Combined ultrasound tomography and electrical impedance tomography: feasibility studies on breast‑mimicking phantoms

Breast cancer is the most frequently diagnosed cancer in women in the United States (excluding skin cancers), and improvements in screening and diagnosis could reduce unnecessary biopsies while enabling earlier detection and better treatment outcomes. Ultrasound tomography (UST) is a novel imaging technique that not only provides structural information but also generates quantitative tissue acoustic maps, such as sound speed and attenuation, which are emerging as valuable biomarkers. While UST improves sensitivity and specificity compared to standard ultrasound, its specificity can be further enhanced by integration with cancer-specific biomarkers. Electrical impedance tomography (EIT), in comparison, provides low-resolution static and dynamic electrical-property information with promising contrast mechanisms for breast cancer imaging. Incorporating the high-resolution structural information from UST can significantly improve EIT reconstructions, overcoming this limitation. Moreover, the geometry of UST ring transducers and EIT electrode arrays allows for straightforward integration of the two modalities into a single system. To the best of our knowledge, this study is the first to explore a combined UST/EIT system and evaluate its performance in a proof-of-principle breast phantom. Our findings show that incorporating boundary information from UST dramatically improves EIT reconstructions, successfully revealing tumor inclusions that were completely obscured without this information. Together, these results suggest that the development of a combined UST/EIT platform offers strong potential as a powerful tool for breast cancer screening and diagnosis.