Abstract P2-03-13: Pathology differentiation during breast conservation surgery using high-frequency ultrasound and peak frequency distribution

Abstract

Abstract Determining breast tissue pathology in surgical margins is a crucial step in breast conservation surgery (BCS) as this diagnosis decides the need for re-excision. Currently, it can take several days for a pathology laboratory to examine BCS tissue specimens, differentiate between different types of neoplasms (e.g., ALH, LCIS, and ILC), and identify positive margins. Re-excisions cause additional emotional strain, pain, and discomfort for patients, as well as increase medical treatment costs. High-frequency (HF) ultrasound (20-80 MHz) provides a potential new method to discriminate between breast tissue pathologies during BCS. HF ultrasound could also be used to analyze either the surgical cavity in vivo or margin specimens ex vivo. In a 17-patient pilot study that included 14 different pathologies, the HF ultrasonic parameter known as peak density—the number of peaks and valleys in the ultrasonic spectra—displayed a strong correlation to tissue pathology. The objective of this study was to conduct a retrospective analysis of the pilot study data to determine if correlations also existed between the distribution of frequencies of the spectral peaks and valleys with pathology. The pilot study data were collected from 55 measurements on 34 specimens at the Huntsman Cancer Institute (Salt Lake City, Utah) immediately following BCS and prior to standard pathology preparation and analysis. Through-transmission measurements were acquired with the use of two 50-MHz transducers (Olympus NDT, V358-SU, 6.35-mm active element diameter), a HF square-wave pulser/receiver (UTEX, UT340), and a 500-MHz digital oscilloscope (Hewlett-Packard, HP-54522A). The transmitting transducer was pulsed with a 100-V half-period square wave with a 10-ns width. Waveforms were averaged in the signal acquisition and downloaded onto a computer. Because of the small wavelength of the transmitted ultrasound (30 μm for 50 MHz) in comparison to the size of the active element, the transmitting transducer produced plane-wave pulses which propagated through the tissue to the receiving transducer. Because of the small wavelength and coherent nature of the measurements, the resulting ultrasonic spectra displayed extinction features (peaks and valleys) resulting directly from acoustic wave scattering from cells and nuclei. In this study, the frequencies of the peaks and valleys were plotted as a function of pathology for analysis. The results showed a strong correlation between peak frequency distribution and pathology, particularly in differentiating between malignant and non-malignant pathologies. The peak frequencies for malignant pathologies displayed greater clustering at higher frequencies, whereas the peak frequencies for the non-malignant pathologies displayed greater clustering at lower frequencies. The analyses also verified that the physical mechanism behind the HF ultrasound method is based on acoustic scattering from cells and nuclei, and on the trends arising from the differences between the sizes and morphologies of normal, pre-cancerous, and cancerous cells and nuclei. These results support the use of HF ultrasound as a prospective new method for rapidly distinguishing between different pathologies in breast tissues during BCS. Citation Format: Dalton CE, Wagner GM, Al-Ghaib HA, Doyle TE. Pathology differentiation during breast conservation surgery using high-frequency ultrasound and peak frequency distribution [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-03-13.