One big challenge with high intensity focused ultrasound (HIFU) is the difficulty in accurate prediction of focal location due to the complex wave propagation in heterogeneous medium even with imaging guidance. This study aims to overcome this by combining therapy and imaging guidance with one single HIFU transducer using the vibro-acoustography (VA) strategy.Based on the VA imaging method, a HIFU transducer consisting of 8 transmitting elements was proposed for therapy planning, treatment and evaluation. Inherent registration between the therapy and imaging created unique spatial consistence in HIFU transducer's focal region in the above three procedures. Performance of this imaging modality was first evaluated through in-vitro phantoms. In-vitro and ex-vivo experiments were then designed to demonstrate the proposed dual-mode system's ability in conducting accurate thermal ablation.Point spread function of the HIFU-converted imaging system had a full wave half maximum of about 1.2 mm in both directions at a transmitting frequency of 1.2 MHz, which outperformed the conventional ultrasound imaging (3.15 MHz) in in-vitro situation. Image contrast was also tested on the in-vitro phantom. Various geometric patterns could be accurately 'burned out' on the testing objects by the proposed system both in vitro and ex vivo.Implementation of imaging and therapy with one HIFU transducer in this manner is feasible and it has potential as a novel strategy for addressing the long-standing problem in the HIFU therapy, possibly pushing this non-invasive technique forward towards wider clinical applications.
// Xiang Zhang 1, 2 , Jiangang Hu 1, 2 , Guanjian Zhao 1, 2 , Ning Huang 1 , Ying Tan 1 , Li Pi 1 , Qing Huang 1 , Feng Wang 1 , Zhigang Wang 2 , Zhibiao Wang 3 , Yuan Cheng 1 1 Department of Neurosurgery, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, 400010, China 2 Chongqing Key Laboratory of Ultrasound Molecular Imaging, Institute of Ultrasound Imaging of Chongqing Medical University, Chongqing, 400016, China 3 Chongqing Key Laboratory of Biomedical Engineering, College of Biomedical Engineering of Chongqing Medical University, Chongqing, 400016, China Correspondence to: Yuan Cheng, email: chengyuan023@aliyun.com Keywords: blood brain barrier, focused ultrasound, acoustic droplet vaporization, perfluoropentane, PLGA Received: January 17, 2017 Accepted: April 05, 2017 Published: April 17, 2017 ABSTRACT Previous studies have shown that focused ultrasound (FUS) combined with systematic administration of microbubbles (MBs) can open the blood brain barrier (BBB) locally, transiently and reversibly. However, because of the micro size diameters, MBs are restricted in the intravascular space and cannot extravasate into diseased sites through the opened BBB. In this study, we fabricated one kind of nanoscale droplets which consisted of encapsulated liquid perfluoropentane cores and poly (ethyleneglycol) - poly (lactide-co-glycolic acid) shells. The nanodroplets had the capacity to realize liquid to gas phase shift under FUS. Significant extravasation of Evan's blue appeared when acoustic pressure reached 1.0 MPa. Intracerebral hemorrhages and erythrocyte extravasations were observed when the pressure was increased to 1.5 MPa. Prolonged sonication duration could enhance the level of BBB opening and broaden the time window simultaneously. Furthermore, compared with MBs, the distribution of EB extravasation was firmly confined within narrow region in the center of focal zone, suggesting the site of FUS induced BBB opening could be controlled with high precision by this procedure. Our results show the feasibility of serving PEGylated PLGA-based phase shift nanodroplet as an effective alternative mediating agent for FUS induced BBB opening.
High-intensity focused ultrasound (HIFU) has become an attractive therapeutic tool for noninvasive tumor treatment. The key component of HIFU systems is the acoustic transducer, which generates a focal region of high-intensity focused ultrasonic energy. A key determinant of safety in HIFU treatment is the size of the focal region. To achieve subwavelength focusing, we previously investigated the feasibility of an ultrasonic spherical cavity resonator (USCR) with two open ends. To further investigate the properties of the USCR, experiments and simulations were performed to comprehensively characterize the acoustic field generated. The emphasis was on the field formation process, the pressure distribution, the frequency dependence, and the acoustic nonlinearity. As a novel simulation approach, an axisymmetric isothermal multi-relaxation-time lattice Boltzmann method (MRT-LBM) model was used to numerically analyze the acoustic field. The reliability of this model was verified by comparing the results generated with those from experiments. The MRT-LBM model gave new insight into conventional acoustic numerical simulations and provided significant indications for USCR parameter optimization. The USCR demonstrated its feasibility for application in HIFU treatment or in other fields that demand high-precision focusing.
Objectives To compare pregnancy outcomes after high-intensity focused ultrasound ablation (HIFU), myomectomy and uterine artery embolization (UAE) for fertility-sparing patients with uterine fibroids and to investigate the possible mechanism of improving pregnancy by HIFU.Materials and methods A meta-analysis of 54 studies containing 12,367 patients was conducted to compare the pregnancy outcomes of three fertility-sparing therapies. And a retrospective self-control study of 26 patients with uterine fibroids from May 2019 to December 2020 was performed to assess the blood flow impedance of bilateral uterine arteries before and after HIFU.Results In the analysis by treatment option, the pregnancy rate after myomectomy was 0.43 (95% CI 0.36–0.49), which was higher than 0.18 (95% CI 0.10–0.26) after HIFU, the latter was significantly higher than that after UAE (ratio 0.08, 95% CI 0.06–0.10). The miscarriage rate after HIFU was 0.08 (95% CI 0.04–0.12), which was similar to 0.15 (95% CI 0.09–0.21) after myomectomy and also similar to 0.16 after UAE (95% CI 0.01–0.30). In the subgroup analysis, women who received ultrasound guided HIFU (USgHIFU) were more likely to have ideal pregnancy outcomes than that after magnetic resonance imaging-guided HIFU. The pulsatility index and resistance index on the right side were significantly higher 3 months after HIFU than before (1.637 ± 0.435 vs. 1.845 ± 0.469; p = 0.033; 0.729 ± 0.141 vs. 0.784 ± 0.081, p = 0.039).Conclusions HIFU, especially USgHIFU, may be an alternative fertility-sparing modality for patients with uterine fibroids over 40 years old. HIFU may contribute to improving pregnancy rates by elevating uterine blood flow impedance.
To investigate the impacts of mouse embryonic stem cells on mouse melanoma B16 cells in vitro co-cultured environment.C57BL / 6 mouse embryonic stem cell lines were established.The effects of mouse embryonic stem cells on tumor cell morphology and growth behavior were observed with establishing a co-culture system in vitro.MTT assay and transwell chamber assay were used to detect change of the co-cultured tumor cell adhesion,migration and invasiveness.Mouse embryonic stem cells could invade and push the mouse melanoma cells to form their own room for growth in co-culturing.The adhesion,migration and invasion ability of the tumor cells after co-cultured with mouse embryonic stem cells significantly declined(P0.05,P0.01).The results implied that the co-culture mouse embryonic stem cells could invade tumor cells and inhibit their related malignant behaviors like adhesion,migration and invasion ability.
This article presents a study on the transient dynamic responses of engagement process of one-way clutch using variable rectangular cross-section torsional spring, which is usually installed on the end of engine for preventing torque being transmitted back. A 2-degree-of-freedom torsional dynamic model is proposed in this article to study the engagement process of clutch under two conditions. Due to the variation of parameters, the torque transfer of the wrap–spring clutch during engagement is described by a multi-parameter equation. The torque transmitted by clutch during engagement process has been described by two phases, spring expanding and spring locking. Physical parameters of spring determining the torque during expanding are discussed. To verify the model, a dynamic experiment on clutch engagement is conducted.
The impacts of the mouse embryo on human ovarian cancer cell HO8910PM were investigated when they were co-cultured together in vitro.The effects of mouse embryos on tumor cell morphology and growth behavior were observed with establishing a co-culture system in vitro.Apoptosis of tumor cells was detected with Annexin V-EGFP/PI in situ apoptosis detection under laser scanning confocal microscope.Adhesion ability of tumor cells was analyzed with MTT assay and migration and invasion ability of tumor cells was studied by transwell experiments.Mouse embryos invaded and pushed away human ovarian cancer cells to form their own growth space.Increased tumor cell apoptosis was observed around the embryo.The migration and invasion ability of the tumor cells after co-cultured with mouse embryos significantly declined(P0.05,P0.01).The results implied that the co-culture mouse embryos could promote apoptosis of human ovarian cancer cells and inhibit their related malignant behaviors like adhesion,migration and invasion ability.
A kind of ultrasound power meter to measure high ultrasound power is developed. It is based on the radiation pressure method, mechanical balance and intelligent controlling techniques in the design. With different kinds of targets, include reflector or absorbing target, the output power of many kinds of ultrasound transducer can be measured by it. It is calibrated by weights and the error analysis shows that it has high resolution and high stability. With cone reflector and absorbing target, the power of a high intensity focused ultrasound treatment transducer driven at voltage in clinical application is measured by it. The results show that the ultrasound power meter can be used to measure high ultrasound power and it has high precision. Also the results show that the power output of high intensity focused ultrasound transducer has high stability when the driven voltage is from 600 V to 2200 V, which is usually applied by doctor. When the driven voltage is less than 600 V or higher than 2200 V, the output of the transducer will has error more than 5% .
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