A Generalized Quantitative Microwave Medical Sensing and Imaging System for the Detection of Alzheimer’s Disease

Alzheimer’s disease (AD) is a neurodegenerative disorder that leads to cognitive impairment and is characterized by high morbidity, mortality, and economic burden. Aβ amyloid is one of pathological features of AD, which has chiral properties, and there are limitations in conventional brain imaging methods for detecting Aβ. Computed tomography (CT) and magnetic resonance imaging (MRI) are unable to detect Aβ, and positron emission tomography (PET) imaging is expensive and has limited availability. Aβ can change the direction of polarization of electromagnetic waves, and thus microwave medical sensing imaging (MMSI) is expected to enable noninvasive measurement of Aβ. In this paper, we propose a generalized MMSI system based on planar Yagi antenna to detect Aβ features, which is mainly used to analyze the effect of chirality on the deflection of electromagnetic waves. In addition, due to the complex electromagnetic environment of the brain and the low signal-to-noise ratio (SNR) during information transmission, we propose to take the axial ratio as the main optimization target for antenna optimization, so as to make the antenna more sensitive to chirality, and then achieve the accurate detection of Aβ. A Yagi antenna with an operating frequency of 1.52–2.21GHz, and the average axial ratio over the operating band is 33dB, was designed and used. According to the simulation, the received signal amplitude will be amplified by a factor of 25 in the presence of chiral substances in the same volume. The results show that the proposed detection system is sensitive to Aβ amyloid and can realize microwave detection of AD.