This paper presents the design of a novel lowcomplexity microwave imaging system for monitoring brain stroke. In particular, the design is concerned with the determination of the optimal layout of the antennas array, namely minimum number, positions and polarization of the radiating elements, enabling the acquisition of an amount of data such to assure a reliable imaging. This goal is achieved by adopting a rigorous design procedure based on the inspection of the singular value decomposition of the relevant discretized scattering operator and taking into account the actual dynamics and signal to noise ratio of the measurement system. The design is first carried out in the case of ideal dipoles and then extended and assessed for actual printed monopole antennas, developed for the imaging system. The resulting system is a helmet equipped with 24 antennas, whose performances have been numerically validated in terms of both spatial resolution and reconstruction capabilities, by employing full-wave numerical simulations, realistic 3-D phantoms of the human head and an accurate modeling of the actual antennas employed in the system.

This work focuses on brain stroke imaging via microwave technology. In particular, the open issue of monitoring patients after stroke onset is addressed here in order to provide clinicians with a tool to control the effectiveness of administered therapies during the follow-up period. In this paper, a novel prototype is presented and characterized. The device is based on a low-complexity architecture which makes use of a minimum number of properly positioned and designed antennas placed on a helmet. It exploits a differential imaging approach and provides 3D images of the stroke. Preliminary experiments involving a 3D phantom filled with brain tissue-mimicking liquid confirm the potential of the technology in imaging a spherical target mimicking a stroke of a radius equal to 1.25 cm.

In this paper, a microwave technique for breast cancer imaging is presented. The approach is based on the use of magnetic nanoparticles as contrast agent to induce a nonnull magnetic contrast selectively localized within the tumor. This allows us to face cancer imaging as the reconstruction of a magnetic contrast from the corresponding scattered field. To extract, from the measured data the contribution due to the magnetic contrast, i.e., the signal meaningful for cancer imaging, the approach exploits the possibility of modulating the magnetic response of magnetic nanoparticles by means of a polarizing magnetic field. The achievable reconstruction capabilities and the robustness against uncertainties on the electric features of the surrounding electric scenario are assessed by means of numerical examples.

This paper deals with the optimal design of phased arrays for medical applications of microwaves, such as hyperthermia treatments and cancer imaging. To address this problem, microwave engineers have to face peculiar and novel challenges, since the region of interest is a 3-D domain in the near field of the array and consists of a highly heterogeneous and lossy medium, whose characteristics change from patient to patient. For this reason, we have to reconsider basic fundamentals about phased array design, in order to devise proper tools and criteria. In particular, we address the design of the system layout, i.e., the choice of the number and locations of the array elements, as this represents the preliminary fundamental problem to face. To this end, we first formulate the two general problems relevant to biomedical applications-the design of an array for therapeutic purposes and of an array for diagnostic/imaging goals. We then address the proper theoretical and analytic tools and methods that enable pursuit of an optimal design with respect to given constraints. Finally, we provide some examples to show how the design procedure can be carried out in practice.

Magnetic nanoparticles-enhanced microwave imaging has been recently proposed to overcome the limitations of conventional microwave imaging methods for breast cancer monitoring. In this paper, we discuss how to tackle the linear inverse scattering problem underlying this novel technique in an effective way. In particular, our aim is to minimize the required a priori patient-specific information, avoid occurrence of false positives, and keep the computational burden low. By relying on an extensive numerical analysis in realistic conditions, we show that the method can provide accurate and reliable images without information on the inner structure of the inspected breast and with an only rough knowledge of its shape. Notably, this allows moving to an offline stage the computationally intensive part of the image formation procedure. In addition, we show how to appraise the total amount of magnetic contrast agent targeted in the tumor.

Purpose: This paper presents a numerical study aiming at assessing the effectiveness of a recently proposed optimisation criterion for determining the optimal operative conditions in magnetic nanoparticle hyperthermia applied to the clinically relevant case of brain tumours. Materials and methods: The study is carried out using the Zubal numerical phantom, and performing electromagnetic–thermal co-simulations. The Pennes model is used for thermal balance; the dissipation models for the magnetic nanoparticles are those available in the literature. The results concerning the optimal therapeutic concentration of nanoparticles, obtained through the analysis, are validated using experimental data on the specific absorption rate of iron oxide nanoparticles, available in the literature. Results: The numerical estimates obtained by applying the criterion to the treatment of brain tumours shows that the acceptable values for the product between the magnetic field amplitude and frequency may be two to four times larger than the safety threshold of 4.85 × 10⁸A/m/s usually considered. This would allow the reduction of the dosage of nanoparticles required for an effective treatment. In particular, depending on the tumour depth, concentrations of nanoparticles smaller than 10 mg/mL of tumour may be sufficient for heating tumours smaller than 10 mm above 42 °C. Moreover, the study of the clinical scalability shows that, whatever the tumour position, lesions larger than 15 mm may be successfully treated with concentrations lower than 10 mg/mL. The criterion also allows the prediction of the temperature rise in healthy tissue, thus assuring safe treatment. Conclusions: The criterion can represent a helpful tool for planning and optimising an effective hyperthermia treatment.