title: Comparison of sound speed measurements on two different ultrasound tomography devices.
abstract: Ultrasound tomography (UST) employs sound waves to produce three-dimensional images of breast tissue and precisely measures the sound speed of breast tissue composition. High breast density is a strong breast cancer risk factor and sound speed is directly proportional to breast density. UST provides a quantitative measure of breast density based on three-dimensional imaging without compression, thereby overcoming the shortcomings of many other imaging modalities. The quantitative nature of the UST breast density measures are tied to an external standard, so sound speed measurement in breast tissue should be independent of specific hardware. The work presented here compares breast sound speed measurement obtained with two different UST devices. The Computerized Ultrasound Risk Evaluation (CURE) system located at the Karmanos Cancer Institute in Detroit, Michigan was recently replaced with the SoftVue ultrasound tomographic device. Ongoing clinical trials have used images generated from both sets of hardware, so maintaining consistency in sound speed measurements is important. During an overlap period when both systems were in the same exam room, a total of 12 patients had one or both of their breasts imaged on both systems on the same day. There were 22 sound speed scans analyzed from each system and the average breast sound speeds were compared. Images were either reconstructed using saved raw data (for both CURE and SoftVue) or were created during the image acquisition (saved in DICOM format for SoftVue scans only). The sound speed measurements from each system were strongly and positively correlated with each other. The average difference in sound speed between the two sets of data was on the order of 1-2 m/s and this result was not statistically significant. The only sets of images that showed a statistical difference were the DICOM images created during the SoftVue scan compared to the SoftVue images reconstructed from the raw data. However, the discrepancy between the sound speed values could be easily handled by uniformly increasing the DICOM sound speed by approximately 0.5 m/s. These results suggest that there is no fundamental difference in sound speed measurement for the two systems and support combining data generated with these instruments in future studies.
authors.affiliation: Karmanos Cancer Institute, Wayne State University, 4100 John R Street, Detroit MI 48201.
authors.forename: Mark
authors.initials: M
authors.lastname: Sak
authors.affiliation: Karmanos Cancer Institute, Wayne State University, 4100 John R Street, Detroit MI 48201 ; Delphinus Medical Technologies, 46701 Commerce Center Dr, Plymouth, MI, 48170.
authors.forename: Neb
authors.initials: N
authors.lastname: Duric
authors.affiliation: Karmanos Cancer Institute, Wayne State University, 4100 John R Street, Detroit MI 48201 ; Delphinus Medical Technologies, 46701 Commerce Center Dr, Plymouth, MI, 48170.
authors.forename: Peter
authors.initials: P
authors.lastname: Littrup
authors.affiliation: Karmanos Cancer Institute, Wayne State University, 4100 John R Street, Detroit MI 48201.
authors.forename: Lisa
authors.initials: L
authors.lastname: Bey-Knight
authors.affiliation: National Cancer Institute, Division of Cancer Prevention, Breast and Gynecologic Cancer Research Group, 9609 Medical Center Drive, Room 5E334, Bethesda, MD 20892.
authors.forename: Mark
authors.initials: M
authors.lastname: Sherman
authors.affiliation: National Cancer Institute, Division of Cancer Epidemiology and Genetics, Hormonal and Reproductive Epidemiology Branch, 9609 Medical Center Drive, Rm. 7-E108, Bethesda, MD 20892.
authors.forename: Gretchen
authors.initials: G
authors.lastname: Gierach
authors.affiliation: Karmanos Cancer Institute, Wayne State University, 4100 John R Street, Detroit MI 48201.
authors.forename: Antonina
authors.initials: A
authors.lastname: Malyarenko
keywords: Breast density; Hardware correlation; Sound speed; Ultrasound tomography