Tarikul Islam

Preterm neonates are vulnerable to periventricular-intraventricular hemorrhage since the periventricular germinal matrix blood vessels are still immature and fragile until around 36 weeks. While cranial ultrasound imaging (cUS) is the standard technique for diagnosing brain injury in neonates, it has limited accuracy in detecting early-stage hemorrhages due to poor sensitivity and specificity. Transfontanelle thermoacoustic imaging (TTAI) combines the advantages of high contrast from electromagnetic absorption with high-resolution from ultrasound imaging and represents a potential alternative to overcome the limitations of conventional cUS systems. We developed a TTAI system and evaluated its performance in a large animal model of intraventricular hemorrhage (IVH) in vivo. Our system demonstrated the ability to detect hemorrhages as small as 0.1 mL, which is better than the previously reported limit of detection for either ultrasound or photoacoustic imaging in the same animal model. These results indicate that TTAI is a novel imaging modality with high potential for accurate detection of IVH in neonates.

Microwave-induced thermoacoustic tomography (TAT) is a hybrid imaging technique that combines microwave excitation with ultrasound detection to create detailed images of biological tissue. Most TAT systems require a costly amplification system (or a sophisticated high-power microwave source), which limits the wide adoption of this imaging modality. We have developed a rotating single-element thermoacoustic tomography (RTAT) system using a low-cost amplifier that has been optimized in terms of microwave signal pulse width and antenna placement. The optimized system, enhanced with signal averaging, advanced signal processing, and a deep learning computational core, successfully produced adequate-quality images. The system has been characterized in terms of spatial resolution, imaging depth, acquisition speed, and multispectral capabilities utilizing tissue-like phantoms, ex-vivo specimens and in-vivo imaging. We believe our low-cost, portable system expands accessibility for the research community, empowering more groups to explore thermoacoustic imaging. It supports the development of advanced signal processing algorithms to optimize both low-power and even high-power TAT systems, accelerating the clinical adoption of this promising imaging modality.

This paper introduces an innovative approach to enhance the circular scanning-based photoacoustic tomography (CSPAT) system for photoacoustic imaging. The proposed method involves using a circular detection geometry with three carefully placed ultrasound transducers (USTs). By strategically selecting the angles of the USTs, the field of view (FOV) is expanded, and tangential resolution is improved without requiring additional imaging time. The new CS-PAT system demonstrates practicality and convenience, providing higher signal-to-noise ratio and better structural similarity compared to the conventional system. This approach overcomes the limitations of the limited size of USTs and widens the application potential of CS-PAT in a straightforward and efficient manner.

In this study, various breast phantom (BP) models for microwave breast imaging (MBI) are investigated and the creation and assessment of designed models are presented. Symmetrical and asymmetrical BP models have been constructed. based on 3D printed structures stuffed with various mixed material combinations that roles various breast tissue layers (skin, healthy fat tissue, glandular tissue, heterogeneous mix tissue, and tumor tissue) in terms of permittivity over the ultra-wide band frequency (3.1–10.6GHz) range. However, the main issue in making such phantoms is coming up with adequate material mixes that mimic those characteristics across the frequency band, as well as creating the phantom with realistic approach. The complex dielectric characteristics are tested after fabrication with a dielectric probe kit coupled to a VNA. Then, the measured complex dielectric properties are compared to the real human breast dielectric values. The symmetrical and asymmetrical phantoms’ integrated structure allows the tumor and BPs to be dynamically combined to provide a test setup based on MBI technologies. Once the breast phantom has been produced, antenna arrays are positioned around it to collect scattering parameter data for tumor characterization. Finally, the extracted feature data was used to reconstruct the image in order to find the undesirable tumor component within the breast phantom using an imaging algorithm.

Summary: A compact and symmetrical five‐port reflectometer (FPR) for microwave imaging application is introduced in this paper. The proposed FPR shows a wide operational impedance matching bandwidth in the frequency span of 1.55–5.31 GHz (about 109.6%). It consists of three layers with a compact size of 42.4 × 42.4 × 3.2 mm³ and comprises five symmetric branch lines which were designed and optimized as a star junction topology and placed at the middle layer to realize an equivalent value of 70 dB for reflection coefficients at a center operating frequency of 2 GHz. Moreover, the measured results indicate that the FPR prototype has realized accuracies of approximately ± 120° in phase, 0.04 and 0.5 magnitudes of reflections and transmission coefficients, respectively, which are relative in parallel to the simulated and theoretical results. The proposed FPR proves higher efficacious capabilities to be used in microwave imaging for biomedical application systems.

Microwave imaging (MI) is a consistent health monitoring technique that can play a vital role in diagnosing anomalies in the breast. The reliability of biomedical imaging diagnosis is substantially dependent on the imaging algorithm. Widely used delay and sum (DAS)-based diagnosis algorithms suffer from some significant drawbacks. The delay multiply and sum (DMAS) is an improved method and has benefits over DAS in terms of greater contrast and better resolution. However, the main drawback of DMAS is its excessive computational complexity. This paper presents a compressed sensing (CS) approach of iteratively corrected DMAS (CS-ICDMAS) beamforming that reduces the channel calculation and computation time while maintaining image quality. The array setup for acquiring data comprised 16 Vivaldi antennas with a bandwidth of 2.70–11.20 GHz. The power of all the channels was calculated and low power channels were eliminated based on the compression factor. The algorithm involves data-independent techniques that eliminate multiple reflections. This can generate results similar to the uncompressed variants in a significantly lower time which is essential for real-time applications. This paper also investigates the experimental data that prove the enhanced performance of the algorithm.

A new Chinese Temple shaped (CTS) slotted monopole UWB patch antenna is introduced in this research for the purposes of microwave imaging applications such as breast imaging. Geometrically the antenna was being comprised of a slotted pentagonal radiator with a diminished slotted ground-plane carved rectangularly. On the patch and ground plane, numerous types of slots were explored. Slotted pentagonal-shape patch and slotted rectangular ground offer significant Gain over 2.4 to 7.8GHz frequency ranges, wide bandwidth, along with comparatively balanced radiation properties. Whole dimension of the prototype is 40×40×1.6mm ³ with 0.320λ×0.320λ×0.0128λ electrical dimension at starting frequency 2.4GHz. The antenna has a fractional bandwidth of 105.88% and an operating bandwidth of 5.4 GHz (2.4-7.8GHz). Several parameters are taken into account and optimized to maximize Gain, and the maximum gain value is 6 dBi. Efficiency reaches a maximum of 96.23% with an average of 94.32% within 2.4-7.8 GHz frequency ranges. Being obtainable and affordable, the prototype mounted on 1.6 mm thick FR-4 substrate with such a 4.6 and 0.002 Permeability and loss tangent respectively. Simulation performed through 3D simulator software CST Microwave Studio 2019 and HFSS. May the antenna really be a respectable contender to use in MI applications for its lightweight structure and high Gain.

A non-invasive, low-powered, and portable electromagnetic (EM) head imaging system is presented using metamaterial (MTM) loaded compact directional 3D antenna. The antenna consists of two slotted dipole elements with 2×3 and 3×3 finite MTM array elements in top and ground, respectively, and folded parasitic elements that operate within the frequency range of 1.12 GHz to 2.5 GHz. The MTM array elements are optimized to enhance the overall performance regarding antenna bandwidth, realized gain, efficiency, and directionality in both free space and proximity to the head model. The mathematical modelling is also analyzed to justify the integration of MTM unit cells to the top and ground side of the antenna. The impact of MTM on SAR analysis is also performed. A tissue-mimicking 3D head phantom is fabricated and measured to validate the antenna performance. A nine-antenna portable setup is used with the fabricated phantom to measure and collect the scattering parameters that are later analyzed to detect and reconstruct the haemorrhage images by applying the updated IC-CF-DMAS algorithm. The overall performance demonstrates the feasibility of the proposed system as a portable platform to successfully detect, locate and monitor the haemorrhages inside the head in EM imaging system.

In this article, a metamaterial loaded high gain nine antennas based microwave breast imaging system has presented to detect an unwanted tumour in the breast phantom. The proposed antenna is designed on a modified version of a basic Vivaldi antenna. Single negative metamaterial structure has been loaded to the modified version Vivaldi to enhance far-field antenna properties like gain and radiation pattern, which is essential for the breast imaging system. The proposed antennas have achieved −10dB impedance bandwidth of 8.45 GHz (2.0- 10.45 GHz) and 7.9 dBi maximum gain in the operating band. To verify the time-domain performance, the fidelity factor is also calculated for the face-to-face orientation, which is near about 92.89%. After optimisation in high load phantom, near field directivity (NFD) is also analysed with the workload to ensure that the near field radiation properties. Finally, the nine metamaterial (MTM) antennas arrays are placed around the breast phantom in a hemispherical order to take the data of scattering parameters for tumour object analysis in a CST simulation environment. The extracted data has been processed through an imaging algorithm to reconstruct the image for identifying the unwanted tumour object inside the breast phantom.