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Purpose Uveal melanoma with a bad prognosis contain high numbers of infiltrating macrophages, especially of the M2 phenotype, and different subsets of lymphocytes. The aim of this study is to determine the presence of inflammatory cells in uveal melanoma‐containing eyes enucleated after different types of irradiation, i.e. ruthenium‐106 brachytherapy, sandwich therapy, or proton beam irradiation. Methods We analyzed 46 eyes enucleated due to tumor recurrence, non‐responsiveness, or complications after irradiation. Immunofluorescence staining was performed to determine the presence of CD68+ and CD68+CD163+macrophages, CD3+, CD8+ and Foxp3+ regulatory T lymphocytes. Outcomes were compared with known clinical and histological prognostic parameters. Results Numbers of CD68+ and CD68+CD163+ macrophages in secondarily‐enucleated eyes varied widely, but was not related to the reason for enucleation. The median of CD3, CD8, FoxP3+ lymphocyte counts was 55, 99 and 9 cells/mm2, respectively. When compared to primarily‐enucleated eyes, the lymphocytic infiltration was significantly (p<.02) higher in irradiated eyes. Conclusion Numbers of T‐lymphocytes and macrophages varied widely. Irradiation has no clear effect on the number and type of macrophages in uveal melanoma. However, there were higher numbers of lymphocytes in previously irradiated uveal melanoma. [ABSTRACT FROM AUTHOR]

The dynamics of coated microbubbles was studied in an in vivo model. Biotinylated lipid-coated microbubbles were prepared in-house and were injected into a chick embryo chorioallantoic membrane (CAM) model on the fifth day of incubation. The microbubbles, ranging between 1.0 and 3.5 μm in diameter, were insonified in the frequency range of 4-7 MHz. Two amplitudes of acoustic pressure were applied: 300 kPa and 400 kPa. The fundamental and subharmonic responses were recorded optically with an ultra-fast camera (Brandaris 128) at 20 million frames per second. A subharmonic response was observed for 44% of the studied bubbles. From the data the frequency of the maximum fundamental and subharmonic response was derived for each individual bubble and resulted in the resonance curves of the microbubbles. All the bubbles showed shell (strain) hardening behavior for a higher acoustic pressure. We conclude that the subharmonic oscillations observed in this study belonged to the transmit at resonance (TR) regime. [ABSTRACT FROM AUTHOR]

Boutsioukis C, Gogos C, Verhaagen B, Versluis M, Kastrinakis E, van der Sluis LWM. The effect of apical preparation size on irrigant flow in root canals evaluated using an unsteady Computational Fluid Dynamics model. International Endodontic Journal, 43, 874–881, 2010. Aim To evaluate the effect of apical preparation size on irrigant flow inside a root canal during final irrigation with a syringe and two different needles types, using a Computational Fluid Dynamics (CFD) model. Methodology A validated CFD model was used to simulate the irrigant flow from either a side-vented or a flat 30G needle positioned inside root canals having sizes of 25, 35, 45 and 55, all with a .06 taper, at 3 mm short of working length (WL). Velocity, pressure and shear stress in the root canal were evaluated. Results Different preparation sizes resulted in minor differences in the flow pattern in the apical root canal. Major differences were observed between the two needle types. The side-vented needle could not achieve irrigant replacement to the WL even in a size 55, .06 taper root canal. Significant irrigant replacement was evident almost to the WL in size 35, 45 and 55, .06 taper root canals with the flat needle. The maximum shear stress decreased as the preparation size increased. The flat needle developed higher mean pressure at the apical foramen. Both needles led to a similar gradual decrease in apical pressure as the preparation size increased. Conclusions Apical preparation size affected irrigant replacement, the shear stress on the canal wall and the pressure at the apical foramen. Root canal enlargement to sizes larger than 25 appeared to improve the performance of syringe irrigation. Adequate space between the needle and the canal wall should be ensured to allow for an effective reverse flow of the irrigant towards the canal orifice. [ABSTRACT FROM AUTHOR]

Boutsioukis C, Gogos C, Verhaagen B, Versluis M, Kastrinakis E, van der Sluis LWM. The effect of root canal taper on the irrigant flow: evaluation using an unsteady Computational Fluid Dynamics model. International Endodontic Journal, 43, 909–916, 2010. Aim To evaluate the effect of root canal taper on irrigant flow inside a prepared root canal during final irrigation with a syringe and two types of needles, using a Computational Fluid Dynamics (CFD) model. Methodology A validated CFD model was used to simulate irrigant flow from either a side-vented or a flat 30G needle positioned inside size 30, .02 taper, 30, .04, 30, .06, ProTaper F3 or size 60, .02 taper root canals, at 3 mm short of working length (WL). Velocity, pressure and shear stress in the root canal were evaluated. Results The side-vented needle could not achieve irrigant replacement to the WL in any of the cases. Significant irrigant replacement was evident further than 2 mm apically to the tip of the flat needle in the size 30, .06 taper, F3 and size 60, .02 taper canal. A wider distribution of wall shear stress was noted as the canal taper increased but the maximum shear stress decreased. The flat needle led to higher mean pressure at the apical foramen. Both needles showed a similar gradual decrease in apical pressure as the taper increased, but the least pressure was calculated in the size 60, .02 taper canal. Conclusions An increase in root canal taper improved irrigant replacement and wall shear stress whilst reducing the risk for irrigant extrusion. Irrigant flow in a minimally tapered root canal with a large apical preparation size also improved irrigant replacement and wall shear stress and reduced the risk for irrigant extrusion, compared to the tapered root canals with a smaller apical preparation size. [ABSTRACT FROM AUTHOR]

Abstract: Radially oscillating microbubbles can deform when in contact with a wall. These nonspherical shapes have a preferential orientation perpendicular to the wall. Conventional microscope setups for microbubble studies have their optical axis perpendicular to the wall (top view); consequently they have a limited view of the deformation of the bubble. We developed a method to image the bubble in a side view by integrating a mirror in the microscope setup. The image was recorded at 14.5 million frames per second by a high-speed camera. When insonified by a 1-MHz, 140-kPa ultrasound pulse, a 9-μm diameter coated bubble appeared spherical in the top view, but strongly nonspherical in the side view. Its shape was alternatively oblate and prolate, with maximum second order spherical harmonic amplitude equal to the radius. (E-mail: H.J.Vos@ErasmusMC.nl) [Copyright &y& Elsevier]

Abstract summary: The advantage of ultrasound contrast agents (UCAs) as drug delivery systems is the ability to non-invasively control the local and triggered release of a drug or gene. In this study we designed and characterized a novel UCA-based drug delivery system, based on polymer-shelled microcapsules filled with a mixture of gas and oil, for the local delivery of lipophilic drugs. [Copyright &y& Elsevier]

Over the past decade, ultrasound (US) has gathered significant attention and research focus in the realm of medical treatments, particularly within the domain of anti-cancer therapies. This growing interest can be attributed to its non-invasive nature, precision in delivery, availability, and safety. While the conventional objective of US-based treatments to treat breast, prostate, and liver cancer is the ablation of target tissues, the introduction of the concept of immunogenic cell death (ICD) has made clear that inducing cell death can take different non-binary pathways through the activation of the patient's anti-tumor immunity. Here, we investigate high-intensity focused ultrasound (HIFU) to induce ICD by unraveling the underlying physical phenomena and resulting biological effects associated with HIFU therapy using an automated and fully controlled experimental setup. Our in-vitro approach enables the treatment of adherent cancer cells (B16F10 and CT26), analysis for ICD hallmarks and allows to monitor and characterize in real time the US-induced cavitation activity through passive cavitation detection (PCD). We demonstrate HIFU-induced cell death, CRT exposure, HMGB1 secretion and antigen release. This approach holds great promise in advancing our understanding of the therapeutic potential of HIFU for anti-cancer strategies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Purpose: Uveal melanoma (UM) is a rare disease, with the highest incidence in people with a fair skin and light eyes. Eye colour is largely genetically determined and defined by a set of single nucleotide polymorphisms (SNPs). We set out to determine whether we could identify a SNP that is related to prognosis., Design: We sequenced DNA from peripheral blood mononuclear cells of 392 patients with UM and obtained the genotype of six common eye colour-related SNPs. Clinical and histopathologic tumour characteristics, tumour chromosome status, and patient survival were compared among patients with different genotypes., Subjects: 392 patients who underwent enucleation for UM at the Leiden University Medical Center, Leiden, The Netherlands., Methods: We isolated DNA from peripheral blood leukocytes of 392 patients with UM and performed sequencing, using six eye colour SNPs from the HIrisPlex-S assay. The genotypes extracted from the sequencing data were uploaded onto the Hirisplex webtool (https://hirisplex.erasmusmc.nl/) for eye colour prediction. We tested the association of eye colour SNPs with tumour characteristics and chromosome aberrations using Pearson's chi-square test and Mann-Whitney U test and survival with Kaplan-Meier curves with log-rank test and Cox regression., Main Outcome Measures: UM-related survival., Results: Of the total cohort of 392 patients with analysable genotype data, 307 (78%) were assigned to have blue eyes, 74 (19%) brown eyes and 11 (3%) could not be assigned to either blue or brown. Patients with a genetically-blue eye colour had a worse survival (p = 0.04). This was related to one genotype: patients with the G/G genotype of rs12913832 (HERC2) which codes for blue eye colour had a worse prognosis (p = 0.017), which was related to more often having high-risk tumours (monosomy of chromosome 3, p = 0.04) than patients with an A/G or A/A genotype., Conclusion: The G/G genotype of rs12913832 (HERC2), which is related to blue eye colour, is not only a genetic factor related to the risk to develop a UM, but is also linked to a worse prognosis, due to an association with a higher risk of developing a high-risk UM (carrying monosomy of chromosome 3)., (Copyright © 2024. Published by Elsevier Inc.)

Objective: Local flow dynamics impact atherosclerosis yet are difficult to quantify with conventional ultrasound techniques. This study investigates the performance of ultrasound vector flow imaging (US-VFI) with and without ultrasound contrast agents in the healthy femoral bifurcation., Methods: High-frame-rate ultrasound data with incremental acoustic outputs were acquired in the femoral bifurcations of 20 healthy subjects before (50V) and after contrast injection (2V, 5V and 10V). 2-D blood-velocity profiles were obtained through native blood speckle tracking (BST) and contrast tracking (echo particle image velocimetry [echoPIV]). As a reference, 4-D flow magnetic resonance imaging (4-D flow MRI) was acquired. Contrast-to-background ratio and vector correlation were used to assess the quality of the US-VFI acquisitions. Spatiotemporal velocity profiles were extracted, from which peak velocities (PSV) were compared between the modalities. Furthermore, root-mean-square error analysis was performed., Results: US-VFI was successful in 99% of the cases and optimal VFI quality was established with the 10V echoPIV and BST settings. A good correspondence between 10V echoPIV and BST was found, with a mean PSV difference of -0.5 cm/s (limits of agreement: -14.1-13.2). Both US-VFI techniques compared well with 4-D flow MRI, with a mean PSV difference of 1.4 cm/s (-18.7-21.6) between 10V echoPIV and MRI, and 0.3 cm/s (-23.8-24.4) between BST and MRI. Similar complex flow patterns among all modalities were observed., Conclusion: 2-D blood-flow quantification of femoral bifurcation is feasible with echoPIV and BST. Both modalities showed good agreement compared to 4-D flow MRI. For the femoral tract the administration of contrast was not needed to increase the echogenicity of the blood for optimal image quality., Competing Interests: Conflict of interest This work was supported in part by the Dutch Research Council VORTECS program (17219) and in part by Rijnstate Vriendenfonds (VF19-a10)., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Functionalized monodisperse microbubbles have the potential to boost the sensitivity and efficacy of molecular ultrasound imaging and targeted drug delivery using bubbles and ultrasound. Monodisperse bubbles can be produced in a microfluidic flow focusing device. However, their functionalization and sequential use require removal of the excess lipids from the bubble suspension to minimize the use of expensive ligands and to avoid competitive binding and blocking of the receptor molecules. To date, excess lipid removal is performed by centrifugation, which is labor intensive and challenging to automate. More importantly, as we show, the increased hydrostatic pressure during centrifugation can reduce bubble monodispersity. Here, we introduce a novel automated microfluidic 'washing' method. First, bubbles are injected in a microfluidic chamber 1 mm in height where they are left to float against the top wall. Second, lipid-free medium is pumped through the chamber to remove excess lipids while the bubbles remain located at the top wall. Third, the washed bubbles are resuspended and removed from the device into a collection vial. We demonstrate that the present method can (i) reduce the excess lipid concentration by 4 orders of magnitude, (ii) be fully automated, and (iii) be performed in minutes while the size distribution, functionality, and acoustic response of the bubbles remain unaffected. Thus, the presented method is a gateway to the fully automated production of functionalized monodisperse microbubbles., (© 2024. The Author(s).)

Objective: Ultrasound-triggered bubble-mediated local drug delivery has shown potential to increase therapeutic efficacy and reduce systemic side effects, by loading drugs into the microbubble shell and triggering delivery of the payload on demand using ultrasound. Understanding the behavior of the microbubbles in response to ultrasound is crucial for efficient and controlled release., Methods: In this work, the response of microbubbles with a coating consisting of poly(2-ethyl-butyl cyanoacrylate) (PEBCA) nanoparticles and denatured casein was characterized. High-speed recordings were taken of single microbubbles, in both bright field and fluorescence., Results: The nanoparticle-loaded microbubbles show resonance behavior, but with a large variation in response, revealing a substantial interbubble variation in mechanical shell properties. The probability of shell rupture and the probability of nanoparticle release were found to strongly depend on microbubble size, and the most effective size was inversely proportional to the driving frequency. The probabilities of both rupture and release increased with increasing driving pressure amplitude. Rupture of the microbubble shell occurred after fewer cycles of ultrasound as the driving pressure amplitude or driving frequency was increased., Conclusion: The results highlight the importance of careful selection of the driving frequency, driving pressure amplitude and duration of ultrasound to achieve the most efficient ultrasound-triggered shell rupture and nanoparticle release of protein-and-nanoparticle-stabilized microbubbles., Competing Interests: Conflict of interest The authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: In arterial disease, the presence of two or more serial stenotic lesions is common. For mild lesions, it is difficult to predict whether their combined effect is hemodynamically significant. This study assessed the hemodynamic significance of idealized serial stenotic lesions by simulating their hemodynamic interaction in a computational flow model., Materials and Methods: Flow was simulated with SimVascular software in 34 serial lesions, using moderate (15 mL/s) and high (30 mL/s) flow rates. Combinations of one concentric and two eccentric lesions, all 50% area reduction, were designed with variations in interstenotic distance and in relative direction of eccentricity. Fluid and fluid-structure simulations were performed to quantify the combined pressure gradient., Results: At a moderate flow rate, the combined pressure gradient of two lesions ranged from 3.8 to 7.7 mmHg, which increased to a range of 12.5-24.3 mmHg for a high flow rate. Eccentricity caused an up to two-fold increase in pressure gradient relative to concentric lesions. At a high flow rate, the combined pressure gradient for serial eccentric lesions often exceeded the sum of the individual lesions. The relative direction of eccentricity altered the pressure gradient by 15-25%. The impact of flow pulsatility and wall deformability was minor., Conclusion: This flow simulation study revealed that lesion eccentricity is an adverse factor in the hemodynamic significance of isolated stenotic lesions and in serial stenotic lesions. Two 50% lesions that are individually non-significant can combine more often than thought to hemodynamic significance in hyperemic conditions., (© 2024. The Author(s).)

Interprofessional Education (IPE) as a preparatory stage for Interprofessional collaboration (IPC) is overlooked in some low-and middle-income countries, including Indonesia. One of the driving forces behind IPC is the development of Interprofessional Identity (IPI), which has yet to be assessed in the Indonesian context. Our study aims were translating and culturally adapting the Extended Professional Identity Scale (EPIS) and confirming its construct validity. We invited third-year students from three programs (medicine, nursing, and dietetics) without previous IPE experience to participate in the study. Using Confirmatory Factor Analysis (CFA), we examined the construct validity, analyzed internal consistency, and conducted a Kruskal-Wallis test to identify variations across professions. Of 513 students approached, 335 participated (response rate 65.3%). The CFA showed factor loadings ranging between .59 and .86, while correlations among subscales varied from .55 to .86. All five goodness-of-fit indices were sufficient. The internal consistency of subscales interprofessional belonging, commitment, and beliefs was .82, .84 and .87, respectively, and .90 for the overall scale. Interprofessional belonging and commitment were different among various students ( p-value = .009 and .004) and the dietetics students had lower scores than other students. The Indonesian EPIS (EPIS-RI) demonstrated reliability and construct validity.

Purpose: To investigate the accuracy of high-framerate echo particle image velocimetry (ePIV) and computational fluid dynamics (CFD) for determining velocity vectors in femoral bifurcation models through comparison with optical particle image velocimetry (oPIV)., Approach: Separate femoral bifurcation models were built for oPIV and ePIV measurements of a non-stenosed (control) and a 75%-area stenosed common femoral artery. A flow loop was used to create triphasic pulsatile flow. In-plane velocity vectors were measured with oPIV and ePIV. Flow was simulated with CFD using boundary conditions from ePIV and additional duplex-ultrasound (DUS) measurements. Mean differences and 95%-limits of agreement (1.96*SD) of the velocity magnitudes in space and time were compared, and the similarity of vector complexity (VC) and time-averaged wall shear stress (TAWSS) was assessed., Results: Similar flow features were observed between modalities with velocities up to 110 and 330    cm / s in the control and the stenosed model, respectively. Relative to oPIV, ePIV and CFD-ePIV showed negligible mean differences in velocity ( < 3    cm / s ), with limits of agreement of ± 25    cm / s (control) and ± 34    cm / s (stenosed). CFD-DUS overestimated velocities with limits of agreements of 13 ± 40 and 16.1 ± 55    cm / s for the control and stenosed model, respectively. VC showed good agreement, whereas TAWSS showed similar trends but with higher values for ePIV, CFD-DUS, and CFD-ePIV compared to oPIV., Conclusions: EPIV and CFD-ePIV can accurately measure complex flow features in the femoral bifurcation and around a stenosis. CFD-DUS showed larger deviations in velocities making it a less robust technique for hemodynamical assessment. The applied ePIV and CFD techniques enable two- and three-dimensional assessment of local hemodynamics with high spatiotemporal resolution and thereby overcome key limitations of current clinical modalities making them an attractive and cost-effective alternative for hemodynamical assessment in clinical practice., (© 2024 The Authors.)

Understanding the ultrasound pressure-driven dynamics of microbubbles confined in viscoelastic materials is relevant for multiple biomedical applications, ranging from contrast-enhanced ultrasound imaging to ultrasound-assisted drug delivery. The volumetric oscillations of spherical bubbles are analyzed using the Rayleigh-Plesset equation, which describes the conservation of mass and momentum in the surrounding medium. Several studies have considered an extension of the Rayleigh-Plesset equation for bubbles embedded into viscoelastic media, but these are restricted to a particular choice of constitutive model and/or to small deformations. Here, we derive a unifying equation applicable to bubbles in viscoelastic media with arbitrary complex moduli and that can account for large bubble deformations. To derive this equation, we borrow concepts from finite-strain theory. We validate our approach by comparing the result of our model to previously published results and extend it to show how microbubbles behave in arbitrary viscoelastic materials. In particular, we use our viscoelastic Rayleigh-Plesset model to compute the bubble dynamics in benchmarked viscoelastic liquids and solids., (© 2024 Acoustical Society of America.)

Background: Needle-based procedures, such as fine needle aspiration and thermal ablation, are often applied for thyroid nodule diagnosis and therapeutic purposes, respectively. With blood vessels and nerves nearby, these procedures can pose risks in damaging surrounding critical structures., Purpose: The development and validation of innovative strategies to manage these risks require a test object with well-characterized physical properties. For this work, we focus on the application of ultrasound-guided thermal radiofrequency ablation., Methods: We have developed a single-use anthropomorphic phantom mimicking the thyroid and surrounding anatomical and physiological structures that are relevant to ultrasound-guided thermal ablation. The phantom was composed of a mixture of polyacrylamide, water, and egg white extract and was cast using molds in multiple steps. The thermal, acoustical, and electrical characteristics were experimentally validated. The ablation zones were analyzed via non-destructive T 2 -weighted magnetic resonance imaging scans utilizing the relaxometry changes of coagulated egg albumen, and the temperature distribution was monitored using an array of fiber Bragg grating sensors., Results: The physical properties of the phantom were verified both on ultrasound as well as in terms of the phantom response to thermal ablation. The final temperature achieved (92°C), the median percentage of the nodule ablated (82.1%), the median volume ablated outside the nodule (0.8 mL), and the median number of critical structures affected (0) were quantified., Conclusion: An anthropomorphic phantom that can provide a realistic model for development and training in ultrasound-guided needle-based thermal interventions for thyroid nodules has been presented., (© 2023 The Authors. Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.)

Background: Ethiopia has scaled up medical education to improve access to healthcare which presented challenges to maintaining training quality. We conducted a study to assess the clinical competence of graduating medical students and the associated factors., Methods and Materials: A pretest assessment of a quasi-experimental study was conducted in 10 medical schools with a sample size of 240 students. We randomly selected 24 students per school. Clinical competence was assessed in a 12-station objective structured clinical examination. The clinical learning environment (CLE), simulation training, and practice exposure were self-rated. Mean scores for clinical competence, and satisfaction in the CLE and simulation training were calculated. Proportions of students with practice exposure, and who agreed on CLE and simulation items were done. Independent t-tests were used to look at competence differences among subgroups. Bivariate and multiple linear regression models were fitted for the outcome variable: competence score. A 95% statistical confidence interval and p-value < 0.05 were used for making statistical decisions. A 75% cut-off score was used to compare competence scores., Results: Graduating medical students had a mean competence score of 72%. Low scores were reported in performing manual vacuum aspiration (62%), lumbar puncture (64%), and managing childbirth (66%). Female students (73%) had a significantly higher competence score than males (70%). Higher cumulative grade point average (CGPA), positive appraisal of the CLE, and conducting more clinical procedures were associated with greater competence scores. Nearly half of the students were not satisfied with the clinical practice particularly due to the large student number and issues affecting the performance assessment. About two-thirds of the students were not satisfied with the sufficiency of models and equipment, and the quality of feedback during simulation training. Nearly one-third of the students never performed lumbar puncture, manual vacuum aspiration, and venipuncture., Conclusions: Medical students had suboptimal clinical competence. A better clinical learning environment, higher cumulative GPA, and more practice exposure are associated with higher scores. There is a need to improve student clinical practice and simulation training. Strengthening school accreditation and graduates' licensing examinations is also a way forward., (© 2023. The Author(s).)

Purpose: To identify potential hemodynamic predictors for limb thrombosis (LT) following endovascular aneurysm repair with the Anaconda endograft in a patient-specific phantom., Materials and Methods: A thin-walled flow phantom, based on a patient's aortic anatomy and treated with an Anaconda endograft, that presented with a left-sided LT was fabricated. Contrast-enhanced ultrasound particle image velocimetry was performed to quantify time-resolved velocity fields. Measurements were performed in the same phantom with and without the Anaconda endograft, to investigate the impact of the endograft on the local flow fields. Hemodynamic parameters, namely vector complexity (VC) and residence time (RT), were calculated for both iliac arteries., Results: In both limbs, the vector fields were mostly unidirectional during the peak systolic and end-systolic velocity phases before and after endograft placement. Local vortical structures and complex flow fields were observed at the diastolic and transitional flow phases. The average VC was higher (0.11) in the phantom with endograft, compared to the phantom without endograft (0.05). Notably, in both left and right iliac arteries, the anterior wall regions corresponded to a 2- and 4-fold increase in VC in the phantom with endograft, respectively. RT simulations showed values of 1.3 to 6 seconds in the phantom without endograft. A higher RT (up to 25 seconds) was observed in the phantom with endograft, in which the left iliac artery, with LT in follow-up, showed 2 fluid stasis regions., Conclusion: This in vitro study shows that unfavorable hemodynamics were present mostly in the limb that thrombosed during follow-up, with the highest VC and longest RT. These parameters might be valuable in predicting the occurrence of LT in the future., Clinical Impact: This in-vitro study aimed to identify potential hemodynamic predictors for limb thrombosis following EVAR using ultrasound particle image velocimetry (echoPIV) technique. It was shown that unfavorable hemodynamic norms were present mostly in the thrombosed limb. Owing to the in-vivo feasibility of the echoPIV, future efforts should focus on the evaluation of these hemodynamic norms in clinical trials. Thereafter, using echoPIV as a bedside technique in hospitals becomes more promising. Performing echoPIV in pre-op phase may provide valuable insights for surgeons to enhance treatment planning. EchoPIV is also applicable for follow-up sessions to evaluate treatment progress and avoid/predict complications., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Prof. Dr R.H. Geelkerken and Prof. Dr M.M.P.J. Reijnen are consultants for Terumo Aortic.

Sonoporation is the process where intracellular drug delivery is facilitated by ultrasound-driven microbubble oscillations. Several mechanisms have been proposed to relate microbubble dynamics to sonoporation including shear and normal stress. The present work aims to gain insight into the role of microbubble size on sonoporation and thereby into the relevant mechanism(s) of sonoporation. To this end, we measured the sonoporation efficiency while varying microbubble size using monodisperse microbubble suspensions. Sonoporation experiments were performed in vitro on cell monolayers using a single ultrasound pulse with a fixed frequency of 1 MHz while the acoustic pressure amplitude and pulse length were varied at 250, 500, and 750 kPa, and 10, 100, and 1000 cycles, respectively. Sonoporation efficiency was quantified using flow cytometry by measuring the FITC-dextran (4 kDa and 2 MDa) fluorescence intensity in 10,000 cells per experiment to average out inherent variations in the bioresponse. Using ultra-high-speed imaging at 10 million frames per second, we demonstrate that the bubble oscillation amplitude is nearly independent of the equilibrium bubble radius at acoustic pressure amplitudes that induce sonoporation (≥ 500 kPa). However, we show that sonoporation efficiency is strongly dependent on the equilibrium bubble size and that under all explored driving conditions most efficiently induced by bubbles with a radius of 4.7 μm. Polydisperse microbubbles with a typical ultrasound contrast agent size distribution perform almost an order of magnitude lower in terms of sonoporation efficiency than the 4.7-μm bubbles. We elucidate that for our system shear stress is highly unlikely the mechanism of action. By contrast, we show that sonoporation efficiency correlates well with an estimate of the bubble-induced normal stress., Competing Interests: Declaration of Competing Interest None, (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Purpose: Contemporary diagnostic modalities, including contrast-enhanced computed tomography (CTA) and duplex ultrasound, have been insufficiently able to predict endograft thrombosis. This study introduces an implementation of image-based computational fluid dynamics (CFD), by exemplification with 4 patients treated with an endograft for occlusive disease of the superficial femoral artery (SFA). The potential of personalized CFD for predicting endograft thrombosis is investigated., Materials and Methods: Four patients treated with endografts for an occluded SFA were retrospectively included. CFD simulations, based on CTA and duplex ultrasound, were compared for patients with and without endograft thrombosis to investigate potential flow-related causes of endograft thrombosis. Time-averaged wall shear stress (TAWSS) was computed, which highlights areas of prolonged residence times of coagulation factors in the graft., Results: CFD simulations demonstrated normal TAWSS (>0.4 Pa) in the SFA for cases 1 and 2, but low levels of TAWSS (<0.4 Pa) in cases 3 and 4, respectively. Primary patency was achieved in cases 1 and 2 for over 2 year follow-up. Cases 3 and 4 were complicated by recurrent endograft thrombosis., Conclusion: The presence of a low TAWSS was associated with recurrent endograft thrombosis in subjects with otherwise normal anatomic and ultrasound assessment and a good distal run-off.

Ultrasound, the primary imaging modality in thyroid nodule management, suffers from drawbacks including: high inter- and intra-observer variability, limited field-of-view and limited functional imaging. Developments in ultrasound technologies are taking place to overcome these limitations, including three-dimensional-Doppler, -elastography, -nodule characteristics-extraction, and novel machine-learning algorithms. For thyroid ablative treatments and biopsies, perioperative use of three-dimensional ultrasound opens a new field of research. This review provides an overview of the current and future applications of ultrasound, and discusses the potential of new developments and trends that may improve the diagnosis, therapy, and follow-up of thyroid nodules., (© 2023 The Authors. Journal of Clinical Ultrasound published by Wiley Periodicals LLC.)

Background: In The Netherlands, physicians specialized in global health and tropical medicine (Ps-GHTM) are trained to work in low-resource settings (LRS) after their training program of 27 months. After working for a period of time in LRS, many Ps-GHTM continue their careers in the Dutch healthcare system. While there is limited evidence regarding the value of international health experience for medical students and residents, it is unknown to what extent this applies to Ps-GHTM and to their clinical practice in the Netherlands., Methods: In this qualitative study we conducted semi-structured interviews and focus group discussions (FGDs) with Ps-GHTM to explore the perceived applicability of their experience abroad for their subsequent return to the Netherlands. Topic guides were developed using literature about the applicability of working abroad. Findings from the interviews served as a starting point for FGDs. The interviews and FGDs were analysed using directed content analysis., Results: 15 themes are described relating experience abroad to healthcare delivery in The Netherlands: broad medical perspective, holistic perspective, adaptive communication skills, creativity, flexibility, cultural awareness, self-reliance, clinical competence, cost awareness, public health, leadership, open-mindedness, organization of care, self-development, and teamwork. Highlighting the variety in competencies and the complexity of the topic, not all themes were recognized by all respondents in the FGDs nor deemed equally relevant. Flexibility, cultural awareness and holistic perspective are examples of important benefits to work experience in LRS., Conclusion: Ps-GHTM bring their competencies to LRS and return to the Netherlands with additionally developed skills and knowledge. These may contribute to healthcare delivery in the Netherlands. This reciprocal value is an important factor for the sustainable development of global health. Identifying the competencies derived from work experience in LRS could give stakeholders insight into the added value of Ps-GHTM and partly help in refining the specialization program., (© 2023. The Author(s).)

Collapse of lipidic ultrasound contrast agents under high-frequency compressive load has been historically interpreted by the vanishing of surface tension. By contrast, buckling of elastic shells is known to occur when costly compressible stress is released through bending. Through quasi-static compression experiments on lipidic shells, we analyse the buckling events in the framework of classical elastic buckling theory and deduce the mechanical characteristics of these shells. They are then compared with that obtained through acoustic characterization. This article is part of the theme issue 'Probing and dynamics of shock sensitive shells'.

Background: An International Health Elective (IHE) can be a unique learning experience for students. However, it has proven difficult to clearly define learning outcomes that capture the complexity of an IHE and are aligned with future professional performance. This study aimed to further define learning outcomes for IHEs in low- to middle-income countries (LMIC) from a student perspective., Methods: We conducted a deductive analysis of pre-departure and post-elective reflective reports of fifth-year medical students who participated in an IHE as part of their program. This provided possible learning objectives that were further explored in semi-structured individual interviews with medical students who had recently returned from an IHE., Results: We analyzed 33 reports of students participating in an IHE from 2017-2019 and held 19 interviews. Thematic analysis revealed 9 themes: developing intercultural competence, developing appreciation for differences in health care delivery systems, understanding international health, understanding the global burden of disease, developing a career perspective, developing clinical skills in resource low settings, becoming cost conscious, developing social responsibility and self-actualization., Conclusions: We identified 9 learning outcomes that are directly and indirectly related to clinical practice. They add to the on-going discourse on the benefits of IHEs. These outcomes can be further developed by investigating the perspectives of home and host supervisors and educationalists, while taking the local context into account. Follow-up studies can evaluate to what extend these outcomes are achieve during an IHE., (© 2023. The Author(s).)

Objectives: Understanding the competency of educators is key to informing faculty development, recruitment and performance monitoring. This study aimed to assess the core teaching competency of nursing, midwifery and biomedical educators, and associated factors in Ethiopia., Design: An institution-based cross-sectional study was conducted in January 2020 using structured tools adapted from the WHO's nurse and midwifery educator competency frameworks., Setting: Two health science colleges and nine student practice sites in Ethiopia., Participants: All classroom instructors and clinical preceptors of nursing, midwifery and biomedical technician training programmes, and all the graduating class students., Measures: Overall teaching competency scores, teaching domain competency scores, competency gaps and performance gaps of educators were outcome measures. Past training on teaching skills courses, teaching experiences and sociodemographic characteristics of educators are associated factors., Results: Most educators were not trained in teaching methods (82%). The teaching competency scores of classroom instructors and clinical preceptors were 61.1% and 52.5%, respectively. Competency gaps were found in using active learning methods, performance assessment, feedback and digital learning. Professional background of classroom instructors had a significant and strong association with their competency score (p=0.004; V = 0.507). Age and teaching experience of clinical preceptors had significant associations with their competency score (p=0.023 and p=0.007, respectively) and had strong associations (V=0.280 and 0.323, respectively). Sex of students and their perceptions of how well the educators give education resources had a significant and strong association (p<0.001; V = 0.429)., Conclusions: Nursing, midwifery and biomedical educators lacked the competency to undertake important teaching roles, which could contribute to the low quality of education. More attention should be given to strengthening faculty development., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Aim: The aim of the study was (a) to develop a three-dimensional numerical model combining the oscillation of a tapered ultrasonic file and the induced irrigant flow along with their two-way interaction in the confinement of a root canal. (b) To validate this model through comparison with experiments and theoretical (analytical) solutions of the flow., Methodology: Two partial numerical models, one for the oscillation of the ultrasonic file and another one for the irrigant flow inside the root canal around the file, were created and coupled in order to take into account the two-way coupled fluid-structure interaction. Simulations were carried out for ultrasonic K-files and for smooth wires driven at four different amplitudes in air or inside an irrigant-filled straight root canal. The oscillation pattern of the K-files was determined experimentally by Scanning Laser Vibrometry, and the flow pattern inside an artificial root canal was analysed using high-speed imaging together with Particle Image Velocimetry. Analytical solutions were obtained from an earlier study. Numerical, experimental and analytical results were compared to assess the validity of the model., Results: The comparison of the oscillation amplitude and node location of the ultrasonic files and of the irrigant flow field showed a close agreement between the simulations, experiments and theoretical solutions., Conclusions: The model is able to predict reliably the file oscillation and irrigant flow inside root canals during ultrasonic activation under similar conditions., (© 2022 The Authors. International Endodontic Journal published by John Wiley & Sons Ltd on behalf of British Endodontic Society.)

Recently, super-resolution ultrasound imaging with ultrasound localization microscopy (ULM) has received much attention. However, ULM relies on low concentrations of microbubbles in the blood vessels, ultimately resulting in long acquisition times. Here, we present an alternative super-resolution approach, based on direct deconvolution of single-channel ultrasound radio-frequency (RF) signals with a one-dimensional dilated convolutional neural network (CNN). This work focuses on low-frequency ultrasound (1.7 MHz) for deep imaging (10 cm) of a dense cloud of monodisperse microbubbles (up to 1000 microbubbles in the measurement volume, corresponding to an average echo overlap of 94%). Data are generated with a simulator that uses a large range of acoustic pressures (5-250 kPa) and captures the full, nonlinear response of resonant, lipid-coated microbubbles. The network is trained with a novel dual-loss function, which features elements of both a classification loss and a regression loss and improves the detection-localization characteristics of the output. Whereas imposing a localization tolerance of 0 yields poor detection metrics, imposing a localization tolerance corresponding to 4% of the wavelength yields a precision and recall of both 0.90. Furthermore, the detection improves with increasing acoustic pressure and deteriorates with increasing microbubble density. The potential of the presented approach to super-resolution ultrasound imaging is demonstrated with a delay-and-sum reconstruction with deconvolved element data. The resulting image shows an order-of-magnitude gain in axial resolution compared to a delay-and-sum reconstruction with unprocessed element data.

Local flow patterns influence stent patency, while blood flow quantification in stents is challenging. The aim of this study was to investigate the feasibility of 2-D blood flow quantification using high-frame-rate, contrast-enhanced ultrasound (HFR-CEUS) and particle image velocimetry (PIV), or echoPIV, in patients with aortoiliac stents. HFR-CEUS measurements were performed at 129 locations in 62 patients. Two-dimensional blood flow velocity fields were obtained using echoPIV. Visual inspection was performed by five observers to evaluate feasibility. The contrast-to-background ratio and average vector correlation were calculated and compared between stented and native vessel segments. Flow quantification with echoPIV was feasible in 128 of 129 locations (99%), with optimal quantification in 40 of 129 locations (31%). Partial quantification was achieved in 88 of 129 locations (68%), where one or multiple limiting issues occurred (not related to the stent) including loss of correlation during systole (57/129), short vessel segments (20/129), loss of contrast during diastole (20/129) and shadow regions (20/129). The contrast-to-background ratio and vector correlation were lower downstream in the imaged blood vessel, independent of the location of the stent. In conclusion, echoPIV was feasible in stents placed in the aortoiliac region, and the stents did not adversely affect flow tracking., Competing Interests: Conflicts of interest disclosure The authors declare no conflicts of interest., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: High-risk human papillomavirus (hrHPV) testing has been recommended by the World Health Organization as the primary screening test in cervical screening programs. The option of self-sampling for this screening method can potentially increase women's participation. Designing screening programs to implement this method among underscreened populations will require contextualized evidence., Methods: PREvention and SCReening Innovation Project Toward Elimination of Cervical Cancer (PRESCRIP-TEC) will use a multi-method approach to investigate the feasibility of implementing a cervical cancer screening strategy with hrHPV self-testing as the primary screening test in Bangladesh, India, Slovak Republic and Uganda. The primary outcomes of study include uptake and coverage of the screening program and adherence to follow-up. These outcomes will be evaluated through a pre-post quasi-experimental study design. Secondary objectives of the study include the analysis of client-related factors and health system factors related to cervical cancer screening, a validation study of an artificial intelligence decision support system and an economic evaluation of the screening strategy., Discussion: PRESCRIP-TEC aims to provide evidence regarding hrHPV self-testing and the World Health Organization's recommendations for cervical cancer screening in a variety of settings, targeting vulnerable groups. The main quantitative findings of the project related to the impact on uptake and coverage of screening will be complemented by qualitative analyses of various determinants of successful implementation of screening. The study will also provide decision-makers with insights into economic aspects of implementing hrHPV self-testing, as well as evaluate the feasibility of using artificial intelligence for task-shifting in visual inspection with acetic acid., Trial Registration: ClinicalTrials.gov, NCT05234112 . Registered 10 February 2022., (© 2022. The Author(s).)

Background: Local blood flow affects vascular disease and outcomes of endovascular treatment, but quantifying it is challenging, especially inside stents. We assessed the feasibility of blood flow quantification in native and stented femoral arteries, using high-frame-rate (HFR) contrast-enhanced ultrasound (CEUS) particle image velocimetry (PIV), also known as echoPIV., Methods: Twenty-one patients with peripheral arterial disease, recently treated with a stent in the femoral artery, were included. HFR CEUS measurements were performed in the native femoral artery and at the inflow and outflow of the stent. Two-dimensional blood flow was quantified through PIV analysis. EchoPIV recordings were visually assessed by five observers and categorised as optimal, partial, or unfeasible. To evaluate image quality and tracking performance, contrast-to-tissue ratio (CTR) and vector correlation were calculated, respectively., Results: Fifty-eight locations were measured and blood flow quantification was established in 49 of them (84%). Results were optimal for 17/58 recordings (29%) and partial for 32 recordings (55%) due to loss of correlation (5/32; 16%), short vessel segment (8/32; 25%), loss of contrast (14/32; 44%), and/or shadows (18/32; 56%). In the remaining 9/58 measurements (16%) no meaningful flow information was visualised. Overall, CTR and vector correlation were lower during diastole. CTR and vector correlation were not different between stented and native vessel segments, except for a higher native CTR at the inflow during systole (p = 0.037)., Conclusions: Blood flow quantification is feasible in untreated and stented femoral arteries using echoPIV. Limitations remain, however, none of them related to the presence of the stent., Trial Registration: ClinicalTrials.gov, NCT04934501 (retrospectively registered)., (© 2022. The Author(s) under exclusive licence to European Society of Radiology.)

Aim: The addition of etidronic acid (HEDP) to sodium hypochlorite (NaOCl) could increase the antibiofilm potency of the irrigant, whilst maintaining the benefits of continuous chelation. Studies conducted so far have shown that mixing HEDP with NaOCl solutions of relatively low concentration does not compromise the antibiofilm efficacy of the irrigant. However, the working lifespan of NaOCl may decrease resulting in a reduction of its antibiofilm efficacy over time (efficiency). In this regard, continuous irrigant replenishment needs to be examined. This study investigated the response of a dual-species biofilm when challenged with 2% and 5% NaOCl mixed with HEDP for a prolonged timespan and under steady laminar flow., Methodology: Dual-species biofilms comprised of Streptococcus oralis J22 and Actinomyces naeslundii T14V-J1 were grown on human dentine discs in a constant depth film fermenter (CDFF) for 96 h. Biofilms were treated with 2% and 5% NaOCl, alone or mixed with HEDP. Irrigants were applied under steady laminar flow for 8 min. Biofilm response was evaluated by means of optical coherence tomography (OCT). Biofilm removal, biofilm disruption, rate of biofilm loss and disruption as well as bubble formation were assessed. One-way anova, Wilcoxon's signed-rank test and Kruskal-Wallis H test were performed for statistical analysis of the data. The level of significance was set at a ≤.05., Results: Increasing NaOCl concentration resulted in increased biofilm removal and disruption, higher rate of biofilm loss and disruption and increased bubble formation. Mixing HEDP with NaOCl caused a delay in the antibiofilm action of the latter, without compromising its antibiofilm efficacy., Conclusions: NaOCl concentration dictates the biofilm response irrespective of the presence of HEDP. The addition of HEDP resulted in a delay in the antibiofilm action of NaOCl. This delay affects the efficiency, but not the efficacy of the irrigant over time., (© 2022 The Authors. International Endodontic Journal published by John Wiley & Sons Ltd on behalf of British Endodontic Society.)

Purpose: The feasibility of using a compressed interwoven Supera stent as a flow diverting device for popliteal aneurysms was recently demonstrated in patients. It is unclear, however, what the optimal flow diverting strategy is, because of the fusiform shape of popliteal aneurysms and their exposure to triphasic flow. To assess this flow diverting strategy for popliteal aneurysms, flow profiles and thrombus formation likelihood were investigated in popliteal aneurysm models., Materials and Methods: Six popliteal aneurysm models were created and integrated into a pulsatile flow set-up. These models covered a bent and a straight anatomy in three configurations: control, single-lined and dual-lined Supera stents. Two-dimensional flow velocities were visualized by laser particle image velocimetry. In addition, the efficacy of the stent configurations for promoting aneurysm thrombosis was assessed by simulations of residence time and platelet activation., Results: On average for the two anatomies, the Supera stent led to a twofold reduction of velocities in the aneurysm for single-lined stents, and a fourfold reduction for dual-lined stents. Forward flow was optimally diverted, whereas backward flow was generally deflected into the aneurysm. The dual-lined configuration led to residence times of 15-20 s, compared to 5-15 s for the single stent configurations. Platelet activation potential was not increased by the flow diverting stents., Conclusion: A compressed Supera stent was successfully able to divert flow in a popliteal aneurysm phantom. A dual-lined configuration demonstrated superior hemodynamic characteristics compared to its single-lined counterpart., (© 2022. The Author(s).)

Ultrasound (US) contrast agents consist of microbubbles ranging from 1 to 10 μm in size. The acoustical response of individual microbubbles can be studied with high-frame-rate optics or an "acoustical camera" (AC). The AC measures the relative microbubble oscillation while the optical camera measures the absolute oscillation. In this article, the capabilities of the AC are extended to measure the absolute oscillations. In the AC setup, microbubbles are insonified with a high- (25 MHz) and low-frequency US wave (1-2.5 MHz). Other than the amplitude modulation (AM) from the relative size change of the microbubble (employed in Renaud, Bosch, van der Steen, and de Jong (2012a). "An 'acoustical camera' for in vitro characterization of contrast agent microbubble vibrations," Appl. Phys. Lett. 100(10), 101911, the high-frequency response from individual vibrating microbubbles contains a phase modulation (PM) from the microbubble wall displacement, which is the extension described here. The ratio of PM and AM is used to determine the absolute radius, R 0 . To test this sizing, the size distributions of two monodisperse microbubble populations ( R = 2.1 and 3.5 μm) acquired with the AC were matched to the distribution acquired with a Coulter counter. As a result of measuring the absolute size of the microbubbles, this "extended AC" can capture the full radial dynamics of single freely floating microbubbles with a throughput of hundreds of microbubbles per hour.

B cells fulfill an important role in the adaptive immunity. Upon activation and immunoglobulin (IG) class switching, these cells function in the humoral immunity compartment as plasma cells. For clinical applications, it can be important to quantify (switched) B cells accurately in a variety of body fluids and tissues of benign, inflammatory and malignant origin. For decades, flow cytometry and immunohistochemistry (IHC) have been the preferred methods for quantification. Although these methods are widely used, both depend on the accessibility of B cell epitopes and therefore require intact (fixed) cells. Whenever samples are low in quantity and/or quality, accurate quantification can be difficult. By shifting the focus from epitopes to DNA markers, quantification of B cells remains achievable. During differentiation and maturation, B cells are subjected to programmed genetic recombination processes like VDJ rearrangements and class switch recombination (CSR), which result in deletion of specific sequences of the IGH locus. These cell type-specific DNA "scars" (loss of sequences) in IG genes can be exploited as B cell markers in digital PCR (dPCR) based quantification methods. Here, we describe a novel, specific and sensitive digital PCR-based method to quantify mature and switched B cells in DNA specimens of benign and (copy number unstable) malignant origin. We compared this novel way of B cell quantitation with flow cytometric and immunohistochemical methods. Through cross-validation with flow cytometric sorted B cell subpopulations, we gained quantitative insights into allelic involvement in different recombination processes in the IGH locus. Our newly developed method is accurate and independent of the cellular context, offering new possibilities for quantification, even for (limited) small samples like liquid biopsies., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)