Author: Zhongping Chen, Yuchen Song, Leshan Sun, Liangzhong Xiang, Yifei Xu 👨🔬
Affiliation: University of California, Irvine, University of California Irvine 🌍
Purpose: Electroacoustic tomography (EAT) monitors the distribution of electrical energy in tissues by detecting acoustics signals induced by electrical pulses during irreversible electroporation (IRE) ablation therapy. The non-contact EA signal acquisition capability of the multi-channel random quadrature ultrasonics system eliminates the need for physical coupling through a medium, as required by traditional piezoelectric transducers. Additionally, it is insensitive to electromagnetic interference, further enhancing the clinical applicability of the technique, reducing the risk of infection for special populations such as infants and individuals with sensitive skin.
Methods: Nanosecond pulse sequences with varying pulse widths and voltages were applied to agarose and potato phantoms using a customized nanosecond pulse generator. Signals were collected by scanning the sample surface with an MCRQ interferometer that employs multimode fibers and optical signal averaging for stable acquisition. Ablation zones in the potato model were stained with 2,3,5-triphenyltetrazolium chloride (TTC) and compared to detected signals. Lastly, the two-dimensional distribution of the electric field energy in the brine was reconstructed by rotational scanning.
Results: EA signals varying with processing parameters and signal profiles in directions orthogonal to the electrodes were detected in the agarose and potato models. The signal intensity was related to the amplitude and pulse width of the electrical pulse. In the potato model, the intensity of the EA signal was correlated with the ablation zone. A two-dimensional distribution of the EA energy in the brine was obtained by rotational scanning and was found in agreement with the simulation results.
Conclusion: The MCRQ ultrasound system provides effective non-contact detection of electroacoustic signals facilitating reconstruction of electrical energy distribution and identification of areas of electroporation. It offers a promising method for monitoring electroporation therapy, eliminating the potential pitfalls associated with physical contact-based detection and enhancing the clinical applicability of the technique.