Monica Cervantes, Utah Valley University
The central research question of this project was to determine if high-frequency ultrasound is sensitive to tissue pathology at the microscopic level. Previous studies on surgical specimens have shown that high-frequency ultrasound may be sensitive to a range of breast pathologies including fibroadenomas, atypical ductal hyperplasia, fibrocystic changes, and carcinomas. The ultrasonic parameters that were sensitive to pathology were the number of peaks (the peak density) of the first-order spectra of the waveforms (one forward Fourier transform), and the slope of the second-order spectra of the waveforms (two consecutive forward Fourier transforms). The ability to determine pathology rapidly and with minimal specimen preparation would make high-frequency ultrasound particularly well-suited for real-time use during cancer surgery to ensure all of the malignant tissue has been removed. The purpose of this research was to determine the sensitivity of the peak density and spectral slope to tissue microstructures other than those found in breast cancer. The results of this study would not only support the results from the breast cancer studies, but also extend those results to the detection of cancer and other diseases in a range of organs and tissues. The research methodology included the following steps. (1) Freshly excised bovine organs were obtained from a meat packaging facility, including the heart, liver, and kidney. (2) Specimens approximately 3x3x1 cm in size were dissected from the organs and tested immediately with ultrasound. (3) Both pitch-catch and pulse-echo waveforms were acquired from the samples. (4) The data were analyzed by determining the peak densities and spectral slopes. The results showed that the more heterogeneous tissues of the heart, the vascular structures (aorta, vena cava, etc.), displayed significantly higher peak densities than the muscle tissues. Similarly, the ureter, which has greater heterogeneities in its structure (larger and more varied), displayed significantly higher peak densities than the cortex and medulla tissues. No significant trends were observed for the liver tissue, or for the spectral slopes except for kidney medulla tissue. Heterogeneity and peak density in high-frequency ultrasonic spectra that may be useful for performing real-time pathology during cancer surgery.