Thermochromic Tissue Phantoms for Evaluating Temperature Distribution in Simulated Clinical Applications of Pulsed Electric Field Therapies.

Irreversible electroporation (IRE) induces cell death through nonthermal mechanisms, however, in extreme cases, the treatments can induce deleterious thermal transients. This study utilizes a thermochromic tissue phantom to enable visualization of regions exposed to temperatures above 60°C. Poly(vinyl alcohol) hydrogels supplemented with thermochromic ink were characterized and processed to match the electrical properties of liver tissue. Three thousand volt high-frequency IRE protocols were administered with delivery rates of 100 and 200 μs/s. The effect of supplemental internal applicator cooling was then characterized. Baseline treatments resulted thermal areas of 0.73 cm, which decreased to 0.05 cm with electrode cooling. Increased delivery rates (200 μs/s) resulted in thermal areas of 1.5 and 0.6 cm without and with cooling, respectively. Thermochromic tissue phantoms enable rapid characterization of thermal effects associated with pulsed electric field treatments. Active cooling of applicators can significantly reduce the quantity of tissue exposed to deleterious temperatures.