敷波 保夫, 蔦 薫, 谷口 雅彦

Yasuo SHIKINAMI, Kaoru TSUTA, Masahiko TANIGUCHI

タキロン㈱メディカル部

Takiron Co., Ltd., Medical Div.

キーワード : Segmented polyether-urethane gel (SPUG), One component system gel, Liquid segment, Polyalkylene oxide, Ultrasonic coupler

We have synthesized segmented polyether-urethane gels (SPUG) consisting of EO/PO copolymer segments and branched chains (M-PEG, Mw: 400) that are liquid at ambient temperatures. The sound velocity (c) and acoustic impedance (ρc) at 3.5, 5.0 and 7.5 MHz resembled those of soft tissue in the living body. The attenuation was lower in the random copolymer segments than in the block copolymer segments. When the random copolymer of polyol component (Mw: 2000) and the random copolymer of the isocyanate component segment (Mw: 830) were EO/PO=50/50 (mol. ratio), M-PEG/P-OH was 5/2 (mol. ratio), and the OH/NCO ratio was 1.05, the attenuation was as low as 0.68 dB/cm at 3.5 MHz. This gel was low modulus, flexible and good elastic recovery, showed no degeneration by breeding out, and was stable over a long time period. The gel's safety on skin has also been confirmed. A clinical application was performed on the thyroid, breast, and abdomen using the gel pad of an acoustic coupler. If the gel thickness was 1∼3 cm, and the gain, dynamic range and sensitivity time control were properly adjusted, the echo was depicted in finer detail and the image was clearer than when no gel was used or when a silicone gel pad was used. Since the gel is transparent, the site of the examination and the site of the lesion could be easily identified. The above results show that the SPUG is valuable as an acoustic coupler gel for ultrasonographic examination of superficial diseases.