Biologically and acoustically compatible chamber for studying ultrasound-mediated delivery of therapeutic compounds

Ultrasound (US), in combination with microbubbles, has been found to be a potential alternative to viral therapies for transfecting biological cells. The translation of this technique to the clinical environment, however, requires robust and systematic optimization of the acoustic parameters needed to achieve a desired therapeutic effect. Currently, a variety of different devices have been developed to transfect cells in vitro, resulting in a lack of standardized experimental conditions and difficulty in comparing results from different laboratories. To overcome this limitation, we propose an easy-to-fabricate and cost-effective device for application in US-mediated delivery of therapeutic compounds. It comprises a commercially available cell culture dish coupled with a silicon-based "lid" developed in-house that enables the device to be immersed in a water bath for US exposure. Described here are the design of the device, characterization of the sound field and fluid dynamics inside the chamber and an example protocol for a therapeutic delivery experiment

Data for Enhancement and passive acoustic mapping of cavitation from fluorescently-tagged MR-visible magnetic microbubbles in vivo

Previous work has demonstrated the potential of magnetically functionalized microbubbles to localize and enhance cavitation activity under focused ultrasound exposure in vitro. The aim of this study was to investigate magnetic targeting of microbubbles for promotion of cavitation in vivo. Fluorescently labelled magnetic microbubbles were administered intravenously in a murine xenograft model. Cavitation was induced using a 0.5 MHz focused ultrasound transducer at peak negative focal pressures of 1.2-2.0 MPa and monitored in real-time using B-mode imaging and passive acoustic mapping. Magnetic targeting was found to increase the amplitude of the cavitation signal by approximately 50% as compared with untargeted bubbles. Post-exposure magnetic resonance imaging indicated deposition of magnetic nanoparticles in tumours. Magnetic targeting was similarly associated with increased fluorescence intensity in the tumours following the experiments. These results suggest that magnetic targeting could be used to improve delivery of cavitation-mediated therapy and that passive acoustic mapping could be used for real-time monitoring of this process

Targeting and characterisation of magnetic microbubbles for drug delivery using passive acoustic mapping

Passive acoustic mapping (PAM) is a versatile technique for monitoring of therapeutic ultrasound, in particular the generation of cavitation and subsequent bubble dynamics. The objective of this thesis was to apply PAM to investigate the activity of different types of cavitation agent and any correlation to therapeutic effects. The work focuses particularly on a new type of agent in the form of microbubbles that can be magnetically targeted, which have shown great potential for localised drug delivery. In this thesis PAM was used to study the behaviour of magnetic microbubbles (MMB) in tissue phantoms, in vitro cell experiments and in vivo mouse models. In tissue phantoms magnetic localisation of microbubble-induced cavitation activity was demonstrated and resolved using PAM. Under clinically relevant flow conditions an increase in the energy of cavitation on the order of 2-5 times was observed using PAM, which was similar to doubling the injected microbubble dose. To facilitate cell experiments a novel chamber system was used with improved variants of MMB as well as condensed magnetic nanodroplets which were shown to enhance uptake of fluorescent small interfering RNA (siRNA), transfection of knockdown siRNA and paclitaxel-induced cell kill. Magnetic targeting was associated with increased cavitation power in PAM as well as increased treatment efficacy measured by biological methods including fluorescence microscopy and flow cytometry. Finally, improved MMB were tested for the first time in vivo under real-time B-mode imaging and PAM, followed by fluorescence and MR imaging to assess distribution. MMB cavitation activity was of similar magnitude to the commercial contrast agent SonoVue®. Cavitation induced by the microbubbles and magnetic targeting were both associated with increases in fluorescence and MRI contrast in tumours. The therapeutic potential of MMB and monitoring power of PAM were thus demonstrated.</p

Data for Enhancement and passive acoustic mapping of cavitation from fluorescently-tagged MR-visible magnetic microbubbles in vivo

Previous work has demonstrated the potential of magnetically functionalized microbubbles to localize and enhance cavitation activity under focused ultrasound exposure in vitro. The aim of this study was to investigate magnetic targeting of microbubbles for promotion of cavitation in vivo. Fluorescently labelled magnetic microbubbles were administered intravenously in a murine xenograft model. Cavitation was induced using a 0.5 MHz focused ultrasound transducer at peak negative focal pressures of 1.2-2.0 MPa and monitored in real-time using B-mode imaging and passive acoustic mapping. Magnetic targeting was found to increase the amplitude of the cavitation signal by approximately 50% as compared with untargeted bubbles. Post-exposure magnetic resonance imaging indicated deposition of magnetic nanoparticles in tumours. Magnetic targeting was similarly associated with increased fluorescence intensity in the tumours following the experiments. These results suggest that magnetic targeting could be used to improve delivery of cavitation-mediated therapy and that passive acoustic mapping could be used for real-time monitoring of this process. This dataset includes processed experimental data for the paper ‘Enhancement and passive acoustic mapping of cavitation from fluorescently-tagged MR-visible magnetic microbubbles in vivo’, accepted for publication in Ultrasound in Medicine and Biology in August 2016. The data is organised in the order of the figures in the paper and includes: Fig 1: TIFF figure and SVG source file, TXT caption Fig 2: TIFF images, CSV data and Matlab FIG files, TXT caption Fig 3: TIFF and Matlab FIG files, TXT caption Fig 4: TIFF image and CSV data files, TXT caption Fig 5: TIFF images and Matlab FIG files, TXT caption Fig 6: TIFF images, Matlab FIG files and CSV data file, TXT caption Fig 7: CSV data file, TXT caption Fig 8: TIFF and PNG images and CSV data file, TXT caption Data were gathered using microscopy, ultrasound and MRI techniques described in detail in the paper

Image quality evaluation of ultrasound imaging systems: advanced B‐modes

The Quality assurance of ultrasound clinical imaging systems is essential for maintaining their performance to the highest level and for complying with the requirements by various regulatory and accrediting agencies. Although there is no standardization yet, most of the quality assessment procedures available in literature are proposed for B-mode and Doppler imaging. However, ultrasound imaging systems offer a variety of advanced imaging modes, besides B-mode and Doppler, which are primarily aimed at improving image quality. This study presents computer-based methods for evaluating image quality for the advanced imaging modes of ultrasound imaging systems: harmonic imaging, spatial compounding imaging, adaptive speckle reduction, and tissue aberration correction. The functions and parameters proposed for evaluating image quality are: grayscale mapping function, image contrast, contrast-to-noise ratio (CNR), and high-contrast spatial resolution. We present our computer-based methods for evaluating image quality of these modes with a number of probe and scanner combinations, which were employed to image targets in ultrasound phantoms. The functions and parameters here proposed in image quality performance evaluation are: grayscale mapping function, image contrast, CNR, and high-contrast spatial resolution. We show that these quantities could be useful in developing standardized methods for evaluating the advanced ultrasound imaging modes, especially when the advanced mode resulted in subtle visual differences

Breast ultrasound technology and performance evaluation of ultrasound equipment: B-mode

Ultrasound (US) has become increasingly important in imaging and image-guided interventional procedures. In order to ensure that the imaging equipment performs to the highest level achievable and thus provides reliable clinical results, a number of quality control (QC) methods have been developed. Such QC is increasingly required by accrediting agencies and professional organizations; however, these requirements typically do not include detailed procedures for how the tests should be performed. In this paper, a detailed overview of QC methods for general and breast US imaging using computer-based objective methods is described. The application of QC is then discussed within the context of a common clinical application (US-guided needle biopsy) as well as for research applications, where QC may not be mandated, and thus is rarely discussed. The implementation of these methods will help in finding early stage equipment faults and in optimizing image quality, which could lead to better detection and classification of suspicious findings in clinical applications, as well as improving the robustness of research studies

Image quality evaluation of ultrasound imaging systems: advanced B-modes

The Quality assurance of ultrasound clinical imaging systems is essential for maintaining their performance to the highest level and for complying with the requirements by various regulatory and accrediting agencies. Although there is no standardization yet, most of the quality assessment procedures available in literature are proposed for B-mode and Doppler imaging. However, ultrasound imaging systems offer a variety of advanced imaging modes, besides B-mode and Doppler, which are primarily aimed at improving image quality. This study presents computer-based methods for evaluating image quality for the advanced imaging modes of ultrasound imaging systems: harmonic imaging, spatial compounding imaging, adaptive speckle reduction, and tissue aberration correction. The functions and parameters proposed for evaluating image quality are: grayscale mapping function, image contrast, contrast-to-noise ratio (CNR), and high-contrast spatial resolution. We present our computer-based methods for evaluating image quality of these modes with a number of probe and scanner combinations, which were employed to image targets in ultrasound phantoms. The functions and parameters here proposed in image quality performance evaluation are: grayscale mapping function, image contrast, CNR, and high-contrast spatial resolution. We show that these quantities could be useful in developing standardized methods for evaluating the advanced ultrasound imaging modes, especially when the advanced mode resulted in subtle visual differences

Ultrasound-enhanced siRNA delivery using magnetic nanoparticle-loaded chitosan-deoxycholic acid nanodroplets

Small interfering RNA (siRNA) has significant therapeutic potential but its clinical translation has been severely inhibited by a lack of effective delivery strategies. Previous work has demonstrated that perfluorocarbon nanodroplets loaded with magnetic nanoparticles can facilitate the intracellular delivery of a conventional chemotherapeutic drug. The aim of this study was to determine whether a similar agent could provide a means of delivering siRNA, enabling efficient transfection without degradation of the molecule. Chitosan-deoxycholic acid nanoparticles containing perfluoropentane and iron oxide (d0 = 7.5 ± 0.35 nm) with a mean hydrodynamic diameter of 257.6 ± 10.9 nm were produced. siRNA (AllStars Hs cell death siRNA) was electrostatically bound to the particle surface and delivery to lung cancer cells and breast cancer cells was investigated with and without ultrasound exposure (500 kHz, 1 MPa peak-to-peak focal pressure, 40 cycles per burst, 1 kHz PRF, 10 seconds duration). The results showed that siRNA functionality was not impaired by the treatment protocol and that the nanodroplets were able to successfully promote siRNA uptake, leading to significant apoptosis (52.4%) 72 hours after ultrasound treatment