Noninvasive Electrical Impedance Tomography for the Monitoring and the Quantification of Tissue Temperature During Liver Cancer Hyperthermia

Accurate non-invasive temperature monitoring during liver tumor hyperthermia remains a significant clinical challenge. This study evaluates the use of electrical impedance tomography (EIT) for quantitative temperature mapping in hepatic thermal therapy by incorporating tissue-specific electrophysiological properties. Based on prior characterization of temperature-dependent electrical conductivity (30–90°C, 1 Hz–1 MHz) in murine hepatocellular carcinoma (HCC) models, computational simulations were developed to demonstrate EIT reconstructed value-temperature correlations. In vivo validation was conducted using orthotopic HCC mice subjected to infrared laser heating (n=6) and radiofrequency ablation (RFA) (n=4), with thermal changes monitored via a custom 16-electrode EIT system operating at 10 kHz. A novel 3D-printed scaffold ensured stable electrode placement on the abdominal surface. Region-of-interest analysis defined tumor, heat affected liver, and distal liver zones. Results revealed strong linear correlations (R²=0.88– 0.93, p<0.0001) between EIT-reconstructed values and thermocouple measured temperatures through tissue-specific temperature-dependent impedance functions. EIT accurately localized thermal lesions and visualized the spatiotemporal evolution of temperature during ablation, with quantification errors of ≤2.8°C (tumor tissue), ≤3.6°C (heated liver tissue), and ≤4.5°C (distal liver tissue), as histologically confirmed. We believe that the technology holds significant potential for improving treatment efficacy in HCC hyperthermia protocols through non-invasive temperature quantification.