Thermoacoustic imaging (TAI) is a promising new technology for biomedical diagnostics. It combines the high contrast of electromagnetic absorption with the high resolution of ultrasound imaging. Traditional TAI systems use circular scanning modes with single or arc detectors, which can be slow and inefficient for body scanning. A linear-array detector, which is commonly used in medical ultrasound imaging systems, can be used to scan biological tissues more efficiently. In this study, we developed a novel linear-array TAI system (LATIS) for the detection of hemorrhage in the brain through fontanelle in neonates. The LATIS uses a linear-array transducer with multiple elements, which enables rapid data acquisition and real-time imaging. A custom-designed trigger mechanism synchronizes the microwave signal generation and data acquisition process, ensuring accurate timing for optimal image quality. We evaluated the LATIS performance by conducting several ex-vivo sheep brain hemorrhage of different amounts of artificially induced blood. The system was able to successfully detect lower grades of intraventricular hemorrhages in ex-vivo experiments. These results demonstrate the potential of LATIS for clinical imaging of brain hemorrhage in neonates as they are vulnerable to intraventricular hemorrhage.
Microwave-induced thermoacoustic tomography has the advantage of a high spatial resolution and a deep imaging depth. This method has been extensively explored over the past decade to find an alternative of existing imaging techniques. In this study, we have developed a compact microwave-induced thermoacoustic tomography (MI-TAT) with a waveguide antenna and a rotating ultrasound transducer unit. We performed a characterization study of the system in terms of pulse width, selection of microwave frequency and resolution. Then the optimized parameters were used to image in-vitro complex structure phantoms. Later, we expanded our system capability for spectroscopic study by imaging different concentrations of methanol and water to mimic the tissue properties and analyze them based on the absorption characteristics of these materials. We hope, this spectroscopic capability broadens the capability of thermoacoustic system to separate the diseased tissue from the healthy one (e.g., malignant from benign) with a high sensitivity and specificity.
Thermoacoustic imaging (TAI) utilizes the advantages of excellent penetration depth and contrast of microwave energy and the high spatial resolution of ultrasound imaging. We evaluate the use of TAI for the detection of hemorrhage in the neonatal brain through fontanelle. We use a 3D human neonatal brain model, an antenna, and a linear array transducer in simulation to characterize the thermoacoustic signal and corresponding reconstructed images. All the characterizations are conducted using Computer Simulation Technology (CST) Studio Suite based on finite integration in technique (FIT). The absorbed electric field by the target and the time varying heating function data are reconstructed with a spatial resolution of 100 μm. To evaluate the impact of the applied microwave beam on the generated acoustic pressure wave, different pulse widths ranging from 0.01μs - 5μs at different frequencies from 1-3 GHz are tested. We also explore the impact of the type of antenna, by evaluating a horn antenna, a waveguide and a helical antenna.
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