treatment time of high-intensity focused ultrasound (HIFU) surgery can be reduced by expanding the focal area per sonication. Previously, a dual-concentric transducer using phase-inverted signals was proposed to axially extend the focal area, but it has suffered from the deep notch point between two focal lobes. In this paper, we propose the improved HIFU transducer with dual-concentric aperture driven by phase-inverted multifrequency signals based on an inversion layer technique. The proposed transducer can generate the expanded focal zone with a significantly reduced level of the notch point between two focal lobes in the axial direction. The performance of the proposed transducer was investigated using finite element analysis simulation. The electrical impedance, one-way impulse response, and acoustic field of the transducer were simulated. Subsequently, the lesion volume was investigated by heat transfer simulation. In the proposed method, the level of the notch point was increased above -6 dB due to various phase interactions between the fundamental and harmonic frequency combinations and the inverted and noninverted frequency combinations. The -6-dB depth of field related to the necrotic lesion size was increased by 141% compared with the conventional single element transducer. Thus, the proposed transducer can be a potential way to enlarge coagulated lesion size resulting in a reduced overall treatment time of HIFU surgery.

Motion compensation with skin contact control for high intensity focused ultrasound surgery in moving organs

High intensity focused ultrasound (HIFU) is an emerging therapeutic solution that enables non-invasive treatment of several pathologies, mainly in oncology. On the other hand, accurate targeting of moving abdominal organs (e.g. liver, kidney, pancreas) is still an open challenge. This paper proposes a novel method to compensate the physiological respiratory motion of organs during HIFU procedures, by exploiting a robotic platform for ultrasound-guided HIFU surgery provided with a therapeutic annular phased array transducer. The proposed method enables us to keep the same contact point between the transducer and the patient’s skin during the whole procedure, thus minimizing the modification of the acoustic window during the breathing phases. The motion of the target point is compensated through the rotation of the transducer around a virtual pivot point, while the focal depth is continuously adjusted thanks to the axial electronically steering capabilities of the HIFU transducer.The feasibility of the angular motion compensation strategy has been demonstrated in a simulated respiratory-induced organ motion environment. Based on the experimental results, the proposed method appears to be significantly accurate (i.e. the maximum compensation error is always under 1 mm), thus paving the way for the potential use of this technique for in vivo treatment of moving organs, and therefore enabling a wide use of HIFU in clinics.

High-Intensity Focused Ultrasound Thermal Lesion Detection Using Entropy Imaging of Ultrasound Radio Frequency Signal Time Series.

Background:During the past few decades, high-intensity focused ultrasound (HIFU) modality has been gaining surging interest in various therapeutic applications such as non- or minimally-invasive cancer treatment. Among other attributes, robust and real-time HIFU treatment monitoring and lesion detection have become essential issues for successful clinical acceptance of the modality. More recently, ultrasound radio frequency (RF) time series imaging has been studied by a number of researchers.Materials and Methods:The objective of this study is to investigate the applicability of entropy parameter of RF time series of ultrasound backscattered signals, a. k. a. Entropy imaging, toward HIFU thermal lesion detection. To this end, five fresh ex vivo porcine muscle tissue samples were exposed to HIFU exposures with total acoustic powers ranging from 30 to 110 Watts. The contrast-to-speckle ratio (CSR) values of the entropy images and their corresponding B-mode images of pre-, during- and post-HIFU exposure for each acoustic power were calculated.Results:The novelty of this study is the use of Entropy parameter on ultrasound RF time series for the first time. Statistically significant differences were obtained between the CSR values for the B mode and entropy images at various acoustic powers. In case of 110 Watt, a CSR value 3.4 times higher than B-mode images was accomplished using the proposed method. Furthermore, the proposed method is compared with the scaling parameter of Nakagami imaging and same data which are used in this study.Conclusion:Entropy has the potential for using as an imaging parameter for differentiating lesions in HIFU surgery.

Direct nanodroplet and microbubble comparison for high intensity focused ultrasound ablation enhancement and safety

High intensity focused ultrasound (HIFU) surgery often requires hours of ablation in order to treat an entire tumor. Both perfluorocarbon gaseous microbubbles and vaporized liquid droplets are known enhancers of HIFU thermal ablation. Microbubbles, however, often lead to surface or skin lesions. Furthermore, they have a relatively short half-life in vivo (minutes) rendering them insufficiently stable for an entire HIFU surgery, which can last several hours. Many droplet formulations require very high pressures to activate. Our aim was to design an agent that could shorten ablation procedures without sacrificing safety. We designed and investigated a perfluorocarbon nanodroplet composed of a 1:1 ratio of dodecafluoropentane and decafluorobutane. These are tuned to change phase and activate at only 2 MPa peak negative pressure with common HIFU pulse lengths, enabling focused and targeted activation. Additionally, they are stable at body temperature.

Influence of Temperature-Dependent Thermal Parameters on Temperature Elevation of Tissue Exposed to High-Intensity Focused Ultrasound: Numerical Simulation

High-intensity focused ultrasound (HIFU) has been used successfully as a non-invasive modality in treating solid tumors. The temperature rise HIFU irradiation causes in a tissue depends on the thermal properties of the tissue. This study was motivated by our observation that the thermal properties of a tissue vary significantly with temperature (Guntur SR, Lee KI, Paeng DG, Coleman AJ, Choi MJ. Ultrasound Med Biol 2013;39:1771–1784). This research investigated how significantly the alteration of tissue thermal parameters, in the ranges of values measured at 25°C–90°C, affects prediction of the temperature elevation of tissue under the same HIFU exposure. The numerical simulation was performed by coupling a non-linear Khokhlov–Zabolotskaya–Kuznetsov equation with a bio-heat transfer function. In the conventional method of prediction, the thermal parameters were set as constants measured at room temperature (25°C). This study compared the conventional prediction with those predicted with different thermal parameters measured at the various temperatures up to 90°C. The results indicated that the conventional method significantly overestimated the rise in focal temperature in the liver tissue exposed to a clinical HIFU field, compared with the prediction made using thermal parameters measured at temperatures that cause thermal denaturation. This finding suggests that temperature-dependent thermal parameters should be considered in predicting the temperature rise in a tissue to avoid use of an insufficient thermal dose in treatment planning for HIFU surgery.

Suppression of therapeutic interference by using Barker code and adaptive notch filtering for real‐time HIFU surgery and ultrasound imaging

Real-time ultrasound imaging during high-intensity focused ultrasound (HIFU) surgery allows for tracking tissue movement and monitoring feedback from a treated target. However, the reflected HIFU interference signals deteriorate the quality of imaging signals received by an imaging transducer during simultaneous therapy and imaging. The purpose of this Letter is to demonstrate that those HIFU interference signals can be significantly reduced in the brightness-mode image by using a coded excitation scheme with adaptive notch filtering. A prototype integrated HIFU/imaging transducer was used to experimentally demonstrate the performance of the proposed method.

Dual concentric-sectored HIFU transducer with phase-shifted ultrasound excitation for expanded necrotic region: a simulation study

In high-intensity focused ultrasound (HIFU) surgery, it is desirable to produce a large necrotic area per sonication for reduced treatment time. It has been well known that the conventional split-focus scheme capable of generating multiple foci can increase a necrotic region in the lateral or elevational direction. To treat a deep-seated target, it is necessary to generate an expanded necrotic region in the axial direction. In this paper, a novel sonication scheme capable of producing an expanded coagulated region in the both lateral and axial directions is presented. The proposed method can generate multi-focal spots in the lateral and axial directions by using a dual concentric-sectored (DCS) HIFU transducer based on phase-shifted ultrasound excitation. A sound field simulation was employed for this investigation. Four electrical signals with identical center frequencies and different phases activated the DCS transducer, composed of a disc and an annular element with a confocal point. Four 4-MHz ultrasound signals with different phases were transmitted to the target simultaneously, resulting in generation of dual-focal spots in the lateral and axial directions. The sound field simulation results showed that the 0-6-dB lateral and axial beamwidths of the DCS transducer were maximally 79% and 91% broader than the single-element transducer. Subsequently, bio-heat transfer and thermal dose simulation results were matched to the sound field simulation. Hence, the DCS HIFU transducer combined with phase-shifted excitation may be a promising approach to treat a deep-seated target and to reduce treatment time for HIFU surgery.

Experiment study of Fe3O4-loaded polymer microspheres for combining with high-intensity focused ultrasound to damage breast cancer of rabbits

Objective To prepare the Fe3O4 loaded polymer microspheres(Fe3O4/PLGA),and to investigate the influence of Fe3O4/PLGA combined with high-intensity focused ultrasound (HIFU) on rabbits bearing breast tumor.Methods Double emulsion method were utilized to prepare the Fe3O4/PLGA.14 days after implantation of VX2 tumor in breast,32 rabbits were randomly divided into four equal groups.In group Ⅱ,Ⅲ,and Ⅳ,the rabbits received a percutaneous injection of 0.5 ml saline,PLGA,and Fe3O4/PLGA microcapsules solution into breast tumor at 3,6,9,12 dots,about 3 mm around the tumor respectively,and massaged for 1 min before receiving HIFU ablation,while HIFU group received HIFU ablation only.HIFU ablation parameters were the same:ablated-dot mode,acoustic power 150 W,exposure duration 5 s.After HIFU ablation,the volume of coagulative necrosis was calculated,HE staining,TEM and immunohistochemical examination of PCNA were performed to detect the structure changes of the targeted tissue caused by HIFU ablation.Results The volume of coagulative necrosis caused by HIFU ablation was substantially larger and the positive index of PCNA was lower in the necrotic region after the injection of Fe3O4/PLGA microcapsules compared to the group without injection agents,the group of saline and the group of pure PLGA microspheres under the same irritation(P ＜0.05).Pathological examination demonstrated the targeted tissue was destroyed severely,Fe3O4 nanoparticles were seen depositing in residual tumor cells under TEM.Conclusions The self-made Fe3O4/PLGA microspheres can effectively enhanced the biomedical effect of HIFU surgery on rabbits bearing VX2 breast tumor. Key words: Ultrasound,high-intensity focused; Breast neoplasms; Synergist

Pulse compression technique for simultaneous HIFU surgery and ultrasonic imaging: A preliminary study

In an ultrasound image-guided High Intensity Focused Ultrasound (HIFU) surgery, reflected HIFU waves received by an imaging transducer should be suppressed for real-time simultaneous imaging and therapy. In this paper, we investigate the feasibility of pulse compression scheme combined with notch filtering in order to minimize these HIFU interference signals. A chirp signal modulated by the Dolph–Chebyshev window with 3–9MHz frequency sweep range is used for B-mode imaging and 4MHz continuous wave is used for HIFU. The second order infinite impulse response notch filters are employed to suppress reflected HIFU waves whose center frequencies are 4MHz and 8MHz. The prototype integrated HIFU/imaging transducer that composed of three rectangular elements with a spherically con-focused aperture was fabricated. The center element has the ability to transmit and receive 6MHz imaging signals and two outer elements are only used for transmitting 4MHz continuous HIFU wave. When the chirp signal and 4MHz HIFU wave are simultaneously transmitted to the target, the reflected chirp signals mixed with 4MHz and 8MHz HIFU waves are detected by the imaging transducer. After the application of notch filtering with pulse compression process, HIFU interference waves in this mixed signal are significantly reduced while maintaining original imaging signal. In the single scanline test using a strong reflector, the amplitude of the reflected HIFU wave is reduced to −45dB. In vitro test, with a sliced porcine muscle shows that the speckle pattern of the restored B-mode image is close to that of the original image. These preliminary results demonstrate the potential for the pulse compression scheme with notch filtering to achieve real-time ultrasound image-guided HIFU surgery.

The rise of high intensity focused ultrasound (HIFU) non-invasive therapy for solid tumors

In the 40 years of last centry American scientists put forward a concep of high intensity focused ultrasound (HIFU) therapeutic technique and had done some technical and clinical studies. Since 90 years the HIFU surgery technique treating tumors anew rised abruptly in the world. China firstly put out a comprehensive HIFU tumor treating sistem and successfully treated many solid tumors such as breast cancer, bone tumor, liver cancer etc.. Now the treating sistem has already exported to England, Italy,Spain, Japan, Colea etc. and treated tens thousands tumor patients. In the field of noninvasive ultrasound treating tumor technique China has continually kept the leading position in the world. Key words: High intensity focused ultrasound; Tumor; Treatment