Amy A Fairbrother, Utah Valley University
Health
Research has shown that high-frequency (HF) ultrasound is capable of detecting structural and biomechanical property changes in tissues and cells at the microscopic level. This capability is currently being tested for the real-time identification of breast tissue pathology in surgical margins during lumpectomies. The objective of this study was to determine if structural and property changes arising in tissue from variations in temperature can be detected by using HF ultrasound. Once a tissue sample is excised from the body, the temperature of the sample decreases rapidly from body temperature to that of the surrounding room temperature. Because of the decrease in heat, the tissue can become more rigid and thus less fluid. These alterations in biomechanical properties can affect HF ultrasonic measurements such as wavespeed and attenuation. These biomechanical changes may also affect the ultrasonic signals sensitive to tissue structure such as the number of peaks in the ultrasonic spectra. The methodology of the research was as follows. Fresh samples of bovine tissue were ultrasonically tested at 3 different temperatures: 37º, 24.5º, and 15º C. Each sample was approximately 7.6 mm thick and 3.8 x 2.5 cm in size. To observe the overall effects of temperature on a sample, the tissue was slowly heated from room temperature to body temperature (37º C) and then tested with HF ultrasound. The sample was then cooled back down to room temperature (24.5º C) and tested again using HF ultrasound. Lastly, the sample was cooled further to 15º C and again tested using HF ultrasound. Ultrasonic waveforms were collected using 50-MHz pitch-catch and pulse-echo measurements. The data was then analyzed to determine changes in wavespeed, attenuation, and spectral peak density with temperature. Results from the study will be presented and discussed with respect to the improvement of HF ultrasound procedures for testing tissue samples.