Comparison of three models at high frequency for ultrasound tissue scattering

Abstract

A mammary carcinoma was grown in mice and imaged with an ultrasound transducer operating with a center frequency of 65 MHz. Quantitative ultrasound (QUS) analysis was used to characterize the tumors using the bandwidth of 30 to 85 MHz. Three models (Gaussian scatterer, fluid-filled sphere, and a new cell scatterer) for scattering were examined and scatterer property estimates were compared to real tissue morphology as seen from optical microscope images of the tumors. The Gaussian scattering model did not fit the data well compared to the fluid-filled sphere and new cell scatterer models. The fluid-filled sphere model fit the measurements better than any other model but did not yield scatterer property estimates that resembled underlying structure. Using the fluid-filled sphere model, the average estimated scatterer diameter was 25.5±0.14 μm. A new cell scatterer model was developed, which was based on scattering from a cell by incorporating the effects of the cytoskeleton and nucleus. The new cell scatterer model yielded estimates that appeared to reflect underlying structure more accurately. Using the new cell scatterer model, the average estimated nuclear diameter was 15.6±2.2 μm compared with 13.2 μm as measured from optical microscope images.