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Phase-change nanodroplets (PCNDs) have been used in ultrasound imaging, targeted drug delivery, blood-brain-barrier (BBB) opening, sonothrombolysis and histotripsy for over a decade. For these ultrasound applications, PCNDs provide higher in vivo lifetime than microbubbles (MBs), the potential for extravasation inside tumour and on demand activation, which is the transition of the liquid-core of nanodroplets to gaseous microbubbles through acoustic droplet vaporisation (ADV). Operating above the ADV threshold can offer repeatable activation of PCNDs and the subsequent oscillation of acoustically activated PCNDs, which is advantageous in imaging and therapeutic applications. Efficient and repeatable activation of PCNDs require a good understanding of ultrasound parameters and nanodroplet composition for different biomedical applications. Therefore, this article presents a meta-analysis of the effect of ultrasound activation parameters on ADV for various PCNDs in different biomedical applications. About 7,500 articles were considered for this study, but only 45 articles were chosen and evaluated in the meta-analysis based on the following criteria: 1): activation parameters, including ultrasound frequency, peak negative pressure, transmit pulse length or duration have been clearly mentioned, 2), droplets range in nanometre size (<1 µm), 3), experiments are performed at a temperature of 37°C and 4) ADV threshold has been clearly mentioned and observations are not due to inertial cavitation (IC). From selected publications, we recorded the activation frequency (0.06–16 MHz), ultrasound pressure (0.18–14.9 MPa), activation pulse length (µs-ms range) and nanodroplet size for different types of perfluorocarbon PCNDs (C3F8, C4F10, C5F12 and C6F14) and evaluated the relation of these parameters to each other. Finally, a Root Mean Square (RMS)-like power metric, which is a combination of ultrasound peak negative pressure and square root of ultrasound pulse length, is proposed for identifying the ADV threshold behaviour instead of using pressure or mechanical index values. [ABSTRACT FROM AUTHOR]

The aim of the present study is the optimization, construction, and workbench validation of a double-tuned 1H- 23Na volume radio frequency (RF) coil suitable for human head imaging at 7 T, based on the birdcage geometry. The birdcage-like design which is considered is the four-ring model, in which two standard birdcage-like structures with the same diameters are nested along the longitudinal axis. Simulations based on Maxwell's equations are performed to evaluate the RF magnetic field homogeneity and the RF coil efficiency varying the coil geometrical parameters. The RF magnetic field homogeneity is evaluated both on the transverse (z = 0) and longitudinal (y = 0) planes without performing the impedance matching procedure, so that the RF coil symmetry is not perturbed by the matching network. The RF coil efficiency is instead dependent on the effective coil input RF power, and it is evaluated after matching the coil, so that the reflected power is minimized, assuming that the stimulation power is totally delivered to the RF coil. Considering the simulation results and the target application, the useful RF coil geometrical parameters are fixed. The four-ring model, which showed the best performances, has been built and tested on a workbench, using a cylindrical phantom filled with a 0.05 M saline solution as load. This provides the first example of a four-ring realization intended 1H- 23Na for human head imaging at 7 T. [ABSTRACT FROM AUTHOR]

Introduction: Microwave imaging presents several potential advantages including its non-ionising and harmless nature. This open, multicentric, interventional, prospective, non-randomised trial aims to validate MammoWave's artificial intelligence (AI)-based classification algorithm, leveraging microwave imaging, to achieve a sensitivity exceeding 75% and a specificity exceeding 90% in breast screening., Methods and Analysis: 10 000 volunteers undergoing regular mammographic breast cancer screening will be recruited across 9 European centres and invited to participate in the clinical study, involving MammoWave testing on both breasts. MammoWave results will be checked against the reference standard, to be intended as the output of conventional breast examination path (with histological confirmation of cancer cases) with 2 years follow-up. Anonymised clinical and MammoWave's results, including microwave images, associated features and a label provided by the AI-based classification algorithm, will be collected and stored in a dedicated electronic case report form. The prospective study will involve a comparative analysis between the output of the conventional breast examination path (control intervention) and the labels provided by MammoWave's AI system (experimental intervention). These labels will categorise breasts into two groups: breast With Suspicious Finding, indicating the presence of a suspicious lesion or No Suspicious Finding, indicating the absence of a lesion or the presence of a low-suspicion lesion. This trial aims to provide evidence regarding the novel MammoWave's AI system for detecting breast cancer in asymptomatic populations during screening., Ethics and Dissemination: This study was approved by the Research Ethics Committee of the Liguria Region (CET), Italy (CET-Liguria: 524/2023-DB id 13399), the Research Ethics Committee of Complejo Hospitalario de Toledo (CEIC), Spain (CEIC-1094), the National Ethics Committee for Clinical Research (CEIC), Portugal (CEIC-2311KC814), the Bioethical Committee of Pomeranian Medical University in Szczecin, Poland (KB-006/23/2024) and the Zurich Cantonal Ethics Commission, Switzerland (BASEC 2023-D0101). The findings of this study will be disseminated through academic and scientific conferences as well as peer-reviewed journals., Trial Registration Number: NCT06291896., Competing Interests: Competing interests: NG, GT, BK and Alessandra Bigotti are employed by UBT—Umbria Bioengineering Technologies Srl. NG and GT are shareholders of UBT—Umbria Bioengineering Technologies. UBT—Umbria Bioengineering Technologies Srl manufactured the microwave imaging device known as MammoWave. This does not alter our adherence to BMJ Open policies., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY. Published by BMJ.)