Ultrasound Tomography Evaluation of Breast Density

Abstract

ObjectivesUltrasound tomography (UST) is an emerging whole-breast 3-dimensional imaging technique that obtains quantitative tomograms of speed of sound of the entire breast. The imaged parameter is the speed of sound which is used as a surrogate measure of density at each voxel and holds promise as a method to evaluate breast density without ionizing radiation. This study evaluated the technique of UST and compared whole-breast volume averaged speed of sound (VASS) with MR percent water content from noncontrast magnetic resonance imaging (MRI).Materials and MethodsForty-three healthy female volunteers (median age, 40 years; range, 29–59 years) underwent bilateral breast UST and MRI using a 2-point Dixon technique. Reproducibility of VASS was evaluated using Bland-Altman analysis. Volume averaged speed of sound and MR percent water were evaluated and compared using Pearson correlation coefficient.ResultsThe mean ± standard deviation VASS measurement was 1463 ± 29 m s−1 (range, 1434–1542 m s−1). There was high similarity between right (1464 ± 30 m s−1) and left (1462 ± 28 m s−1) breasts (P = 0.113) (intraclass correlation coefficient, 0.98). Mean MR percent water content was 35.7% ± 14.7% (range, 13.2%–75.3%), with small but significant differences between right and left breasts (36.3% ± 14.9% and 35.1% ± 14.7%, respectively; P = 0.004). There was a very strong correlation between VASS and MR percent water density (r2 = 0.96, P < 0.0001).ConclusionsUltrasound tomography holds promise as a reliable and reproducible 3-dimensional technique to provide a surrogate measure of breast density and correlates strongly with MR percent water content.

Using Whole Breast Ultrasound Tomography to Improve Breast Cancer Risk Assessment: A Novel Risk Factor Based on the Quantitative Tissue Property of Sound Speed

“…In this paper, we describe the results of an exploratory case-control study aimed at assessing breast sound speed as a risk factor for breast cancer. The study builds upon our previous work showing that sound speed is a surrogate measure of BD [24][25][26][27][28][29] and, by inference, a potential risk factor for breast cancer. The motivation for our current study was to explore whether UST-derived sound speed is associated with breast cancer risk.…”

“…Potential reasons for the stronger observed effects for VASS versus MPD include the true volumetric nature of BD assessment by UST of the uncompressed breast. Indeed, prior work has shown that VASS is strongly correlated with other volumetric breast imaging metrics, such as automated volumetric measures from mammography [28] as well as MRI percent water content [25]. However, in contrast to MRI, UST is a cost-effective (similar price as digital mammography) and rapid imaging strategy, requiring a water source and computer to complete the scan in 2-3 min (versus up to 45 min for MRI), without contrast or a specialized exam room.…”

“…Data were reconstructed from the raw data collected by UST and output as DICOM images which were viewed on a standard display workstation ( Figure 2). The volume averaged sound speed of the breast (VASS) was calculated using techniques previously developed [1,[20][21][22][23][24][25][26][27][28][29] and summarized as follows:…”

“…Previously, we proposed a new analog to MPD based on speed of sound measurements of breast tissue derived from whole breast ultrasound tomography (UST) [1,[20][21][22][23][24][25][26][27][28][29]. This method uses true volume measurements and, unlike mammography, the measure is quantitative and the method does not require exposure to ionizing radiation.…”

Breast Ultrasound Past, Present, and Future

“…Dense tissue tends to have high transmission and attenuation of sound (characterized as white on the tomographic image), while fatty tissue demonstrates low-sound speed and low attenuation (appears as dark on the tomographic image). Given these parameters some authors have suggested that it can provide a surrogate measure of breast density [62]. Others suggest that it can improve specificity by determining solid masses from complicated cysts [63].…”