Supported lipid bilayers (SLBs) are popular models of cell membranes with potential biotechnological applications, yet the mechanism of SLB formation is only partially understood. In this study, the adsorption and subsequent conformational changes of sonicated unilamellar vesicles on silica supports were investigated by quartz crystal microbalance with dissipation monitoring and atomic force microscopy, using mixtures of zwitterionic, negatively charged, and positively charged lipids, both in the presence and in the absence of Ca 2 + ions. Four different pathways of vesicle deposition could be distinguished. Depending on their charge, vesicles i), did not adsorb; ii), formed a stable vesicular layer; or iii), decomposed into an SLB after adsorption at high critical coverage or iv), at low coverage. Calcium was shown to enhance the tendency of SLB formation for negatively charged and zwitterionic vesicles. The role of vesicle-support, interbilayer, and intrabilayer interactions in the formation of SLBs is discussed.

Pathways of lipid vesicle deposition on solid surfaces: A combined QCM-D and AFM study

Here, we present two different brain diagnostic devices based on microwave technology and the associated two first proof-of-principle measurements that show that the systems can differentiate hemorrhagic from ischemic stroke in acute stroke patients, as well as differentiate hemorrhagic patients from healthy volunteers. The system was based on microwave scattering measurements with an antenna system worn on the head. Measurement data were analyzed with a machine-learning algorithm that is based on training using data from patients with a known condition. Computer tomography images were used as reference. The detection methodology was evaluated with the leave-one-out validation method combined with a Monte Carlo-based bootstrap step. The clinical motivation for this project is that ischemic stroke patients may receive acute thrombolytic treatment at hospitals, dramatically reducing or abolishing symptoms. A microwave system is suitable for prehospital use, and therefore has the potential to allow significantly earlier diagnosis and treatment than today.

https://publications.lib.chalmers.se/records/fulltext/207371/local_207371.pdf

Microwave-Based Stroke Diagnosis Making Global Prehospital Thrombolytic Treatment Possible

Widely used medical imaging systems in clinics currently rely on X-rays, magnetic resonance imaging, ultrasound, computed tomography, and positron emission tomography. The aforementioned technologies provide clinical data with a variety of resolution, implementation cost, and use complexity, where some of them rely on ionizing radiation. Microwave sensing and imaging (MSI) is an alternative method based on nonionizing electromagnetic (EM) signals operating over the frequency range covering hundreds of megahertz to tens of gigahertz. The advantages of using EM signals are low health risk, low cost implementation, low operational cost, ease of use, and user friendliness. Advancements made in microelectronics, material science, and embedded systems make it possible for miniaturization and integration into portable, handheld, mobile devices with networking capability. MSI has been used for tumor detection, blood clot/stroke detection, heart imaging, bone imaging, cancer detection, and localization of in-body RF sources. The fundamental notion of MSI is that it exploits the tissue-dependent dielectric contrast to reconstruct signals and images using radar-based or tomographic imaging techniques. This paper presents a comprehensive overview of the active MSI for various medical applications, for which the motivation, challenges, possible solutions, and future directions are discussed.

On the Opportunities and Challenges in Microwave Medical Sensing and Imaging

Hyperthermia therapy (HT) is the exposure of a region of the body to elevated temperatures to achieve a therapeutic effect. HT anticancer properties and its potential as a cancer treatment have been studied for decades. Techniques used to achieve a localised hyperthermic effect include radiofrequency, ultrasound, microwave, laser and magnetic nanoparticles (MNPs). The use of MNPs for therapeutic hyperthermia generation is known as magnetic hyperthermia therapy (MHT) and was first attempted as a cancer therapy in 1957. However, despite more recent advancements, MHT has still not become part of the standard of care for cancer treatment. Certain challenges, such as accurate thermometry within the tumour mass and precise tumour heating, preclude its widespread application as a treatment modality for cancer. MHT is especially attractive for the treatment of glioblastoma (GBM), the most common and aggressive primary brain cancer in adults, which has no cure. In this review, the application of MHT as a therapeutic modality for GBM will be discussed. Its therapeutic efficacy, technical details, and major experimental and clinical findings will be reviewed and analysed. Finally, current limitations, areas of improvement, and future directions will be discussed in depth.

Magnetic hyperthermia therapy for the treatment of glioblastoma: a review of the therapy's history, efficacy and application in humans.

Clinical trials have shown that hyperthermia (HT), i.e. an increase of tissue temperature to 39–44 °C, significantly enhance radiotherapy and chemotherapy effectiveness [1]. Driven by the developments in computational techniques and computing power, personalised hyperthermia treatment planning (HTP) has matured and has become a powerful tool for optimising treatment quality. Electromagnetic, ultrasound, and thermal simulations using realistic clinical set-ups are now being performed to achieve patient-specific treatment optimisation. In addition, extensive studies aimed to properly implement novel HT tools and techniques, and to assess the quality of HT, are becoming more common. In this paper, we review the simulation tools and techniques developed for clinical hyperthermia, and evaluate their current status on the path from ‘model’ to ‘clinic’. In addition, we illustrate the major techniques employed for validation and optimisation. HTP has become an essential tool for improvement, control, and ...

https://www.tandfonline.com/doi/pdf/10.3109/02656736.2013.790092

Simulation techniques in hyperthermia treatment planning

The present invention relates to a method and system for selective heating of an object based on a model of said object, the method comprising the steps of: modeling of a wave front of a source, which wave front is propagated through the model object from a virtual antenna placed in the model of the specific region where heating is desired, simulating a radiated field and measuring the same using computer models of surrounding antenna system, time-reversing, transferring and synthesizing the signal in a real system, transmitting by a real antenna system the field in a time reversed order, and refocusing of time reversed signal at the original s the invariance of a wave equation under time reversal.

Method and system relating to hyperthermia

An efficient 3D microwave tomography system based on wide band antennas and detailed modelling using the finite difference time domain methods is presented together with a microwave system design study and a novel microwave hyperthermia cancer treatment system based on a time reversal algorithms.

Broadband microwave based diagnostics and treatment

Addition of hyperthermia to radiotherapy has been shown beneficial in management of many types of cancer [1], including Head and Neck tumors [2] The objective of hyperthermia treatment is to raise the temperature in the tumor to a therapeutic level 40–44°C for typically 60 minutes to achieve cell death or render the cells more sensitive to ionizing radiation and chemical toxins In our work, we aim to develop H&N applicator that is capable of modifying the focus size according to tumor position and volume The system consists of a number of antennas placed around a patient, relying on a constructive wave interference to selectively heat the tumour The spatial control of the foci spot and thus the quality of hyperthermia treatment can be controled by varying operational frequency in addition to amplitude and phase optimization Due to different wavelengths, treatment associated hot spots often appear at different locations In conjunction with cooling effect of the blood, the multi-frequency system have potential to achieve higher tumor temperature with ‘same’ constraints on hot spots In this paper we investigated if combination of treatment plans utilizing sequential application of various frequencies is superior to the heating with single frequency settings

Multifrequency approach in hyperthermia treatment planning: Impact of frequency on SAR distribution in head and neck

The laboratory prototype of an UWB hyperthermia applicator is presented and tested for treatment of tumors in head and neck region. The focusing ability of the presented applicator for treatment of neck tumors has been tested on a homogeneous muscle phantom at 500 MHz. Two tumor positions were investigated: one in the center and one in the side of the mid-transverse plane of the phantom. The captured temperature images show the agreement between the planned and the measured focal spots and acceptable temperature increase in these areas.

Experimental evaluation of UWB applicator prototype for head and neck hyperthermia

Microwave based diagnostics and treatment will be discussed with application to stroke diagnostics, 3-D microwave tomography with application to breast cancer diagnostics and microwave hyperthermia with application to cancer treatment.

Hana Dobsicek Trefna

Papers

Method and system relating to hyperthermia

Broadband microwave based diagnostics and treatment

Multifrequency approach in hyperthermia treatment planning: Impact of frequency on SAR distribution in head and neck

Experimental evaluation of UWB applicator prototype for head and neck hyperthermia

Microwave based diagnostics and treatment