BIOPHYSICAL AND HISTOPATHOLOGICAL CHARACTERIZATION OF RFTC LESIONS IN PAG PHANTOMS AND IN VIVO RAT MODELS

Radiofrequency thermocoagulation (RFTC) delivered through SEEG electrodes is a minimally invasive treatment option for drug-resistant epilepsy, yet its optimization is limited by an incomplete characterization of lesion biophysics and tissue response. This study presents a two-phase approach integrating an in vitro phantom and an in vivo rat model to generate ground-truth data for lesion in-silico modeling. In the in vitro phase, polyacrylamide gel (PAG) phantoms were used to characterize lesion formation during monopolar and bipolar RFTC (using contiguous contacts) at 3–5 W, monitoring impedance and duration. In vivo, 3 W monopolar RFTC was applied to the CA1 region of the hippocampus in healthy Sprague-Dawley rats to assess histological outcomes. Using the PAG platform as a controllable testbed, we systematically varied electrode configuration (monopolar/bipolar), power amplitude, and pulse duration to map parameter–lesion relationships. For each setting, we quantified pre- and post-RFTC impedance and lesion geometry (shape and volume), yielding tightly clustered measurements across replicates. This reproducibility establishes PAG-RFTC as a reliable entry point for subsequent data acquisition and for calibrating computational models to simulate lesions in rat and, ultimately, in patients. Histological analysis of the in vivo model identified three distinct zones: central necrosis, peri-lesional edema, and preserved healthy tissue. These findings provide parameter-to-lesion transfer functions and histopathological bases essential for calibrating future in-silico heat-transfer models. Further research into the molecular and cellular changes in healthy tissue at short and long-term intervals is required to establish a foundation for translating these findings to epileptic tissue models.