Feasibility of shear modulus imaging technique for monitoring the effectiveness of the interstitial rf electromagnetic wave thermal therapy

It is well known that the static mechanical properties of living soft tissues reversibly or irreversibly change by the degree of the thermal energy exposure, several researchers including us applied various ultrasonic elasticity imaging techniques to visualize variously energy-induced thermal tissues. Particularly, in this report we proposed that our previously developed ultrasonic strain measurement-based shear modulus imaging technique is used for monitoring the effectiveness of the interstitial RF electromagnetic wave thermal treatment. Since previously through in vivo experiment on human breast tissues we could confirm that the technique has high potential as the practical tool for differentiating early stage malignancies, we in novel realized the thermal applicator using only needle-type electrodes. Since we would also apply this therapy to deeply situated tissues, we also confirmed on in vivo human liver that shear modulus image could be stably obtained. Furthermore, to verify the feasibility as the monitoring technique we performed heating/imaging on the fresh in vitro calf liver. This imaging could specify the spatial and temporal change of elasticity due to tissue heating and cooling down. We believe that this monitoring technique will allow this type interstitial RF electromagnetic wave thermal therapy to be widely performed on various tissues. Moreover, low-invasively obtained insights about tissue thermal properties will significantly contribute to heightening the treatment efficiencies of various type thermal therapy systems.