Overview of therapeutic ultrasound applications and safety considerations

An Analytical Equivalent Circuit Model for Optimization Design of a Broadband Piezoelectric Micromachined Ultrasonic Transducer With an Annular Diaphragm

This paper presents an equivalent circuit model, a systematic design, and optimization method for developing a broadband annular diaphragm piezoelectric micromachined ultrasonic transducer (A-PMUT). By utilizing array analysis methods, an annular diaphragm is regarded as an array consisting of equally spaced sector diaphragms influencing each other by crosstalk effect. The model successfully explains the phenomenon of multi-resonance peaks in the frequency response curve, sharing the same vibration mode. The study finds that the analytical predictions of the model are in good agreement with the simulation and experimental results. Meanwhile, based on the phenomenon of multi-resonance peaks, a systematic design method is proposed to extend the bandwidth of the A-PMUT. In this method, the radiation impedance of the A-PMUT is separated into crosstalk-free and crosstalk contributed parts. This method enables the determination of the optimal structure counting for the influences on the frequency response of A-PMUTs for broadband applications. The model here can also be further generalized to be a guideline for the design and optimization of broadband PMUTs.

Recent developments on foaming mechanical and electronic techniques for the management of varicose veins

Introduction: Varicose veins are a common disease, causing significant impairment of quality of life to afflicted individuals. Conventional surgery has represented the traditional treatment for years, with significant post-operative complications. By the end of the 20^th century, novel approaches had been developed to induce biochemical sclerosis into the treated vein in order to exclude it from blood circulation.Areas covered: Foaming techniques for treatment of varicose veins, both clinically-approved methods and those under experimental studies. A brief description of cavitation, which is the basis of microbubbles formation, and an overview of foam properties have been also provided, including a discussion on clinical efficacy and safety profile.Expert commentary: Foam sclerotherapy has rapidly gained popularity since it represents the most minimally invasive and cost-effective procedure in the short term. Several different methods of foam preparation have been described in literature. In general, the foam generation method may affect characteristics such as stability and bubble size distribution, which in turn affect the therapeutic action of foam itself. Therefore, the selection of a suitable foaming technique is of importance for treatment success. Future developments on foaming techniques are expected to make sclerotherapy, already an effective treatment, even safer and more versatile therapeutic procedure.

Low Intensity Pulsed Ultrasound Prevents Recurrent Ischemic Stroke in a Cerebral Ischemia/Reperfusion Injury Mouse Model via Brain-derived Neurotrophic Factor Induction

The incidence of stroke recurrence is still higher despite the advanced progression of therapeutic treatment and medical technology. Low intensity pulsed ultrasound (LIPUS) has been demonstrated to possess therapeutic effects on neuronal diseases and stroke via brain-derived neurotrophic factor (BDNF) induction. In this study, we hypothesized that LIPUS treatment possessed therapeutic benefits for the improvement of stroke recurrence. Adult male C57BL/6J mice were subjected to a middle cerebral artery occlusion (MCAO) surgery and then followed to secondary MCAO surgery as a stroke recurrence occurred after nine days from the first MCAO. LIPUS was administered continuously for nine days before secondary MCAO. LIPUS treatment not only decreased the mortality but also significantly moderated neuronal function injury including neurological score, motor activity, and brain pathological score in the recurrent stroke mice. Furthermore, the administration of LIPUS attenuated the apoptotic neuronal cells and increased Bax/Bcl-2 protein expression ratio and accelerated the expression of BDNF in the brain of the recurrent stroke mice. Taken together, these results demonstrate for the first time that LIPUS treatment arouses the expression of BDNF and possesses a therapeutic benefit for the improvement of stroke recurrence in a mouse model. The neuroprotective potential of LIPUS may provide a useful strategy for the prevention of a recurrent stroke.

Intense Therapeutic Ultrasound for Pain Relief in the Treatment for Chronic Plantar Fasciopathy

Background:

Intense therapeutic ultrasound (ITU) is an innovative ultrasound-based therapy where sound waves are concentrated into select musculoskeletal tissue. These focused waves generate thermal coagula at a controlled depth and space while preserving surrounding tissues. A multicenter study was conducted evaluating the efficiency, safety, and patient tolerance of ITU for the treatment of chronic plantar fasciitis (CPF) pain.

Methods:

Seventy-four CPF patients, having failed conservative and/or minimally invasive treatment, participated in the study. Randomized participants either received 2 ITU treatments or 2 sham ITU treatments in addition to standard-of-care therapy. Plantar fascia pain was assessed pretreatment and at 4, 8, 12, and 26 weeks after treatment. Diagnostic ultrasonographic images were analyzed to examine hypoechoic, perifascial lesions whose volumes were calculated until week 12. Function and patient satisfaction were measured using self-reported outcome measures.

Results:

The treated group reported significant average pain reduction (–26%, –33%, –43%) and hypoechoic lesion volume (–33%, –53%, –68%) at weeks 4, 8, and 12 compared to baseline. Although the control/sham group reported insignificant pain changes at the same time points (–5%, +8%, and +2%) and increased hypoechoic lesion volume (+15%, +28%, +58%). Treated patients reported a significant increase in daily living activities (+28%, +42%, +47%, +40%) compared to the sham/control group (+0.12%, +12%, +3%, +21%). Patient satisfaction remained more than 80% at weeks 8, 12, and 26 for all treatment groups.

Conclusion:

ITU is an effective pain relief treatment for CPF, which is refractory to either conservative measures or minimally invasive treatments.

Level of Evidence:

Level II.

Adsorption and Desorption of a Phospholipid from Single Microbubbles under Pulsed Ultrasound Irradiation for Ultrasound-Triggered Drug Delivery

Microbubbles have potential for applications as drug and gene delivery systems, in which the release of a substance is triggered by an ultrasonic pulse. In this paper, we discuss the adsorption and desorption of a film of phospholipid on the surface of a single microbubble under ultrasound irradiation. Our optical observation system consisted of a high-speed camera, a laser Doppler vibrometer, and an ultrasound cell; 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) was used as the surfactant. The adsorption of the DMPC molecules onto the surface of the bubble was evaluated by measuring the contact angle between the bubble and a glass plate. A decrease of the contact angle of the bubble indicates desorption of the DMPC molecules from the bubble surface into the surrounding aqueous solution. The amount of DMPC molecules adsorbed on the bubble's surface is shown to decrease over time after bubble generation. The type and intensity of the pulsed ultrasound waves were varied so as to mimic ultrasound-triggered drug release. Increasing the number of cycles and the amplitude of the sound pressure of the pulsed ultrasound yielded a greater increase of the contact angle. We also measured the radial vibrations of the microbubbles in the ultrasound field. The vibrational characteristics of the microbubbles and the desorption characteristics of the DMPC molecules showed the same variation; namely, a greater sound pressure amplitude induced greater vibrational displacement and a larger amount of molecular desorption under resonance conditions. These results support the possibility of controlling drug release with pulsed ultrasound in a microbubble-based drug delivery system.

Transcutaneous ultrasound energy harvesting using capacitive triboelectric technology

A major challenge for implantable medical systems is the inclusion or reliable delivery of electrical power. We use ultrasound to deliver mechanical energy through skin and liquids and demonstrate a thin implantable vibrating triboelectric generator able to effectively harvest it. The ultrasound can induce micrometer-scale displacement of a polymer thin membrane to generate electrical energy through contact electrification. We recharge a lithium-ion battery at a rate of 166 microcoulombs per second in water. The voltage and current generated ex vivo by ultrasound energy transfer reached 2.4 volts and 156 microamps under porcine tissue. These findings show that a capacitive triboelectric electret is the first technology able to compete with piezoelectricity to harvest ultrasound in vivo and to power medical implants.

Safety of transcranial focused ultrasound stimulation: A systematic review of the state of knowledge from both human and animal studies

BACKGROUND

Low-intensity transcranial focused ultrasound stimulation (TFUS) holds great promise as a highly focal technique for transcranial stimulation even for deep brain areas. Yet, knowledge about the safety of this novel technique is still limited.

OBJECTIVE

To systematically review safety related aspects of TFUS. The review covers the mechanisms-of-action by which TFUS may cause adverse effects and the available data on the possible occurrence of such effects in animal and human studies.

METHODS

Initial screening used key term searches in PubMed and bioRxiv, and a review of the literature lists of relevant papers. We included only studies where safety assessment was performed, and this results in 33 studies, both in humans and animals.

RESULTS

Adverse effects of TFUS were very rare. At high stimulation intensity and/or rate, TFUS may cause haemorrhage, cell death or damage, and unintentional blood-brain barrier (BBB) opening. TFUS may also unintentionally affect long-term neural activity and behaviour. A variety of methods was used mainly in rodents to evaluate these adverse effects, including tissue staining, magnetic resonance imaging, temperature measurements and monitoring of neural activity and behaviour. In 30 studies, adverse effects were absent, even though at least one Food and Drug Administration (FDA) safety index was frequently exceeded. Two studies reported microhaemorrhages after long or relatively intense stimulation above safety limits. Another study reported BBB opening and neuronal damage in a control condition, which intentionally and substantially exceeded the safety limits.

CONCLUSION

Most studies point towards a favourable safety profile of TFUS. Further investigations are warranted to establish a solid safety framework for the therapeutic window of TFUS to reliably avoid adverse effects while ensuring neural effectiveness. The comparability across studies should be improved by a more standardized reporting of TFUS parameters.

Ultrasound improves the outcomes of cardiopulmonary resuscitation in rats by stimulating the cholinergic anti‑inflammatory pathway

The present study investigated the effects of the ultrasound (US), a noninvasive technique, on ischemia-reperfusion injury (IRI) following cardiopulmonary resuscitation (CPR). The animals used in the present study were randomized into five groups (n=8 per group) as follows: i) The CPR group, where the rats underwent 6 min of untreated ventricular fibrillation (VF) followed by CPR and defibrillation; ii) the US group, in which the treatment was identical to the CPR group with the exception that rats were exposed to US treatment 24 h prior to CPR; iii) the MLA group, in which the treatment was identical to the US group with the exception that the α7 nicotinic acetylcholine receptor (α7nAChR) antagonist MLA (4 mg/kg) was administered 30 min prior to US and VF respectively; iv) the GTS group, in which the treatment was identical to the CPR group with the exception that the α7nAChR agonist GTS-21 (4 mg/kg) was injected 30 min prior to VF; and v) the SHAM group, in which the rats were exposed to surgical preparation without CPR and US application. At 1 day prior to CPR, the US treatment was administered to the left kidney by US pulses (contrast general mode with 9 MHz) with a bursting mechanical index of 0.72 for 2 min. Following treatment of the left kidney, the right kidney was exposed to identical US treatment for an additional 2 min. The results demonstrated that US preconditioning decreased the number of defibrillations required and shortened the duration of CPR. US also suppressed tumor necrosis factor-α and interleukin-6 levels following resuscitation (P<0.05), and a significantly longer overall survival time was observed in the US-treated animals (P<0.01). In addition, US attenuated neuronal injury and promoted the expression of α7nAChR in hippocampal neurons (P<0.05). However, the protective effects of US were abolished by MLA and imitated by GTS-21. The results of the present study demonstrated that prior exposure to US may improve animal outcomes following CPR, and the protective effects of US may be dependent on the cholinergic anti-inflammatory pathway (CAP) via α7nAChR.

Therapeutic ultrasound attenuates DSS-induced colitis through the cholinergic anti-inflammatory pathway

BACKGROUND

Ulcerative Colitis (UC) is an Inflammatory Bowel Disease (IBD) characterized by uncontrolled immune response, diarrhoea, weight loss and bloody stools, where sustained remission is not currently achievable. Dextran Sulphate Sodium (DSS)-induced colitis is an animal model that closely mimics human UC. Ultrasound (US) has been shown to prevent experimental acute kidney injury through vagus nerve (VN) stimulation and activation of the cholinergic anti-inflammatory pathway (CAIP). Since IBD patients may present dysfunctional VN activity, our aim was to determine the effects of therapeutic ultrasound (TUS) in DSS-induced colitis.

METHODS

Acute colitis was induced by 2% DSS in drinking water for 7 days and TUS was administered to the abdominal area for 7 min/day from days 4-10. Clinical symptoms were analysed, and biological samples were collected for proteomics, macroscopic and microscopic analysis, flow cytometry and immunohistochemistry.

FINDINGS

TUS attenuated colitis by reducing clinical scores, colon shortening and histological damage, inducing proteomic tolerogenic response in the gut during the injury phase and early recovery of experimental colitis. TUS did not improve clinical and pathological outcomes in splenectomised mice, while α7nAChR (α7 nicotinic acetylcholine receptor - indicator of CAIP involvement) knockout animals presented with disease worsening. Increased levels of colonic F4/80+α7nAChR+ macrophages in wild type mice suggest CAIP activation.

INTERPRETATION

These results indicate TUS improved DSS-induced colitis through stimulation of the splenic nerve along with possible contribution by VN with CAIP activation. FUND: Intramural Research Programs of the Clinical Centre, the National Institute of Biomedical Imaging and Bioengineering at the NIH and CAPES/Brazil.

The effects of ultrasound pressure and temperature fields in millisecond bubble nucleation

A phenomenological implementation of Classical Nucleation Theory (CNT) is employed to investigate the connection between high intensity focused ultrasound (HIFU) pressure and temperature fields with the energetic requirements of bubble nucleation. As a case study, boiling histotripsy in tissue-mimicking phantoms is modelled. The physics of key components in the implementation of CNT in HIFU conditions such as the derivation of nucleation pressure thresholds and approximations regarding the surface tension of the liquid are reviewed and discussed. Simulations show that the acoustic pressure is the ultimate trigger for millisecond bubble nucleation in boiling histotripsy, however, HIFU heat deposition facilitates nucleation by lowering nucleation pressure thresholds. Nucleation thus occurs preferentially at the regions of highest heat deposition within the HIFU field. This implies that bubble nucleation subsequent to millisecond HIFU heat deposition can take place at temperatures below 100 °C as long as the focal HIFU peak negative pressure exceeds the temperature-dependent nucleation threshold. It is also found that the magnitude of nucleation pressure thresholds decreases with decreasing frequencies. Overall, results indicate that it is not possible to separate thermal and mechanical effects of HIFU in the nucleation of bubbles for timescales of a few milliseconds. This methodology provides a promising framework for studying time and space dependencies of the energetics of bubble nucleation within a HIFU field.

Cavitation Induced by Janus-Like Mesoporous Silicon Nanoparticles Enhances Ultrasound Hyperthermia

The presence of nanoparticles lowers the levels of ultrasound (US) intensity needed to achieve the therapeutic effect and improves the contrast between healthy and pathological tissues. Here, we evaluate the role of two main mechanisms that contribute to the US-induced heating of aqueous suspensions of biodegradable nanoparticles (NPs) of mesoporous silicon prepared by electrochemical etching of heavily boron-doped crystalline silicon wafers in a hydrofluoric acid solution. The first mechanism is associated with an increase of the attenuation of US in the presence of NPs due to additional scattering and viscous dissipation, which was numerically simulated and compared to the experimental data. The second mechanism is caused by acoustic cavitation leading to intense bubble collapse and energy release in the vicinity of NPs. This effect is found to be pronounced for as-called Janus NPs produced via a nano-stopper technique, which allow us to prepare mesoporous NPs with hydrophobic inner pore walls and hydrophilic external surface. Such Janus-like NPs trap air inside the pores when dispersed in water. The precise measurement of the heating dynamics in situ enabled us to detect the excessive heat production by Janus-like NPs over their completely hydrophilic counterparts. The excessive heat is attributed to the high intensity cavitation in the suspension of Janus-like NPs. The present work elicits the potential of specifically designed Janus-like mesoporous silicon NPs in the field of nanotheranostics based on ultrasound radiation.

Direct Evidence of Multibubble Sonoluminescence Using Therapeutic Ultrasound and Microbubbles

The intense conditions generated in the core of a collapsing bubble have been the subject of intense scrutiny from fields as diverse as marine biology and nuclear fusion. In particular, the phenomenon of sonoluminescence, whereby a collapsing bubble emits light, has received significant attention. Sonoluminescence has been associated predominantly with millimeter-sized bubbles excited at low frequencies and under conditions far removed from those associated with the use of ultrasound in medicine. In this study, however, we demonstrate that sonoluminescence is produced under medically relevant exposure conditions by microbubbles commonly used as contrast agents for ultrasound imaging. This provides a mechanistic explanation for the somewhat controversial reports of "sonodynamic" therapy, in which light-sensitive drugs have been shown to be activated by ultrasound-induced cavitation. To illustrate this, we demonstrate the activation of a photodynamic therapy agent using microbubbles and ultrasound. Since ultrasound can be accurately focused at large tissue depths, this opens up the potential for generating light at locations that cannot be reached by external sources. This could be exploited both for diagnostic and therapeutic applications, significantly increasing the range of applications that are currently restricted by the limited penetration of light in the tissue.

Acoustic modification of collagen hydrogels facilitates cellular remodeling

Developing tunable biomaterials that have the capacity to recreate the physical and biochemical characteristics of native extracellular matrices (ECMs) with spatial fidelity is important for a variety of biomedical, biological, and clinical applications. Several factors have made the ECM protein, collagen I, an attractive biomaterial, including its ease of isolation, low antigenicity and toxicity, and biodegradability. However, current collagen gel formulations fail to recapitulate the range of collagen structures observed in native tissues, presenting a significant challenge in achieving the full potential of collagen-based biomaterials. Collagen fiber structure can be manipulated in vitro through mechanical forces, environmental factors, or thermal mechanisms. Here, we describe a new ultrasound-based fabrication technology that exploits the ability of ultrasound to generate localized mechanical forces to control the collagen fiber microstructure non-invasively. The results indicate that exposing soluble collagen to ultrasound (7.8 or 8.8 MHz; 3.2-10 W/cm2) during hydrogel formation leads to local variations in collagen fiber structure and organization that support increased levels of cell migration. Furthermore, multiphoton imaging revealed increased cell-mediated collagen remodeling of ultrasound-exposed but not sham-exposed hydrogels, including formation of multicellular aggregates, collagen fiber bundle contraction, and increased binding of collagen hybridizing peptides. Skin explant cultures obtained from diabetic mice showed similar enhancement of cell-mediated remodeling of ultrasound-exposed but not sham-exposed collagen hydrogels. Using the mechanical forces associated with ultrasound to induce local changes in collagen fibril structure and organization to functionalize native biomaterials is a promising non-invasive and non-toxic technology for tissue engineering and regenerative medicine.

Application of Direct Sonoporation from a Defined Surface Area of the Peritoneum: Evaluation of Transfection Characteristics in Mice

In the present study, we developed a sonoporation system, namely “direct sonoporation”, for transfecting the peritoneum from a defined surface area to avoid systematic side effects. Here, the transfection characteristics are explained because there is less information about direct sonoporation. Naked pDNA and nanobubbles were administered to diffusion cell attached to the visceral and parietal peritoneum from the liver and peritoneal wall surface, respectively. Then, ultrasound was irradiated. Direct sonoporation showed a higher transfection efficacy at the applied peritoneum site from the liver surface while other sites were not detected. Moreover, transgene expression was observed in the peritoneal mesothelial cells (PMCs) at the applied peritoneum site. No abnormality was observed in the inner part of the liver. Although transgene expression of the visceral peritoneum was tenfold higher than that of the parietal peritoneum, transgene expression was observed in the PMCs on both the applied peritoneum sites. These results suggest that direct sonoporation is a site-specific transfection method of the PMCs on the applied peritoneum site without transgene expression at other sites and show little toxicity in the inner tissues at the applied site via cavitation energy. This information is valuable for the development of an intraperitoneal sonoporation device for treatment of peritoneal diseases such as peritoneal fibrosis.

High-intensity focused ultrasound-induced mechanochemical transduction in synthetic elastomers

While study in the field of polymer mechanochemistry has yielded mechanophores that perform various chemical reactions in response to mechanical stimuli, there is not yet a triggering method compatible with biological systems. Applications such as using mechanoluminescence to generate localized photon flux in vivo for optogenetics would greatly benefit from such an approach. Here we introduce a method of triggering mechanophores by using high-intensity focused ultrasound (HIFU) as a remote energy source to drive the spatially and temporally resolved mechanical-to-chemical transduction of mechanoresponsive polymers. A HIFU setup capable of controlling the excitation pressure, spatial location, and duration of exposure is employed to activate mechanochemical reactions in a cross-linked elastomeric polymer in a noninvasive fashion. One reaction is the chromogenic isomerization of a naphthopyran mechanophore embedded in a polydimethylsiloxane (PDMS) network. Under HIFU irradiation evidence of the mechanochemical transduction is the observation of a reversible color change as expected for the isomerization. The elastomer exhibits this distinguishable color change at the focal spot, depending on ultrasonic exposure conditions. A second reaction is the demonstration that HIFU irradiation successfully triggers a luminescent dioxetane, resulting in localized generation of visible blue light at the focal spot. In contrast to conventional stimuli such as UV light, heat, and uniaxial compression/tension testing, HIFU irradiation provides spatiotemporal control of the mechanochemical activation through targeted but noninvasive ultrasonic energy deposition. Targeted, remote light generation is potentially useful in biomedical applications such as optogenetics where a light source is used to trigger a cellular response.

Ultrasound-mediated delivery of siESE complexed with microbubbles attenuates HER2+/- cell line proliferation and tumor growth in rodent models of breast cancer

The highly tunable, noninvasive and spatially targeted nature of microbubble-enhanced, ultrasound-guided (MB+US) drug delivery makes it desirable for a wide variety of therapies. In breast cancer, both HER2+ and HER2- type neoplasms pose significant challenges to conventional therapeutics in greater than 40% of breast cancer patients, even with the widespread application of biologics such as trastuzumab. To address this therapeutic challenge, we examined the novel combination of tumor-injected microbubble-bound siRNA complexes and monodisperse size-isolated microbubbles (4-µm diameter) to attenuate tumor growth in vivo, as well as MB+US-facilitated shRNA and siRNA knockdown of ESE-1, an effector linked to dysregulated HER2 expression in HER2+/- cell line propagation. We first screened six variants of siESE and shESE for efficient knockdown of ESE in breast cancer cell lines. We demonstrated efficient reduction of BT-474 (PR+, ER+, HER2+; luminal B) and MDA-MB-468 (PR-, ER-, HER2-; triple-negative) clonogenicity and non-adherent growth after knockdown of ESE-1. A significant reduction in proliferative potential was seen for both cell lines using MB+US to deliver shESE and siESE. We then demonstrated significant attenuation of BT-474 xenograft tumor growth in Nod/SCID female mice using direct injection of microbubble-adsorbed siESE to the tumor and subsequent sonication. Our results suggest a positive effect on drug delivery from MB+US, and highlights the feasibility of using RNAi and MB+US for breast cancer pathologies. RNAi coupled with MB+US may also be an effective theranostic approach to treat other acoustically accessible tumors, such as melanoma, thyroid, parotid and skin cancer.

Mesenchymal Stromal Cell Homing: Mechanisms and Strategies for Improvement

Mesenchymal stromal cells (MSCs) have been widely investigated for their therapeutic potential in regenerative medicine, owing to their ability to home damaged tissue and serve as a reservoir of growth factors and regenerative molecules. As such, clinical applications of MSCs are reliant on these cells successfully migrating to the desired tissue following their administration. Unfortunately, MSC homing is inefficient, with only a small percentage of cells reaching the target tissue following systemic administration. This attrition represents a major bottleneck in realizing the full therapeutic potential of MSC-based therapies. Accordingly, a variety of strategies have been employed in the hope of improving this process. Here, we review the molecular mechanisms underlying MSC homing, based on a multistep model involving (1) initial tethering by selectins, (2) activation by cytokines, (3) arrest by integrins, (4) diapedesis or transmigration using matrix remodelers, and (5) extravascular migration toward chemokine gradients. We then review the various strategies that have been investigated for improving MSC homing, including genetic modification, cell surface engineering, in vitro priming of MSCs, and in particular, ultrasound techniques, which have recently gained significant interest. Contextualizing these strategies within the multistep homing model emphasizes that our ability to optimize this process hinges on our understanding of its molecular mechanisms. Moving forward, it is only with a combined effort of basic biology and translational work that the potential of MSC-based therapies can be realized.

Intense Therapeutic Ultrasound for Treatment of Chronic Plantar Fasciitis: A Pivotal Study Exploring Efficacy, Safety, and Patient Tolerance

Intense therapeutic ultrasound for chronic plantar fasciitis musculoskeletal tissue pain reduction was evaluated in a pivotal clinical trial examining effectiveness, safety, and patient tolerance. In this single-blinded study, 33 patients received 2 treatments that were 4 weeks apart on plantar fascia tissue along with conservative standard of care. Patients were followed for up to 6 months after the first treatment, receiving a physical examination and diagnostic ultrasound at each follow-up visit and completing patient-/subject-reported outcome measure and Foot Function Index surveys. The goal was to reduce overall pain by ≥25% on average and >25% individually. Hypoechoic area changes on diagnostic ultrasound and adverse events were measured. The percentage meeting pain reduction criteria at weeks 4, 8, 12, and 26 were 72%, 81%, 86%, and 79%, respectively. Mean pain scores at each visit were significantly different from baseline (p < .001) at -39%, -49%, -51%, and -44%. Hypoechoic lesions were found in all patients and decreased in size significantly (p < .05) at weeks 8 and 12 (-56% and -67%). Foot Function Index scores declined favorably from baseline (p < .001) at all time points (-32%, -46%, -49%, and -32%). The percentages of patients meeting satisfaction criteria were 72%, 85%, 90%, and 83%. The mean pain score during treatment 1 was 3.4, and during treatment 2, 2.9. Attrition of only 1 patient owing to pain occurred, after treatment 1. No adverse events occurred. Intense therapeutic ultrasound for chronic plantar fasciitis is shown to be effective, safe, and well tolerated in this pivotal clinical trial.

COMPUTATIONAL ALGORITHM OF TWO PARALLEL ULTRASOUND BEAMS OF 1D CANCER TISSUE MODEL FOR SAFE AND EFFECTIVE HYPERTHERMIA TREATMENT

The mathematical algorithm of two parallel ultrasound beams on a one-dimensional (1D) cancer tissue model for hyperthermia treatment was created using Matlab software. Physically, the model incorporated two beams; the first beam was permanently placed at the center of the tumor, whereas the other was set between the first beam and the tumor. The computational implementation of this technique relies on the Crank–Nicolson method. This technique is a finite different method that offers an exact heat transfer calculation based on the heat analysis of the heat node structure from a 1D biological tissue model. The Matlab software implementation was composed of two stages: tissue temperature profile calculation and optimization computation. To obtain the tissue temperature profile, the beam heat was varied from 45∘C to 75∘C (seven different levels of heat from the same source), while the second beam was allowed to move between the first beam and the tumor to locations at distances of 1 to 9[Formula: see text]mm (nine positions). The obtained tissue temperature profiles were subsequently analyzed to achieve the optimal time, beam position, and beam heat of the treatment. As a result of the optimization, the best position for the second beam was determined to be 5[Formula: see text]mm from the center of the tumor. Further, all tumor cells were observed to have died, whereas all normal tissues were safe. The optimal time, beam position, and beam heat of the treatment were finally collected to create and fit a mathematical function for further hyperthermia treatment.

Four-dimensional optoacoustic monitoring of tissue heating with medium intensity focused ultrasound

Medium-intensity focused ultrasound (MIFU) concerns therapeutic ultrasound interventions aimed at stimulating physiological mechanisms to reinforce healing responses without reaching temperatures that can cause permanent tissue damage. The therapeutic outcome is strongly affected by the temperature distribution in the treated region and its accurate monitoring represents an unmet clinical need. In this work, we investigate on the capacities of four-dimensional optoacoustic tomography to monitor tissue heating with MIFU. Calibration experiments in a tissue-mimicking phantom have confirmed that the optoacoustically-estimated temperature variations accurately match the simultaneously acquired thermocouple readings. The performance of the suggested approach in real tissues was further shown with bovine muscle samples. Volumetric temperature maps were rendered in real time, allowing for dynamic monitoring of the ultrasound focal region, estimation of the peak temperature and the size of the heat-affected volume.

The secondary Bjerknes force between two oscillating bubbles in Kelvin-Voigt-type viscoelastic fluids driven by harmonic ultrasonic pressure

The interaction between two small bubbles experiencing transient cavitation in a nonlinear Kelvin-Voigt fluid is investigated. The time-delay effect in the interaction is incorporated in the coupled Keller-Miksis model. The refined model predicts that bubbles with radii smaller than 2μm will be repelled by large bubbles, in contrast to predictions from previous models. The matching pressure needed to obtain same level of transient cavitation in different Kelvin-Voigt fluids is shown to depend mainly on the shear modulus and is insensitive to other parameters, which makes it a useful parameter to correlate the results. When the radii of the bubbles fall between 4μm and 6μm, the secondary Bjerknes force obtained with matching pressures shows only weak dependence on the shear modulus. For the pressure amplitudes investigated, equilibrium distances can be found between two bubbles when the equilibrium radius of one of the bubbles is in a narrow range around 2 μm. The equilibrium distance decreases when the shear modulus is increased. A simple relation between the two quantities is established.

Point-of-Care Ultrasound in the Intensive Care Unit

Spreading beyond the realm of tertiary academic medical centers, point-of-care ultrasound in the intensive care unit is an important diagnostic tool. The real-time feedback garnered can lead to critical and clinically relevant changes in management and decrease potential complications. Bedside ultrasound evaluation in the intensive care setting with a small, portable equipment is well-suited for placement of central lines, lumbar puncture, thoracentesis or other bedside ICU procedures and in the evaluation of cardiac activity, pleural and abdominal cavity and the overall fluid volume. Formalized curriculums centering on point-of-care ultrasound are emerging that will enhance its applicability and relevance.

Ultrasonic Generation of Pulsatile and Sequential Therapeutic Delivery Profiles from Calcium-Crosslinked Alginate Hydrogels

Control over of biological processes can potentially be therapeutically regulated through localized biomolecular deliveries. While implantable hydrogels can provide localized therapeutic deliveries, they do not traditionally provide the temporally complex therapeutic delivery profiles required to regulate complex biological processes. Ionically crosslinked alginate hydrogels have been shown to release encapsulated payloads in response to a remotely applied ultrasonic stimulus, thus potentially enabling more temporally complex therapeutic delivery profiles. However, thorough characterizations of how different types of therapeutic payloads are retained and ultrasonically released need to be performed. Additionally, the impact of potentially disruptive ultrasonic stimulations on hydrogel structure and temperature need to be characterized to better understand what range of ultrasonic signals can be used to trigger release. To perform these characterizations, calcium-crosslinked alginate hydrogels were loaded with various model macromolecules (dextrans), chemotherapeutics, and protein signaling factors and exposed to a variety of single-pulse and multi-pulse ultrasonic signals at various amplitudes and durations. In response to single-pulsed ultrasonic exposures, quantifications of molecular release, degree of gel erosion, and increase in hydrogel temperature revealed that the ultrasonic stimulations required for statistically significant therapeutic deliveries often eroded and heated the gels to unacceptable levels. However, multi-pulse ultrasonic exposures were shown to achieve significant amounts of therapeutic release while keeping gel erosion and temperature increase at modest levels. Finally, experiments were performed demonstrating that ultrasonic stimulation could be used to generate drug release profiles shown to have potential therapeutic benefits (e.g., pulsatile and sequential anticancer delivery profiles). This work underscores the potential of using ultrasonically responsive polymeric hydrogels for providing on-demand control over more complex therapeutic deliver profiles and enhancing drug delivery strategies in cancer therapies and beyond.

Bubble cloud dynamics in an ultrasound field

The dynamics of bubble clouds induced by high-intensity focused ultrasound are investigated in a regime where the cloud size is similar to the ultrasound wavelength. High-speed images show that the cloud is asymmetrical; the bubbles nearest the source grow to a larger radius than the distal ones. Similar structures of bubble clouds are observed in numerical simulations that mimic the laboratory experiment. To elucidate the structure, a parametric study is conducted for plane ultrasound waves with various amplitudes and diffuse clouds with different initial void fractions. Based on an analysis of the kinetic energy of liquid induced by bubble oscillations, a new scaling parameter is introduced to characterize the dynamics. The new parameter generalizes the cloud interaction parameter originally introduced by d'Agostino & Brennen (1989). The dynamic interaction parameter controls the energy localization and consequent anisotropy of the cloud. Moreover, the amplitude of the far-field, bubble-scattered acoustics is likewise correlated with the proposed parameter. Findings of the present study not only shed light on the physics of cloud cavitation, but may also be of use to quantification of the effects of cavitation on outcomes of ultrasound therapies including HIFU-based lithotripsy.

Nonuniform Bessel-Based Radiation Distributions on A Spherically Curved Boundary for Modeling the Acoustic Field of Focused Ultrasound Transducers

Therapeutic focused ultrasound is a technique that can be used with different intensities depending on the application. For instance, low intensities are required in nonthermal therapies, such as drug delivering, gene therapy, etc.; high intensity ultrasound is used for either thermal therapy or instantaneous tissue destruction, for example, in oncologic therapy with hyperthermia and tumor ablation. When an adequate therapy planning is desired, the acoustic field models of curve radiators should be improved in terms of simplicity and congruence at the prefocal zone. Traditional ideal models using uniform vibration distributions usually do not produce adequate results for clamped unbacked curved radiators. In this paper, it is proposed the use of a Bessel-based nonuniform radiation distribution at the surface of a curved radiator to model the field produced by real focused transducers. This proposal is based on the observed complex vibration of curved transducers modified by Lamb waves, which have a non-negligible effect in the acoustic field. The use of Bessel-based functions to approximate the measured vibration instead of using plain measurements simplifies the rationale and expands the applicability of this modeling approach, for example, when the determination of the effects of ultrasound in tissues is required.

Broadband ultrasound-trapping barrier based on hollow cylinder with a periodic grating

It is important to modulate ultrasonic waves in some ultrasonic application fields. We formed an ultrasound-trapping barrier through a hollow cylinder with a periodic grating on the surface and simulated the barrier using the finite element method. Using the Schlieren imaging technique, we visualized the ultrasound field distribution in the structure. Both the experimental and simulation results revealed that the structure can work in a broadband frequency range, demonstrating the effectiveness and practicability of the structure as a virtual ultrasound barrier. We also describe how the silent region and the ultrasound intensity can be adjusted in the hollow cylinder.

The Effects of Nerve and Tendon Gliding Exercises Combined with Low-level Laser or Ultrasound Therapy in Carpal Tunnel Syndrome

BACKGROUND

Carpal tunnel syndrome (CTS) is a common medical condition that doctors and physiotherapists come across in clinical practice. There are no explicit recommendations concerning which physical therapy methods should be applied in its treatment; however, there have also been no studies on the effects of combining low-level laser therapy (LLLT) or ultrasound with nerve and tendon gliding exercises. The purpose of this study was to evaluate the therapeutic efficacy of ultrasound and LLLT combined with gliding exercises.

MATERIALS AND METHODS

A total of seventy patients with mild to moderate CTS, divided into two groups, were included in this study. Group 1 received ultrasound treatment, whereas Group 2 underwent LLLT. The treatment lasted 2 weeks (5 sessions/week). In addition, both groups were treated with nerve and tendon gliding exercises three times daily. The clinical evaluation involved an interview on subjective and objective sensory abnormalities, the intensity of pain, the measurement of grip strength, Phalen's test, Tinel's sign, and the Boston Carpal Tunnel Questionnaire. The assessment was performed before and after the treatment.

RESULTS

A decrease in sensory impairments, improvement in visual analog scale, hand grip strength and the Boston Questionnaire results were significant in all patients after therapy. No meaningful differences between groups were noted in any of the examined variables after treatment. No adverse effects were observed.

CONCLUSIONS

The results of this study may suggest the clinical efficacy of LLLT or ultrasound combined with gliding exercises in patients with mild to moderate CTS.

Ultrasound-Targeted Delivery Technology: A Novel Strategy for Tumor- Targeted Therapy

Background:

Ultrasound has been widely used in clinical diagnosis because it is noninvasive, inexpensive, simple, and reproducible. With the development of molecular imaging, material science, and ultrasound contrast agents, ultrasound-targeted delivery technology has emerged. The interaction of ultrasound and molecular probes can be exploited to change the structures of cells and tissues in order to promote the targeted release of therapeutic substances to local tumors. The targeted delivery of drugs, genes, and gases would not only improve the efficacy of tumor treatment but also avoid the systemic toxicity and side effects caused by antitumor treatments. This technology was recently applied in clinical trials and showed enormous potential for clinical application.

Objective:

This article briefly introduces the characteristics of the tumor microenvironment and the principle of ultrasound-targeted delivery technology. To present recent progress in this field, this review focuses on the application of ultrasound-targeted delivery technology in tumor-targeted therapy, including drug delivery, gene transfection, and gas treatment.

Results:

The results of this study show that ultrasound-targeted delivery technology is a promising therapeutic strategy for tumor treatment.

Conclusion:

Ultrasound-targeted delivery technology shows promise with regard to cancer treatment.

Recent advances in ultrasound-based transdermal drug delivery

The transdermal transport of pharmaceuticals possesses various advantageous properties over conventional drug administration techniques such as oral delivery and hypodermic injections. However, the stratum corneum persists as the main barrier, which impedes percutaneous transport. The ultrasound-based transdermal delivery of therapeutics is one of the techniques that are being investigated to overcome this obstacle. This review outlines the background information pertaining to sonophoresis and then discusses the individual sections of sonophoretic research. These areas include the sonophoretic application of various drugs, dual-frequency sonophoresis, synergistic combinations of transdermal drug delivery techniques, and the use of nanosized carriers in ultrasound-based transdermal delivery. The various challenges associated with sonophoretic drug delivery and trends of future research are also highlighted.

Thrombolysis Enhancing by Magnetic Manipulation of Fe₃O₄ Nanoparticles

In this paper, an effective method of accelerating urokinase-administrated thrombolysis through a rotating magnetic field (RMF) of guided magnetic nanoparticles (NPs) in the presence of low-dose urokinase is proposed. The dispersed Fe₃O₄ NPs mixed with urokinase were injected into microfluidic channels occluded by thrombus prepared in vitro. These magnetic NPs aggregated into elongated clusters under a static magnetic field, and were then driven by the RMF. The rotation of Fe₃O₄ aggregates produced a vortex to enhance the diffusion of urokinase to the surface of the thrombus and accelerate its dissolution. A theoretical model based on convective diffusion was constructed to describe the thrombolysis mechanism. The thrombus lysis speed was determined according to the change of the thrombus dissolution length with time in the microfluidic channel. The experimental results showed that the thrombolysis speed with rotating magnetic NPs is significantly increased by nearly two times compared with using the same dose of pure urokinase. This means that the magnetically-controlled NPs approach provides a feasible way to achieve a high thrombolytic rate with low-dose urokinase in use.

Frequency-induced morphology alterations in microconfined biological cells

Low-intensity therapeutic ultrasound has demonstrated an impetus in bone signaling and tissue healing for decades now. Though this technology is clinically well proven, still there are breaches in studies to understand the fundamental principle of how osteoblast tissue regenerates physiologically at the cellular level with ultrasound interaction as a form of acoustic wave stimuli. Through this article, we illustrate an analysis for cytomechanical changes of cell membrane periphery as a basic first physical principle for facilitating late downstream biochemical pathways. With the help of in situ single-cell direct analysis in a microfluidic confinement, we demonstrate that alteration of low-intensity pulse ultrasound (LIPUS) frequency would physically perturb cell membrane and establish inherent cell oscillation. We experimentally demonstrate here that, at LIPUS resonance near 1.7 MHz (during 1-3 MHz alteration), cell membrane area would expand to 6.85 ± 0.7% during ultrasound exposure while it contracts 44.68 ± 0.8% in post actuation. Conversely, cell cross-sectional area change (%) from its previous morphology during and after switching off LIPUS was reversibly different before and after resonance. For instance, at 1.5 MHz, LIPUS exposure produced 1.44 ± 0.5% expansion while in contrast 2 MHz instigates 1.6 ± 0.3% contraction. We conclude that alteration of LIPUS frequency from 1-3 MHz keeping other ultrasound parameters like exposure time, pulse repetition frequency (PRF), etc., constant, if applied to a microconfined biological single living cell, would perturb physical structure reversibly based on the system resonance during and post exposure ultrasound pulsing. We envision, in the near future, our results would constitute the foundation of mechanistic effects of low-intensity therapeutic ultrasound and its allied potential in medical applications. Graphical Abstract Frequency Dependent Characterization of Area Strain in Cell Membrane by Microfluidic Based Single Cell Analysis.

Fully tuned RBF neural network controller for ultrasound hyperthermia cancer tumour therapy

Thermal dose is an important clinical efficacy index for hyperthermia cancer treatment. This paper presents a new direct radial basis function (RBF) neural network controller for high-temperature hyperthermia thermal dose during the therapeutic procedure of cancer tumours by short-time pulses of high-intensity focused ultrasound (HIFU). The developed controller is stabilized and automatically tuned based on Lyapunov functions and ant colony optimization (ACO) algorithm, respectively. In addition, this thermal dose control system has been validated using one-dimensional (1-D) biothermal tissue model. Simulation results showed that the fully tuned RBF neural network controller outperforms other controllers in the previous studies by achieving targeted thermal dose with shortest treatment times less than 13.5 min, avoiding the tissue cavitation during the thermal therapy. Moreover, the maximum value of its mean integral time absolute error (MTAE) is 98.64, which is significantly less than the resulted errors for the manual-tuned controller under the same treatment conditions of all tested cases. In this study, integrated ACO method with robust RBF neural network controller provides a successful and improved performance to deliver accurate thermal dose of hyperthermia cancer tumour treatment using the focused ultrasound transducer without external cooling effect.

Effect of a Controlled Release of Epinephrine Hydrochloride from PLGA Microchamber Array: In Vivo Studies

This paper presents the synthesis of highly biocompatible and biodegradable poly(lactide- co-glycolide) (PLGA) microchamber arrays sensitive to low-intensity therapeutic ultrasound (1 MHz, 1-2 W, 1 min). A reliable method was elaborated that allowed the microchambers to be uniformly filled with epinephrine hydrochloride (EH), with the possibility of varying the cargo amount. The maximum load of EH was 4.5 μg per array of 5 mm × 5 mm (about 24 pg of EH per single microchamber). A gradual, spontaneous drug release was observed to start on the first day, which is especially important in the treatment of acute patients. Ultrasound triggered a sudden substantial release of EH from the films. In vivo real-time studies using a laser speckle contrast imaging system demonstrated changes in the hemodynamic parameters as a consequence of EH release under ultrasound exposure. We recorded a decrease in blood flow as a vascular response to EH release from a PLGA microchamber array implanted subcutaneously in a mouse. This response was immediate and delayed (1 and 2 days after the implantation of the array). The PLGA microchamber array is a new, promising drug depot implantable system that is sensitive to external stimuli.

Energy shielding by cavitation bubble clouds in burst wave lithotripsy

Combined laboratory experiment and numerical simulation are conducted on bubble clouds nucleated on the surface of a model kidney stone to quantify the energy shielding of the stone caused by cavitation during burst wave lithotripsy (BWL). In the experiment, the bubble clouds are visualized and bubble-scattered acoustics are measured. In the simulation, a compressible, multi-component flow solver is used to capture complex interactions among cavitation bubbles, the stone, and the burst wave. Quantitative agreement is confirmed between results of the experiment and the simulation. In the simulation, a significant shielding of incident wave energy by the bubble clouds is quantified. The magnitude of shielding can reach up to 90% of the energy of the incoming burst wave that otherwise would be transmitted into the stone, suggesting a potential loss of efficacy of stone comminution. There is a strong correlation between the magnitude of the energy shielding and the amplitude of the bubble-scattered acoustics, independent of the initial size and the void fraction of the bubble cloud within a range addressed in the simulation. This correlation could provide for real-time monitoring of cavitation activity in BWL.

A review on the use of magnetic fields and ultrasound for non-invasive cancer treatment

Current popular cancer treatment options, include tumor surgery, chemotherapy, and hormonal treatment. These treatments are often associated with some inherent limitations. For instances, tumor surgery is not effective in mitigating metastases; the anticancer drugs used for chemotherapy can quickly spread throughout the body and is ineffective in killing metastatic cancer cells. Therefore, several drug delivery systems (DDS) have been developed to target tumor cells, and release active biomolecule at specific site to eliminate the side effects of anticancer drugs. However, common challenges of DDS used for cancer treatment, include poor site-specific accumulation, difficulties in entering the tumor microenvironment, poor metastases and treatment efficiency. In this context, non-invasive cancer treatment approaches, with or without DDS, involving the use of light, heat, magnetic field, electrical field and ultrasound appears to be very attractive. These approaches can potentially improve treatment efficiency, reduce recovery time, eliminate infections and scar formation. In this review we focus on the effects of magnetic fields and ultrasound on cancer cells and their application for cancer treatment in the presence of drugs or DDS.

Application of Ultrasound in Food Science and Technology: A Perspective

Ultrasound is composed of mechanical sound waves that originate from molecular movements that oscillate in a propagation medium. The waves have a very high frequency, equal to approximately 20 kHz, are divided into two categories (i.e., low-intensity and high-intensity waves) and cannot be perceived by the human ear. Nature has created the first ultrasound applications. Bats use ultrasound to navigate in the dark, and many cetaceans use echolocation to detect prey or obstacles using ultrasound produced by their vocal system. Ultrasound is commonly associated with the biomedical field. Today, ultrasound-based methods and equipment are available to detect organs, motion, tumour masses, and pre/post-natal handicaps, and for kidney stone removal, physiotherapy, and aesthetic cures. However, ultrasound has found multiple applications in many other fields as well. In particular, ultrasound has recently been used in the food industry to develop various effective and reliable food processing applications. Therefore, this review summarizes the major applications of ultrasound in the food industry. The most common applications in the food industry include cell destruction and extraction of intracellular material. Depending on its intensity, ultrasound is used for the activation or deactivation of enzymes, mixing and homogenization, emulsification, dispersion, preservation, stabilization, dissolution and crystallization, hydrogenation, tenderization of meat, ripening, ageing and oxidation, and as an adjuvant for solid-liquid extraction for maceration to accelerate and to improve the extraction of active ingredients from different matrices, as well as the degassing and atomization of food preparations.

Short-Term Observation of Ultrasonic Cyclocoagulation in Chinese Patients with End-Stage Refractory Glaucoma: A Retrospective Study

Purpose

To assess the efficacy and safety of HIFU-based ultrasonic cyclocoagulation in Chinese patients with end-stage refractory glaucoma.

Method

Patients were recruited consecutively from May 2016 to May 2017 in the Zhongshan Ophthalmic Center. Ultrasonic cyclocoagulation was performed on every patient, using the EyeOP1 ultrasound emitting device. Return visits were set at 1 day, 7 days, 1 month, and 3 months after the treatment. An intraocular pressure (IOP) reduction of ≥20% while IOP ≥ 5 mmHg was deemed as success. Mean IOP change was assessed. Efficacy of two modes (6 sectors and 8 sectors) was also compared. Complications were recorded for safety evaluation.

Results

61 eyes were treated in this study. The baseline IOP (mean ± SD) was 41.11 ± 10.65 mmHg. The percentage of IOP reduction after treatment was 29.2%, 43.2%, 34.8%, and 23.1% at 1 day, 7 days, 1 month, and 3 months, respectively. Overall success rate at 3 months was 50.0% (26/52). No significant difference was found between the 6 sectors group and the 8 sectors group in terms of the success rate (48.6% vs. 52.9%, p=0.768) as well as IOP reduction (p=0.417) at 3 months. Primary angle-closure glaucoma (PACG) had the highest success rate (80.0%, 12/15). Scleral thinning existed in 12 eyes, among which 2 developed hypotony (2 mmHg and 3 mmHg). Average pain score decreased massively compared with baseline data.

Conclusion

With high percentage of IOP reduction and a good safety profile observed in our study, HIFU-based ultrasonic cyclocoagulation might become a promising alternative to cyclodestructive methods. Long-term efficacy and safety need further assessment. The study was registered with Chinese Clinical Trial Registry (http://www.chictr.org.cn; Registration number: ChiCTR-OOC-17014028).

Influence of Magnetic Nanoparticles on the Focused Ultrasound Hyperthermia

Ultrasound hyperthermia is a medical treatment used to increase temperature of tissues. It can be used independently or as a supportive method for an anticancer treatment. The therapeutic efficacy of focused ultrasound hyperthermia can be improved using sonosensitizers, nanoparticles enhancing the attenuation and dissipation of acoustic energy. As sonosensitizers, we propose magnetic nanoparticles owing to their biodegradability, biocompatibility, and simple positioning in tissues using a magnetic field. Focused ultrasound hyperthermia studies were performed using tissue-mimicking phantoms. Temperature changes were measured at various ultrasound powers and distances from the center of the ultrasound focus. Specific absorption rate (SAR) values, describing the power deposition in the tissues during the hyperthermia treatment, were evaluated for the center of the focus point and for various distances from it. The results show that the addition of nanoparticles increases the SAR almost two times compared to that for the pure phantom. The highest SAR is obtained in the ultrasound focus; it decreases with the increase of the distance from the focus.

Global competencies for midwives: external cephalic version; ultrasonography, and tobacco cessation intervention

PROBLEM AND BACKGROUND

The International Confederation of Midwives (ICM) conducts regular updates to the Essential Competencies for Basic Midwifery Practice to determine the introduction or retention of items in the global scope of midwifery practice guidance document.

AIM

This article presents the review process that underpinned the deliberation about three specific clinical practices: external cephalic version, prenatal ultrasonography, and tobacco cessation interventions that occurred during the 2016-2017 global update study.

METHODS

A brief outline of the research methodology used in the 2016-2017 study is provided. Literature summaries about safety and effectiveness of three clinical skills are offered. Data addressing global and regional variations in support of each practice and final disposition of the items are documented.

FINDINGS

External cephalic version did not receive sufficient document support for inclusion in the initial list of items to be tested in the study. Prenatal ultrasonography was supported as an advanced (76.6%) or country-specific (18.8%) skill that midwives could acquire, to promote wider global access for pregnant women. Midwives' participation in tobacco cessation counselling was supported (≥85%) in each of ICM's regions. Knowledge about World Health Organization recommendations for nicotine replacement therapy was endorsed as an additional (62.4%) or country-specific (29.3%) skill.

DISCUSSION AND CONCLUSION

The current evidence of safety of midwives performing external cephalic version led to the recommendation that it be considered in the next document update. Conflicting views of midwives' role in acquiring skills to conduct prenatal ultrasound were evident. There was strong support for participation in smoking cessation counselling, but knowledge of World Health Organization recommendations was not highly endorsed.

Laser generated ultrasound sources using carbon-polymer nanocomposites for high frequency metrology

The characterization of ultrasound fields generated by diagnostic and therapeutic equipment is an essential requirement for performance validation and to demonstrate compliance against established safety limits. This requires hydrophones calibrated to a traceable standard. Currently, the upper calibration frequency range available to the user community is limited to 60 MHz. However, high frequencies are increasingly being used for both imaging and therapy necessitating calibration frequencies up to 100 MHz. The precise calibration of hydrophones requires a source of high amplitude, broadband, quasi-planar, and stable ultrasound fields. There are challenges to using conventional piezoelectric sources, and laser generated ultrasound sources offer a promising solution. In this study, various nanocomposites consisting of a bulk polymer matrix and multi-walled carbon nanotubes were fabricated and tested using pulsed laser of a few nanoseconds for their suitability as a source for high frequency calibration of hydrophones. The pressure amplitude and bandwidths were measured using a broadband hydrophone from 27 different nanocomposite sources. The effect of nonlinear propagation of high amplitude laser generated ultrasound on bandwidth and the effect of bandlimited sensitivity response on the deconvolved pressure waveform were numerically investigated. The stability of the nanocomposite sources under sustained laser pulse excitation was also examined.

Superselective Drug Delivery Using Doxorubicin-Encapsulated Liposomes and Ultrasound in a Mouse Model of Lung Metastasis Activation

Conventional treatment of lymph node metastasis involves dissection of the tumor and regional lymph nodes, but this may cause activation of latent metastatic tumor cells. However, there are few reports on animal models regarding the activation of latent metastatic tumor cells and effective methods of treating activated tumor cells. Here, we report the use of a superselective drug delivery system in a mouse model of lung metastasis in which activated tumor cells are treated with doxorubicin-encapsulated liposomes (DOX-LP) and ultrasound. The axillary lymph node was injected with DOX-LP and exposed to ultrasound so that the released DOX would be delivered from the axillary lymph node to the metastatic lung via the subclavian vein, heart and pulmonary artery. The size of the DOX-LP was optimized to a diameter of 460 nm using indocyanine green-encapsulated liposomes, and the ultrasound intensity was 0.5 W/cm². We found that compared with DOX or DOX-LP alone, the superselective drug delivery system was effective in the treatment of metastasis in both the lung and axillary lymph node. We anticipate that this superselective drug delivery system will be a starting point for the development of new techniques for treating lung metastasis in the clinical setting. Furthermore, the superselective drug delivery system may be used to screen novel drugs for the treatment of lung cancer and investigate the mechanisms of tumor cell activation after resection of a primary tumor or lymph nodes.