Andrea Quiroz, Utah Valley University
Health
The stimulation and inhibition of tissue vascularization has important applications to tissue engineering and oncology. Approaches to quantitatively evaluate neovascularization in vivo in adult animals with differentiated tissue include both invasive methods that use an implanted or injury-induced matrix in the study organism, or noninvasive small animal imaging methods such as MRI, CT, and PET. The objective of this study was to determine if ultrasonic spectra in the 10-100 MHz range could be used as an in vivo neovascularization assay. Numerical simulations and phantoms were used as model systems to test the feasibility of the approach. The simulations modeled ultrasonic scattering from microscopic vascular networks using randomly oriented cylinders to represent blood vessels and cylindrical wave functions to represent ultrasonic waves. Phantoms were fabricated from a gelatin-soluble fiber mixture and agarose gel. The agarose gel was embedded in the gelatin-fiber in order to simulate vascular tissue. Ultrasonic tests were performed using two broadband ultrasonic transducers centered at 50 MHz. Pitch-catch data were collected and analyzed by calculating the peak density of the ultrasonic frequency spectrum, which is the number of peaks and valleys in the spectrum (a measure of the spectrum’s complexity). Control specimens were tested to determine the differences in the sound wave properties between the gelatin-fiber and the agarose gel. The controls demonstrated the instrument’s ability to differentiate between the two types of material. Measurements of agarose inclusions in the gelatin-fiber showed a significantly higher peak density than those for the control gelatin-fiber. These results indicate that the agarose gel structures are scattering sound to a greater extent than the gelatin-fiber alone. The results thus far have provided a strategy for proceeding with the project in the future. The phantoms will be refined and made more realistic to produce an adequate mimic for vascular tissue.