Safety of ultrasonic examinations; thermal and mechanical indices

Preliminary Study on Pharmacokinetics and Antitumor Pharmacodynamics of Folic Acid Modified Crebanine Polyethyleneglycol-Polylactic Acid Hydroxyacetic Acid Copolymer Nanoparticles

Purpose

Liver cancer is associated significantly with morbidity and mortality. The combination of low-intensity ultrasound with nanomedicine delivery systems holds promise as an alternative for the treatment for liver cancer. This study focuses on the utilization of folic acid (FA) modified nanoparticles, which are loaded with fluorescent dye DiR and liquid fluorocarbon (PFP). These nanoparticles have the potential to enhance liver cancer targeting under ultrasound stimulation and future applications in vivo.

Methods

The pharmacokinetics and tissue distribution of folic acid-modified Crebanine polyethylene glycol-polylactic acid copolymer nanoparticles (FA-Cre@PEG-PLGA NPs) were investigated. The pharmacokinetic parameters, liver targeting, and in vivo distribution were assessed. Additionally, the inhibitory impacts of FA-Cre@PEG-PLGA NPs in combination with ultrasonic irradiation on the proliferation and acute toxicity of H22 cells of mouse hepatoma were investigated in vitro. The tumor targeting and anti-tumor efficacy of FA-Cre@PEG-PLGA NPs were assessed utilizing a small animal in vivo imaging system and an in situ hepatocellular carcinoma transplantation model, respectively.

Results

The pharmacokinetic studies and tissue distribution tests demonstrated that FA-Cre@PEG-PLGA NPs conspicuously prolonged the half-life and retention time of the drug in rats, and the liver targeting effect was pronounced. Additionally, the in vivo acute toxicity test indicated that FA-Cre@PEG-PLGA NPs had minimal adverse reactions and could fulfill the aim of attenuating the drug. The outcomes of the animal experiments further substantiated that FA-Cre@PEG-PLGA NPs had a longer retention time at the tumor site, a superior anti-tumor effect, and less damage to liver and kidney tissue.

Conclusion

The integration of FA-Cre@PEG-PLGA NPs with ultrasound irradiation demonstrated exceptional safety and potent anti-tumor efficacy in vivo, presenting a promising therapeutic strategy for the treatment of liver cancer through the combination of ultrasound technology with a nanomedicine delivery system.

Therapeutic ultrasound: an innovative approach for targeting neurological disorders affecting the basal ganglia

The basal ganglia are involved in motor control and action selection, and their impairment manifests in movement disorders such as Parkinson's disease (PD) and dystonia, among others. The complex neuronal circuitry of the basal ganglia is located deep inside the brain and presents significant treatment challenges. Conventional treatment strategies, such as invasive surgeries and medications, may have limited effectiveness and may result in considerable side effects. Non-invasive ultrasound (US) treatment approaches are becoming increasingly recognized for their therapeutic potential for reversibly permeabilizing the blood-brain barrier (BBB), targeting therapeutic delivery deep into the brain, and neuromodulation. Studies conducted on animals and early clinical trials using ultrasound as a therapeutic modality have demonstrated promising outcomes for controlling symptom severity while preserving neural tissue. These results could improve the quality of life for patients living with basal ganglia impairments. This review article explores the therapeutic frontiers of ultrasound technology, describing the brain mechanisms that are triggered and engaged by ultrasound. We demonstrate that this cutting-edge method could transform the way neurological disorders associated with the basal ganglia are managed, opening the door to less invasive and more effective treatments.

Advancements in strategies for overcoming the blood-brain barrier to deliver brain-targeted drugs

The blood-brain barrier is known to consist of a variety of cells and complex inter-cellular junctions that protect the vulnerable brain from neurotoxic compounds; however, it also complicates the pharmacological treatment of central nervous system disorders as most drugs are unable to penetrate the blood-brain barrier on the basis of their own structural properties. This dramatically diminished the therapeutic effect of the drug and compromised its biosafety. In response, a number of drugs are often delivered to brain lesions in invasive ways that bypass the obstruction of the blood-brain barrier, such as subdural administration, intrathecal administration, and convection-enhanced delivery. Nevertheless, these intrusive strategies introduce the risk of brain injury, limiting their clinical application. In recent years, the intensive development of nanomaterials science and the interdisciplinary convergence of medical engineering have brought light to the penetration of the blood-brain barrier for brain-targeted drugs. In this paper, we extensively discuss the limitations of the blood-brain barrier on drug delivery and non-invasive brain-targeted strategies such as nanomedicine and blood-brain barrier disruption. In the meantime, we analyze their strengths and limitations and provide outlooks on the further development of brain-targeted drug delivery systems.

Quality of referrals for lower extremity ultrasonography and computed tomography pulmonary angiography and associations with positive findings of venous thromboembolism

INTRODUCTION

The referral is the basis for radiologists' assessment of modality, protocol and urgency, and insufficient information may threaten patient safety. The aim of this study was to assess the completeness of referrals for lower extremity venous duplex ultrasonography (LEVDUS) and computed tomography pulmonary angiography (CTPA), and to investigate associations between the provided clinical information including risk factors, symptoms and lab results in the referrals and positive findings of deep vein thrombosis (DVT) and pulmonary embolism (PE), respectively.

METHODS

Referrals for LEVDUS (801) and CTPA (800) performed from 2016 to 2019 were obtained. Three categories of clinical information from the referrals were recorded: symptoms, risk factors and laboratory results, as well as positive imaging findings of venous thromboembolism (VTE). Referral completeness was rated from zero to three according to how many categories of clinical information the referral provided.

RESULTS

Information from all three clinical information categories was provided in 15% and 25% of referrals for LEVDUS and CTPA, respectively, while 2% and 10% of referrals did not contain any clinical information. Symptoms were provided most often (85% for LEVDUS and 94% for CTPA). Provided information about risk factors was significantly associated with positive findings for LEVDUS, (p = 0.02) and CTPA (p < 0.001).

CONCLUSION

A great majority of referrals failed to provide one or more categories of clinical information. Risk factors were associated with a positive finding of VTE on LEVDUS and CTPA.

IMPLICATIONS FOR PRACTICE

Improving clinical information in referrals may improve justification, patient safety and quality of radiology services.

Effects of prenatal Doppler ultrasound on the retina of the chick embryo in ovo

Currently, the effect of prenatal ultrasound on foetal development is intensively discussed and the guidelines for prenatal diagnostics have been changed. However, data supporting these concerns are scarce. Therefore, we used an established in ovo model of the chicken embryo to investigate cell proliferation and apoptosis within the retina. A total of 21 chicken eggs were fenestrated on Day 5 and allocated to either the control (n = 8) or exposition group (n = 13). The exposition group was treated with pulsed-wave Doppler ultrasound (PWD) for 10 min while controls remained without treatment. After subsequent incubation (6-48 h), the eggs were sacrificed, and chicken embryos were examined morphologically (HE-staining) and immunohistochemically. Counting of apoptotic and proliferating cells per retina was performed using antibodies specific for phospho-histone-H3 and active caspase-3 in combination with a biotin-labelled secondary antibody and peroxidase conjugated avidin-biotin complex for chromogenic detection. Due to a rather low number of specimens at each time point after ultrasound exposition, we neglected the effects of incubation time and focused on treatment effects. This approach revealed that the median number of proliferating cells is reduced after 10 min of exposure to PWD (569 vs. 766), while the number of apoptotic cells is fairly comparable between groups (5 vs. 6). Our data contribute to a better understanding of prenatal US on foetal development by suggesting that PWD could have an impact on the number of proliferating cells in the developing chicken retina and therefore justify further investigations.

A Coded Excitation Framework for High SNR Transcranial Ultrasound Imaging

Robust transcranial ultrasound imaging is difficult due to poor image quality. In particular, low signal-to-noise ratio (SNR) limits sensitivity to blood flow and has hindered clinical translation of transcranial functional ultrasound neuroimaging thus far. In this work, we present a coded excitation framework to increase SNR in transcranial ultrasound without negatively impacting frame rate or image quality. We applied this coded excitation framework in phantom imaging and showed SNR gains as large as 24.78 dB and signal-to-clutter ratio gains as high as 10.66 dB with a 65 bit code. We also analyzed how imaging sequence parameters can impact image quality and showed how coded excitation sequences can be designed to maximize image quality for a given application. In particular, we show that considering the number of active transmit elements and the transmit voltage is critical for coded excitation with long codes. Finally, we applied our coded excitation technique in transcranial imaging of ten adult subjects and showed an average SNR gain of 17.91 ± 0.96 dB without a significant increase in clutter using a 65 bit code. We also performed transcranial power Doppler imaging in three adult subjects and showed contrast and contrast-to-noise ratio improvements of 27.32 ± 8.08 dB and 7.25 ± 1.61 dB, respectively with a 65 bit code. These results show that transcranial functional ultrasound neuroimaging may be possible using coded excitation.

Conformable ultrasound breast patch for deep tissue scanning and imaging

Ultrasound is widely used for tissue imaging such as breast cancer diagnosis; however, fundamental challenges limit its integration with wearable technologies, namely, imaging over large-area curvilinear organs. We introduced a wearable, conformable ultrasound breast patch (cUSBr-Patch) that enables standardized and reproducible image acquisition over the entire breast with less reliance on operator training and applied transducer compression. A nature-inspired honeycomb-shaped patch combined with a phased array is guided by an easy-to-operate tracker that provides for large-area, deep scanning, and multiangle breast imaging capability. The in vitro studies and clinical trials reveal that the array using a piezoelectric crystal [Yb/Bi-Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3] (Yb/Bi-PIN-PMN-PT) exhibits a sufficient contrast resolution (~3 dB) and axial/lateral resolutions of 0.25/1.0 mm at 30 mm depth, allowing the observation of small cysts (~0.3 cm) in the breast. This research develops a first-of-its-kind ultrasound technology for breast tissue scanning and imaging that offers a noninvasive method for tracking real-time dynamic changes of soft tissue.

Release of liposomally formulated near-infrared fluorescent probes included in giant cluster vesicles by ultrasound irradiation

Detection of tumors and regional lymph nodes during surgery has been proposed in the diagnosis of lymphatic metastasis and the surgical treatment of malignant diseases. Giant cluster vesicles (GCVs), including liposomally formulated indocyanine green (LP-ICG) derivatives, are a possible candidate for agents to realize the two contradictory properties, i.e., retention in tissue for lesion-marking and trace for sentinel lymph nodes (SLNs) identification. We attempted to release the LP-ICG derivatives from GCVs using ultrasound contrast agents (UCAs) under ultrasound irradiation. An absorption spectrophotometer quantitatively evaluated the amounts of released LP-ICG derivatives. As a result, we demonstrated that it depended on conditions for sound pressure, burst length, and number density of UCAs, and had a sound pressure threshold independent of burst length and number density of UCAs. The results will aid to determine appropriate conditions to maximize the released amount of LP-ICG derivatives while keeping safety.

A Review on Biological Effects of Ultrasounds: Key Messages for Clinicians

Ultrasound (US) is acoustic energy that interacts with human tissues, thus, producing bioeffects that may be hazardous, especially in sensitive organs (i.e., brain, eye, heart, lung, and digestive tract) and embryos/fetuses. Two basic mechanisms of US interaction with biological systems have been identified: thermal and non-thermal. As a result, thermal and mechanical indexes have been developed to provide a means of assessing the potential for biological effects from exposure to diagnostic US. The main aims of this paper were to describe the models and assumptions used to estimate the "safety" of acoustic outputs and indices and to summarize the current state of knowledge about US-induced effects on living systems deriving from in vitro models and in vivo experiments on animals. This review work has made it possible to highlight the limits associated with the use of the estimated safety values of thermal and mechanical indices relating above all to the use of new US technologies, such as contrast-enhanced ultrasound (CEUS) and acoustic radiation force impulse (ARFI) shear wave elastography (SWE). US for diagnostic and research purposes has been officially declared safe, and no harmful biological effects in humans have yet been demonstrated with new imaging modalities; however, physicians should be adequately informed on the potential risks of biological effects. US exposure, according to the ALARA (As Low As Reasonably Achievable) principle, should be as low as reasonably possible.

Ultrasound-mediated blood-brain barrier opening: An effective drug delivery system for theranostics of brain diseases

Blood-brain barrier (BBB) remains a significant obstacle to drug therapy for brain diseases. Focused ultrasound (FUS) combined with microbubbles (MBs) can locally and transiently open the BBB, providing a potential strategy for drug delivery across the BBB into the brain. Nowadays, taking advantage of this technology, many therapeutic agents, such as antibodies, growth factors, and nanomedicine formulations, are intensively investigated across the BBB into specific brain regions for the treatment of various brain diseases. Several preliminary clinical trials also have demonstrated its safety and good tolerance in patients. This review gives an overview of the basic mechanisms, ultrasound contrast agents, evaluation or monitoring methods, and medical applications of FUS-mediated BBB opening in glioblastoma, Alzheimer's disease, and Parkinson's disease.

Closed-loop transcranial ultrasound stimulation with a fuzzy controller for modulation of motor response and neural activity of mice

Objective. We propose a closed-loop transcranial ultrasound stimulation (TUS) with a fuzzy controller to realize real-time and precise control of the motor response and neural activity of mice.Approach. The mean absolute value (MAV) of the electromyogram (EMG) and peak value (PV) of the local field potential (LFP) were measured under different ultrasound intensities. A model comprising the characteristics of the MAV of the EMG, PV of the LFP, and ultrasound intensity was built using a neural network, and a fuzzy controller, proportional-integral-derivative (PID) controller, and immune feedback controller were proposed to adjust the ultrasound intensity using the feedback of the EMG MAV and the LFP PV.Main results. In simulation, the quantitative calculation indicated that the maximum relative errors between the simulated EMG MAV and the expected values were 17% (fuzzy controller), 110% (PID control), 66% (immune feedback control); furthermore, the corresponding values of the LFP PV were 12% (fuzzy controller), 53% (PID control), 55% (immune feedback control). The average relative errors of fuzzy controller, PID control, immune feedback control were 4.97%, 13.15%, 11.52%, in the EMG closed-loop experiment and 7.76%, 11.84%, 13.56%, in the LFP closed-loop experiment.Significance. The simulation and experimental results demonstrate that the closed-loop TUS with a fuzzy controller can realize the tracking control of the motor response and neural activity of mice.

The EFSUMB Guidelines and Recommendations for Musculoskeletal Ultrasound - Part I: Extraarticular Pathologies

The first part of the guidelines and recommendations for musculoskeletal ultrasound, produced under the auspices of the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB), provides information about the use of musculoskeletal ultrasound for assessing extraarticular structures (muscles, tendons, entheses, ligaments, bones, bursae, fasciae, nerves, skin, subcutaneous tissues, and nails) and their pathologies. Clinical applications, practical points, limitations, and artifacts are described and discussed for every structure. After an extensive literature review, the recommendations have been developed according to the Oxford Centre for Evidence-based Medicine and GRADE criteria and the consensus level was established through a Delphi process. The document is intended to guide clinical users in their daily practice.

Therapeutic Ultrasound-Enhanced Transcorneal PHMB Delivery In Vitro

OBJECTIVE

Delivery of therapeutic agents to the cornea is a difficult task in the treatment of parasitic keratitis. In this study, we looked at using different combinations of ultrasound parameters to enhance corneal permeability to polyhexamethylene biguanide (PHMB), a clinically available ophthalmic antiparasitic formulation.

METHODS

Permeability of PHMB was investigated in vitro using a standard diffusion cell setup. Continuous or 25% duty-cycle ultrasound was used at frequencies of 400 or 600 kHz, intensities of 0.5 or 0.8 W/cm² , and exposure times ranging from 1 to 5 minutes. Structural changes in the cornea were examined using light microscopy.

RESULTS

Ultrasound exposure produced increases in transcorneal delivery in every treatment parameter combination when compared to the sham treatment. The highest increase was 2.36 times for 5 minutes of continuous ultrasound at a frequency of 600 kHz and an intensity of 0.5 W/cm² with statistical significance (p <.001). Histological analysis showed that ultrasound application only caused structural changes in the corneal epithelium, with most damage being at the surface layers.

CONCLUSIONS

This study suggests the possibility of therapeutic ultrasound as a novel drug delivery technique for the treatment of parasitic keratitis. Further studies are needed to examine the thermal effects of these proposed ultrasound applications and the long-term viability of this treatment.

Deep impact of superficial skin inking: acoustic analysis of underlying tissue

Abstract Background: Skin tattoos are a common decoration, but profound scientific study whether the presence of a skin tattoo alters the acoustic response from superficial tissue, and therefore from underlying tissue, was previously lacking. Any image aberrations caused by tattoo presence may have been thought negligible, yet empirically found artifacts in brightness-mode images of tattooed skin suggest otherwise. This study investigated the nature of these artifacts theoretically and experimentally in extremely simplified cases of perfectly flat and homogenous layered media and in tattooed pork.Methods: Theory was derived for computing the acoustic response from horizontally and vertically layered media containing a thin inked layer. Experiments were performed in vitro. Artificial and pork skin were tattooed, attached to phantom material, and sonicated with a 13‐6-MHz probe. The speed of sound of these materials was determined, and the perceived refraction angles was measured.Results: The measured speeds of sound of tattooed materials were higher than those of their uninked counterparts. The presence of tattoo ink was found to have increased the linear acoustic attenuation by 1 dB/cm. This value is negligible for typical tattoos of only few millimeters. The perceived critical refraction angles of adjacent materials could be detected, and their corresponding speeds of sound were quantified. These coincided with values derived from theory.Conclusion: The ratio of speeds of sound of adjacent materials was shown to create distinct highlights in brightness-mode images. The artifacts observed in in vitro and in vivo brightness-mode scans were explained from near-vertical transitions between areas of different sound speed. This is the first study correlating so-called critical refraction highlighting with speed-of-sound information. In addition, it was found that phantom material is a room-temperature acoustic alternative for experiments on live human skin. In summary, the presence of superficial tattoos has a small but quantifiable effect on the acoustic response from deeper tissues.