139超音波歪計測に基づく組織弾性再構成法のハイパーサーミア治療効果のモニタリング技法としての可能性

Abstract

We have developed the ultrasonic (US) strain measurement-based shear modulus reconstruction technique. Briefly, we developed the iterative US rf-echo phase matching method using successively acquired rf-echo data frames for measuring strains generated in vivo in soft tissues due to spontaneous heart motion and/or externally applied pressures. Moreover, we developed the method using the measured strain data for stably reconstructing the globally relative shear modulus distribution with respect to reference shear moduli. As the elasticity of the soft tissues irreversibly changes by heating, we propose that the developed shear modulus reconstruction technique is used as a monitoring technique for the effectiveness of thermal therapy. Particularly in this report, we applied the reconstruction technique to interstitial RF electromagnetic wave thermal therapy. To verify the feasibility we conducted in vivo experiment using a fresh calf liver. The pair of needle electrodes with the diameter of 2 mm were inserted into the liver tissue and the electric current with the frequency of 13.56 MHz was injected. During heating the tissues, we collected rf-echo data frames containing the heated region. Obtained reconstructions could satisfactorily visualize the expansion of heated regions. This result indicates that it has a high potential value as a practical tool for monitoring the effectiveness of thermal therapy.