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Magnetic nanoparticles enhanced microwave imaging has a great potential in breast cancer diagnosis. In fact, thanks to the non-magnetic nature of human issues, it would allow high specificity diagnosis already at early stages. To meet this goal, a crucial requirement is to design and built an imaging device free of spurious magnetic effects, which could hide the useful signal due to the magnetic nanoparticles targeted to the tumor or induce false positives. In particular, spurious effect -free measurements must be ensured up to the precision required to gather the very low useful signal. In this communication, we report the preliminary results on an investigation aimed to assess the origin of the possible spurious magnetic signals, in order to devise effective actions for their elimination.

This paper concerns with a recently proposed approach of blind focused microwave hyperthermia, exploiting magnetic nanoparticles as contrast agents, and aims at numerically assessing the approach in the clinically relevant case of the treatment of neck tumors. To this respect, a realistic scheme, inspired by the prototypal system called Hypercollar, has been adopted. The well-known Zubal phantom has been exploited as human model. The numerical results show that the proposed approach works well also in a realistic and complex situations like the one considered in this study.

Magnetic nanoparticles enhanced microwave imaging relies on the capability of modulating the response of such nanocomponents at microwaves by means of a (low frequency) polarizing magnetic field. In medical imaging, this capability allows for the detection and imaging of tumors loaded with nanoparticles. As the useful signal is the one which arises from nanoparticles, it is crucial to remove sources of undesired disturbance to enable the diagnosis of early-stage tumors. In particular, spurious signals arise from instrumental drift, as well as from the unavoidable interaction between the polarizing field and the imaging system. In this paper, we experimentally assess and characterize such spurious effects in order to set the optimal working conditions for magnetic nanoparticles enhanced microwave imaging of cancer. To this end, simple test devices, which include all components typically comprised in a microwave imaging system, have been realized and exploited. The experiment’s results allow us to derive design formulas and guidelines useful for limiting the impact of unwanted magnetic effects, as well as that relative to the instrumental drift on the signal generated by the magnetic nanoparticles-loaded tumor.

Magnetic nanoparticles-aided microwave imaging is an emerging modality for the diagnosis of early stage tumors. It exploits the possibility of modulating the response at microwaves of magnetic nanoparticles, employed as contrast agent selectively accumulated into the tumor. In this paper, we describe the results of an experimental study aimed at establishing the actual detection limits of the approach, namely the minimum amount of magnetic nanoparticles to be delivered for a reliable imaging. The assessment is carried out on breast phantoms made of ex-vivo minced pig tissues and using commercially available magnetic nanoparticles. The results show that it is possible to detect amounts of magnetic nanoparticles between 2 and 7 mg, dispersed in a volume of about one cubic centimeter, depending on the breast type. While such quantities are already consistent with those currently reachable via active selective targeting, an in-depth analysis of the results allows to identify strategies to further lower the detection limits up to four times, by refining the measurement set-up and setting the amplitude of the polarizing magnetic field modulating the nanoparticle response to a suitable value.

This paper aims to assess a recently proposed approach for microwave hyperthermia, exploiting magnetic nanoparticles as modulable contrast agents in order to blindly focus on the tumor the electric field radiated by an antenna array. The approach has been improved and numerically assessed in the realistic and clinically relevant case of the treatment of neck tumors. To this end, a realistic system, whose layout is inspired to an existing one, currently under clinical testing, has been considered. The Zubal phantom has been exploited to carry out the simulations. The numerical results show that the proposed blind focusing approach works properly even in realistic and complex situations like the one considered in this paper. Moreover, the results compare very well with those obtained through not-blind focusing approaches, based on the knowledge of geometry, positioning, and electric properties of the irradiated tissues. The robustness of approach against the measurement noise has been also analyzed, in order to identify the requirements that the measurement apparatuses must satisfy and the minimum amount of magnetic nanoparticles to be administered to the patient in order to make the approach feasible. The performed thermal analysis confirmed the ability of the approach to selectively heat the tumor. The proposed approach could be a valid alternative to achieve an effective field focusing without any a priori information on the electric and geometrical properties of the anatomical region to be treated. Moreover, it could be employed in combination with magnetic hyperthermia to improve the effectiveness of the therapy.