Effective scatterer size estimation based on mathematical form factors in a rat fibroadenoma model.

Abstract

Quantitative ultrasound imaging is a model‐based approach aimed at lesion detection and classification. In this study, the backscattered rf from rat fibroadenomas was fitted to two mathematical models to yield effective scatterer diameter (ESD). The goal was to aid in understanding potential sources of scattering in live rat tumors. Data were acquired using three single‐element transducers with center frequencies of 3.5, 7.5, and 13 MHz. Reference scans were acquired from a Plexiglas plate. Two different theoretical models of scattering were fitted to the data; a fluid filled sphere model, which does not support shear waves, and the spherical Gaussian model for the scatterer. Twenty histologically confirmed fibroadenomas were analyzed. The ESD values obtained spanned the range of typical acini sizes observed in the histology of the fibroadenomas, from approximately 50 μm with the 13‐MHz transducer up to 200–300 μm with the 3.5‐MHz transducer. The estimates from the Gaussian model were consistently higher than for the fluid filled sphere. The estimates of ESD decreased with increasing frequency, and microstructures corresponding to these different scales were observed in histology. [Work supported by NIH Grant R01CA111289.]