Tsujimoto Yukako, Morimoto Mai, Nitta Naotaka, Akiyama Iwaki
Medical Ultrasound Research Center, Doshisha University, 1-3 Tataramiyakodani, Kyotanabe, Kyoto, Japan.
National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan.
J Med Ultrason (2001). 2019 Jan;46(1):35-43. doi: 10.1007/s10396-018-0916-8. Epub 2018 Nov 15.
Tissue characterization in terms of the differences in thermo-physical properties of biological tissues was investigated in this study. The objective was to measure the ratio of variation in sound velocity due to ultrasonic heating and to derive the relational expression between the ratio and thermo-physical properties.
The ratio of sound velocity variation before and after the temperature rise of tissue samples exposed to ultrasound was measured by ultrasonic pulse echo method. The thermo-physical properties were estimated for a tissue-mimicking material and porcine muscle and fat tissues due to theoretical expression. The transducer for heating had a resonance frequency of 3.2 MHz, and the transducer for measurement of sound velocity variation had a resonance frequency of 5.2 MHz.
In the phantom study, the measured values of the temperature rise agreed with the values calculated by a finite element method (FEM). The estimated values of the temperature rise from the sound velocity variations of muscle and fat tissues were 0.36 °C and 1.1 °C, respectively. Also, the estimated values of thermo-physical properties agreed with the reference values within an error of 10%.
The thermo-physical properties of the porcine tissues were measured by sound velocity variation due to ultrasonic heating within the safety regulations.
本研究探讨了根据生物组织热物理性质差异进行组织表征。目的是测量超声加热引起的声速变化率，并推导该变化率与热物理性质之间的关系表达式。
采用超声脉冲回波法测量暴露于超声的组织样本温度升高前后的声速变化率。根据理论表达式估算了仿组织材料以及猪肌肉和脂肪组织的热物理性质。加热换能器的共振频率为3.2MHz，声速变化测量换能器的共振频率为5.2MHz。
在体模研究中，测得的温度升高值与有限元法（FEM）计算的值一致。根据肌肉和脂肪组织的声速变化估算的温度升高值分别为0.36°C和1.1°C。此外，热物理性质的估算值与参考值的误差在10%以内。
在安全规定范围内，通过超声加热引起的声速变化测量了猪组织的热物理性质。
