"Multimodal Fusion of Ultrasound and Electrical Impedance Tomography for Soft Tissue Characterization in Layered Phantom"

"Electrical Impedance Tomography (EIT) offers low-cost functional impedance imaging, whereas ultrasound provides high-resolution morphological visualization. In this study, we propose a novel hybrid Ultrasound\u2013EIT fusion framework for soft-tissue characterization in multilayer biological phantoms, using a controlled chicken-tissue model. Methods: A custom EIT acquisition system captured 208 voltage measurements across three tissue-layer thicknesses and four frequency\u2013voltage conditions. Five FEM-based reconstruction algorithms-Back Projection (BP), Gauss\u2013Newton (GN), Tikhonov Regularization (TIK), GREIT, and a linearized one-step reconstruction mimicking the EIDORS approach-were implemented in a complete stand-alone MATLAB platform. Ultrasound images acquired using a GE VScan Air CL probe using musculoskeletal (MSK) mode were fused with theEIT image reconstruction for better soft-tissue characterization. A Multimodal fusion pipeline was developed integrating impedance reconstruction, ultrasound texture\u2013echogenicity mapping, and statistical correlation metrics. Results: Quantitative analysis using CNR, SSIM, PSNR, resolution index, correlation coefficients, Bland\u2013Altman plots, and CDFs demonstrated consistent layer separation and structural\u2013electrical association (r\u22480.37\u20130.45) for the three cases. Frequency and voltage variation significantly influenced reconstruction quality. Multimodal overlay fusion improved structural interpretability compared to stand-alone EIT. Conclusion: The proposed dual-modality framework provides a low-cost route for integrating functional impedance information with morphological ultrasound imaging in soft tissues, enabling improved tissue-layer discrimination even when collagen quantification is not feasible. Significance: This work establishes a foundation for low-cost, wearable hybrid EIT-US systems, demonstrating a proof-of-concept for using ultrasound to provide spatial context for functional EIT imaging in layered soft tissues"