High-frequency ultrasound of histology mimicking phantoms for evaluating breast cancer surgical margins

Abstract

The ability to differentiate between malignant and normal tissues in surgical margins during breast cancer surgery would reduce the risk of local recurrence and subsequent surgeries. Clinical studies at the Huntsman Cancer Institute show that high-frequency (HF) ultrasound (20–80 MHz), and the parameters peak density (number of spectral peaks and valleys in the 20–80 MHz range) and attenuation, are sensitive to breast tissue pathology. The objective of this study was to determine the effect of tissue microstructure on these parameters using histology mimicking phantoms. Phantoms were created from distilled water, agarose powder, 10X TBE stock solution, and polyethylene microspheres to simulate breast tissue histology. Microsphere size (59–925μm diameter) and weight percent (0.00–0.06g) were varied in the experiments. Pitch-catch measurements were acquired using 50-MHz transducers, a HF pulser-receiver, a 1-GHz digital oscilloscope, and glycerol as the coupling agent. Both peak density and attenuation showed sensitivity to microsphere diameter and the number of scatterers present. Peak density followed an inverse-size relationship to microsphere diameter, whereas attenuation showed a sensitivity to the total weight percent of scatterers. The phantom results confirm that peak density and attenuation are complementary parameters for characterizing breast tissue pathology and validate the clinical studies.