Study on the Heat and Fluid Transport inside the Biological Tissues Subject to Boiling Saline-Based Tumor Hyperthermic Injection

Percutaneous hot saline injection therapy (PSIT) is becoming a very effective way of killing the target tumor in deep human body through direct heat deposition. Although the old-style injector may scald the healthy tissues along the insertion path of the needle during the operation, the newly proposed concentric tube structure of syringe by incorporating a cooling film will make the PSIT a practical method. However, as a relatively young clinical strategy for tumor treatment, the operational features of the PSIT received little attention up to now. In particular, little is known about its heating performances, and no mathematical model was ever established to characterize this behavior. To better understand the temperature responses of the living tissues subject to PSIT, this paper presents research on the modeling of heat and fluid transport inside the biological tissues when injected with hot water. Following the operational features of the new-style syringe, a one-dimensional mathematical model in spherical coordinate was proposed. Preliminary experiments through a single or multiple injections on pork tissues were performed to validate the theoretical predictions. The obtained results indicate that this model can predict well the heat and fluid transport process in the tissues heated by the injected flowing hot water and thus provide very useful information for the clinical practices. Further, parametric studies were performed to test the effects of a series of either physiological or heating parameters, such as tissue porosity, tissue and blood absorption coefficient, blood perfusion rate, injector diameter, injection velocity of hot water, or tissue position. Their implementations in PSIT are discussed, and some useful instructions for operating the PSIT are suggested. The results also indicate that the influence of blood perfusion rate may be negligible if a high degree of accuracy is not especially required. This study may find significant applications in the treatment planning of a PSIT on destroying a certain specific target tumor.