Performance assessment of microwave tomography and radar imaging using an anthropomorphic brain phantom

IEEE Open J. Antennas Propag.

Karadima

et al. 2022

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Over the last two decades, metamaterials (MMs) and metasurfaces (MTSs) have been used to fabricate innovative antenna designs, offering cost-effective solutions compared to conventional radiating systems. This paper investigates the feasibility of combining MM design concepts and imaging techniques to create innovative microwave imaging systems. In particular, we present an experimental study with the aim of enhancing microwave imaging for haemorrhagic stroke detection using a new MTS design. First, we show the improvement in performance for a stand-alone MTS-loaded antenna, by studying its operating characteristics in the near and far fields. Then, we assess the performance of the MTS on the reconstruction results from simulations and measurements on two tissue-mimicking gel-based brain phantoms with a cylindrical target representing the bleeding in haemorrhagic stroke. The brain phantom was immersed inside an imaging tank filled with 90% glycerol matching liquid. To perform the image reconstructions, we used both a Huygens based radar algorithm and a DBIM-TwIST tomography algorithm. Our simulation and measurement results indicate that the proposed MTS design improves target localization and decreases image artefacts for the tomographic algorithm and enables target's detection through our radar technique, paving the way for a hybrid microwave imaging prototype with MTS enhanced antennas.

Section: Introductionmentioning

confidence: 85%

“…To examine the performance of both algorithms experimentally, gelatin-oil mixtures based on the phantom preparation method described in [39], and investigated on phantoms in [21], [23], were prepared. Two mixtures were produced to mimic the average brain and blood layers.…”

Section: Experimental Methodologymentioning

confidence: 99%

The Use of Metasurfaces to Enhance Microwave Imaging: Experimental Validation for Tomographic and Radar-Based Algorithms

Ghavami

IEEE Open J. Antennas Propag.

Karadima

et al. 2022

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“…Our previous developed microwave tomography (MWT) scanner proposed for microwave head imaging [12], [13] consists of eight spear patch antennas immersed in a 90% glycerol-water mixture and placed elliptically around our anthropomorphic head model. This 3D printed head model is made of nylon and is used as a holder for our liquid phantom that, once solidified, can mimic the brain.…”

Section: Antenna Systemsmentioning

confidence: 99%

A New Metasurface-Enhanced Microstrip Patch Antenna for Haemorrhagic Stroke Detection

2021 15th European Conference on Antennas and Propagation (EuCAP)

Guo

et al. 2021

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This paper presents a new printed square monopole antenna (PSMA) for haemorrhagic stroke detection, enhanced by a metasurface (MTS) superstrate. To show the capabilities of MTS technology in microwave brain imaging, three different tomographic systems are compared in CST Microwave Studio. Our previous developed headband scanner operating in a lossy matching medium is compared to two brain scanners operating in air: a 8-PSMA system and a 8-MTS-enhanced PSMA system. For image reconstruction we used the distorted Born iterative method (DBIM) combined with two-step iterative shrinkage/thresholding (TwIST) algorithm. Our results indicate that a blood-mimicking target placed inside the brain volume of our head model can be detected avoiding the use of a liquid and bulky matching medium. In addition, our MTS superstrate enhances the antennas' reflection coefficient and increases the signal difference due to the presence of the target, which translates into more accurate reconstructions. Thus, MTS technology may be a significant hardware advancement towards the development of functional and ergonomic MWI scanners for haemorrhage detection.

“…To this end, this work validates our previous designed MTS film by presenting experiments with an elliptical brain phantom including cylindrical stroke-mimicking targets. Our experimental results suggest that the MTS film employed to enhance the sensitivity of our custom-made MWT prototype [ 31 ] can have a positive impact when placed on the head, closely fixed to the MWI array’s antennas. Then, we show a detailed simulation study on the performance of a new MTS-enhanced printed square monopole antenna (PSMA) operating in air.…”

Section: Introductionmentioning

confidence: 99%

Metasurface-Enhanced Antennas for Microwave Brain Imaging

Guo

et al. 2021

Diagnostics

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Stroke is a very frequent disorder and one of the major leading causes of death and disability worldwide. Timely detection of stroke is essential in order to select and perform the correct treatment strategy. Thus, the use of an efficient imaging method for an early diagnosis of this syndrome could result in an increased survival’s rate. Nowadays, microwave imaging (MWI) for brain stroke detection and classification has attracted growing interest due to its non-invasive and non-ionising properties. In this paper, we present a feasibility study with the goal of enhancing MWI for stroke detection using metasurface (MTS) loaded antennas. In particular, three MTS-enhanced antennas integrated in different brain scanners are presented. For the first two antennas, which operate in a coupling medium, we show experimental measurements on an elliptical brain-mimicking gel phantom including cylindrical targets representing the bleeding in haemorrhagic stroke (h-stroke) and the not oxygenated tissue in ischaemic stroke (i-stroke). The reconstructed images and transmission and reflection parameter plots show that the MTS loadings improve the performance of our imaging prototype. Specifically, the signal transmitted across our head model is indeed increased by several dB‘s over the desired frequency range of 0.5–2.0 GHz, and an improvement in the quality of the reconstructed images is shown when the MTS is incorporated in the system. We also present a detailed simulation study on the performance of a new printed square monopole antenna (PSMA) operating in air, enhanced by a MTS superstrate loading. In particular, our previous developed brain scanner operating in an infinite lossy matching medium is compared to two tomographic systems operating in air: an 8-PSMA system and an 8-MTS-enhanced PSMA system. Our results show that our MTS superstrate enhances the antennas’ return loss by around 5 dB and increases the signal difference due to the presence of a blood-mimicking target up to 25 dB, which leads to more accurate reconstructions. In conclusion, MTS structures may be a significant hardware advancement towards the development of functional and ergonomic MWI scanners for stroke detection.