5C-2 Non-Invasive Ultrasound Elastic Modulus Estimates on Tissue Scaffold Mechanical Property Change

Tissue engineers are greatly interested in non- invasively evaluating the extent of cell growth, scaffold degradation, and tissue development both in vitro and in vivo as a function of time. Current evaluation methods such as cell histology and direct mechanical measurements can only provide static snapshots using different specimens at different time points. These measurements introduce specimen to specimen and animal to animal variation. MRI and CT can monitor scaffold degradation and tissue growth in the same specimen over time, but provide only morphological information. Ultrasound Elasticity Imaging based on phase sensitive speckle tracking can characterize the internal structural and compositional change at a high resolution of a few hundreds of microns. In this study, ultrasound elasticity imaging was applied to poly (1, 8 octanediol-co-citrate) (POC) scaffold embedded in a gelatin phantom at different stages of chemically induced degradation and compared with direct mechanical measurements. Although ultrasound strain imaging measures the mechanical property change of the scaffold as degradation progresses, further investigation on absolute elastic modulus estimate is needed. Novel elastic modulus reconstruction algorithm was applied to the displacement estimates from speckle tracking. The reconstructed elastic modulus compared well with direct mechanical measurements.