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2015 Abstracts

Measuring the Effect of Breast Density on High Frequency Ultra sound using Tissue Phantoms

Zachary Coffman, Utah Valley University

Physical Sciences

Breast density describes the proportion of connective tissue versus the fat tissue in the breast. Studies have shown that women with higher breast density are four to five times more likely to develop breast cancer than women with lower breast densities, ( Higher breast densities have proven to make current breast cancer imaging and detection more difficult. A pilot study done at the Huntsman Cancer institute showed that the ultrasonic parameter peak density, generated by high-frequency (HF) ultrasound (20-80 MHz), was sensitive to breast tissue pathology. The objective of this study was to determine the effect of breast density on ultrasound wave propagation from high frequency ultrasound using phantoms that mimic the histology of breast tissues. Phantoms were created from a mixture of distilled water, agarose powder, and 10X TBE stock solution. In order to simulate breast tissue histology and breast density, polyethylene microspheres were embedded into the phantoms in layers, totaling 4 layers per phantom. The polyethylene microsphere size (90-106 μm diameter) was kept constant within each phantom while the weight percent concentration of the microspheres varied (0.00g to 0.06g). Pitch-catch and pulse-echo measurements were acquired using 50-MHz transducers (Olympus NDT, V358-SU, 50 MHz, 0.635-cm diameter active element), a HF pulser-receiver (UTEX, UT340), and a 1-GHz digital oscilloscope (Agilent DSOX3104A). Glycerol (Genesis Scientific) was used as a coupling agent between the transducers and the phantoms. Spectra were derived from the data, giving peak density (the number of peaks and valleys in a specified spectral range), velocity, and attenuation values. The results showed that peak density did not start to show a trend until phantoms of 0.03g concentrations, where it increased from a value of 14.0 peaks (0.03g) to 18.7 peaks (0.06g). Velocity showed a statistically significant increase with greater polyethylene microsphere concentration, from 1508 m/s for 0.00g to 1536 m/s for 0.06g. No trends were observed for attenuation. These results indicate that higher levels of scattering centers in dense breast tissues will be detectable with high frequency ultrasound. This additionally shows that high frequency ultrasound may also be sensitive to greater amounts of connective tissue present in dense breast pathologies. High frequency ultrasound is sensitive to the weight percent of polyethylene microspheres. Future research is planned to further understand this relationship, including repeat studies and studies of phantoms containing chopped polyethylene fibers and triple the polyethylene microsphere concentrations to more closely simulate dense breast tissues.