Investigation of temperature elevation and saline injection induced electrical conductivity change of hepatic tissue by using micro probe

摘要

Radiofrequency ablation (RFA) has been used for a variety of clinical treatments including treatment of non-resectable liver tumors with good clinical success. Liver pretreatment with injected saline increases the volume of the RFA treatment and is a potential tool for strategically treating larger tumors. Understanding the electrical conductivity of the affected tissue is required to improve the applicator performance and to accurately control the ablation area. We have developed a micro two-electrode probe capable of measuring the local electrical conductivity of tissues at different temperature levels and recording the transient change of electrical conductivity with saline pretreatment. An optical temperature sensor was attached on the probe tip for real-time temperature monitoring to capture the dynamic effects of temperature changes. Three methods which were implemented by water bath and a commercial RF ablation applicator (Cool-tip RF ablation system) were used to heat the hepatic tissues. The results show that at elevated temperatures the electrical conductivity increases by a factor of two compared to the values at the body temperature and different heating methods cause different levels of electrical conductivity change. The preliminary measurements of the local electrical conductivity after the saline injection indicate a dynamic pattern in electrical conductivity. The results serve to provide guidance for accurate prediction of RFA area when using saline injection pretreatment.